(Radiology. 1999;213:901-904.)
© RSNA, 1999
Percutaneous Interventions in the Presacral Space: CT-guided Precoccygeal Approach-Early Experience1
Jonathan J. Trambert, MD
1 From the Department of Radiology, J. D. Weiler Hospital of the Albert Einstein College of Medicine, Division of the Montefiore Medical Center, 1825 Eastchester Rd, Bronx, NY 10461. Received July 6, 1998; revision requested August 5; final revision received April 13, 1999; accepted July 1, 1999. Address reprint requests to the author (e-mail: jtrambert@pol.net).
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Abstract
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A computed tomography (CT)-guided, precoccygeal approach was used for interventions in the presacral space in four patients (three biopsies, one abscess drainage). Localization comprised palpation of the coccyx and measurement of the distance from the coccyx to the lesion on a prone CT scan. This approach provided an easy, straight vector to all points in the presacral space and involved no radiation exposure to the physician.
Index terms: Abscess, percutaneous drainage, 339.242, 80.242 • Biopsies, technology, 339.1261, 339.1262, 80.126 • Computed tomography (CT), guidance, 339.126 • Pelvic organs, abscess, 80.242 • Pelvic organs, biopsy, 80.1261 • Pelvic organs, interventional procedure, 80.1261 • Sacrum, neoplasms, 339.30, 80.30
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Introduction
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Patients who have undergone resection of rectal carcinoma, with or without a primary anastomosis, can develop soft-tissue thickening in the presacral space as a consequence of granulation tissue, scarring, and fibrosis. Unfortunately, presacral thickening can also represent recurrent carcinoma (1). Although cross-sectional imaging, particularly magnetic resonance imaging, can sometimes allow differentiation between posttreatment fibrosis and recurrent tumor (2), biopsy may be necessary. Primary end-to-end rectal anastomosis can also be complicated by anastomotic leak and consequent development of presacral abscess (3). Because of the sacrum, routes of access to the presacral space for biopsy or abscess drainage are limited. Approaches that have been described include the transgluteal approach via the greater sciatic foramen with computed tomographic (CT) guidance (1,4), transrectal approach with ultrasonographic (US) guidance (5), and dorsal approach through the sacrum itself (6).
Transgluteal interventions pose a substantial risk for sciatica and local insertion site pain, particularly when large-bore abscess drainage catheters are placed via this route (4,7). Furthermore, masses or collections located immediately anterior to the sacrum and/or in the middle of the pelvis superior to the greater sciatic foramen may be difficult or even impossible to reach with these approaches. A direct lateral approach can be taken to lesions directly anterior to the sacrum that are unreachable with the transsciatic, transgluteal approach (8). However, this could entail traversing a prohibitive distance through buttock fat and gluteal muscles before reaching the presacral space, especially in obese patients. A transperineal CT-guided paracoccygeal approach and a transperineal fluoroscopy-guided presacral approach have been described for drainage of presacral abscesses (9,10).
In the technique modification described herein, the coccyx is used as a palpable bone landmark for choosing the site of needle entry, and transverse CT images are obtained to help calculate how far cephalad the access needle must be advanced to reach the pathologic condition, which simplifies the needle trajectory geometry for planning biopsy or abscess drainage in the presacral space. Furthermore, because no fluoroscopy is needed, there is no radiation exposure to the physician. Precoccygeal and presacral anatomic considerations are also discussed as they relate to interventions in this area.
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Materials and Methods
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Between April 1987 and April 1997, three patients (one man and two women; age range, 63–71 years; mean age, 68 years) underwent CT-guided (CT 9800; GE Medical Systems, Milwaukee, Wis) biopsy of presacral masses suspected to be recurrent tumor after resection of rectal carcinoma, and one male patient (age, 71 years) underwent percutaneous drainage of a presacral abscess that was a consequence of a leak after rectal carcinoma resection and primary end-to-end anastomosis.
After informed consent had been obtained, each patient was placed prone on the CT table, and the lesion was localized with transverse CT images that were continued caudad to the coccyx. On the basis of findings on these images and knowledge of the spacing interval between each image, the distance from the tip of the coccyx to the lesion was calculated. The coccyx was palpated, and the skin site just anterior to the tip of the coccyx was marked with indelible ink. The skin around that site was prepared and draped in a sterile manner, with care taken to isolate the anus from the puncture site by using the drape.
Local anesthesia was administered at the puncture site, after which a small nick was made in the skin. A 22-gauge spinal needle was then used to deliver deep anesthesia with lidocaine, by "walking" the needle cranially along the sacrum while injecting lidocaine, until the needle reached a depth calculated to be the distance from the coccygeal tip to the lesion. For the biopsies, the mass was then approached with the biopsy needle along the same vector (Fig 1), and the needle tip location within the mass was confirmed on CT images (Fig 2). Then, a specimen was obtained.
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Figure 1. Precoccygeal approach to biopsy of presacral mass. Lateral prone CT scan demonstrates biopsy needle (arrowheads) in superiorly directed approach via puncture site just anterior to tip of coccyx (arrow).
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The approach was similar for the patient who underwent percutaneous precoccygeal drainage of a presacral abscess (Fig 3a). After local anesthesia was administered in the same manner used for the biopsies, the needle of a coaxial introducer set (Accustick; Medi-tech/Boston Scientific, Watertown, Mass) was advanced cranially anterior to the coccyx and sacrum to the calculated depth, and its position within the abscess was confirmed on CT images (Fig 3b). The needle vector allowed a guide wire to be advanced directly up into the main cavity of the abscess in the middle of the pelvis (Fig 3c). Then, a 14-F sump drainage catheter (vanSonnenberg; Medi-tech/Boston Scientific) was advanced over a guide wire into the abscess cavity (Fig 3d). The catheter was secured to the skin with sutures placed away from the anus.
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Figure 3a. Percutaneous precoccygeal drainage of posterior pelvic abscess secondary to leaking primary end-to-end rectal anastomosis after low anterior resection of rectal carcinoma. (a) Transverse supine CT image demonstrates inferior extent of presacral abscess (arrow) near rectal anastomosis (arrowheads). (b) Transverse prone CT image demonstrates tip of access needle (arrow) in lower extent of abscess. (c) Transverse prone CT image demonstrates 0.018-inch introducer wire (arrows) coiled in main part of abscess cavity in the middle of the pelvis. (d) Lateral prone CT scan illustrates precoccygeal, presacral path of drainage catheter to abscess. (e) Transverse supine CT image, at level similar to that in c, demonstrates drainage catheter (arrows) and complete evacuation of abscess.
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Figure 3b. Percutaneous precoccygeal drainage of posterior pelvic abscess secondary to leaking primary end-to-end rectal anastomosis after low anterior resection of rectal carcinoma. (a) Transverse supine CT image demonstrates inferior extent of presacral abscess (arrow) near rectal anastomosis (arrowheads). (b) Transverse prone CT image demonstrates tip of access needle (arrow) in lower extent of abscess. (c) Transverse prone CT image demonstrates 0.018-inch introducer wire (arrows) coiled in main part of abscess cavity in the middle of the pelvis. (d) Lateral prone CT scan illustrates precoccygeal, presacral path of drainage catheter to abscess. (e) Transverse supine CT image, at level similar to that in c, demonstrates drainage catheter (arrows) and complete evacuation of abscess.
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Figure 3c. Percutaneous precoccygeal drainage of posterior pelvic abscess secondary to leaking primary end-to-end rectal anastomosis after low anterior resection of rectal carcinoma. (a) Transverse supine CT image demonstrates inferior extent of presacral abscess (arrow) near rectal anastomosis (arrowheads). (b) Transverse prone CT image demonstrates tip of access needle (arrow) in lower extent of abscess. (c) Transverse prone CT image demonstrates 0.018-inch introducer wire (arrows) coiled in main part of abscess cavity in the middle of the pelvis. (d) Lateral prone CT scan illustrates precoccygeal, presacral path of drainage catheter to abscess. (e) Transverse supine CT image, at level similar to that in c, demonstrates drainage catheter (arrows) and complete evacuation of abscess.
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Figure 3d. Percutaneous precoccygeal drainage of posterior pelvic abscess secondary to leaking primary end-to-end rectal anastomosis after low anterior resection of rectal carcinoma. (a) Transverse supine CT image demonstrates inferior extent of presacral abscess (arrow) near rectal anastomosis (arrowheads). (b) Transverse prone CT image demonstrates tip of access needle (arrow) in lower extent of abscess. (c) Transverse prone CT image demonstrates 0.018-inch introducer wire (arrows) coiled in main part of abscess cavity in the middle of the pelvis. (d) Lateral prone CT scan illustrates precoccygeal, presacral path of drainage catheter to abscess. (e) Transverse supine CT image, at level similar to that in c, demonstrates drainage catheter (arrows) and complete evacuation of abscess.
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Figure 3e. Percutaneous precoccygeal drainage of posterior pelvic abscess secondary to leaking primary end-to-end rectal anastomosis after low anterior resection of rectal carcinoma. (a) Transverse supine CT image demonstrates inferior extent of presacral abscess (arrow) near rectal anastomosis (arrowheads). (b) Transverse prone CT image demonstrates tip of access needle (arrow) in lower extent of abscess. (c) Transverse prone CT image demonstrates 0.018-inch introducer wire (arrows) coiled in main part of abscess cavity in the middle of the pelvis. (d) Lateral prone CT scan illustrates precoccygeal, presacral path of drainage catheter to abscess. (e) Transverse supine CT image, at level similar to that in c, demonstrates drainage catheter (arrows) and complete evacuation of abscess.
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Results
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Results in the three presacral biopsies were positive for recurrent rectal carcinoma in one case (Fig 2) and fibrotic tissue compatible with postoperative scar tissue in two cases. The patient in whom the presacral abscess was drained tolerated the precoccygeal catheter entry site without excessive discomfort and without complication. The abscess was successfully evacuated (Fig 3e) and, after a temporary diverting colostomy, the anastomotic leak healed, and the drainage catheter was removed. In all four patients, the prone, precoccygeal puncture approach was quick and well tolerated.
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Discussion
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Possible routes for percutaneous access to the presacral space that have been described include the transgluteal greater sciatic foramen, transrectal, transgluteal-lateral, and transperineal approaches (1,4,5,8–10). Imaging guidance can be with fluoroscopy, US, or CT. Fluoroscopic guidance, especially lateral fluoroscopy to help visualization of a needle anterior to the sacrum, potentially entails considerable radiation exposure to the physician's hands and is potentially cumbersome (10). Transrectal US-guided drainage of pelvic abscesses has been described (11), as has transrectal US-guided prostate biopsy (12), and can thus potentially be used for biopsy of presacral masses. Obviously, the transrectal route is unavailable in patients who have undergone abdominoperineal resection and is ill suited for masses or abscesses out of reach of digital rectal examination. US guidance has been used for the performance of transperineal prostate biopsy in patients who have undergone abdominoperineal resection (13) and could conceivably be used to perform transperineal drainage of abscesses very close to the skin. However, transperineal US depiction of presacral masses or abscesses is limited by rapid image degradation with distance and the limited transducer contact area with the perineum, especially in patients with an intact anus.
The technique described herein takes advantage of a simple anatomic principle: A needle advanced in a cranial direction, just anterior to the palpable coccygeal tip, can reach virtually any point in the presacral space without having to traverse the rectum or any other major structure, as long as the needle tip is kept just anterior to the sacrum as it is advanced. Making a puncture site immediately anterior to the palpable coccyx centers the beginning of the cephalic access vector essentially in the midline, and walking the needle up along the anterior surface of the sacrum effectively keeps the tip of the needle in the presacral space. The needle is essentially guided to the mass or abscess by the curvature of the sacrum, with little need to fine tune the needle position for biopsy or commencement of abscess drainage. The distance the needle must be advanced to reach the lesion is easily calculable on the sequential transverse images obtained between the lesion and the coccygeal tip.
Anatomic structures that are potentially affected by the midline precoccygeal puncture approach include the middle sacral artery, coccygeal gland or body, anococcygeal ligament, and sympathetic ganglion impar. The middle sacral artery is the terminal branch of the abdominal aorta that arises at the aortic bifurcation. It then courses immediately anterior to the sacrum in the midline and terminates in the glomus coccygeum or coccygeal gland or body. The middle sacral artery is potentially susceptible to trauma as the needle is walked superiorly along the sacrum to a lesion, but if the walking maneuver is performed with a 22- or 21-gauge biopsy or introduction needle, clinically important hemorrhage is unlikely. Furthermore, patients who have undergone resection of rectal carcinoma will likely have considerable scarring or fibrosis in the presacral space, which further decreases the likelihood of hemorrhage from the middle sacral artery. The coccygeal gland or body is an approximately 2.5-mm-diameter structure of unknown function that lies immediately anterior to the coccyx (14). The main concern with regard to a puncture tract involving the coccygeal gland is bleeding from the tuft of vessels that compose it, but it is at the terminus of a vessel and easily accessible with manual compression. Problematic bleeding was not encountered in the four patients in this series.
The anococcygeal ligament is the median raphe that runs from the posterior part of the anus to the coccyx and constitutes the midline meeting of the posterior fibers of the levator ani muscles and external anal sphincter (15). There are no actual muscle fibers in the presacral space more superiorly. The sympathetic ganglion impar also lies just anterior to the coccyx. It is the caudal termination of the paired paravertebral sympathetic chains, where the two chains converge (16,17). Trauma to the sympathetic chains in the pelvis can potentially have adverse visceral consequences, such as impotence or bladder dysfunction. The ganglion impar, however, lies caudad to all visceral sympathetic nerve branches. Furthermore, use of a midline precoccygeal-presacral approach decreases the likelihood of trauma to the sacral motor and sensory nerve roots that exit the sacral foramina or to the paired sympathetic chains, structures potentially jeopardized with use of a more lateral paracoccygeal vector. The relative dearth of muscle and neural structures encountered in this approach is especially important when dealing with large-bore abscess drainage catheters, which, when placed via the greater sciatic foramen approach, can irritate or damage the sciatic nerve and cause puncture site pain due to a path through the gluteal muscle. The precoccygeal drainage catheter in the one patient in this series was tolerated well. Furthermore, because the superiorly directed precoccygeal approach provides a straight line vector to all points in the presacral space, including those in the middle of the pelvis, this approach was found to be useful for access to small presacral masses (Fig 2) or a presacral abscess located primarily in the middle of the pelvis cephalad to the greater sciatic foramen (Fig 3c).
Use of the coccygeal tip as a palpable bone landmark and of transverse CT images to calculate the length of the needed cephalic access vector from the perineal skin to the lesion simplifies the geometry in the planning of biopsy of a mass or drainage of an abscess in the presacral space and eliminates radiation exposure to the physician performing these procedures compared to that with the fluoroscopically guided approach. In my opinion, this technique will potentially be made even simpler and of greater value with the availability of stacked multiplanar reconstructions from images acquired at helical CT of the pelvis. Sagittal reconstruction of the plane including the coccygeal tip and the presacral lesion will potentially allow distance measurement and vector plotting directly by the computer.
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Footnotes
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Author contributions: Guarantor of integrity of entire study, J.J.T.
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References
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Abstract
Introduction
