DOI: 10.1148/rg.252045157
RadioGraphics 2005;25:503-523
© RSNA, 2005
Medical Devices of the Abdomen and Pelvis1
Tim B. Hunter, MD and
Mihra S. Taljanovic, MD
1 From the Department of Radiology, University of Arizona College of Medicine, 1501 N Campbell Ave, PO Box 245067, Tucson, AZ 85724-5067. Received August 10, 2004; revision requested August 25 and received September 15; accepted September 17. Both authors have no financial relationships to disclose.
Address correspondence to T.B.H. (e-mail: tbh{at}3towers.com).
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Abstract
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Medical devices in the abdomen and pelvis are probably less frequently seen than those in the chest or extremities, but they are important and should be recognized. These devices can be grouped into a few major categories: intestinal tubes, genitourinary devices, postoperative apparatus, and a wide variety of odds and ends. Many of these devices are used to monitor or treat gastrointestinal and genitourinary disease. Some of them, such as inferior vena cava filters and drug infusion pumps, treat systemic problems, and some of them are devices used in treating another anatomic region. It is strongly recommended that scout views for chest, abdominal, and pelvic computed tomographic studies be carefully examined for medical apparatus. Medical devices are often more easily recognized on scout images, and their inappropriate locations and complications can be better appreciated on the subsequent cross-sectional images if one is alerted to their presence in the first place. The evaluation of routine medical devices should be considered as important as any other aspect of a radiologic examination.
© RSNA, 2005
Abbreviations: PEG = percutaneous endoscopic gastrostomy, IUD = intrauterine contraceptive device, TIPS = transjugular intrahepatic portosystemic shunt
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Introduction
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The abdomen and pelvis contain a complex array of gastrointestinal and genitourinary organs as well as supporting musculoskeletal structures. A moderate variety of devices are used to treat or monitor abdominal and pelvic disease, and many devices are evident in the abdomen and pelvis as incidental findings. It is often too easy to overlook seemingly innocuous and routine medical devices because of rushing to examine the cross-sectional images to assess the patient’s problems. Their evaluation should be considered as important as any other aspect of a radiologic examination.
Although the numbers and types of abdominal devices are less than those for the bones and joints and the chest, abdominal and pelvic medical devices are nevertheless quite common and important. These devices can be easily grouped into a few major categories for simplification. They consist of intestinal tubes, genitourinary devices, postoperative apparatus, and a wide variety of odds and ends.
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Gastrointestinal Tubes
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Stomach tubes and intestinal tubes have long been employed to decompress the stomach and small intestine. They are also useful for sampling bowel contents and for providing an access for patient nutrition. The most familiar intestinal tube is the large-bore, somewhat stiff, traditional nasogastric tube, which is ubiquitous in hospitals and clinics (Fig 1). It is used for only temporary bowel decompression and fluid sampling.
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Figure 1. Traditional nasogastric tube. Chest radiograph shows the tip of a nasogastric tube (arrow) in the fundus of the stomach. Electrocardiographic leads on the chest and left lower lobe atelectasis are seen.
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Small, soft, flexible enteric tubes (feeding tubes) are used to feed chronically ill patients over long periods of time. The larger-bore nasogastric tubes are constructed from polyethylene or polyvinyl chloride that tends to harden if left in the stomach or small intestine for a long period, predisposing the patient to mucosal injury and bowel perforation. Feeding tubes, on the other hand, are constructed of biocompatible plastic, silicone, or other suitable materials designed for patient tolerance and extended use. They usually have flexible metallic tips, which provide a lead point for peristalsis to move the tube through the stomach into the small intestine. Ideally, feeding tubes should be located beyond the stomach in the distal duodenum or proximal jejunum to prevent buildup of fluid within the stomach, which could lead to aspiration (Fig 2).
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Figure 2. Supine abdominal view shows a feeding tube with its tip in the descending portion of the duodenum (white arrow). A right femoral catheter (black arrow), a gown snap (G), a Foley catheter (F), and a unipolar left hip hemiarthroplasty (*) are also visible.
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In prior years, long intestinal tubes, such as the Miller-Abbott or Cantor tube, were used for bowel decompression, particularly in cases of small bowel obstruction. These tubes are no longer used (1). The Miller-Abbott tube was a double-lumen, radiopaque rubber tube with one lumen for bowel decompression and a second lumen to provide a route for injecting mercury into a weighted balloon at the end of the tube. The weighted balloon was designed to help peristalsis "pull" the end of the tube farther distally in the intestinal tract. Similar tubes, such as the Maglinte tube and the multipurpose diagnostic and enteroclysis (MDEC) tube (Mallinckrodt, Hazelwood, Mo), have replaced the Miller-Abbott tube and are designed for enteroclysis or treatment of small bowel distention (2). The Maglinte tube was specifically designed for enteroclysis and has an expandable balloon that is used to occlude the small bowel lumen to prevent reflux of fluid into the stomach. The multipurpose (diagnostic and therapeutic) MDEC tube is a closed-end triple-lumen tube made of radiopaque polyvinyl chloride. Its largest lumen is used for suction or fluid installation, and its medium-sized lumen is a sump port, which is connected to the larger lumen by small holes proximal to a weighted tip. The smallest lumen acts as a balloon inflation port. When the balloon is inflated, it prevents the proximal migration of fluid and barium into the stomach during enteroclysis.
Intestinal tubes are safe and effective in most cases. Radiologists should be aware of their proper location and functions. Complications, although rare, include perforation of the gastrointestinal tract, inadvertent placement in the lungs, gastrointestinal hemorrhage, and aspiration of gastrointestinal contents caused by improper tube placement and monitoring (3–5).
Gastrostomy and jejunostomy tubes (Figs 3–5) are surgically, endoscopically, or percutaneously placed in patients who require very long-term, sometimes permanent, assisted feeding. These tubes may be placed in either the stomach or the proximal jejunum. They may be inserted with a combination of endoscopic and percutaneous radiographic techniques (percutaneous endoscopic gastrostomy [PEG]) tubes), or, in some patients, only an open surgical procedure can be used to place the tubes (6). Patients requiring a gastrostomy or jejunostomy tube typically have an esophageal or gastric obstruction or severe neuromuscular problems that render them unable to swallow effectively.
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Figure 3. Abdominal radiograph shows the recent placement of a gastrostomy tube (arrows). Note the tube balloon (B) in the stomach lumen, the surgical clips outside the stomach, and the Dacron cuff (D) in the subcutaneous tissues of the anterior abdominal wall. The cuff incites a soft-tissue reaction, which helps anchor the tube.
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Figure 4a. (a) Photograph of a PEG button. The acorn-shaped portion of the button (*) is pulled up against the wall of the stomach to hold the button in place, while the cylindrical portion of the button (**) traverses the anterior abdominal wall. Its opening (O) is available for instilling feedings into the stomach or for removal of gastric contents, and it can be clamped shut with the attached plug (P). (b) Lateral view of the abdomen in a young child shows a PEG button (arrows).
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Figure 4b. (a) Photograph of a PEG button. The acorn-shaped portion of the button (*) is pulled up against the wall of the stomach to hold the button in place, while the cylindrical portion of the button (**) traverses the anterior abdominal wall. Its opening (O) is available for instilling feedings into the stomach or for removal of gastric contents, and it can be clamped shut with the attached plug (P). (b) Lateral view of the abdomen in a young child shows a PEG button (arrows).
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Figure 5. Bilateral ureteral stents in a 61-year-old woman. Abdominal radiograph shows the left ureteral stent, which was placed in an antegrade fashion (the tapered end is in the bladder), and the right ureteral stent, which was placed in a retrograde direction (the tapered end is in the renal pelvis). There is also a surgically placed gastrostomy tube with a Malecot tip (G), a left colostomy (O), and a flat silicone drain (D) in the pelvis.
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Once a gastrostomy tract has matured after many weeks, the PEG tube can be removed and a PEG button inserted (Fig 4). This button is placed in the anterior abdominal wall, with its rounded acornlike end fastened in the stomach. The capped end sits on the abdominal wall and is available for feedings, insertion of tubes, or withdrawal of stomach contents.
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Genitourinary Devices
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Urinary Stents
Ureteral stents are the most common type of urinary stent (Fig 5). They are designed to traverse an area of ureteral obstruction caused by benign or malignant disease and to allow urine to flow unimpeded into the bladder. Ureteral stents are also used to bypass areas of ureteral dehiscence, to bypass obstructing calculi, and to help with fistula healing. These stents may be inserted either percutaneously in an antegrade fashion or in a retrograde fashion at cystoscopy. The most common design for a ureteral stent is the double-pigtail configuration, with one pigtail residing in the renal pelvis and the other in the bladder. Ureteral stents can perforate the genitourinary tract, cause severe bleeding, be a source of sepsis, or be a site for calculus formation. Stents should be monitored while in place and promptly removed when no longer needed. They also must be changed periodically if they are to be left in place for long periods (7).
Urethral and bladder neck stents and artificial urinary sphincters are uncommon, but they may occasionally be seen in the bladder neck or in the urethra (Fig 6). They are used to bypass benign or malignant strictures or to provide for healing of dehisced wounds and to treat fistula formation (8).
Artificial urinary sphincters replace the function of the natural urinary sphincter in patients with sphincter damage or neurologic disease. They are most commonly used to treat patients with urinary incontinence following surgery for prostate cancer (8). They are sometimes used in combination with a bladder neck stent. A typical design includes a urethral cuff at the bladder neck or proximal urethra. The cuff is attached to a pump and fluid balloon reservoir. The pump resides in the scrotum and can be manually used to inflate or deflate the urethral cuff by redistributing the fluid in the balloon reservoir. Inflation of the cuff constricts the sphincter, and deflation of the cuff allows urine to leave the bladder and flow through the urethra.
Foley Catheters
Frederick E. B. Foley and Charles Russell Bard developed the first balloon catheter to treat urinary discomfort nearly 100 years ago. Their device evolved into the common present-day Foley catheter. The Foley catheter (or indwelling bladder catheter) is one of the most universal medical devices used in the human body (Fig 7a). If a patient is judged to need a nasogastric tube, he or she is often given a Foley catheter as well. These catheters are made from soft plastic or rubber and come in a large variety of sizes. The Foley catheter consists of a simple tube to which is attached a balloon that is inflated to keep the catheter in place in the bladder. The balloon may be filled with sterile saline, sterile water, or air. Unless the balloon is filled with air or there is contrast agent within the bladder, the catheter is usually not visible radiographically.
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Figure 7a. (a) Photograph shows a typical Foley catheter. (b) Pelvic radiograph shows a suprapubic catheter (arrows), which is made visible by the surrounding contrast material in the bladder.
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Figure 7b. (a) Photograph shows a typical Foley catheter. (b) Pelvic radiograph shows a suprapubic catheter (arrows), which is made visible by the surrounding contrast material in the bladder.
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Foley catheters are used to decompress a distended bladder, collect urine, and monitor patient urine output. Some Foley catheters include a temperature probe to monitor the patient’s urine (body) temperature. The temperature probe, which is an electrically insulated thermistor, is placed in a secondary lumen, with the sensing end near the tip of the catheter (9). Foley catheters are intended for short-term use. At times, long-term urinary drainage is needed. Such treatment is often accomplished by placement of a suprapubic indwelling catheter (Fig 7b). These catheters are placed surgically or percutaneously and are typically sewn in place and attached to a drainage bag.
Nephrostomy Tubes
Surgical and percutaneous nephrostomy drainage of the kidneys is a common procedure. The usual indications for a nephrostomy include external drainage of the renal collecting system in a patient with a high-grade urinary tract obstruction, provision of an access route for placement of a ureteral stent, provision of a route for extraction of a renal or ureteral calculus, treatment of a urinary tract infection superimposed on a urinary obstruction, and treatment of urinary tract leaks and fistulas. Percutaneous placement of a nephrostomy tube is generally preferred to surgical placement and is highly successful most of the time (10,11). Several catheter types may be used for a nephrostomy, including simple angiographic catheters, pigtail catheters, and self-retaining catheters (Fig 8). In the past, the Malecot (mushroom- or tulip-shaped catheter tip) was popular. Today, catheters with a self-retaining design are more common.
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Figure 8. View of the abdomen shows a left nephrostomy tube (curved arrow); guide wires (straight arrows) in the right renal pelvis, right ureter, and right side of the bladder for placement of a right ureteral stent; skin staples from recent surgery (white arrowheads); and vascular surgical clips (black arrowheads).
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Contraceptive Devices
Intrauterine contraceptive devices (IUDs) are a very popular form of contraception worldwide, although their use in the United States is more limited. Most of the previously popular IUDs have been withdrawn from the U.S. market. Nevertheless, IUDs no longer marketed in the United States may still be found in women who keep them in place for many years (Fig 9). IUDs are usually visible on radiographs, and they are recognizable on ultrasonographic (US) and computed tomographic (CT) images if one is familiar with their appearance. They should be located centrally in the uterine canal (12) (Fig 10).
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Figure 10a. (a) Pelvic radiograph shows a typical IUD (arrowhead). A tampon (arrow) is present in the vagina. (b) Sagittal transvaginal pelvic US image shows a linear region of marked echogenicity (*), the normal appearance of a properly situated IUD. (c) Pelvic CT image of a different patient shows a normal IUD.
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Figure 10b. (a) Pelvic radiograph shows a typical IUD (arrowhead). A tampon (arrow) is present in the vagina. (b) Sagittal transvaginal pelvic US image shows a linear region of marked echogenicity (*), the normal appearance of a properly situated IUD. (c) Pelvic CT image of a different patient shows a normal IUD.
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Figure 10c. (a) Pelvic radiograph shows a typical IUD (arrowhead). A tampon (arrow) is present in the vagina. (b) Sagittal transvaginal pelvic US image shows a linear region of marked echogenicity (*), the normal appearance of a properly situated IUD. (c) Pelvic CT image of a different patient shows a normal IUD.
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There are two main types of IUDs available in the United States at this time: the Copper Para-Gard T 380A, a high-dose copper-releasing device (FEI Products, Tonawanda, NY), and the Mirena, a progesterone-releasing device (Berlex, Montville, NJ). All these devices have a somewhat similar T-shaped configuration on radiographs (Fig 10a). They may perforate the uterine wall and become free floating in the peritoneum. In such cases, they are left in place if the patient is asymptomatic and has no signs of infection (13). An IUD carries a risk of causing a miscarriage or premature birth if a patient becomes pregnant while an IUD is in place. In such cases, the IUD should be removed regardless of whether the pregnancy is continued. IUDs also increase the risk of a possible ectopic pregnancy.
Although it is not an abdominal or pelvic device, the Norplant contraceptive implant (Wyeth Pharmaceuticals, Madison, NJ) is occasionally encountered during patient examination. The implant consists of six, small, long, thin drug capsules placed in a radial fan distribution in the subdermal tissues of the forearm or upper arm. These capsules release a steady small amount of levonorgestrel, a synthetic progestin. The Norplant implant provides effective birth control for up to 5 years. Norplant capsules are difficult to visualize on radiographs, and they may be difficult to see on US images unless one is aware of their presence (14). Fortunately, the Norplant capsules are usually easily palpated and removed by means of local incision.
The hormonal contraceptive vaginal ring consists of a transparent, flexible polymer ring that releases a continuous low dose of etonogestrel and ethinyl estradiol that is absorbed in the systemic circulation through the vaginal mucosa. The ring is inserted into the vagina between the 1st and 5th days of the menstrual cycle and is left in place for 3 weeks. The ring is then removed, and after 1 week, a new ring is inserted. Vaginal rings are radiolucent and not easily noted on radiographs or even on CT scans. On CT scans, a vaginal ring appears as a low-attenuation circular ring (15). Its shape and appearance are similar to those of a pessary, but it is smaller and may lie in any orientation in the vagina. Pessaries are usually placed only in older multiparous women with pelvic laxity.
Tubal Ligation and Vasectomy Devices
Tubal ligation and vasectomy are common forms of birth control. They usually do not have any specific radiographic findings, but occasionally surgical clips may be evident in the pelvis or in the scrotum from these procedures. Sometimes, special tubal ligation clips may be evident (Fig 11). A new metallic implant, the ESSURE device (Conceptus, San Carlos, Calif), has also been developed for permanent contraception. It is a small, expanding microcoil placed in the proximal portion of the fallopian tube. It incites a benign tissue ingrowth, which anchors the device and permanently closes the fallopian tube. It is safe for women with IUDs, vaginal rings, tubal ligation clips, and ESSURE devices to undergo magnetic resonance imaging with static magnetic fields of 1.5 T or less (16,17).
Pessaries
Pessaries have been used for over 100 years to treat vaginal and uterine prolapse. They are simple mechanical devices inserted in the vagina and left in place for long periods, even years (Fig 12). Pessaries are designed to press against the wall of the vagina to uplift and displace the bladder forward or to support a prolapsed uterus or vagina (18). A pessary is usually placed in the most posterior aspect of the vagina around the cervix. Even though pessaries are safe and effective, they have largely been replaced by modern surgical treatment for uterine prolapse.
Penile Prostheses
Many types of penile prostheses have been used over the years, but their popularity has decreased since the introduction of effective medications for erectile dysfunction (19,20). Some penile prostheses have semirigid, malleable cores, which are placed in the corpora cavernosa (Fig 13). With such prostheses, the patient has a permanent erection. Other designs allow the patient to control his erection by using an inflatable prosthesis. This device consists of two distensible cylinders implanted in the corpora cavernosa. The cylinders are distended by fluid, to which water-soluble contrast material is added to make them visible. The fluid is pumped into the corporal cylinders from an implantable reservoir located in the abdomen, pelvis, or thigh. There are a series of valves, which are manually controlled by the patient to regulate fluid flow in and out of the corporal implants to control erections.
Tandem and Ovoid Implants for Gynecologic Brachytherapy
Brachytherapy involves placement of implants or radiation sources inside the patient. Brachytherapy is quite useful for treatment of gynecologic tumors, such as cervical and ovarian neoplasms, whereby radioactive cesium or iridium is placed inside or adjacent to the uterus and cervix. This type of therapy is often combined with external radiation therapy. Three types of applicators are used for gynecologic brachytherapy: tandems, ovoids, and cylinders (Fig 14). The tandem is a metal tube placed in the uterus to treat that area. Ovoids are round, hollow holders that are placed in the vagina on both sides of the cervix, and cylinders are hollow holders that are placed in the vagina. Various combinations of tandems, ovoids, and cylinders may be used for a specific patient. Their exact placement is important and is generally determined by the radiation oncologist caring for the patient (21).
Residual Thorotrast Deposits
A 20% colloidal suspension of thorium dioxide (Thorotrast) was a common contrast agent in the 1930s and 1940s until its discontinuance in the 1950s because of concerns about its safety. Thorotrast produced excellent radiographic contrast, but thorium is radioactive, and Thorotrast was found to induce various neoplasms, particularly cholangiocarcinoma, hepatocellular carcinoma, and liver angiosarcoma. It also caused local and distant fibrosis, cirrhosis, and veno-occlusive disease (22). Even at this late date, there are still some patients alive who have residual Thorotrast in their reticuloendothelial system. Because it was a colloidal suspension, Thorotrast tended to accumulate in lymph nodes, the spleen, and the liver, and it has a characteristic appearance (Fig 15).
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Figure 15. Thorium dioxide (Thorotrast) deposition in the spleen of a 57-year-old man. Abdominal radiograph shows opacity in the spleen (arrows), which does not represent dystrophic calcifications but actually Thorotrast with its high atomic number. The spleen is small because of radiation fibrosis. (Courtesy of George Barnes, Jr, MD, University Medical Center, Tucson, Ariz.)
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Postoperative Surgical Apparatus
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Surgical apparatus is frequently visible in patients after abdominal and pelvic operations. Commonly seen materials include large rubber abdominal wall retention sutures, wire sutures, surgical drains, surgical staples, skin staples, vascular clips, and abdominal wound gauze packs and bandages (23–25).
Surgical Sutures, Staples, Clips, and Glue
Surgical sutures, staples, clips, and glue are ubiquitous findings on postoperative images. Major skin lacerations and surgical closure of the skin, subcutaneous tissues, and musculature after major surgery, no matter the body part, require the use of large skin and scalp sutures, vascular clips, and staples of various kinds (Figs 16, 17). The type used depends on the preference of the surgeon and the type of wounds being repaired. The technologic aspects for facilitating wound healing are advancing, and even special surgical glues may be used to close major surgical wounds with or without supporting sutures and staples.
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Figure 17a. (a) Magnified image of the right lung shows small surgical staples (arrow) used to repair the lung after resection of a cavity. (b) Oblique view of the lumbar spine shows skin clips (SC), hemostatic clips (H), an iliac artery stent graft (VS), and two double rows of tiny surgical staples (arrow) from a recent bowel resection and anastomosis. There is also residual contrast material in the colon.
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Figure 17b. (a) Magnified image of the right lung shows small surgical staples (arrow) used to repair the lung after resection of a cavity. (b) Oblique view of the lumbar spine shows skin clips (SC), hemostatic clips (H), an iliac artery stent graft (VS), and two double rows of tiny surgical staples (arrow) from a recent bowel resection and anastomosis. There is also residual contrast material in the colon.
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It is sometimes difficult to tell whether a particular set of sutures or large staples are internal to the abdomen or pelvis or whether they are external and present in the skin and subcutaneous tissues. Some abdominal and pelvic surgeries leave behind recognizable signs, such as right upper quadrant clips from gallbladder removal and vascular clips in the pelvis from major prostate or bladder surgery. Vascular clips (hemostatic clips) are very popular (Figs 16c, 17b). They have a great range in size and are mainly used for rapid closure of bleeding vessels, although they may sometimes be used to mark the bed of a resected tumor or lymph node group. Many surgeons also use small surgical staples for various internal anastomoses, such as joining two portions of intestine together after bowel resection or repairing the lung after thoracic surgery (Fig 17).
Surgical Sponges
Radiopaque markers for surgical sponges have been used for years (23–27). The sponge body may be faintly visible on radiographs, but the radiopaque sponge marker provides an important means for radiographically identifying a sponge (Fig 18). Some sponges may be packed into an open wound, but the presence of a sponge after surgery should always be questioned, because in most cases they were inadvertently left inside the patient.
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Figure 18a. Surgical sponges. (a) Photograph shows laparotomy sponges (1), Rey-Tec sponges (2), surgical patties (3), Neuro sponges (4), and Tonsil sponges (5). (b) Radiograph of these same sponges with the same orientation of the sponges. Note the various types of metallic identifying markers. (The sponges were provided by Stefen Wigert, RN.) (c) Radiograph obtained during spinal surgery to ascertain correct placement of pedicle screws. A laparotomy sponge (arrow) and Rey-Tec sponges (arrowheads) are visible. (d) Radiograph of the left upper chest obtained immediately after placement of a pacemaker shows retained surgical sponges (S).
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Figure 18b. Surgical sponges. (a) Photograph shows laparotomy sponges (1), Rey-Tec sponges (2), surgical patties (3), Neuro sponges (4), and Tonsil sponges (5). (b) Radiograph of these same sponges with the same orientation of the sponges. Note the various types of metallic identifying markers. (The sponges were provided by Stefen Wigert, RN.) (c) Radiograph obtained during spinal surgery to ascertain correct placement of pedicle screws. A laparotomy sponge (arrow) and Rey-Tec sponges (arrowheads) are visible. (d) Radiograph of the left upper chest obtained immediately after placement of a pacemaker shows retained surgical sponges (S).
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Figure 18c. Surgical sponges. (a) Photograph shows laparotomy sponges (1), Rey-Tec sponges (2), surgical patties (3), Neuro sponges (4), and Tonsil sponges (5). (b) Radiograph of these same sponges with the same orientation of the sponges. Note the various types of metallic identifying markers. (The sponges were provided by Stefen Wigert, RN.) (c) Radiograph obtained during spinal surgery to ascertain correct placement of pedicle screws. A laparotomy sponge (arrow) and Rey-Tec sponges (arrowheads) are visible. (d) Radiograph of the left upper chest obtained immediately after placement of a pacemaker shows retained surgical sponges (S).
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Figure 18d. Surgical sponges. (a) Photograph shows laparotomy sponges (1), Rey-Tec sponges (2), surgical patties (3), Neuro sponges (4), and Tonsil sponges (5). (b) Radiograph of these same sponges with the same orientation of the sponges. Note the various types of metallic identifying markers. (The sponges were provided by Stefen Wigert, RN.) (c) Radiograph obtained during spinal surgery to ascertain correct placement of pedicle screws. A laparotomy sponge (arrow) and Rey-Tec sponges (arrowheads) are visible. (d) Radiograph of the left upper chest obtained immediately after placement of a pacemaker shows retained surgical sponges (S).
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The most common, retained surgical foreign body is the rectangular, cotton laparotomy sponge (Fig 18a, 18c). This sponge is used to pack the corners of the exposed body cavity. It absorbs blood and other fluids. Its ribbonlike marker is characteristic and easily identified on abdominal radiographs, even though the strip often appears crenulated. An open wound that has been packed with such material should be well known to the doctors and nurses caring for the patient. Neurosurgical sponges used in spinal operative procedures are smaller and may be more difficult to visualize, but they should all contain visible radiopaque markers. It is wise for radiologists to be familiar with the radiographic and CT appearances of the sponges used in their institutions.
Surgical Needles and Other Miscellaneous Equipment
There are many types of surgical needles, ties, and drains. These surgical devices have a standard appearance and function, and radiologists should become familiar with those items used at their own medical centers. Some surgical needles, such as those used for fine-detail plastic surgery and ophthalmology, may be only a few millimeters in size and are not easily recognizable because of their small size. Surgical ties are usually indistinct on radiographs, and, as previously noted, hemostatic clips and skin staples can have a similar appearance. Small internal surgical staples used for intestinal or pulmonary anastomoses appear similar to skin staples, except for their tiny size.
Surgical Drains
Surgical drains remove blood and extracellular fluid to facilitate wound healing. They are designed to remove fluid collections that could otherwise lead to an infection, abscess formation, or wound breakdown. The use of drains for a particular procedure and the type of drain employed are subject to the experience of the individual surgeon, and it is often a matter of considerable debate. Most drains are radiopaque, and there are three general types: closed-wound suction drains, gravity drains, and sump drains (Figs 5, 19a).
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Figure 19a. (a) Radiograph of a patient with complications from multiple surgical procedures demonstrates a flat silicone drain (arrowheads), large retention suture bridges (arrows), a colostomy (O), and a sump drain (SD) in the pelvis. There is also contrast material (*) in a mucus fistula. (b) Abdominal radiograph of a different patient shows a T-tube biliary drain (black arrow) and a left Malecot nephrostomy tube (white arrow).
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Figure 19b. (a) Radiograph of a patient with complications from multiple surgical procedures demonstrates a flat silicone drain (arrowheads), large retention suture bridges (arrows), a colostomy (O), and a sump drain (SD) in the pelvis. There is also contrast material (*) in a mucus fistula. (b) Abdominal radiograph of a different patient shows a T-tube biliary drain (black arrow) and a left Malecot nephrostomy tube (white arrow).
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Closed-wound suction drains produce a constant level of suction, often with a choice of suction pressures. Usually, there is an internal drainage catheter attached to an evacuator bottle or collector. Closed-wound suction systems use a soft, inert silicone drain. The drains come in round and flat designs and are of different lengths, hole patterns, and sizes for varying needs. Generic terms used for these drains by surgeons are Jackson-Pratt drains or JP drains. Sometimes, the appearances of a retained surgical sponge and a flat silicone drain may be similar and cause confusion (28).
Gravity drains rely on gravity and fluid tension dynamics to drain fluids away from surgical beds. Traditional gravity drains include the Penrose and T-tube drains. Penrose drains vary in length and width, and they are probably more familiar to many physicians as tourniquets rather than as drains. T-tubes are most often used for bile duct drainage.
Sump drains often have a triple-lumen design. They have a large central lumen for maximum fluid removal, with a second lumen used to suction air into the drain site to maintain pressure for forcing the fluid out of the surgical bed or abscess cavity. The air intake is usually filtered to prevent bacterial contamination of the wound site, and the device often has a suture tab for suturing the drainage tube in place. The third lumen is used to irrigate the drain site and instill medication.
Biliary Drainage Catheters and Stents
Drainage of the biliary system is performed for relief of obstructive jaundice. It may be done percutaneously, surgically, or endoscopically, or it may be achieved through a combination of these techniques. The main indications for such drainage are obstructive jaundice with pruritus, septicemia, and deteriorating liver function. Biliary drainage is most commonly used as a palliative procedure for an unresectable malignancy, but benign strictures may be treated with biliary stents. In addition, biliary drainage may be used for preoperative decompression of the biliary tree or as a temporary procedure after surgery. Biliary drainage can be internal-external, such as a T-tube temporarily placed after gallbladder surgery. Alternatively, it may consist of retrograde drainage only, with external drainage to a bag or sump tube, or it may be internal, with antegrade drainage of biliary contents via a stent going from the intrahepatic biliary tract to the duodenum.
Most biliary catheters and stents are sufficiently opaque to be visible radiographically (Fig 20). Their designs vary, and some of them are amenable to periodic replacement. However, the majority of biliary drains represent a permanently placed polymer or metallic stent used to bypass an obstructing neoplasm.
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Figure 20a. (a) Radiograph shows an internal biliary stent. (b) Radiograph of a different patient with biliary strictures treated with right and left external biliary drainage shows the locking pigtail catheters (C) and two metallic Gianturco-Rosch Z stents (arrows).
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Figure 20b. (a) Radiograph shows an internal biliary stent. (b) Radiograph of a different patient with biliary strictures treated with right and left external biliary drainage shows the locking pigtail catheters (C) and two metallic Gianturco-Rosch Z stents (arrows).
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Metallic Stents, Metallic Coils, and Embolic Materials
Endoprosthetic stents composed of metals were originally designed for intravascular use, but they have been applied to other body systems. Stents have many applications, including treatment of benign and malignant lesions in the biliary tree and the gastrointestinal and genitourinary tracts, as well as treatment of atherosclerotic disease in the vascular system (29,30). Metallic stents are seen in the abdomen and pelvis, mainly in the biliary tree and the vascular tree. Angioplasty and stent placement are common treatment options for atherosclerotic disease in the femoral, iliac, and renal circulation (Fig 21a). Endovascular stents are also being widely used for treatment of abdominal aortic aneurysms (Fig 21b).
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Figure 21a. (a) Frontal view of the pelvis shows a right iliac arterial stent placed for atherosclerotic occlusive vascular disease. There are also multiple small metallic coils from past embolotherapy. (b) Supine view of the abdomen in a different patient shows aortic and iliac stent grafts for treatment of an abdominal aortic aneurysm. There is also an inflated Foley balloon in the bladder. (c) Longitudinal US scan of the liver in a different patient shows a TIPS catheter (arrows).
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Figure 21b. (a) Frontal view of the pelvis shows a right iliac arterial stent placed for atherosclerotic occlusive vascular disease. There are also multiple small metallic coils from past embolotherapy. (b) Supine view of the abdomen in a different patient shows aortic and iliac stent grafts for treatment of an abdominal aortic aneurysm. There is also an inflated Foley balloon in the bladder. (c) Longitudinal US scan of the liver in a different patient shows a TIPS catheter (arrows).
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Figure 21c. (a) Frontal view of the pelvis shows a right iliac arterial stent placed for atherosclerotic occlusive vascular disease. There are also multiple small metallic coils from past embolotherapy. (b) Supine view of the abdomen in a different patient shows aortic and iliac stent grafts for treatment of an abdominal aortic aneurysm. There is also an inflated Foley balloon in the bladder. (c) Longitudinal US scan of the liver in a different patient shows a TIPS catheter (arrows).
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Metallic and plastic stents have found varied use in the tracheobronchial tree, the esophagus, and the coronary artery circulation (31). Vascular stents are more common in the arterial system, but they are also used in major veins, such as the superior vena cava, for malignant and benign disease. Expandable stents are also used for treatment of benign and malignant gastrointestinal obstructions, such as strictures and tumors. Palliative relief of colonic neoplasms is sometimes performed with expandable stents.
Portosystemic shunting is an effective procedure in selected patients for treatment of refractory bleeding from esophageal and gastric varices. Portosystemic shunting may be performed surgically, but placement of a transjugular intrahepatic portosystemic shunt (TIPS) is often the preferred method of therapy. In these circumstances, a self-expanding metallic stent, such as a Wallstent, is deployed to form a bridge between a major portal vein and one of the hepatic veins (32). The stent is sometimes visible on radiographs, and it can be detected at US, which can often be used to establish the patency and flow rate through the stent (Fig 21c) (33).
There are many stent designs, and these are constantly being modified. Some of the stent designs more commonly encountered are the Wallstent (Boston Scientific, Natick, Mass), the Gianturco-Rosch Z stent (Wilson-Cook Medical, Winston-Salem, NC), and the Palmaz stent (Cordis, Miami Lakes, Fla). Correct identification of a particular stent by name would be difficult for a general radiologist, who does not perform interventional vascular procedures. However, the objectives of the general radiologist are not to give a correct name, but to recognize the presence of a stent and to reasonably ascertain its function and be aware of its potential complications, such as misplacement.
Transcatheter embolotherapy is a standard tool for treating arteriovenous malformations, for devascularizing tumors before their surgical removal, and for stopping or slowing life-threatening hemorrhage. There are many types of embolic materials, some of which are readily evident on abdominal and pelvic radiographs (Figs 21a, 22). Embolic metallic coils are especially common for controlling bleeding associated with pelvic fractures. Beside metal coils, small particles containing barium, tantalum, oil-based contrast material (Ethiodol), and detachable balloons may be apparent on radiographs. Many materials are not visible at radiography, and these include cyanoacrylates (glues), autologous blood clots, silicone spheres, powder and plugs of absorbable gelatin sponge (Gelfoam), fragments of polyvinyl alcohol, collagen particles, ethanol, hypertonic dextrose, thrombin, and other irritating clot-producing chemical agents.
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Figure 22. Pelvic radiograph of a motor vehicle accident victim, who has hypotension from internal bleeding, shows metallic embolization coils (arrows) in the internal iliac artery distribution. There are sacral and pelvic fractures, large abdominal retention suture bridges (RB), skin staples, external fixator pins in the iliac bones, and prominent linear opacities (arrowhead) produced by a trauma board.
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Inferior Vena Cava Filters
Inferior vena cava filters are frequent findings on abdominal imaging studies (Fig 23). They have been widely used for the prevention of thromboembolism in patients with ongoing thromboembolic disease and who have failed heparin therapy or for whom anticoagulation therapy is contraindicated (34). These filters interrupt the transit of clots from the pelvis and lower extremities to the heart and lungs, while they maintain blood flow in the inferior vena cava. There are many types of these filters, and it is hard for the general radiologist to keep up with them and provide a specific name for a particular filter. However, such filters should be recognized, and their location noted. In most cases, inferior vena cava filters are placed in an infrarenal location to preserve the venous drainage from the kidneys, although they are sometimes placed higher if an inferior vena cava thrombus has extended above that level. The most common filters are the Greenfield filter (Boston Scientific), the bird’s nest filter, the Vena Tech filter (B. Braun Medical, Bethlehem, Pa), and the Simon Nitinol filter (NMT Medical, Boston, Mass). These filters were originally designed to be left in place for the duration of the patient’s life, but some newer designs allow temporary replacement and later removal.
Vascular Grafts
Vascular bypass surgery is performed in all parts of the body to treat severe atherosclerosis, vascular occlusions, vascular injuries, and aneurysms. Synthetic aortofemoral (iliac) bypass grafts and other vascular bypass grafts are quite common in the abdomen and pelvis. They are typically composed of Dacron, Gore-Tex, or similar materials (Fig 24). Aortic aneurysms and aortic dissection are usually treated either with an interposition graft and removal of the diseased aorta or with an inclusion graft. For an inclusion graft, the graft is inserted in the diseased aorta, and the aorta is wrapped around the graft.
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Figure 24. Collimated view of the pelvis shows a Gore-Tex left femoral to right femoral artery bypass graft (white arrows) for an obstructed left iliac artery. There is also a Palmaz stent in the right external iliac artery (black arrow).
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Odds and Ends
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Many incidental devices and materials lie within or on top of the lower chest, abdomen, and pelvis. These items include foreign bodies, medications ingested by the patient, and unusual medical devices situated in an abdominal or pelvic location (24,31). Common items include pills in the upper or lower intestinal tract, Pepto-Bismol or similar medication in the stomach, colon and rectal decompression tubes, surgical cholangiography catheters, T-tube biliary catheters, biliary stents, small radiopaque markers to assess gastric emptying and bowel motility, patient restraint devices, ileostomy or colostomy bags, bowel biopsy devices, fetal monitoring equipment, and even residual contrast material from a remote lymph-angiographic or myelographic examination (Fig 25).
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Figure 25a. (a) Collimated frontal view of the lumbosacral junction shows a drop of Pantopaque contrast material (arrow) remaining from past myelography. Hemostatic clips and pedicle screws are also visible. (b) Collimated view of the upper abdomen in another patient shows Pepto-Bismol (arrows) in the stomach and jejunum. (c) CT scan of a third patient demonstrates lymphangiographic contrast material in the paracaval and paraaortic lymph nodes (arrows). (d) Frontal view of the pelvis in an elderly patient shows a colostomy (arrows), surgical clips from a prostate resection, and residual contrast material in scattered colonic diverticula.
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Figure 25b. (a) Collimated frontal view of the lumbosacral junction shows a drop of Pantopaque contrast material (arrow) remaining from past myelography. Hemostatic clips and pedicle screws are also visible. (b) Collimated view of the upper abdomen in another patient shows Pepto-Bismol (arrows) in the stomach and jejunum. (c) CT scan of a third patient demonstrates lymphangiographic contrast material in the paracaval and paraaortic lymph nodes (arrows). (d) Frontal view of the pelvis in an elderly patient shows a colostomy (arrows), surgical clips from a prostate resection, and residual contrast material in scattered colonic diverticula.
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Figure 25c. (a) Collimated frontal view of the lumbosacral junction shows a drop of Pantopaque contrast material (arrow) remaining from past myelography. Hemostatic clips and pedicle screws are also visible. (b) Collimated view of the upper abdomen in another patient shows Pepto-Bismol (arrows) in the stomach and jejunum. (c) CT scan of a third patient demonstrates lymphangiographic contrast material in the paracaval and paraaortic lymph nodes (arrows). (d) Frontal view of the pelvis in an elderly patient shows a colostomy (arrows), surgical clips from a prostate resection, and residual contrast material in scattered colonic diverticula.
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Figure 25d. (a) Collimated frontal view of the lumbosacral junction shows a drop of Pantopaque contrast material (arrow) remaining from past myelography. Hemostatic clips and pedicle screws are also visible. (b) Collimated view of the upper abdomen in another patient shows Pepto-Bismol (arrows) in the stomach and jejunum. (c) CT scan of a third patient demonstrates lymphangiographic contrast material in the paracaval and paraaortic lymph nodes (arrows). (d) Frontal view of the pelvis in an elderly patient shows a colostomy (arrows), surgical clips from a prostate resection, and residual contrast material in scattered | |
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Abstract
Introduction
