DOI: 10.1148/rg.241035063
(Radiographics. 2004;24:175-189.)
© RSNA, 2004
Various Approaches for CT-guided Percutaneous Biopsy of Deep Pelvic Lesions: Anatomic and Technical Considerations1
Sanjay Gupta, MD,
Huan Luong Nguyen, MD,
Frank A. Morello, Jr, MD,
Kamran Ahrar, MD,
Michael J. Wallace, MD,
David C. Madoff, MD,
Ravi Murthy, MD and
Marshall E. Hicks, MD
1 From the Department of Diagnostic Radiology, Section of Vascular and Interventional Radiology, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Blvd, Unit 325, Houston, TX 77030-4009. Recipient of a Certificate of Merit award for an education exhibit at the 2002 RSNA scientific assembly. Received March 14, 2003; revision requested April 14 and received May 13; accepted May 14. Address correspondence to S.G. (e-mail: sgupta@mdanderson.org).
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Abstract
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Access route planning for computed tomography–guided biopsy of deep pelvic masses remains challenging because vital structures often obstruct the projected needle path. The classical approach through the lower anterior abdominal wall allows access to lesions located anterior, superior, or lateral to the urinary bladder. However, this approach has limitations: Deep masses are difficult to reach because of intervening structures, the bowel or bladder may be unavoidably traversed, and peritoneal transgression is often painful. A transgluteal approach is useful for biopsy of presacral and perirectal lesions and lesions located posterolateral to the bladder. An anterolateral approach through the iliopsoas muscle allows safe extraperitoneal access to external and internal iliac nodes, masses located along the lateral pelvic sidewall, and adnexal lesions. A transosseous (transsacral or transiliac) approach can occasionally be used for otherwise inaccessible lesions. Use of a curved needle, change in patient position, or injection of saline solution to displace intervening structures may also be helpful. Familiarity with normal cross-sectional pelvic anatomy facilitates planning of a safe access route and helps avoid injury to adjacent structures. A thorough understanding of the advantages and disadvantages of each approach allows the clinician to choose the most appropriate approach in a given situation.
© RSNA, 2004
Index Terms: Biopsies, complications, **.4582 • Biopsies, technology • Pelvic organs, biopsy, **.126 • Pelvis, CT, **.1211
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Introduction
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Imaging-guided percutaneous biopsy has been established as a safe, effective procedure. However, deep pelvic masses pose problems for interventional radiologists because overlying bowel, bladder, vessels, and bones, as well as the uterus and adnexa in female patients, often preclude safe access to these lesions. The success and safety of percutaneous needle biopsy depend on safe access route planning, which requires a thorough understanding of the cross-sectional anatomy of the pelvis. Different approaches have been advocated for needle aspiration of pelvic lesions under computed tomographic (CT) guidance (1–9).
In this article, we review the normal pelvic anatomy as it relates to percutaneous needle biopsy of deep pelvic lesions. We also describe the various approaches for CT-guided pelvic biopsy (anterior or lateral transabdominal, transgluteal, anterolateral extraperitoneal, transosseous). In addition, we discuss potential complications associated with these approaches.
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Normal Pelvic Anatomy
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Safe access planning for percutaneous needle biopsy of deep pelvic lesions requires a thorough knowledge of the complex anatomy of this region (Fig 1). Familiarity with the appearance and location of various structures at CT is especially important (Fig 2).
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Figure 1a. (a) Schematic shows an anterior view of the pelvis. civs = common iliac vessels, eivs = external iliac vessels, iivs = internal iliac vessels, ilps = iliopsoas muscles, ur = ureter. On the right side of the pelvis, the piriform muscle (prf) and sciatic nerve (scn) are seen coursing through the greater sciatic foramen. (b) Schematic shows a posterior view of the pelvis. The piriform muscle (prf), sciatic nerve (scn), and superior gluteal vessels (sgvs) are seen coursing through the greater sciatic foramen. ssl = sacrospinous ligament, stl = sacrotuberous ligament.
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Figure 1b. (a) Schematic shows an anterior view of the pelvis. civs = common iliac vessels, eivs = external iliac vessels, iivs = internal iliac vessels, ilps = iliopsoas muscles, ur = ureter. On the right side of the pelvis, the piriform muscle (prf) and sciatic nerve (scn) are seen coursing through the greater sciatic foramen. (b) Schematic shows a posterior view of the pelvis. The piriform muscle (prf), sciatic nerve (scn), and superior gluteal vessels (sgvs) are seen coursing through the greater sciatic foramen. ssl = sacrospinous ligament, stl = sacrotuberous ligament.
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Figure 2a. (a) CT scan through the upper pelvis shows the ascending colon (ac), descending colon (dc), and small bowel loops (sbl) occupying the anterior portion of the pelvis. Note the relationship of the common iliac artery (cia), common iliac vein (civ), ureter (ur), and testicular vessels (tvs) to the psoas muscle (ps). il = iliac muscle, ilvs = iliolumbar vessels. (b) On a CT scan through the S2 vertebra, the common iliac vessels have divided into external (eivs) and internal (iivs) iliac vessels. Small bowel loops (sbl) and the sigmoid colon (sgc) occupy a major portion of the pelvis. Note also the left ureter (ur), the inferior epigastric vessels (ievs) posterior to the rectus muscle (rm), the deep circumflex iliac vessels (dcvs) medial to the iliac muscle (il), and the lumbosacral nerve (lsn) anterior to the sacrum. The femoral nerve (fmn) located in the groove between the iliac muscle and the psoas muscle (ps) is usually difficult to identify but is clearly depicted on this image. (c) CT scan through the midpelvis shows the external iliac artery (eia) and external iliac vein (eiv) coursing along the medial aspect of the iliopsoas muscle, the internal iliac vessels (iivs), and the superior gluteal vessels (sgvs) coursing through the upper portion of the greater sciatic foramen. dcvs = deep circumflex iliac vessels, ievs = inferior epigastric vessels, igvs = inferior gluteal vessels, on = obturator nerve, scn = sciatic nerve, sgc = sigmoid colon, tvs = testicular vessels, ub = urinary bladder, ur = ureter. (d) CT scan of a female patient through the midpelvis shows the uterus (ut) and the left adnexa (adn). eivs = external iliac vessels, iivs = internal iliac vessels, lbl = large bowel loop, sbl = small bowel loops, ur = ureter. (e) CT scan through the cephalic portion of the greater sciatic foramen (gsf) shows the obturator internus (oi) and piriform (prf) muscles and the sciatic nerve (scn) close to the ischium, as well as the external iliac vessels (eivs), inferior epigastric vessels (ievs), inferior gluteal vessels (igvs), internal pudendal vessels (ipvs), obturator nerve (on), rectum (re), urinary bladder (ub), ureter (ur), and vas deferens (vd). (f) CT scan through the caudal portion of the sciatic foramen shows the urinary bladder (ub), rectum (re), sacrospinous ligament (ssl), seminal vesicles (sv), inferior gluteal vessels (igvs), and external iliac vessels (eivs). Note the cranial portion of the periprostatic venous plexus (pvp) located medial to the obturator internus muscle (oi).
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Figure 2b. (a) CT scan through the upper pelvis shows the ascending colon (ac), descending colon (dc), and small bowel loops (sbl) occupying the anterior portion of the pelvis. Note the relationship of the common iliac artery (cia), common iliac vein (civ), ureter (ur), and testicular vessels (tvs) to the psoas muscle (ps). il = iliac muscle, ilvs = iliolumbar vessels. (b) On a CT scan through the S2 vertebra, the common iliac vessels have divided into external (eivs) and internal (iivs) iliac vessels. Small bowel loops (sbl) and the sigmoid colon (sgc) occupy a major portion of the pelvis. Note also the left ureter (ur), the inferior epigastric vessels (ievs) posterior to the rectus muscle (rm), the deep circumflex iliac vessels (dcvs) medial to the iliac muscle (il), and the lumbosacral nerve (lsn) anterior to the sacrum. The femoral nerve (fmn) located in the groove between the iliac muscle and the psoas muscle (ps) is usually difficult to identify but is clearly depicted on this image. (c) CT scan through the midpelvis shows the external iliac artery (eia) and external iliac vein (eiv) coursing along the medial aspect of the iliopsoas muscle, the internal iliac vessels (iivs), and the superior gluteal vessels (sgvs) coursing through the upper portion of the greater sciatic foramen. dcvs = deep circumflex iliac vessels, ievs = inferior epigastric vessels, igvs = inferior gluteal vessels, on = obturator nerve, scn = sciatic nerve, sgc = sigmoid colon, tvs = testicular vessels, ub = urinary bladder, ur = ureter. (d) CT scan of a female patient through the midpelvis shows the uterus (ut) and the left adnexa (adn). eivs = external iliac vessels, iivs = internal iliac vessels, lbl = large bowel loop, sbl = small bowel loops, ur = ureter. (e) CT scan through the cephalic portion of the greater sciatic foramen (gsf) shows the obturator internus (oi) and piriform (prf) muscles and the sciatic nerve (scn) close to the ischium, as well as the external iliac vessels (eivs), inferior epigastric vessels (ievs), inferior gluteal vessels (igvs), internal pudendal vessels (ipvs), obturator nerve (on), rectum (re), urinary bladder (ub), ureter (ur), and vas deferens (vd). (f) CT scan through the caudal portion of the sciatic foramen shows the urinary bladder (ub), rectum (re), sacrospinous ligament (ssl), seminal vesicles (sv), inferior gluteal vessels (igvs), and external iliac vessels (eivs). Note the cranial portion of the periprostatic venous plexus (pvp) located medial to the obturator internus muscle (oi).
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Figure 2c. (a) CT scan through the upper pelvis shows the ascending colon (ac), descending colon (dc), and small bowel loops (sbl) occupying the anterior portion of the pelvis. Note the relationship of the common iliac artery (cia), common iliac vein (civ), ureter (ur), and testicular vessels (tvs) to the psoas muscle (ps). il = iliac muscle, ilvs = iliolumbar vessels. (b) On a CT scan through the S2 vertebra, the common iliac vessels have divided into external (eivs) and internal (iivs) iliac vessels. Small bowel loops (sbl) and the sigmoid colon (sgc) occupy a major portion of the pelvis. Note also the left ureter (ur), the inferior epigastric vessels (ievs) posterior to the rectus muscle (rm), the deep circumflex iliac vessels (dcvs) medial to the iliac muscle (il), and the lumbosacral nerve (lsn) anterior to the sacrum. The femoral nerve (fmn) located in the groove between the iliac muscle and the psoas muscle (ps) is usually difficult to identify but is clearly depicted on this image. (c) CT scan through the midpelvis shows the external iliac artery (eia) and external iliac vein (eiv) coursing along the medial aspect of the iliopsoas muscle, the internal iliac vessels (iivs), and the superior gluteal vessels (sgvs) coursing through the upper portion of the greater sciatic foramen. dcvs = deep circumflex iliac vessels, ievs = inferior epigastric vessels, igvs = inferior gluteal vessels, on = obturator nerve, scn = sciatic nerve, sgc = sigmoid colon, tvs = testicular vessels, ub = urinary bladder, ur = ureter. (d) CT scan of a female patient through the midpelvis shows the uterus (ut) and the left adnexa (adn). eivs = external iliac vessels, iivs = internal iliac vessels, lbl = large bowel loop, sbl = small bowel loops, ur = ureter. (e) CT scan through the cephalic portion of the greater sciatic foramen (gsf) shows the obturator internus (oi) and piriform (prf) muscles and the sciatic nerve (scn) close to the ischium, as well as the external iliac vessels (eivs), inferior epigastric vessels (ievs), inferior gluteal vessels (igvs), internal pudendal vessels (ipvs), obturator nerve (on), rectum (re), urinary bladder (ub), ureter (ur), and vas deferens (vd). (f) CT scan through the caudal portion of the sciatic foramen shows the urinary bladder (ub), rectum (re), sacrospinous ligament (ssl), seminal vesicles (sv), inferior gluteal vessels (igvs), and external iliac vessels (eivs). Note the cranial portion of the periprostatic venous plexus (pvp) located medial to the obturator internus muscle (oi).
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Figure 2d. (a) CT scan through the upper pelvis shows the ascending colon (ac), descending colon (dc), and small bowel loops (sbl) occupying the anterior portion of the pelvis. Note the relationship of the common iliac artery (cia), common iliac vein (civ), ureter (ur), and testicular vessels (tvs) to the psoas muscle (ps). il = iliac muscle, ilvs = iliolumbar vessels. (b) On a CT scan through the S2 vertebra, the common iliac vessels have divided into external (eivs) and internal (iivs) iliac vessels. Small bowel loops (sbl) and the sigmoid colon (sgc) occupy a major portion of the pelvis. Note also the left ureter (ur), the inferior epigastric vessels (ievs) posterior to the rectus muscle (rm), the deep circumflex iliac vessels (dcvs) medial to the iliac muscle (il), and the lumbosacral nerve (lsn) anterior to the sacrum. The femoral nerve (fmn) located in the groove between the iliac muscle and the psoas muscle (ps) is usually difficult to identify but is clearly depicted on this image. (c) CT scan through the midpelvis shows the external iliac artery (eia) and external iliac vein (eiv) coursing along the medial aspect of the iliopsoas muscle, the internal iliac vessels (iivs), and the superior gluteal vessels (sgvs) coursing through the upper portion of the greater sciatic foramen. dcvs = deep circumflex iliac vessels, ievs = inferior epigastric vessels, igvs = inferior gluteal vessels, on = obturator nerve, scn = sciatic nerve, sgc = sigmoid colon, tvs = testicular vessels, ub = urinary bladder, ur = ureter. (d) CT scan of a female patient through the midpelvis shows the uterus (ut) and the left adnexa (adn). eivs = external iliac vessels, iivs = internal iliac vessels, lbl = large bowel loop, sbl = small bowel loops, ur = ureter. (e) CT scan through the cephalic portion of the greater sciatic foramen (gsf) shows the obturator internus (oi) and piriform (prf) muscles and the sciatic nerve (scn) close to the ischium, as well as the external iliac vessels (eivs), inferior epigastric vessels (ievs), inferior gluteal vessels (igvs), internal pudendal vessels (ipvs), obturator nerve (on), rectum (re), urinary bladder (ub), ureter (ur), and vas deferens (vd). (f) CT scan through the caudal portion of the sciatic foramen shows the urinary bladder (ub), rectum (re), sacrospinous ligament (ssl), seminal vesicles (sv), inferior gluteal vessels (igvs), and external iliac vessels (eivs). Note the cranial portion of the periprostatic venous plexus (pvp) located medial to the obturator internus muscle (oi).
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Figure 2e. (a) CT scan through the upper pelvis shows the ascending colon (ac), descending colon (dc), and small bowel loops (sbl) occupying the anterior portion of the pelvis. Note the relationship of the common iliac artery (cia), common iliac vein (civ), ureter (ur), and testicular vessels (tvs) to the psoas muscle (ps). il = iliac muscle, ilvs = iliolumbar vessels. (b) On a CT scan through the S2 vertebra, the common iliac vessels have divided into external (eivs) and internal (iivs) iliac vessels. Small bowel loops (sbl) and the sigmoid colon (sgc) occupy a major portion of the pelvis. Note also the left ureter (ur), the inferior epigastric vessels (ievs) posterior to the rectus muscle (rm), the deep circumflex iliac vessels (dcvs) medial to the iliac muscle (il), and the lumbosacral nerve (lsn) anterior to the sacrum. The femoral nerve (fmn) located in the groove between the iliac muscle and the psoas muscle (ps) is usually difficult to identify but is clearly depicted on this image. (c) CT scan through the midpelvis shows the external iliac artery (eia) and external iliac vein (eiv) coursing along the medial aspect of the iliopsoas muscle, the internal iliac vessels (iivs), and the superior gluteal vessels (sgvs) coursing through the upper portion of the greater sciatic foramen. dcvs = deep circumflex iliac vessels, ievs = inferior epigastric vessels, igvs = inferior gluteal vessels, on = obturator nerve, scn = sciatic nerve, sgc = sigmoid colon, tvs = testicular vessels, ub = urinary bladder, ur = ureter. (d) CT scan of a female patient through the midpelvis shows the uterus (ut) and the left adnexa (adn). eivs = external iliac vessels, iivs = internal iliac vessels, lbl = large bowel loop, sbl = small bowel loops, ur = ureter. (e) CT scan through the cephalic portion of the greater sciatic foramen (gsf) shows the obturator internus (oi) and piriform (prf) muscles and the sciatic nerve (scn) close to the ischium, as well as the external iliac vessels (eivs), inferior epigastric vessels (ievs), inferior gluteal vessels (igvs), internal pudendal vessels (ipvs), obturator nerve (on), rectum (re), urinary bladder (ub), ureter (ur), and vas deferens (vd). (f) CT scan through the caudal portion of the sciatic foramen shows the urinary bladder (ub), rectum (re), sacrospinous ligament (ssl), seminal vesicles (sv), inferior gluteal vessels (igvs), and external iliac vessels (eivs). Note the cranial portion of the periprostatic venous plexus (pvp) located medial to the obturator internus muscle (oi).
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Figure 2f. (a) CT scan through the upper pelvis shows the ascending colon (ac), descending colon (dc), and small bowel loops (sbl) occupying the anterior portion of the pelvis. Note the relationship of the common iliac artery (cia), common iliac vein (civ), ureter (ur), and testicular vessels (tvs) to the psoas muscle (ps). il = iliac muscle, ilvs = iliolumbar vessels. (b) On a CT scan through the S2 vertebra, the common iliac vessels have divided into external (eivs) and internal (iivs) iliac vessels. Small bowel loops (sbl) and the sigmoid colon (sgc) occupy a major portion of the pelvis. Note also the left ureter (ur), the inferior epigastric vessels (ievs) posterior to the rectus muscle (rm), the deep circumflex iliac vessels (dcvs) medial to the iliac muscle (il), and the lumbosacral nerve (lsn) anterior to the sacrum. The femoral nerve (fmn) located in the groove between the iliac muscle and the psoas muscle (ps) is usually difficult to identify but is clearly depicted on this image. (c) CT scan through the midpelvis shows the external iliac artery (eia) and external iliac vein (eiv) coursing along the medial aspect of the iliopsoas muscle, the internal iliac vessels (iivs), and the superior gluteal vessels (sgvs) coursing through the upper portion of the greater sciatic foramen. dcvs = deep circumflex iliac vessels, ievs = inferior epigastric vessels, igvs = inferior gluteal vessels, on = obturator nerve, scn = sciatic nerve, sgc = sigmoid colon, tvs = testicular vessels, ub = urinary bladder, ur = ureter. (d) CT scan of a female patient through the midpelvis shows the uterus (ut) and the left adnexa (adn). eivs = external iliac vessels, iivs = internal iliac vessels, lbl = large bowel loop, sbl = small bowel loops, ur = ureter. (e) CT scan through the cephalic portion of the greater sciatic foramen (gsf) shows the obturator internus (oi) and piriform (prf) muscles and the sciatic nerve (scn) close to the ischium, as well as the external iliac vessels (eivs), inferior epigastric vessels (ievs), inferior gluteal vessels (igvs), internal pudendal vessels (ipvs), obturator nerve (on), rectum (re), urinary bladder (ub), ureter (ur), and vas deferens (vd). (f) CT scan through the caudal portion of the sciatic foramen shows the urinary bladder (ub), rectum (re), sacrospinous ligament (ssl), seminal vesicles (sv), inferior gluteal vessels (igvs), and external iliac vessels (eivs). Note the cranial portion of the periprostatic venous plexus (pvp) located medial to the obturator internus muscle (oi).
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The osseous walls of the pelvis are formed by the innominate bones anteriorly and laterally and the sacrum and coccyx posteriorly. The abdominal muscles, including the rectus abdominis, external and internal oblique, and transverse abdominis muscles, form the anterior and anterolateral walls of the pelvis. The iliac and psoas muscles join to form the iliopsoas muscle, which courses anterolaterally through the pelvis medial to the iliac wing. The greater sciatic foramen is bounded by the iliac bone superiorly, the sacrospinous ligament inferiorly, the sacrum posteriorly, and the ischium anteriorly. The sacrospinous ligament divides the greater sciatic foramen into superior and inferior portions. The important vasculature and nerve bundles exit the greater sciatic bundle cephalad to the level of the sacrospinous ligament. The piriform muscle originates from the lateral sacrum, exits the pelvis through the greater sciatic foramen, and inserts into the greater trochanter of the femur. The obturator internus muscle forms the lateral wall of the pelvis and the ischiorectal fossa. The gluteal muscles lie posterior to the innominate bones.
Major intrapelvic visceral structures include the urinary bladder, rectum, and sigmoid colon in both sexes, the uterus and ovaries in females, and the prostate gland and seminal vesicles in males. In addition, the superior portion of the pelvis is occupied by variable amounts of small bowel loops and the ascending, descending, and sigmoid colon. The uterus is seen as a soft-tissue-attenuation structure between the bladder and rectum. Although the position of the ovaries is highly variable, they are usually located posterolateral to the uterus between the external iliac vessels and the ureter. In the upper part of the pelvis, the ureters are anterior to the common iliac vessels and anteromedial to the psoas muscle. The ureters then course inferiorly and posteriorly, and at the level of the midpelvis are located posterior to the external iliac vessels, anterior to the internal iliac vessels, and medial to the obturator nerve and artery. At the level of the sciatic foramen, the ureters turn medially toward the lateral angle of the bladder.
The common iliac arteries course downward and laterally on the anterolateral surface of the fourth and fifth lumbar vertebrae along the medial aspect of the psoas muscles before dividing into the internal and external iliac arteries. The external iliac arteries run along the anteromedial border of the psoas muscles and continue as the common femoral arteries below the level of the inguinal ligament. The internal iliac arteries lie posteriorly in close relation to the lumbosacral plexus before dividing into multiple branches at the level of the greater sciatic foramen. The external iliac veins are situated posteromedial to the arteries. The right common iliac vein is posterolateral to the corresponding artery, whereas the left common iliac vein ascends obliquely from the medial side of the left common iliac artery to pass posterior to the right common iliac artery.
At the level of the pelvis, the testicular or ovarian vessels are located laterally on the psoas muscles and lateral to the ureters. The inferior epigastric artery runs superiorly within the lateral umbilical fold and then along the posterior surface of the rectus abdominis muscle. The deep circumflex iliac artery, along with the corresponding vein, ascends along the anterior abdominal wall laterally near the iliac crest and is located just medial to the anterior portion of the iliac muscle. The superior gluteal arteries arise from the posterior division of the internal iliac vessels and can be seen exiting the greater sciatic foramen anterior and cephalad to the piriform muscle. The internal pudendal and inferior gluteal vessels exit through the inferior part of the greater sciatic foramen between the piriform and coccygeal muscles.
The major pelvic nerve trunks can be visualized at CT. The greater sciatic nerve is formed from the sacral plexus. The nerve courses inferiorly on the ventral aspect of the piriform muscle, exits the greater sciatic foramen below the piriform muscle, and courses immediately posterior to the acetabulum. The femoral nerve can be seen posterior to the psoas muscle at about the L5 level. This nerve travels anteriorly and laterally in a fat plane between the iliac and psoas muscles; in this location, it is difficult to differentiate the femoral nerve from the iliac fascia. The nerve then joins the external iliac vessels and is located lateral to the common femoral artery below the inguinal ligament. The obturator nerve emerges from the medial edge of the psoas muscle above the pelvic brim and courses inferiorly, anterior to the internal iliac and obturator vessels and posterior to the external iliac vessels. The sacral canal contains five pairs of sacral nerve roots that exit through the corresponding sacral foramina. All the major nerve roots exit anteriorly, whereas the dorsal foramina carry only minor cutaneous nerves.
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Anterior or Lateral Transabdominal Approach
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Technique
In an anterior or lateral transabdominal approach, the needle is inserted through the lower abdominal wall muscles and the peritoneum (Fig 3). The inferior epigastric vessels are located immediately behind the rectus abdominis muscle; as such, they are easy to identify and should be avoided. The deep circumflex iliac vessels ascend along the anterior abdominal wall laterally near the iliac crest and should be avoided when using the lateral ap-proach. As mentioned earlier, bowel loops occupy a major portion of the upper pelvis. An attempt should be made to avoid bowel transgression. It is important to remember that bowel loops may change position and shape during the course of the biopsy. In addition, bowel peristalsis may deflect the needle from its projected path. Hence, CT scans should be obtained between incremental needle advancements to determine the exact location of the needle with respect to the bowel loops. Transgression of bowel loops with a thin 22-gauge needle is generally considered safe (Fig 4).
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Figure 3a. Anterior transabdominal approach. (a) CT scan shows a hypoattenuating mass (m) located anterior to the psoas muscle (ps) and iliac vessels (arrow). Note the potential access point between bowel loops (arrowheads). (b) CT scan clearly depicts an 18-gauge needle that was advanced between the bowel loops (arrowheads) for biopsy of the mass (m). Arrow indicates the iliac vessels. ps = psoas muscle.
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Figure 3b. Anterior transabdominal approach. (a) CT scan shows a hypoattenuating mass (m) located anterior to the psoas muscle (ps) and iliac vessels (arrow). Note the potential access point between bowel loops (arrowheads). (b) CT scan clearly depicts an 18-gauge needle that was advanced between the bowel loops (arrowheads) for biopsy of the mass (m). Arrow indicates the iliac vessels. ps = psoas muscle.
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Figure 4. Inadvertent bowel transgression. CT scan obtained during biopsy (anterior abdominal approach) of an external iliac lymph node (n) shows a 22-gauge needle transgressing a small bowel loop (arrow). Note the external iliac vessels (arrrowhead) located just anterolateral to the node.
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Modifications
The patient can be placed in a lateral decubitus position to move the bowel loops out of the projected needle path (Fig 5). Injection of saline solution through the guide needle can be used to displace intervening bowel loops and allow safe access to an otherwise unreachable lesion (Fig 5). It is theoretically possible that the injection of saline solution may interfere with lesion visualization, especially if the target lesion is of water attenuation; however, in our experience and in that of other authors (10), this has never been a real problem. A custom-tailored, curved 22-gauge needle advanced coaxially through a straight guide needle can be used to circumvent intervening structures (Fig 6). As described previously (11), the tip of the needle is grasped with a hemostat and bent to impart a curved shape. Occasionally, emptying the urinary bladder may allow access to deep lesions. CT fluoroscopy can also be used to facilitate percutaneous biopsy of masses with difficult or narrow access routes; it can be especially useful for biopsy of lesions that may be intermittently surrounded by bowel loops (12). Angling of the CT gantry is another technique that has been advocated to avoid intervening structures at CT-guided biopsy of the abdomen (13).
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Figure 5a. Modified lateral transabdominal approach. (a) Supine CT scan shows the large bowel (lb) and small bowel (sb) anterior to a node (n) located posterolateral to the common iliac vessels (arrow). (b) CT scan obtained with the patient in the left lateral decubitus position demonstrates a newly created window lateral to the large bowel (lb). n = common iliac node. (c) CT scan obtained during the injection of saline solution (arrows) through an 18-gauge needle shows further displacement of the large bowel (lb). n = common iliac node. (d) CT scan shows a 22-gauge needle that was advanced through the guide needle for biopsy of the node (n). lb = large bowel.
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Figure 5b. Modified lateral transabdominal approach. (a) Supine CT scan shows the large bowel (lb) and small bowel (sb) anterior to a node (n) located posterolateral to the common iliac vessels (arrow). (b) CT scan obtained with the patient in the left lateral decubitus position demonstrates a newly created window lateral to the large bowel (lb). n = common iliac node. (c) CT scan obtained during the injection of saline solution (arrows) through an 18-gauge needle shows further displacement of the large bowel (lb). n = common iliac node. (d) CT scan shows a 22-gauge needle that was advanced through the guide needle for biopsy of the node (n). lb = large bowel.
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Figure 5c. Modified lateral transabdominal approach. (a) Supine CT scan shows the large bowel (lb) and small bowel (sb) anterior to a node (n) located posterolateral to the common iliac vessels (arrow). (b) CT scan obtained with the patient in the left lateral decubitus position demonstrates a newly created window lateral to the large bowel (lb). n = common iliac node. (c) CT scan obtained during the injection of saline solution (arrows) through an 18-gauge needle shows further displacement of the large bowel (lb). n = common iliac node. (d) CT scan shows a 22-gauge needle that was advanced through the guide needle for biopsy of the node (n). lb = large bowel.
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Figure 5d. Modified lateral transabdominal approach. (a) Supine CT scan shows the large bowel (lb) and small bowel (sb) anterior to a node (n) located posterolateral to the common iliac vessels (arrow). (b) CT scan obtained with the patient in the left lateral decubitus position demonstrates a newly created window lateral to the large bowel (lb). n = common iliac node. (c) CT scan obtained during the injection of saline solution (arrows) through an 18-gauge needle shows further displacement of the large bowel (lb). n = common iliac node. (d) CT scan shows a 22-gauge needle that was advanced through the guide needle for biopsy of the node (n). lb = large bowel.
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Figure 6a. Modified lateral transabdominal approach. (a) Supine CT scan shows a soft-tissue mass (m) posterior to the urinary bladder (ub) and bowel loops (arrows). (b) CT scan obtained with the patient in the decubitus position shows a straight needle (arrowhead) that was advanced coaxially through a guide needle (arrow) but did not reach the center of the mass (m). ub = urinary bladder. (c) CT scan shows a curved 22-gauge needle (arrowhead) that was advanced coaxially through the guide needle to circumvent the urinary bladder (ub), thereby allowing safe biopsy of the mass (m).
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Figure 6b. Modified lateral transabdominal approach. (a) Supine CT scan shows a soft-tissue mass (m) posterior to the urinary bladder (ub) and bowel loops (arrows). (b) CT scan obtained with the patient in the decubitus position shows a straight needle (arrowhead) that was advanced coaxially through a guide needle (arrow) but did not reach the center of the mass (m). ub = urinary bladder. (c) CT scan shows a curved 22-gauge needle (arrowhead) that was advanced coaxially through the guide needle to circumvent the urinary bladder (ub), thereby allowing safe biopsy of the mass (m).
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Figure 6c. Modified lateral transabdominal approach. (a) Supine CT scan shows a soft-tissue mass (m) posterior to the urinary bladder (ub) and bowel loops (arrows). (b) CT scan obtained with the patient in the decubitus position shows a straight needle (arrowhead) that was advanced coaxially through a guide needle (arrow) but did not reach the center of the mass (m). ub = urinary bladder. (c) CT scan shows a curved 22-gauge needle (arrowhead) that was advanced coaxially through the guide needle to circumvent the urinary bladder (ub), thereby allowing safe biopsy of the mass (m).
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Target Lesions
The transabdominal approach through the lower anterior or lateral abdominal wall is suitable for lesions that are situated either cranial to the level of the urinary bladder or anterior or lateral to the bladder. This approach is commonly used for biopsy of lymph nodes that are located (a) along the common iliac vessels or (b) anterior or lateral to the psoas muscles. Mesenteric masses may also be accessible with this approach. Masses located along the external iliac vessels can be accessed, provided intervening bowel loops can be avoided.
Advantages and Disadvantages
The major advantage of the transabdominal approach is that the patient remains in a comfortable supine position during the procedure, which becomes especially important during long procedures. On the other hand, deep pelvic lesions are often difficult to reach with this approach because of intervening bowel and bladder (as well as uterus and adnexa in females). The potential risk of inadvertent transgression of bowel (Fig 4) or bladder limits the size of the biopsy needle that can be used, and the use of thin needles precludes the option of obtaining a core specimen. In addition, this approach can be painful because of peritoneal transgression. Finally, the presence of abdominal wounds, surgical dressings, or colostomy bags may preclude immediate access in postoperative patients.
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Transgluteal Approach
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Technique
For the transgluteal approach, the patient is usually placed in the prone or prone oblique position. Alternatively, a lateral decubitus position can be used in patients who are unable to lie prone. This approach is also called the transsciatic approach because the needle traverses the greater sciatic foramen. The needle should be inserted through the sacrospinous ligament (Fig 7) in the caudal part of the notch below the level of the piriform muscle to avoid injury to the gluteal vessels and the sacral plexus, which lie anterior to the muscle (1,4,6). Injury to the sciatic nerve and gluteal vessels can be avoided by placing the needle close to the edge of the sacrum (Fig 7) because the neurovascular structures exit the pelvis in the anterior portion of the notch, close to the ischium. Care should be taken to avoid the rectum and the terminal branches of the internal iliac artery (inferior gluteal and internal pudendal arteries), which course in the sciatic foramen. Use of an 18-gauge guide needle serves to stabilize the flexible 22-gauge biopsy needle, thus preventing deflection of the thin needle from its intended path.
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Figure 7. Transgluteal approach. CT scan shows a needle that passes through the sacrospinous ligament (arrow) close to the sacrum and posterior to the inferior gluteal vessels (arrowhead) for biopsy of a presacral mass (m).
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Target Lesions
The transgluteal approach is suitable for biopsy of lesions located in the presacral (Fig 7) and perirectal (Fig 8) regions. In addition, lesions located posterior or posterolateral to the urinary bladder (Fig 9) and adnexal masses (Fig 10) can be accessed with this technique. In general, this approach is used for posterior pelvic lesions in the lower part of the pelvis at the level of the greater sciatic foramen that are not accessible with an anterior approach because of intervening bowel, bladder, uterus, and iliac vessels.
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Figure 8. Transgluteal approach. CT scan shows a needle that traverses the sacrospinous ligament (arrowheads) and the inferior portion of the piriform muscle (straight arrow) for biopsy of a perirectal nodule (curved arrow).
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Figure 9. Transgluteal approach. CT scan shows a curved inner needle (arrowhead) that was advanced coaxially through a guide needle for biopsy of an internal iliac lymph node (curved arrow) posterior to the urinary bladder. The needles were inserted through the sacrospinous ligament and between the rectum (re) and the inferior gluteal vessels (straight arrow).
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Figure 10. Transgluteal approach. Prone CT scan shows a needle (arrowhead) that traverses the piriform muscle (prf) adjacent to the sacrum (sa) and medial to the internal iliac vessel branches (arrows) for biopsy of an adnexal mass (m).
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Advantages and Disadvantages
The transgluteal approach makes it possible to avoid peritoneal transgression and minimize the risk of injury to the bladder, bowel loops and external iliac vessels. In addition, a needle advanced through the gluteal muscles is more stable and less prone to deflection than one that is advanced transabdominally. However, the prone position may be uncomfortable for the patient. Obese patients and patients with abdominal wounds, multiple surgical dressings, drainage tubes, or colostomy bags may not be able to lie prone. The prone position is also difficult to achieve and sustain for patients with respiratory compromise. In addition, there is a risk of injury to the sciatic nerve, gluteal vessels, and branches of the sacral plexus. Moreover, gluteal muscle transgression can occasionally be painful, and a distended rectum may obstruct the needle path.
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Anterolateral Extraperitoneal Approach
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Technique
The anterolateral extraperitoneal approach involves needle transgression through the iliopsoas muscle (7,14). A coaxial technique is used, whereby an 18-gauge guide needle is inserted medial to the iliac crest and advanced through the iliopsoas muscle toward the target lesion, using CT to check the trajectory of the needle and ensure that the needle remains lateral to the iliac vessels. When the trajectory and position of the guide needle are considered satisfactory, a 22-gauge Chiba needle of an appropriate length is advanced coaxially through the guide needle into the lesion (Figs 11–13). The deep circumflex iliac vessels are located just medial to the anterior portion of the iliac muscle and should be avoided when using this approach. For most patients who have previously undergone diagnostic contrast material–enhanced CT, the preliminary unenhanced CT scans are sufficient for biopsy planning. However, contrast material administration is occasionally necessary to differentiate vessels from lymph nodes (Fig 14). Before coursing medially to enter the base of the urinary bladder, the ureter is located posterior to the external iliac vessels and anterior to the internal iliac vessels; consequently, care should be taken to avoid puncturing the ureter.
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Figure 11a. Anterolateral approach. (a) CT scan shows an obturator lymph node (arrow). Note how the urinary bladder (ub), sigmoid colon (sgc), and external iliac vessels (arrowhead) obstruct an anterior approach. A transgluteal approach was obstructed by the sacrum. (b) CT scan shows a needle that was advanced through the iliopsoas muscle medial to the external iliac vessels (arrowhead) for biopsy of the node (arrow).
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Figure 11b. Anterolateral approach. (a) CT scan shows an obturator lymph node (arrow). Note how the urinary bladder (ub), sigmoid colon (sgc), and external iliac vessels (arrowhead) obstruct an anterior approach. A transgluteal approach was obstructed by the sacrum. (b) CT scan shows a needle that was advanced through the iliopsoas muscle medial to the external iliac vessels (arrowhead) for biopsy of the node (arrow).
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Figure 12a. Anterolateral approach. (a) CT scan shows an obturator node (straight arrow). Note how the external (curved arrow) and internal (arrowhead) iliac vessels, rectum (re), and urinary bladder (ub) preclude direct access. (b) CT scan shows a needle (arrowhead) that was advanced through the iliopsoas muscle for biopsy of the node (arrow).
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Figure 12b. Anterolateral approach. (a) CT scan shows an obturator node (straight arrow). Note how the external (curved arrow) and internal (arrowhead) iliac vessels, rectum (re), and urinary bladder (ub) preclude direct access. (b) CT scan shows a needle (arrowhead) that was advanced through the iliopsoas muscle for biopsy of the node (arrow).
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Figure 13. Anterolateral approach. CT scan shows a needle that was advanced through the iliopsoas muscle for biopsy of an external iliac node (arrow) located anterior to the external iliac vessels (curved arrow). A direct anterior approach was obstructed by bowel loops (arrowheads).
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Figure 14a. Anterolateral approach. (a) Contrast-enhanced CT scan shows a soft-tissue mass (m) engulfing the iliac vessels (arrows). The presence of bowel loops (b) precluded a direct anterior approach. The straight line at the upper left represents the planned needle trajectory. (b) CT scan shows a needle (arrow) that passes lateral to the bowel (b) and through the iliopsoas muscle for biopsy of the mass (m).
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Figure 14b. Anterolateral approach. (a) Contrast-enhanced CT scan shows a soft-tissue mass (m) engulfing the iliac vessels (arrows). The presence of bowel loops (b) precluded a direct anterior approach. The straight line at the upper left represents the planned needle trajectory. (b) CT scan shows a needle (arrow) that passes lateral to the bowel (b) and through the iliopsoas muscle for biopsy of the mass (m).
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Modifications
When the location of the external iliac vessels and the slope of the iliac wing preclude a straight route to the target lesion, a curved 22-gauge needle advanced coaxially through a straight 18-gauge guide needle can be used to obtain a biopsy specimen (Fig 15).
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Figure 15a. Modified anterolateral approach. (a) CT scan shows a loculated fluid collection (fl) adjacent to the external iliac vessels (arrow). A direct approach was obstructed by bowel loops (b). (b) CT scan shows a curved 22-gauge needle (straight arrow) that has been advanced through a straight 18-gauge guide needle (curved arrow) and passes anterior to the iliac vessels (arrowhead) and into the fluid collection (fl).
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Figure 15b. Modified anterolateral approach. (a) CT scan shows a loculated fluid collection (fl) adjacent to the external iliac vessels (arrow). A direct approach was obstructed by bowel loops (b). (b) CT scan shows a curved 22-gauge needle (straight arrow) that has been advanced through a straight 18-gauge guide needle (curved arrow) and passes anterior to the iliac vessels (arrowhead) and into the fluid collection (fl).
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Target Lesions
The anterolateral extraperitoneal approach is ideally suited for percutaneous biopsy of lesions located along the medial aspect of the iliopsoas muscle. This approach provides safe access to obturator or deep external iliac (Figs 11, 12), anterior external iliac (Fig 13), and internal iliac lymph nodes. The anterior transabdominal approach to these lesions is obstructed by intervening bladder, bowel, uterus, and iliac vessels. These nodes are also usually not accessible with the posterior transgluteal approach because of the presence of osseous structures (Fig 11) or internal iliac vessel branches (Fig 12) in the needle path. In addition, a transgluteal approach to internal iliac or obturator nodes often requires needle placement close to the ischial tuberosity, which increases the risk of injury to the sciatic nerve and gluteal vessels. Soft-tissue masses (Fig 14) or loculated fluid collections (Fig 15) along the lateral pelvic sidewall, adnexal masses (Fig 16), and common iliac nodes located posterior to the vessels can also be sampled with this technique. Furthermore, this approach can occasionally be used for biopsy of posteriorly located lesions in patients who have difficulty lying prone because of recent surgery, colostomy bags, or abdominal wounds (14).
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Figure 16a. Anterolateral approach. (a) CT scan shows how a direct anterior or posterior approach to an adnexal mass (m) is obstructed by bowel (b) and by the external (arrow) and internal (arrowheads) iliac vessels. (b) CT scan shows a needle that has been advanced through the iliopsoas muscle and passes medial to the iliac vessels (arrow) for biopsy of the mass (m).
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Figure 16b. Anterolateral approach. (a) CT scan shows how a direct anterior or posterior approach to an adnexal mass (m) is obstructed by bowel (b) and by the external (arrow) and internal (arrowheads) iliac vessels. (b) CT scan shows a needle that has been advanced through the iliopsoas muscle and passes medial to the iliac vessels (arrow) for biopsy of the mass (m).
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Advantages and Disadvantages
Although some radiologists believe that advancing the needle through the iliopsoas muscle can be painful, it has been our experience that the anterolateral approach through the iliopsoas muscle is less painful and better tolerated by patients than the anterior transperitoneal approach because it does not transgress the peritoneum (14). Because the anterolateral approach poses no risk of bowel or bladder injury, use of large-caliber needles and performance of core biopsies is possible. The iliac bone prevents lateral deviation of the needle, allowing accurate needle placement. Advancement of the biopsy needle through the iliopsoas muscle stabilizes the needle, permitting long needle paths without the risk of deflection due to anterior abdominal wall movement or bowel peristalsis, which is a potential problem with the anterior transabdominal approach. Another advantage of the anterolateral extraperitoneal approach is that it is performed with the patient lying comfortably in a supine position, which is especially useful for patients who are unable to lie prone owing to obesity, abdominal wounds, or colostomy bags.
However, needle advancement through the iliopsoas muscle poses a theoretical risk of injury to the femoral nerve, which runs in the fat plane separating the iliac and psoas muscles. Still, injury is unlikely because the femoral nerve is located at the medial end of the fissure between the muscles, whereas the needle usually passes through the lateral portion of the fissure. In addition, we believe that the guide needle is not sharp enough to puncture and injure the nerve, but only displaces the nerve. We did not encounter any complications directly attributable to the transiliopsoas approach during 57 biopsies performed with this technique (14).
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Transosseous (Transsacral or Transiliac) Approach
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Technique
In the transsacral approach, the guide needle is advanced through the sacrum, taking care to avoid the sacral foramina and sacral canal so as not to injure the sacral nerve roots and the sacral plexus (Figs 17, 18). It is especially important to avoid the ventral neural foramina because they contain the major nerve roots. The needle should be advanced through the medial portion of the sacrum between the central canal and the foramina, or through the extreme lateral part of the sacrum. Occasionally, bone involvement by tumor extension may create a path for needle advancement (Fig 19).
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Figure 17. Transsacral approach. CT scan shows the use of transsacral access for biopsy of a presacral lesion (m) located above the level of the sciatic foramen, which precludes a transgluteal approach. An anterior approach was obstructed by bowel loops. The needle has been advanced through the sacrum lateral to the sacral foramen (arrow).
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Figure 18a. Transsacral approach. (a) Supine CT scan shows a soft-tissue mass (m) located posterior to the urinary bladder (ub) and sigmoid colon (sgc) and anterior to the rectum (re). Branches of the internal iliac vessels (arrow) precluded a transgluteal approach. (b) Prone CT scan shows that a transsacral approach with a curved inner needle (arrowhead) allowed safe access to the mass (m).
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Figure 18b. Transsacral approach. (a) Supine CT scan shows a soft-tissue mass (m) located posterior to the urinary bladder (ub) and sigmoid colon (sgc) and anterior to the rectum (re). Branches of the internal iliac vessels (arrow) precluded a transgluteal approach. (b) Prone CT scan shows that a transsacral approach with a curved inner needle (arrowhead) allowed safe access to the mass (m).
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Abstract
Introduction
