Sonographically-guided Parasacrum Infrapiriformis Drainage of Deep Pelvic Abscesses: An Anatomical Safety Study Using SYNAPSE VINCENT

Abstract

Objectives: Deep pelvic abscesses are surrounded by the pelvic bones, bladder, gynecological organs, intestinal tract, and nerve and vascular systems, and are approached by various routes for drainage. The transgluteal approach is often performed under computed tomography guidance; however, if ultrasonography can be used to confirm the approach, it is considered more effective because it reduces radiation exposure and allows for real-time puncture under sonographic and fluoroscopic guidance.

Methods: This retrospective study was conducted at Tobata Kyoritsu Hospital (Fukuoka, Japan) between April 1, 2021, and December 31, 2022. Sonographically guided transgluteal drainage with fluoroscopy was performed in five consecutive cases of deep pelvic abscesses using a 3D image analysis system (SYNAPSE VINCENT) to study the anatomy for safe puncture.

Results: Three patients had postoperative abscesses from colorectal cancer, one caused by perforation of the appendicitis, and one caused by sigmoid diverticulitis. The average drainage duration was 11 days (SD = 6.7). No complications, such as bleeding or nerve damage, were observed.

Conclusions: We constructed a 3D image of the puncture route of the trans greater sciatic foramen using SYNAPSE VINCENT to objectively comprehend the anatomy and puncture route. The ideal transgluteal approach is to insert the catheter as close to the sacrum as possible at the level of the infrapiriformis. The parasacrum infrapiriformis approach can be performed safely and easily using ultrasound guidance and fluoroscopy.

Keywords: SYNAPSE VINCENT; pelvic abscess; sonography; transgluteal drainage.

Figure 1.

(a) An 85-year-old woman with pelvic abscess (arrow) after colorectal cancer surgery. (b) The sonogram shows the puncture needle tip (arrow head) in the collected fluid from a transgluteal approach. Shadowing (open arrow) at the left edge of the image is originating from the sacrum (coccyx) (Supplementary-material). (c) Fluoroscopic imaging allows the shape of the abscess cavity to be determined and facilitates the manipulation of guidewire and tube placement. (d) A fluoroscopy can be used in conjunction with irrigoscopy.

Figure 2.

(a) Axial computed tomography (CT) image at the level of the sacrospinous ligament (open arrow) showing the rectum compressed dorsal to the abscess cavity (asterisk). (b) Sonography shows the high echoic lesion (open arrow) originating from the sacrum (coccyx). As with the CT scan, a rectum is visible that had been compressed into the abscess cavity. (c) Tubes can be placed appropriately in the abscess cavity using fluoroscopy.

Figure 3.

(a) Axial computed tomography (CT) image at the level of the piriformis muscle (asterisk) of a 73-year-old woman with pelvic abscess due to diverticulitis of the sigmoid colon. (b) Drainage was performed in the prone position under local anesthesia only. The lower end of the sacrum or coccyx is palpated as a merkmal and punctured cephalad and medially from near the sacrum or coccyx. (c) Sonography shows ascites in the Douglas pouch of the rectum and abscess formation in the sigmoid mesentery, similar to CT images. (d) Fluoroscopic imaging allows easy manipulation of the guidewire. (e) CT scan after drainage showing disappearance of the abscess cavity and puncture avoiding the piriform muscle (asterisk).

Figure 4.

(a) The greater sciatic foramen is a large foramen bounded by the ilium and sciaticum, sacrotuberous ligament (connecting the sacrum and sciatic tuberosity), and sacrospinous ligament (connecting the sacrum and sciatic spine). (b) The piriform muscle passes through the center of this foramen and is divided into upper and lower piriform foramina (circle). (c) The superior foramen contains the superior gluteal arteriovenous system and nerves. The inferior foramen is passed through the inferior gluteal arteriovenous system and nerve: the sciatic nerve, the internal genital arteriovenous system, and the genital nerves. These nerves and vessels run in a lateral and anterior direction under the piriform muscle; therefore, an avascular area exists on the inner side. The puncture route passes through this infrapiriform foramen. (d) The parasacral infrapiriformis approach, which passes through the inferior piriform foramen and punctures the cephalad and medially.