Endoscopic Ultrasound Guided Transrectal Drainage of a Nonresolving Multiloculated Rectal Abscess in a Patient With Advanced Anal Squamous Cell Carcinoma

CASE REPORT Endoscopic ultrasound (EUS)–guided pelvic abscess drainage is an emerging minimally invasive technique with high technical success.1–5 However, its application in malignant, multiloculated collections with a friable and vascular tumor bed remains limited. We present a 48-year-old man with HIV and metastatic anal squamous cell carcinoma admitted with septic shock due to a complex multiloculated pelvic abscess associated with an ulcerated anorectal mass. Despite broad-spectrum antibiotics, diverting colostomy, and transgluteal drainage by interventional radiology, he had persistent purulent rectal discharge. Imaging demonstrated an enlarging, noncommunicating rectovesical abscess (Figure 1), prompting EUS-guided transrectal drainage for definitive source control (Video 1).Figure 1.: Computed tomography of the pelvis. At index presentation with multiloculated perirectal abscess (yellow arrow). The largest component of the abscess is in the rectovesical space and does not communicate with the pelvic drain. {"href":"Single Video Player","role":"media-player-id","content-type":"play-in-place","position":"float","orientation":"portrait","label":"Video 1","caption":"Endoscopic ultrasound-guided transrectal drainage of a complex perirectal abscess associated with anal squamous cell carcinoma.","object-id":[{"pub-id-type":"doi","id":""},{"pub-id-type":"other","content-type":"media-stream-id","id":"1_tn9r4f8l"},{"pub-id-type":"other","content-type":"media-source","id":"Kaltura"}]} The EUS scope used was the Olympus GF-UCT180 (curvilinear array ultrasound gastrovideoscope), and the processor was the ALOKA ARIETTA 850. EUS identified a hypoechoic anterior perirectal cavity (Figure 2). After Doppler confirmation of a safe, nonvascular, nontumorous access window, a 19-gauge needle was advanced with aspiration of purulent fluid (Figure 3). A guidewire was coiled under fluoroscopic guidance. The tract was dilated with a Cook Endoscopy Cotton Graduated dilation catheter (8.5 F with tapered 7-5 F tip), followed by the 8-mm biliary dilation balloon (Boston). Two 10 Fr double-pigtail stents with 4-cm length were placed to facilitate drainage (Figure 4). The procedure was completed without complications. The patient received intravenous antibiotics and transitioned to oral antibiotics for a total duration of 6 weeks. Follow-up imaging confirmed resolution of the abscess, and the patient remained clinically well at 6 months without any fever (Figure 4). Given the palliative intent of the procedure, the indwelling stents were left in place indefinitely.Figure 2.: Echoendoscope (A) Side lens view: Showing a fungating, partially obstructing large mass, 6 cm in length, situated about 14 cm from the anal verge; (B) Sonographic view: Showing a hypoechoic anterior perirectal cavity consistent with an abscess.Figure 3.: Echoendoscope sonographic view showing the entry track of a 19-G needle advanced into the abscess through a nontumorous tissue and nonvascular pathway.Figure 4.: Outcome and follow-up: (A) Fluoroscopy: Immediate postprocedure image showing 2 double-pigtail stents (10 F × 3 cm) secured (yellow arrow); (B) Computed tomography of the pelvis at the 6-month follow-up, showing resolution of abscess (yellow arrow).This case highlights that EUS-guided transrectal drainage is a viable option for complex pelvic abscesses in the setting of malignancy when percutaneous or surgical approaches are limited by anatomy or lack of communication between collections. The presence of a friable, vascular tumor bed necessitates meticulous preprocedural planning, including detailed cross-sectional imaging and real-time Doppler assessment to avoid hemorrhage and ensure a safe access tract. Double-pigtail plastic stents were selected over lumen-apposing metal stents to minimize the risk of tissue injury in the setting of adjacent friable malignancy. The use of electrocautery-enhanced, large-diameter lumen-apposing metal stents may increase the risk of bleeding, mucosal disruption, and uncontrolled tract formation when traversing or working near tumor tissue. By contrast, plastic stents allow for a more controlled, stepwise tract dilation, while providing effective long-term internal drainage. The pigtail configuration reduces the risk of stent migration and allows for safe long-term drainage without the need for planned stent exchange or removal. Compared with percutaneous drainage, EUS offers precise localization, internal drainage, and avoidance of external catheters, which may improve patient comfort and reduce infection risk. However, concerns remain regarding tumor traversal, stent-related complications, and long-term management, particularly in immunocompromised patients. Tumor traversal carries a theoretical risk of malignant seeding along the tract and increased bleeding, particularly in irradiated or necrotic tumor beds; however, careful Doppler-guided selection of a nonvascular window and minimizing trans-tumoral passage can mitigate these risks. Prospective data are needed to better define safety, optimal stent strategy, and outcomes in malignant and multiloculated pelvic sepsis. DISCLOSURES Author contributions: This paper was conceptualized by S. Ingawale and TL Jue. The investigation and review of relevant data and articles were done by S. Ingawale, HJ Kim, and TL Jue. Case analysis was done by S. Ingawale, HJ Kim, and TL Jue. The original draft was written by S. Ingawale. Review and editing were done by S. Ingawale, HK, and TL Jue. All authors discussed the findings described in the case and approved the final manuscript. The article guarantor is TL Jue. Financial disclosure: Terry L. Jue: Boston Scientific (Jan 2024, Honorarium received for serving as an Instructor at Fellows' Tissue resection course). Informed consent was obtained for this case report.