DOI: 10.1148/rg.243035100
RadioGraphics 2004;24:717-735
© RSNA, 2004
The Inaccessible or Undrainable Abscess: How to Drain It1
Michael M. Maher, MD,
Debra A. Gervais, MD,
Mannudeep K. Kalra, MD,
Brian Lucey, MD,
Dushyant V. Sahani, MD,
Ronald Arellano, MD,
Peter F. Hahn, MD, PhD and
Peter R. Mueller, MD
1 From the Division of Abdominal Imaging and Intervention, Massachusetts General Hospital, White 270, 55 Fruit St, Boston, MA 02114. Recipient of a Certificate of Merit award for an education exhibit at the 2001 RSNA scientific assembly. Received April 9, 2003; revision requested July 8 and received September 22; accepted September 23. All authors have no financial relationships to disclose. Address correspondence to P.R.M. (e-mail: pmueller@partners.org).
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Abstract
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Percutaneous abscess drainage is a safe, effective, and widely used technique for the treatment of patients with abdominal or pelvic sepsis. The majority of abdominal and pelvic abscesses afford reasonably straightforward access and are amenable to percutaneous drainage. However, requests are occasionally received for drainage of abscesses or fluid collections that initially appear unsuitable for percutaneous drainage. Factors that render collections seemingly unsuitable for imaging-guided drainage include inaccessibility due to surrounding organs, difficult location, and thickened contents (eg, clotted blood, thick pus). Well-established alternative approaches (eg, transgluteal, transvaginal, transrectal) can be used to facilitate drainage of deep-seated collections that are inaccessible via more traditional routes. Other factors that may improve the accessibility of collections include modifications in patient positioning or in the use of imaging hardware (eg, angling of the computed tomography scanner gantry). Use of these techniques and modifications can allow percutaneous drainage of less accessible intraabdominal abscesses, thus eliminating the need for laparotomy.
© RSNA, 2004
Index Terms: Abdomen, abscess, **.2422 • Abscess, CT, **.1211 • Abscess, percutaneous drainage • Abscess, US, **.1298 • Catheters and catheterization • Computed tomography (CT), guidance • Ultrasound (US), catheter identification • Ultrasound (US), guidance • Ultrasound (US), transvaginal
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LEARNING OBJECTIVES
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After reading this article and taking the test, the reader will be able to:
- Discuss the feasibility of abscess drainage in different anatomic locations.
- Identify alternative drainage techniques and imaging methods that may improve access to deep-seated collections.
- Describe situations in which imaging-guided abscess drainage is either unhelpful or contraindicated.
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Introduction
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Percutaneous abscess drainage is standard therapy for patients with intraabdominal or pelvic abscesses who do not have other indications for surgery. The majority of these abscesses afford reasonably straightforward access and can be drained percutaneously. However, a minority of abscesses may initially appear to be inaccessible or undrainable due to their location or to the proximity of adjacent structures to the proposed path of a drainage catheter. In addition, the feasibility of percutaneous abscess drainage frequently depends on the consistency of the contents within a collection.
In this article, we discuss criteria for assessing the appropriateness of imaging-guided drainage for an abscess or collection and methods of managing seemingly "undrainable" abscesses. We describe the use of alternative access routes (transgluteal, transvaginal, transrectal), which can facilitate the drainage of deep-seated collections that are inaccessible by more traditional routes. We also discuss modifications in patient positioning and in the use of imaging hardware (eg, angling the computed tomography [CT] scanner gantry). In addition, we discuss situations in which imaging-guided abscess drainage should not be attempted. The knowledgeable interventional radiologist will often succeed in draining difficult-to-reach abscesses, and the informed diagnostic radiologist can help obviate surgery.
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Imaging Guidance
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CT and Ultrasonography
In the majority of cases in which abscesses or fluid collections are deep-seated, making percutaneous access difficult, drainage is performed under CT guidance. CT has certain advantages in guiding percutaneous abscess drainage. CT has better spatial resolution than ultrasonography (US), thereby allowing more accurate depiction of the abscess, adjacent organs, and organs along the proposed access route. In addition, the use of CT reduces the likelihood of mistaking fluid-filled bowel loops for fluid collections.
Although CT offers many advantages over US in imaging guidance for many interventional procedures, it does not always yield better results. US is a real-time imaging modality that allows the course of needles and catheters to be monitored as they traverse tissue planes along the path to the abscess. In addition, angulation from the axial plane (when required) can frequently be more easily achieved and monitored with US than with CT. When combined with US, fluoroscopy can be useful for performing drainage with the Seldinger technique, avoiding loss of access or guide wire kinking during tract dilatation, and monitoring the placement of catheters with the aid of torquing catheters.
CT Fluoroscopy
CT fluoroscopy is emerging as a useful additional tool in performing difficult abscess drainage and promises to reduce the time required for interventional radiologic procedures (Fig 1). However, care needs to be taken to reduce the radiation dose to the patient and exposure to medical personnel while performing CT fluoroscopy. Nawfel at al (1) reported that there is potential for high levels of radiation exposure during CT fluoroscopy and advocate the placement of a lead drape caudad to the scanning plane at the needle entry site as a means of reducing exposure to medical personnel. Also, once initial CT has been performed to identify and locate the abscess or tumor, scanning parameters for CT fluoroscopy can be modified to reduce the radiation dose to a level that protects the operator while still allowing visualization of the lesion and catheter path (1).
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Figure 1a. Value of CT fluoroscopy in gaining access. (a) Contrast material-enhanced CT scan obtained in a 72-year-old man shows a left psoas muscle abscess (arrow) that is difficult to access because of intervening osseous structures. (b) CT fluoroscopic image shows the abscess being drained with the trocar technique. CT fluoroscopy provided excellent real-time guidance, which facilitated access to the collection and significantly reduced the duration of the procedure. (c) Postprocedure CT scan helps confirm excellent catheter position.
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Figure 1b. Value of CT fluoroscopy in gaining access. (a) Contrast material-enhanced CT scan obtained in a 72-year-old man shows a left psoas muscle abscess (arrow) that is difficult to access because of intervening osseous structures. (b) CT fluoroscopic image shows the abscess being drained with the trocar technique. CT fluoroscopy provided excellent real-time guidance, which facilitated access to the collection and significantly reduced the duration of the procedure. (c) Postprocedure CT scan helps confirm excellent catheter position.
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Figure 1c. Value of CT fluoroscopy in gaining access. (a) Contrast material-enhanced CT scan obtained in a 72-year-old man shows a left psoas muscle abscess (arrow) that is difficult to access because of intervening osseous structures. (b) CT fluoroscopic image shows the abscess being drained with the trocar technique. CT fluoroscopy provided excellent real-time guidance, which facilitated access to the collection and significantly reduced the duration of the procedure. (c) Postprocedure CT scan helps confirm excellent catheter position.
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Aspiration versus Catheter Placement
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In the majority of patients with abscess, we favor catheter placement over needle aspiration for definitive treatment. When catheter drainage is performed, the catheter is usually secured in position for several days, particularly if the material aspirated with the localizing needle is suggestive of pus or infected material or if the patient demonstrates signs of sepsis (2). Percutaneous aspiration is contraindicated for definitive treatment of a collection if it is suspected that the collection communicates with bowel or the biliary or urinary tracts. Simple aspiration of collections that communicate with bowel is invariably ineffective because immediate reaccumulation of the collection usually occurs once the needle or temporary catheter is removed.
On rare occasions, collections or abscesses are encountered that remain inaccessible for percutaneous catheter placement despite the use of all available access routes, patient positions, and various imaging techniques and modifications (Fig 2). In our experience, this situation is most commonly seen in the pelvis, particularly in patients with Crohn disease who have a propensity for developing interloop abscesses. It is occasionally considered necessary to aspirate these "inaccessible" abscesses or collections prior to surgery to make the surgical field clean, thus facilitating primary bowel anastomosis, or if concern exists because the patient is undergoing immunosuppression therapy. We reluctantly treat such collections by transgressing intervening bowel with a 20-gauge needle and aspirating the collection dry.
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Figure 2a. Inaccessible abscess treated with aspiration. (a) CT scan obtained in a 32-year-old man with Crohn disease reveals an interloop abscess (straight arrows) that is inaccessible with percutaneous catheter placement due to multiple bowel loops (curved arrows). (b) CT scan shows the abscess being aspirated with a 20-gauge needle traversing the bowel as a temporizing measure. (c) Postprocedure CT scan demonstrates excellent results.
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Figure 2b. Inaccessible abscess treated with aspiration. (a) CT scan obtained in a 32-year-old man with Crohn disease reveals an interloop abscess (straight arrows) that is inaccessible with percutaneous catheter placement due to multiple bowel loops (curved arrows). (b) CT scan shows the abscess being aspirated with a 20-gauge needle traversing the bowel as a temporizing measure. (c) Postprocedure CT scan demonstrates excellent results.
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Figure 2c. Inaccessible abscess treated with aspiration. (a) CT scan obtained in a 32-year-old man with Crohn disease reveals an interloop abscess (straight arrows) that is inaccessible with percutaneous catheter placement due to multiple bowel loops (curved arrows). (b) CT scan shows the abscess being aspirated with a 20-gauge needle traversing the bowel as a temporizing measure. (c) Postprocedure CT scan demonstrates excellent results.
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Traversal of Organs
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Occasionally, even with the use of CT and alternative routes, a collection cannot be accessed without traversing an intervening organ. In this situation, two options usually exist: (a) the collection or abscess can be deemed unsuitable for percutaneous abscess drainage and the case referred back to the surgeon, or (b) the intervening organ can be traversed with a catheter. The stomach and liver are examples of organs that we consider safe to traverse in most circumstances to allow treatment of an epigastric collection when no other option exists (Fig 3). It is important when traversing the liver to ensure that coagulation parameters are normal. It is also important that the chosen catheter course through the liver be as short as possible, away from major blood vessels or dilated biliary ducts and away from other organs such as the gallbladder. Furthermore, the catheter side holes should be completely contained within the abscess to avoid contamination of the adjacent liver or biliary tract. The stomach is most commonly traversed for percutaneous drainage of pancreatic abscesses or pseudocysts. Indeed, some centers choose a transgastric approach to promote the formation of a tract between the pancreatic collection and the stomach. A catheter with multiple side holes is deployed with side holes in both the pancreatic collection and the stomach. Such catheters are usually left in place for 6 weeks to promote the formation of a cystogastrostomy tract. The rationale for this approach is that, when a communication exists between a pseudocyst and the pancreatic duct, the duct contents will theoretically empty into the stomach. However, there is no proved benefit to transgastric drainage of pancreatic pseudocysts, and it has not been definitively proved that cystogastrostomies develop and remain patent for drainage of these pseudocysts. At our institution, we do not routinely use the percutaneous cystogastrostomy approach because we believe that the lifetime of such tracts is very short.
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Figure 3a. Transhepatic abscess drainage in an 89-year-old woman who was deemed unfit for surgery. (a) Contrast-enhanced CT scan shows a retroperitoneal abscess (long arrows) secondary to a perforated duodenal diverticulum (short arrow). Three catheters were placed during different stages of the patient’s illness. (b) CT scan shows the abscess being drained with a transhepatic catheter. This approach was used to access a component of the collection located between the liver and the retroperitoneum posterior to the pancreas. (c) Postprocedure CT scan shows satisfactory catheter position with reduction in abscess size. Note the presence of a second catheter (arrow), which was placed with a right paravertebral approach. (d) Fluoroscopic image obtained after catheter placement (arrowhead) shows communication with the duodenal diverticulum (straight arrow) and duodenum (curved arrow).
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Figure 3b. Transhepatic abscess drainage in an 89-year-old woman who was deemed unfit for surgery. (a) Contrast-enhanced CT scan shows a retroperitoneal abscess (long arrows) secondary to a perforated duodenal diverticulum (short arrow). Three catheters were placed during different stages of the patient’s illness. (b) CT scan shows the abscess being drained with a transhepatic catheter. This approach was used to access a component of the collection located between the liver and the retroperitoneum posterior to the pancreas. (c) Postprocedure CT scan shows satisfactory catheter position with reduction in abscess size. Note the presence of a second catheter (arrow), which was placed with a right paravertebral approach. (d) Fluoroscopic image obtained after catheter placement (arrowhead) shows communication with the duodenal diverticulum (straight arrow) and duodenum (curved arrow).
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Figure 3c. Transhepatic abscess drainage in an 89-year-old woman who was deemed unfit for surgery. (a) Contrast-enhanced CT scan shows a retroperitoneal abscess (long arrows) secondary to a perforated duodenal diverticulum (short arrow). Three catheters were placed during different stages of the patient’s illness. (b) CT scan shows the abscess being drained with a transhepatic catheter. This approach was used to access a component of the collection located between the liver and the retroperitoneum posterior to the pancreas. (c) Postprocedure CT scan shows satisfactory catheter position with reduction in abscess size. Note the presence of a second catheter (arrow), which was placed with a right paravertebral approach. (d) Fluoroscopic image obtained after catheter placement (arrowhead) shows communication with the duodenal diverticulum (straight arrow) and duodenum (curved arrow).
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Figure 3d. Transhepatic abscess drainage in an 89-year-old woman who was deemed unfit for surgery. (a) Contrast-enhanced CT scan shows a retroperitoneal abscess (long arrows) secondary to a perforated duodenal diverticulum (short arrow). Three catheters were placed during different stages of the patient’s illness. (b) CT scan shows the abscess being drained with a transhepatic catheter. This approach was used to access a component of the collection located between the liver and the retroperitoneum posterior to the pancreas. (c) Postprocedure CT scan shows satisfactory catheter position with reduction in abscess size. Note the presence of a second catheter (arrow), which was placed with a right paravertebral approach. (d) Fluoroscopic image obtained after catheter placement (arrowhead) shows communication with the duodenal diverticulum (straight arrow) and duodenum (curved arrow).
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It is generally accepted that it is safe to traverse the vagina and rectum when using transcavitary routes for imaging-guided abscess drainage. Most interventional radiologists choose not to traverse the bladder or small bowel when performing percutaneous abscess drainage, although some authors have attested to the safety of using these routes in extreme circumstances. Intervening vascular structures should always be avoided during percutaneous abscess drainage. Doppler US is very useful in avoiding damage to intervening vascular structures.
There are a number of organs that should be avoided and should not be traversed during percutaneous abscess drainage. These organs include the pancreas, spleen, gallbladder, small and large bowel, urinary bladder, uterus and ovaries, prostate gland, and most blood vessels. Abscesses within many of these organs can be drained percutaneously, but the organs should usually not be traversed in trying to reach a deep-seated collection. Blood vessels should be avoided if possible, and examination of a preprocedure contrast-enhanced CT scan can be useful for identifying the site of such vessels. Serious incidents of hemorrhage have been reported following injury to the superior and inferior epigastric arteries as well as the internal mammary and intercostal arteries (Fig 4) (3). The placement of catheters through the skin in the midline ensures that the linea alba (an avascular plane) is traversed and that injury to the superior and inferior epigastric arteries is avoided. However, midline puncture and catheterization may be unsafe in patients with portal hypertension, who can have a turgid recanalized umbilical vein. In situations in which midline catheter placement is not feasible, review of a preprocedure contrast-enhanced CT scan is advised because the scan usually demonstrates the course of the superior and inferior epigastric arteries; thus, the catheter course can be planned so as to avoid these vessels.
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Figure 4a. Arterial injury and hematoma due to non-imaging-guided paracentesis performed in a 60-year-old man with ascites. The patient experienced abdominal pain and hypotension after undergoing the procedure. (a) Unenhanced CT scan shows a large left rectus sheath hematoma (arrow). (b) Selective angiogram of the inferior epigastric artery shows extravasation of contrast material (arrow), a finding that is consistent with arterial injury. The patient was successfully treated with catheter embolization.
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Figure 4b. Arterial injury and hematoma due to non-imaging-guided paracentesis performed in a 60-year-old man with ascites. The patient experienced abdominal pain and hypotension after undergoing the procedure. (a) Unenhanced CT scan shows a large left rectus sheath hematoma (arrow). (b) Selective angiogram of the inferior epigastric artery shows extravasation of contrast material (arrow), a finding that is consistent with arterial injury. The patient was successfully treated with catheter embolization.
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Abscesses in Difficult Locations
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Deep Pelvis
Deep pelvic abscesses pose difficulty because of numerous intervening structures that can preclude safe anterior or lateral approaches. Thus, finding a safe access route and avoiding bowel and other organs is frequently more problematic than in the upper abdomen. The main intervening structures that can make access very difficult include bone and large blood vessels and nerves laterally, bowel anterolaterally, and bladder anteriorly. Several approaches have been devised to address these problems, including a transvaginal US-guided approach, a transrectal US- or CT-guided approach, and a transgluteal CT-guided approach.
Transvaginal and transrectal drainage with US or CT guidance allows safe access to deep-seated abscesses in the vicinity of the vagina or rectum, which would otherwise be inaccessible with percutaneous methods (4). Transvaginal and transrectal US-guided pelvic abscess drainage is now much easier to perform, with improvements in US hardware and in the spatial resolution of images acquired with transvaginal and transrectal probes due to the increased frequency of the probes and their proximity to the abscess being drained. These improved high-frequency intracavitary probes offer excellent visualization of the abscess and the internal architecture of the collection that is usually far superior to that possible with CT. In addition, real-time visualization of the catheter course to pelvic abscesses or collections is usually easy to achieve. For transrectal and transvaginal US-guided biopsy, special needle guides are available that facilitate the mounting of needles on the intracavitary probe to achieve satisfactory real-time US guidance. At present, we are not aware of any commercially available kits for mounting hydrophilic catheters for transrectal or transvaginal drainage, which would, in our opinion, be worth the extra expense. Instead, we create our own kit as shown in Figure 5 (4).
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Figure 5a. (a) Drawing illustrates a peel-away sheath mounted on the back of a US probe, where the needle guide is normally placed. The sheath is fixed in position with additional rubber bands. Note the strict alignment of the sheath along the midline of the back of the probe. (b) Drawing illustrates a gel-lined outer condom covering the probe-sheath combination. The catheter is inserted through the sheath and will perforate the condom before entering the abscess cavity. (Fig 5 reprinted, with permission, from reference 4.)
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Figure 5b. (a) Drawing illustrates a peel-away sheath mounted on the back of a US probe, where the needle guide is normally placed. The sheath is fixed in position with additional rubber bands. Note the strict alignment of the sheath along the midline of the back of the probe. (b) Drawing illustrates a gel-lined outer condom covering the probe-sheath combination. The catheter is inserted through the sheath and will perforate the condom before entering the abscess cavity. (Fig 5 reprinted, with permission, from reference 4.)
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We believe that, before undergoing transrectal or transvaginal US-guided abscess drainage, a patient should undergo CT of the upper abdomen and pelvis. We advocate CT because (a) many pelvic abscesses are associated with collections in the upper abdomen that may be missed if only transrectal or transabdominal US is performed, and (b) CT allows assessment for organs that may inadvertently be injured by the needle or catheter. Some infectious disease physicians prefer to have the collection sampled and cultured before administering antibiotics; however, because of the danger of contaminating a sterile collection during drainage, all of our patients receive antibiotics immediately before undergoing transvaginal or transrectal drainage.
Transvaginal US-guided drainage of pelvic abscesses via the transvaginal route is useful for deep-seated abscesses located close to the vagina. However, no attempt should be made to drain presacral abscesses via the transvaginal route (4). It is important to adequately identify the structures adjacent to the abscess cavity, particularly the urinary bladder, so that they are not traversed during the procedure. In addition, if pressure is exerted on the transvaginal probe, the bladder can be compressed and may be difficult to identify, thus increasing the risk of bladder transgression. Likewise, the proposed path of a catheter should be examined, without applying too much pressure to the probe, for other intervening structures such as the small bowel or colon. Moreover, the transvaginal route should not be used to drain abscesses that are located too high in the pelvis. Attempting to do so may increase the risk of bladder or bowel transgression or vascular injury.
One of the major drawbacks of transvaginal pelvic abscess drainage is the risk of patient discomfort (4). The vaginal vault is made of muscular tissue that is difficult to puncture and dilate without causing some discomfort. Nevertheless, adequate conscious sedation and the administration of lidocaine at the site of vaginal puncture usually help reduce discomfort. The risk of complications with transvaginal drainage is low despite the theoretic risk of hemorrhage from large blood vessels such as the uterine arteries that course close to the vaginal vault (4). No major bleeding complications have been seen at our institution, and, to our knowledge, none have not been reported in the literature. At our institution, we generally favor catheter drainage over needle aspiration in patients with tubo-ovarian abscesses. We use the trocar method with a hydrophilic catheter rather than the Seldinger technique (Fig 6) (4), which is much more time consuming and painful for the patient. It is also more difficult to monitor the position of the guide wire with the Seldinger technique, a difficulty that increases the risk of guide wire kinking and loss of access. Regardless of the drainage method used, however, the vagina is a tough structure, and traversing the vagina can occasionally be difficult and painful. The use of smaller (eg, 7–8-F) hydrophilic catheters can minimize these difficulties.
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Figure 6a. Transvaginal drainage technique. (a) Transvaginal US image obtained in a 32-year-old woman with pelvic inflammatory disease shows loculated pelvic abscesses (arrows). (b) Contrast-enhanced CT scan helps confirm the presence of an abscess anterior to the rectum (arrow). The patient is placed in the lithotomy position, and the vagina (with speculum in place) and perineum are prepared using sterile technique. Under direct US guidance with a biopsy guide, the abscess is initially aspirated with a 20-gauge needle. The aspirated fluid is immediately stained with the Gram method. If sterile, the collection is aspirated dry with a needle or a 7-F hydrophilic catheter, and the needle or catheter is removed. If the collection is infected, an 8-F self-locking hydrophilic catheter is inserted under transvaginal US guidance and left in position for a few days. (c) Transvaginal US image shows the catheter (arrow) being inserted into the collection. (d) Postprocedure CT scan shows good positioning of the catheter (arrow).
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Figure 6b. Transvaginal drainage technique. (a) Transvaginal US image obtained in a 32-year-old woman with pelvic inflammatory disease shows loculated pelvic abscesses (arrows). (b) Contrast-enhanced CT scan helps confirm the presence of an abscess anterior to the rectum (arrow). The patient is placed in the lithotomy position, and the vagina (with speculum in place) and perineum are prepared using sterile technique. Under direct US guidance with a biopsy guide, the abscess is initially aspirated with a 20-gauge needle. The aspirated fluid is immediately stained with the Gram method. If sterile, the collection is aspirated dry with a needle or a 7-F hydrophilic catheter, and the needle or catheter is removed. If the collection is infected, an 8-F self-locking hydrophilic catheter is inserted under transvaginal US guidance and left in position for a few days. (c) Transvaginal US image shows the catheter (arrow) being inserted into the collection. (d) Postprocedure CT scan shows good positioning of the catheter (arrow).
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Figure 6c. Transvaginal drainage technique. (a) Transvaginal US image obtained in a 32-year-old woman with pelvic inflammatory disease shows loculated pelvic abscesses (arrows). (b) Contrast-enhanced CT scan helps confirm the presence of an abscess anterior to the rectum (arrow). The patient is placed in the lithotomy position, and the vagina (with speculum in place) and perineum are prepared using sterile technique. Under direct US guidance with a biopsy guide, the abscess is initially aspirated with a 20-gauge needle. The aspirated fluid is immediately stained with the Gram method. If sterile, the collection is aspirated dry with a needle or a 7-F hydrophilic catheter, and the needle or catheter is removed. If the collection is infected, an 8-F self-locking hydrophilic catheter is inserted under transvaginal US guidance and left in position for a few days. (c) Transvaginal US image shows the catheter (arrow) being inserted into the collection. (d) Postprocedure CT scan shows good positioning of the catheter (arrow).
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Figure 6d. Transvaginal drainage technique. (a) Transvaginal US image obtained in a 32-year-old woman with pelvic inflammatory disease shows loculated pelvic abscesses (arrows). (b) Contrast-enhanced CT scan helps confirm the presence of an abscess anterior to the rectum (arrow). The patient is placed in the lithotomy position, and the vagina (with speculum in place) and perineum are prepared using sterile technique. Under direct US guidance with a biopsy guide, the abscess is initially aspirated with a 20-gauge needle. The aspirated fluid is immediately stained with the Gram method. If sterile, the collection is aspirated dry with a needle or a 7-F hydrophilic catheter, and the needle or catheter is removed. If the collection is infected, an 8-F self-locking hydrophilic catheter is inserted under transvaginal US guidance and left in position for a few days. (c) Transvaginal US image shows the catheter (arrow) being inserted into the collection. (d) Postprocedure CT scan shows good positioning of the catheter (arrow).
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The equipment setup is illustrated in Figure 5. The most important aspect of setting up the catheter is aligning the guide (ie, the peel-away introducer sheath) along the shaft of the transvaginal US probe. The sheath (Peel-Away; Cook, Bloomington, Ind) should be attached securely to the probe with rubber bands so that optimal alignment between the guide and the catheter (Mac-Loc Ultrathane Dawson-Mueller Drainage Catheter, Cook) is maintained, thus optimizing real-time guidance during the procedure. Transvaginal pelvic abscess drainage is usually performed with the patient in the lithotomy position.
Maintaining optimal catheter position is usually much more difficult with transvaginal catheters than with percutaneous catheters. Consequently, we suture transvaginal catheters to the medial aspect of the thigh. Still, these catheters require frequent inspection by the interventional radiology team to ensure that proper position is maintained.
Transrectal US-guided abscess drainage is the only intracavitary approach available to male patients and can also be used in female patients with presacral abscesses that are not amenable to transvaginal drainage. Transrectal US-guided drainage can be used for abscesses that are anterior and posterior to the rectum. We have found this technique particularly useful in male patients with prostatic abscesses (Fig 7), which are frequently difficult to access via either the transgluteal or percutaneous route because of intervening osseous structures.
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Figure 7a. Transrectal drainage technique. (a) Contrast-enhanced CT scan obtained in a 24-year-old man with recurrent prostatic abscess, severe pain, and fever shows an abscess of the prostate gland (arrow). (b) US image demonstrates successful transrectal drainage of the abscess performed with techniques similar to those used for transvaginal drainage. Note that the guide facilitates positioning of the probe so that the catheter (arrow) can be well visualized as it enters the abscess.
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Figure 7b. Transrectal drainage technique. (a) Contrast-enhanced CT scan obtained in a 24-year-old man with recurrent prostatic abscess, severe pain, and fever shows an abscess of the prostate gland (arrow). (b) US image demonstrates successful transrectal drainage of the abscess performed with techniques similar to those used for transvaginal drainage. Note that the guide facilitates positioning of the probe so that the catheter (arrow) can be well visualized as it enters the abscess.
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Transrectal drainage of pelvic abscesses with transrectal US, CT, and combined US-fluoroscopic guidance has been described in the radiology literature (5). We favor the use of transrectal US guidance. Transrectal US is performed with the same catheter setup as was described for transvaginal US (Fig 5) (4). Again, we advocate using the trocar technique, which, unlike with transvaginal drainage, is usually performed with the patient in the left lateral decubitus position. The catheter course should be visualized at all times with real-time US guidance during placement. As with transvaginal drainage, catheter fixation is more difficult than in transgluteal or percutaneous drainage.
Most centers now use CT guidance for transgluteal percutaneous drainage of a pelvic abscess. The patient is placed prone on the CT table. In the past, many radiologists were concerned about the risk of damaging the sciatic nerve and avoided using the transgluteal approach (2). However, if a skin site close to the sacrum is chosen, the sciatic nerve and adjacent vessels can be avoided and large catheters can be placed (Fig 8) (6). Once the localizing CT scans have been obtained, the position of the sciatic nerve and adjacent vessels can be identified. The optimal approach is to insert the localizing needle at the level of the sacrospinous ligament as close as possible to the sacrum (2). At this level, the sciatic nerve and adjacent vessels are situated more laterally and can easily be avoided. At a slightly higher level, the sacral plexus and branches of the superior and inferior gluteal vessels lie adjacent to the piriformis muscle. Studies have shown that a puncture site at the level of the piriformis muscle is associated with a higher prevalence of transient buttock pain (6). For this reason, an infrapiriformis muscle approach (when possible) is preferred. Although the sciatic nerve and vessels are occasionally in proximity to the catheter during transgluteal catheter insertion, injury to the neurovascular bundle rarely occurs. Significant hemorrhage following transgluteal catheter placement is also rare. Imaging performed after catheter insertion may show a significant pelvic hematoma or may manifest later as pain or hemodynamic instability. Angiography should be performed because it can depict a pseudoaneurysm of the inferior gluteal artery. Malden and Picus (7) reported a case of significant hemorrhage that occurred following transgluteal drainage and was successfully treated with catheter embolization.
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Figure 8a. Transgluteal drainage technique. (a) CT scan obtained in a 40-year-old patient with a postoperative pelvic abscess (arrows) shows a localizing needle placed as close as possible to the sacrum at the level of the sacrospinous ligament. At this level, the sciatic nerve and adjacent vessels are situated more laterally and can easily be avoided. At a slightly higher level, the sacral plexus and branches of the superior gluteal vessels lie adjacent to the piriformis muscle. (b) CT scan obtained after satisfactory needle position was confirmed shows a hydrophilic catheter that has been advanced with the trocar technique in tandem with the localizing needle to a predetermined depth in the pelvis.
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Figure 8b. Transgluteal drainage technique. (a) CT scan obtained in a 40-year-old patient with a postoperative pelvic abscess (arrows) shows a localizing needle placed as close as possible to the sacrum at the level of the sacrospinous ligament. At this level, the sciatic nerve and adjacent vessels are situated more laterally and can easily be avoided. At a slightly higher level, the sacral plexus and branches of the superior gluteal vessels lie adjacent to the piriformis muscle. (b) CT scan obtained after satisfactory needle position was confirmed shows a hydrophilic catheter that has been advanced with the trocar technique in tandem with the localizing needle to a predetermined depth in the pelvis.
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Occasionally, if an abscess is located high in the pelvis, angulation of the CT gantry in a cephalic direction can facilitate transgluteal drainage (Fig 9). Gantry angulation is also useful when all proposed access routes in the axial plane have bowel or other vital organs in their paths. A direct route to the abscess that avoids vital organs can usually be planned by angling the gantry in a cranial or caudal direction. By knowing the gantry angle, the operator can easily adjust the angle of the localizing needle and catheter.
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Figure 9a. Transgluteal drainage with an angled CT gantry. (a) Contrast-enhanced CT scan obtained in a 24-year-old man with Crohn disease shows an abscess located high in the pelvis (arrow). (b) CT fluoroscopic image obtained with the gantry at a 22o angle shows a catheter that was successfully advanced into the collection with the trocar technique. In this case, the abscess was very difficult to access due to intervening bowel and osseous structures. Occasionally, if an abscess is located high in the pelvis, angulation of the CT gantry in a cephalic direction can facilitate transgluteal drainage. (c) Postprocedure CT scan shows the catheter in good position within the abscess.
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Figure 9b. Transgluteal drainage with an angled CT gantry. (a) Contrast-enhanced CT scan obtained in a 24-year-old man with Crohn disease shows an abscess located high in the pelvis (arrow). (b) CT fluoroscopic image obtained with the gantry at a 22o angle shows a catheter that was successfully advanced into the collection with the trocar technique. In this case, the abscess was very difficult to access due to intervening bowel and osseous structures. Occasionally, if an abscess is located high in the pelvis, angulation of the CT gantry in a cephalic direction can facilitate transgluteal drainage. (c) Postprocedure CT scan shows the catheter in good position within the abscess.
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Figure 9c. Transgluteal drainage with an angled CT gantry. (a) Contrast-enhanced CT scan obtained in a 24-year-old man with Crohn disease shows an abscess located high in the pelvis (arrow). (b) CT fluoroscopic image obtained with the gantry at a 22o angle shows a catheter that was successfully advanced into the collection with the trocar technique. In this case, the abscess was very difficult to access due to intervening bowel and osseous structures. Occasionally, if an abscess is located high in the pelvis, angulation of the CT gantry in a cephalic direction can facilitate transgluteal drainage. (c) Postprocedure CT scan shows the catheter in good position within the abscess.
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Low Pelvis
Abscesses located low in the presacral space or in the perirectal space or perineum can sometimes be accessed with a transperineal approach. There are two imaging methods for achieving a satisfactory trajectory: (a) CT guidance with angulation of the gantry, and (b) US guidance, which is useful because the catheter angulation can be monitored in real time (Fig 10).
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Figure 10a. Transperineal drainage with US guidance. (a) Contrast-enhanced CT scan obtained in a 63-year-old woman who had undergone hysterectomy shows an abscess in the perineum (arrows). (b) US image shows the guide wire (arrows) that was used to help drain the abscess with the Seldinger technique. (c) Fluoroscopic image obtained after catheter placement helps confirm optimal catheter position. The main disadvantage of using the transperineal route is patient discomfort. The liberal use of local anesthetic and conscious sedation is advised.
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Figure 10b. Transperineal drainage with US guidance. (a) Contrast-enhanced CT scan obtained in a 63-year-old woman who had undergone hysterectomy shows an abscess in the perineum (arrows). (b) US image shows the guide wire (arrows) that was used to help drain the abscess with the Seldinger technique. (c) Fluoroscopic image obtained after catheter placement helps confirm optimal catheter position. The main disadvantage of using the transperineal route is patient discomfort. The liberal use of local anesthetic and conscious sedation is advised.
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Figure 10c. Transperineal drainage with US guidance. (a) Contrast-enhanced CT scan obtained in a 63-year-old woman who had undergone hysterectomy shows an abscess in the perineum (arrows). (b) US image shows the guide wire (arrows) that was used to help drain the abscess with the Seldinger technique. (c) Fluoroscopic image obtained after catheter placement helps confirm optimal catheter position. The main disadvantage of using the transperineal route is patient discomfort. The liberal use of local anesthetic and conscious sedation is advised.
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The percutaneous drainage of subphrenic collections is challenging because of access difficulties, particularly if the collections are small. All interventions in the upper abdomen involve the risk of pleural complications. Nevertheless, subphrenic abscesses can be drained successfully with an acceptable risk of complications. Pleural transgression can be avoided by choosing the lowest, most anterior access route possible (Fig 11). However, in many cases parietal pleural transgression cannot be avoided while accessing subphrenic collections.
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Figure 11a. Subcostal approach to a subphrenic collection in a 53-year-old man who had undergone gastric surgery. The patient was initially treated with percutaneous placement of two standard 12-F drainage catheters but remained febrile, and it was decided to attempt percutaneous placement of a large-bore catheter. (a) Fluoroscopic image shows a left-sided subphrenic abscess (arrow) being accessed with the Seldinger technique. (b, c) Fluoroscopic images show a guide wire that has been directed into the subphrenic space (b) and an optimally positioned large-bore catheter (c). Fluoroscopic guidance and torquing catheters were used for the procedure.
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Figure 11b. Subcostal approach to a subphrenic collection in a 53-year-old man who had undergone gastric surgery. The patient was initially treated with percutaneous placement of two standard 12-F drainage catheters but remained febrile, and it was decided to attempt percutaneous placement of a large-bore catheter. (a) Fluoroscopic image shows a left-sided subphrenic abscess (arrow) being accessed with the Seldinger technique. (b, c) Fluoroscopic images show a guide wire that has been directed into the subphrenic space (b) and an optimally positioned large-bore catheter (c). Fluoroscopic guidance and torquing catheters were used for the procedure.
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Figure 11c. Subcostal approach to a subphrenic collection in a 53-year-old man who had undergone gastric surgery. The patient was initially treated with percutaneous placement of two standard 12-F drainage catheters but remained febrile, and it was decided to attempt percutaneous placement of a large-bore catheter. (a) Fluoroscopic image shows a left-sided subphrenic abscess (arrow) being accessed with the Seldinger technique. (b, c) Fluoroscopic images show a guide wire that has been directed into the subphrenic space (b) and an optimally positioned large-bore catheter (c). Fluoroscopic guidance and torquing catheters were used for the procedure.
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Postsplenectomy subphrenic collections pose additional technical difficulty because the splenectomy bed is filled by loops of bowel. The main difficulty in draining subphrenic collections is the risk of pleural transgression, which can result in pneumothorax, pleural effusion, or empyema.
To avoid traversing the pleura, a subcostal anterior approach should be used if possible. This approach can often be used successfully with US-fluoroscopic guidance, the collection being accessed inferiorly from a skin site below the costal margin followed by angulation of the needle and catheter up into the subphrenic collection (Fig 11). Alternatively, CT guidance can be used, with angulation of the gantry frequently allowing accurate superior angulation from an inferior subcostal skin access site. The risk of traversing the pleura is smaller if an anterior approach to the collection is used. Occasionally, pleural transgres-sion cannot be avoided during the course of subphrenic abscess drainage; however, the lung should never be transgressed. Thus, when pleural transgression does occur, it is essential to monitor the patient closely for pneumothorax on CT scans and serial chest radiographs obtained following the procedure. Pneumothorax should be treated with a chest tube only if the patient is symptomatic or if serial chest radiographs show increasing size or lack of resolution of a large pneumothorax following 2–3 days of observation. If pleural effusion is seen to develop at postprocedure radiography or CT, early chest tube placement is advised to avoid the other potential complication of pleural empyema.
Left-sided subphrenic collections can have numerous causes, but the operator should be aware that associated pancreatic tail injury is a common cause. Therefore, all fluid aspirated from this area should be analyzed for amylase content, and the catheter should be injected prior to removal to assess for communication with the pancreatic duct. McNicholas et al (8) retrospectively reviewed the experience at our institution with transpleural percutaneous drainage of postsplenectomy subphrenic collections. The authors reported that complications were encountered in four of 18 patients (8). There were pneumothoraces with no occurrence of pleural empyema in two patients and inadvertent catheter placement in the pleural space in two patients (8).
Right-sided subphrenic collections have multiple causes, but at tertiary referral centers, bilomas following hepatic surgery or iatrogenic bile duct injuries account for a large percentage of cases. Subphrenic collections can be large and usually extend over the surface of the liver in both anteroposterior and craniocaudal planes. US-fluoroscopic guidance has advantages over CT guidance in gaining access and in manipulating guide wires to achieve optimal catheter position. For large collections, catheters with multiple side holes can help maximize drainage (Fig 12).
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Figure 12a. Value of a catheter with multiple side holes. The patient was a 45-year-old woman with a subphrenic biloma who had undergone laparoscopic cholecystectomy. The biloma was initially drained with a CT-guided intercostal approach and a 10-F pigtail catheter. (a) CT scan shows a residual subphrenic collection (arrows) located cephalad to the catheter. (b) Fluoroscopic image obtained after catheter placement shows that the catheter (arrow) is located at the periphery of the collection. A stiff guide wire was advanced through the indwelling catheter. The catheter was removed, and torquing catheters were used to manipulate the guide wire into a more medial and cephalic position (cf Fig 11). Once the guide wire was in satisfactory position, a catheter with multiple side holes was advanced into a more cephalic location. (c) Fluoroscopic image shows the catheter in a more cephalic position within the collection. (d) CT scan shows the catheter with multiple side holes (arrows) in excellent position high in the subphrenic space.
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Figure 12b. Value of a catheter with multiple side holes. The patient was a 45-year-old woman with a subphrenic biloma who had undergone laparoscopic cholecystectomy. The biloma was initially drained with a CT-guided intercostal approach and a 10-F pigtail catheter. (a) CT scan shows a residual subphrenic collection (arrows) located cephalad to the catheter. (b) Fluoroscopic image obtained after catheter placement shows that the catheter (arrow) is located at the periphery of the collection. A stiff guide wire was advanced through the indwelling catheter. The catheter was removed, and torquing catheters were used to manipulate the guide wire into a more medial and cephalic position (cf Fig 11). Once the guide wire was in satisfactory position, a catheter with multiple side holes was advanced into a more cephalic location. (c) Fluoroscopic image shows the catheter in a more cephalic position within the collection. (d) CT scan shows the catheter with multiple side holes (arrows) in excellent position high in the subphrenic space.
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Figure 12c. Value of a catheter with multiple side holes. The patient was a 45-year-old woman with a subphrenic biloma who had undergone laparoscopic cholecystectomy. The biloma was initially drained with a CT-guided intercostal approach and a 10-F pigtail catheter. (a) CT scan shows a residual subphrenic collection (arrows) located cephalad to the catheter. (b) Fluoroscopic image obtained after catheter placement shows that the catheter (arrow) is located at the periphery of the collection. A stiff guide wire was advanced through the indwelling catheter. The catheter was removed, and torquing catheters were used to manipulate the guide wire into a more medial and cephalic position (cf Fig 11). Once the guide wire was in satisfactory position, a catheter with multiple side holes was advanced into a more cephalic location. (c) Fluoroscopic image shows the catheter in a more cephalic position within the collection. (d) CT scan shows the catheter with multiple side holes (arrows) in excellent position high in the subphrenic space.
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Figure 12d. Value of a catheter with multiple side holes. The patient was a 45-year-old woman with a subphrenic biloma who had undergone laparoscopic cholecystectomy. The biloma was initially drained with a CT-guided intercostal approach and a 10-F pigtail catheter. (a) CT scan shows a residual subphrenic collection (arrows) located cephalad to the catheter. (b) Fluoroscopic image obtained after catheter placement shows that the catheter (arrow) is located at the periphery of the collection. A stiff guide wire was advanced through the indwelling catheter. The catheter was removed, and torquing catheters were used to manipulate the guide wire into a more medial and cephalic position (cf Fig 11). Once the guide wire was in satisfactory position, a catheter with multiple side holes was advanced into a more cephalic location. (c) Fluoroscopic image shows the catheter in a more cephalic position within the collection. (d) CT scan shows the catheter with multiple side holes (arrows) in excellent position high in the subphrenic space.
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Epigastrium and Peripancreatic Area
The major consideration in choosing imaging modalities and access routes to facilitate percutaneous procedures for epigastric, pancreatic, or peripancreatic collections is to avoid crossing small or large bowel or major mesenteric, peripancreatic, or retroperitoneal vessels (9). Potential access routes to these collections are depicted in Figure 13. For collections in or near the pancreatic head, the most common access route is through the gastrocolic ligament, by which transgression of major organs, bowel, or vessels can be avoided. Collections in this region stretch and displace the gastrocolic ligaments, creating a safe access route between the stomach and transverse colon. When access to the pancreatic head via the gastrocolic ligament is not possible, a transhepatic approach is frequently necessary (Fig 3). It is essential to avoid the gallbladder, and the porta hepatis should also be avoided to prevent major vascular or bile duct injury. Collections in the region of the pancreatic tail are usually approached through the left anterior pararenal space (Fig 14). This approach is possible because fluid collections in the pancreatic tail region extend into the left pararenal space and displace the colon anteriorly. Less commonly, the pancreatic body and tail are accessed through the gastrosplenic ligament (Fig 15). There is controversy regarding the value of a transgastric approach for pancreatic and peripancreatic collections. The risk of superinfection is not thought to be significant because the acidic nature of gastric juices renders the effluent sterile. The colon or small bowel should never be transgressed in trying to reach an epigastric or peripancreatic fluid collection or an area of necrosis.
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Figure 13. Schematic illustrates the common access routes to collections in the epigastric, pancreatic, and peripancreatic areas, including transhepatic (a), transgastric (b), and gastrosplenic (c) routes, left anterior pararenal space access (d), paravertebral access (e), right anterior pararenal space access (f), and the transduodenal approach (g).
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Figure 14a. Pancreatic body abscess. CT scans obtained in a 69-year-old man show a pancreatic body abscess (arrows in a) being accessed via the left anterior pararenal space with the trocar technique. This procedure is facilitated by placing the patient in a nearly right lateral decubitus position, which allows bowel and other organs to fall away from the path of the catheter.
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Figure 14b. Pancreatic body abscess. CT scans obtained in a 69-year-old man show a pancreatic body abscess (arrows in a) being accessed via the left anterior pararenal space with the trocar technique. This procedure is facilitated by placing the patient in a nearly right lateral decubitus position, which allows bowel and other organs to fall away from the path of the catheter.
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Figure 15a. Pancreatic body abscess. (a) Unenhanced CT scan obtained in a 65-year-old man demonstrates a fluid collection in the body of the pancreas (arrows). (b) CT scan shows the collection being accessed through the gastrosplenic ligament.
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Figure 15b. Pancreatic body abscess. (a) Unenhanced CT scan obtained in a 65-year-old man demonstrates a fluid collection in the body of the pancreas (arrows). (b) CT scan shows the collection being accessed through the gastrosplenic ligament.
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Mediastinum and Retroperitoneum
Collections in the mediastinum and retroperitoneum can be difficult to access but occasionally cross the midline, in which case access is sometimes possible from the contralateral side. A contralateral approach may be necessary in selected cases in which retroperitoneal and mediastinal structures such as the duodenum, the esophagus, or certain vascular structures (eg, aorta, inferior vena cava) lie along an access route on one side but leave a clear path to the abscess from the contralateral side.
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Risks Involving the Bowel and Esophagus
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In the majority of patients with abscesses, particularly those in whom percutaneous access is difficult, a CT scan obtained with oral and intravenous contrast material is indicated prior to drainage. Good bowel enhancement is important to avoid incorrect diagnosis of abscess with resultant catheter placement within bowel loops (Fig 16). In addition, caution is advised in US-guided drainage of pelvic abscesses to avoid inadvertent catheter placement in bowel (Fig 17). Similar problems can be encountered during percutaneous drainage of mediastinal collections or abscesses because of the risk of injury to the esophagus. This risk can be minimized by administering air through a nasogastric tube or by administering effervescent granules orally prior to imaging.
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Figure 16a. Importance of adequate bowel enhancement. (a) Initial contrast-enhanced CT scan obtained in a 45-year-old renal transplant recipient with sepsis suggests the presence of a pelvic fluid collection with foci of gas (arrows). (b) CT scan obtained after administration of additional oral contrast material reveals that this "fluid collection" represents unenhanced small bowel (arrows).
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Figure 16b. Importance of adequate bowel enhancement. (a) Initial contrast-enhanced CT scan obtained in a 45-year-old renal transplant recipient with sepsis suggests the presence of a pelvic fluid collection with foci of gas (arrows). (b) CT scan obtained after administration of additional oral contrast material reveals that this "fluid collection" represents unenhanced small bowel (arrows).
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Figure 17a. Inadvertent catheter placement in bowel. (a) CT scan obtained in an 83-year-old man shows a pelvic abscess (arrows). The abscess was originally drained percutaneously under CT guidance, and the catheter was removed. During placement of a new catheter under US guidance, the fluid-filled sigmoid colon (arrowhead) was mistaken for an abscess. (b) CT scan shows the catheter inadvertently placed in the sigmoid colon. In the setting of dilated fluid-filled loops of bowel, CT guidance helps avoid this complication.
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Figure 17b. Inadvertent catheter placement in bowel. (a) CT scan obtained in an 83-year-old man shows a pelvic abscess (arrows). The abscess was originally drained percutaneously under CT guidance, and the catheter was removed. During placement of a new catheter under US guidance, the fluid-filled sigmoid colon (arrowhead) was mistaken for an abscess. (b) CT scan shows the catheter inadvertently placed in the sigmoid colon. In the setting of dilated fluid-filled loops of bowel, CT guidance helps avoid this complication.
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Difficulties Due to Underlying Causes
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Pancreatitis
Fluid collections are common in acute pancreatitis, and many require no intervention. The different types of pancreatitis-associated fluid collections are discussed in the following paragraphs.
Acute Pancreatitis-related Fluid Collections.—
Acute pancreatitis-related fluid collections are usually small with concave borders and often appear triangular on CT scans. Intervention is not usually performed. In febrile patients with no other obvious signs of sepsis, needle aspiration for culture can be performed if there is concern for development of infection.
Pancreatic Pseudocysts.—
By definition, pancreatic pseudocysts require 4 weeks to develop. These collections are usually round with a perceptible wall consisting of a nonepithelialized capsule. Because more than one-half of pancreatic pseudocysts resolve spontaneously and resolution depends on size, only symptomatic or large pseudocysts should be drained. In current practice, aspiration is often performed endoscopically, but percutaneous drainage is also effective.
Pancreatic Abscesses.—
A pancreatic abscess is defined as any infected fluid collection associated with pancreatitis. Such abscesses should be drained if there is no indication for immediate surgery.
Pancreatic or Peripancreatic Necrosis.—
Pancreatic or peripancreatic necrosis is not usually amenable to percutaneous drainage early in its course because it is solid at this stage. After the necrosis has become liquefied at a later stage, it can be drained percutaneously. Large 22–24-F catheters are frequently required, and two or more catheters are frequently used in an attempt to achieve a "sump" effect. Percutaneous treatment of pancreatic necrosis requires commitment on the part of interventional radiologists to thorough daily evaluation of catheters, follow-up imaging, and frequent replacement and repositioning of catheters to maintain adequate drainage of the liquefied areas.
Tumor Abscess
Abscesses may arise from tumor necrosis with hematogenous seeding or from tumor invasion of bowel or of urinary or biliary structures, resulting in direct injection of the tumor. Most patients who develop tumor abscess are in the advanced stages of disease and cannot be cured. Because the tumor will remain, the abscess is not "curable." However, a patient with sepsis or who is ill from the infection may improve substantially following drainage (Fig 18). Nonetheless, our experience suggests that it is frequently very difficult to eradicate infection completely with percutaneous abscess drainage, and many patients require either surgery or lifetime catheter drainage (10). Therefore, any such drainage must proceed with the patient’s understanding that the catheter will likely remain in place for life, or redrainage may be required for recurrence of the "abscess."
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Figure 18a. Drainage of a large, infected, unresectable desmoid tumor. (a) Contrast-enhanced CT scan obtained in a 36-year-old man with Gardner syndrome shows a large desmoid tumor (arrows) containing an air-fluid level, a finding that suggests bowel communication. The tumor was drained under US-fluoroscopic guidance, and the patient improved clinically. (b) Repeat CT scan shows that the abscess cavity has not contracted around the catheter (arrows) despite excellent catheter position. Oral contrast material is now seen within the lesion, a finding that also suggests communication with bowel. The catheter remains in position 1 years later.
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Figure 18b. Drainage of a large, infected, unresectable desmoid tumor. (a) Contrast-enhanced CT scan obtained in a 36-year-old man with Gardner syndrome shows a large desmoid tumor (arrows) containing an air-fluid level, a finding that suggests bowel communication. The tumor was drained under US-fluoroscopic guidance, and the patient improved clinically. (b) Repeat CT scan shows that the abscess cavity has not contracted around the catheter (arrows) despite excellent catheter position. Oral contrast material is now seen within the lesion, a finding that also suggests communication with bowel. The catheter remains in position 1 years later.
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Crohn Disease
The role of percutaneous abscess drainage in Crohn disease has been questioned by some because of the frequent need for affected patients to undergo surgery in addition to percutaneous drainage. Most patients with Crohn disease undergo at least one operation during their lifetime, and many undergo two or three surgical procedures, a fact that must be remembered when assessing the apparent limitations of abscess drainage in this setting. Our experience suggests that abscess drainage is successful in completely evacuating pus in up to 96% of cases, and approximately 50% of patients will require no additional short-term surgical procedures. Postoperative abscesses are more likely than spontaneous abscesses to be drained without the need for subsequent surgery. Small interloop abscesses cannot be treated with percutaneous catheter placement because of adjacent bowel, and drainage is often impractical because of the large number and small size of these abscesses.
Infrequently, it is considered necessary to aspirate interloop abscesses, which are inaccessible, for the purpose of catheter placement. In this uncommon situation, we transgress the bowel with a 20-gauge needle and aspirate the collection dry (Fig 2).
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Difficulties Due to Thickened Contents
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Fibrinous products are often found in abscesses and hematomas. However, the introduction of adjunctive thrombolytics into the abscess through a catheter has proved effective in many cases (Fig 19).
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Figure 19a. Value of intracavitary streptokinase. The patient was a 52-year-old woman with subphrenic biloma who had undergone laparoscopic cholecystectomy. (a) Contrast-enhanced CT scan obtained after CT-guided drainage shows a residual pericatheter collection (arrows). The patient remained febrile and complained of right upper quadrant pain. (b) On a CT scan obtained after 3 days of treatment with intracavitary streptokinase (125,000 IU in 50 mL of saline solution twice daily), the collection is smaller (arrows). The patient’s fever abated, and her abdominal pain lessened.
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Figure 19b. Value of intracavitary streptokinase. The patient was a 52-year-old woman with subphrenic biloma who had undergone laparoscopic cholecystectomy. (a) Contrast-enhanced CT scan obtained after CT-guided drainage shows a residual pericatheter collection (arrows). The patient remained febrile and complained of right upper quadrant pain. (b) On a CT scan obtained after 3 days of treatment with intracavitary streptokinase (125,000 IU in 50 mL of saline solution twice daily), the collection is smaller (arrows). The patient’s fever abated, and her abdominal pain lessened.
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Situations in Which Imaging-guided Drainage Is Inappropriate
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Finally, even with all the "tricks," there are some patients in whom drainage catheter placement is not appropriate. As discussed earlier, there is only a limited role for catheter placement in certain pancreatitis-related collections, and placing a transvaginal drainage catheter for noninfected collections is not appropriate. If clinical evaluation suggests peritonitis, the patient should proceed to surgery even if imaging demonstrates drainable collections. In patients in whom physical examination is limited by obtundation, imaging findings may help in deciding between immediate surgery and percutaneous drainage. Extraluminal air and fluid in a "contained" distribution immediately adjacent to underlying diseased bowel (eg, in diverticulitis or appendicitis) can be drained. However, a patient with a similar abscess but with extensive and massive free air or fluid remote from the perforation site should usually undergo surgery for such an "uncontained" perforation.
It is also important to discuss the clinical findings with the surgeon to avoid inappropriate abscess drainage in the presence of free hollow organ perforation and acute peritonitis (Fig 20). Acute peritonitis is best treated surgically rather than with percutaneous drainage, except in extreme circumstances in which a patient is deemed unfit for surgical intervention. In contrast, abscesses that form as a result of walled-off perforations are optimally treated with imaging-guided drainage. Indeed, in most circumstances, diverticular abscesses secondary to perforated diverticulitis are best treated with imaging-guided percutaneous catheter placement, which can obviate creation of a stoma. For such abscesses, percutaneous treatment combined with administration of systemic antibiotics permits control of acute "flare-up," thus allowing elective resection of the diseased bowel at 6–8 weeks. As a result, resection and primary anastomosis can be performed, thus eliminating the need for stoma creation, which is usually required if surgery is performed during an episode of acute diverticulitis.
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Figure 20. Imaging-guided drainage versus surgery in perforated appendicitis. Contrast-enhanced CT scan obtained in a 28-year-old woman with perforated appendicitis and peritonitis shows a pelvic abscess and multiple interloop abscesses (arrows). The case was discussed with the surgeons, and it was jointly decided that surgery was the preferred treatment.
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Symptomatic fluid collections adjacent to surgical implants of any type (eg, vascular grafts, mesh used for hernia repair, joint prostheses) should be drained only if infected. Catheter placement for drainage of a noninfected collection poses the risk of infecting the implant. Infection can be confirmed with needle aspiration and Gram stain and culture.
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Conclusions
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Percutaneous abscess drainage is a safe, effective, and widely used treatment for patients with abdominal or pelvic sepsis. The use of the techniques described in this article can allow percutaneous drainage of less accessible intraabdominal abscesses, thus eliminating the need for laparotomy.
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Footnotes
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2**. multiple body systems 
See also the article by Gervais et al (pp 737–754)
in this issue.
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References
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- Nawfel RD, Judy PF, Silverman SG, Hooton S, Tuncali K, Adams DF. Patient and personnel exposure during CT fluoroscopy-guided interventional procedures. Radiology 2000; 216:180-184.[Abstract/Free Full Text]
- Ryan JM, Murphy BL, Boland GW, Mueller PR. Use of transgluteal route for percutaneous abscess drainage in acute diverticulitis to facilitate delayed surgical repair. AJR Am J Roentgenol 1998; 170:1189-1193.[Free Full Text]
- Todd AW. Inadvertent puncture of the inferior epigastric artery during needle biopsy with fatal outcome. Clin Radiol 2001; 56:989-990.[CrossRef][Medline]
- Varghese JC, O’Neill MJ, Gervais DA, Boland GW, Mueller PR. Transvaginal catheter drainage of tuboovarian abscess using the trocar method: technique and literature review. AJR Am J Roentgenol 2001; 177:139-144.[Free Full Text]
- Gervais DA, Hahn PF, O’Neill MJ, Mueller PR. CT-guided transgluteal drainage of deep pelvic abscesses in children: selective use as an alternative to transrectal drainage. AJR Am J Roentgenol 2000; 175:1393-1396.[Abstract/Free Full Text]
- Harisinghani MG, Gervais DA, Varghese JC, Cho CH, Mueller PR. CT-guided drainage of deep pelvic abscesses: results of 154 consecutive procedures (abstr). Radiology 2001; 221(P):292.
- Malden ES, Picus D. Hemorrhagic complication of transgluteal pelvic abscess drainage: successful percutaneous treatment. J Vasc Intervent Radiol 1992; 3:323-328.[Medline]
- McNicholas MM, Mueller PR, Lee MJ, et al. Percutaneous drainage of subphrenic fluid collections that occur after splenectomy: efficacy and safety of transpleural versus extrapleural approach. AJR Am J Roentgenol 1995; 165:355-359.[Abstract/Free Full Text]
- Lee MJ, Wittich GR, Mueller PR. Percutaneous intervention in acute pancreatitis. RadioGraphics 1998; 18:711-724.[Abstract]
- Mueller PR, White EM, Glass-Royal M, et al. Infected abdominal tumors: percutaneous catheter drainage. Radiology 1989; 173:627-629.[Abstract/Free Full Text]
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Abstract
LEARNING OBJECTIVES
