V54 - Resolution of Discordant Staging in a Rectal Lesion by Transanal US and Single-Port Robotic Transanal Excision with Single Port Access

Purpose/Background: Accurate preoperative staging of distal rectal lesions is critical in determining appropriate management. However, discordance between imaging and pathology can pose a clinical challenge. Historically, transanal minimally invasive surgery has evolved from conventional laparoscopic platforms to robotic assisted techniques using the da Vinci Si and Xi systems. The rise of da Vinci Single-Port platforms offers enhanced visualization, superior instrument dexterity, and the ability to work through a single access site, making it the preferred platform. This video details the multidisciplinary work up and management of a low rectal lesion incorporating techniques of transanal ultrasound and the da Vinci Single-Port (SP) robotic platform with the single-port access port.

Methods/Interventions: A 68-year-old female with history of atrial fibrillation on Coumadin and prior TIAs presented with rectal bleeding for several months. Colonoscopy revealed a posterior polypoid lesion located 6 cm from the anal verge. Biopsy showed a tubulovillous adenoma without high-grade dysplasia. Due to the initial endoscopist's concern for deeper malignancy not represented by biopsy, the patient underwent staging. Cross-sectional imaging with CT showed distal rectal thickening without lymphadenopathy or distant metastases. Pelvic MRI suggested a mT3aN0 lesion with a negative mesorectal fascia and no extramural venous invasion, raising concern for an invasive carcinoma despite benign biopsy findings. Given the discordant biopsy and MRI findings, multidisciplinary tumor board discussions recommended an transanal ultrasound, which demonstrated no invasion of the muscularis propria. This aligned with the benign biopsy. The lesion was therefore removed as a large excisional biopsy using the da Vinci SP Robotic platform with SP access port.

Results/Outcomes: The video emphasizes key technical steps, including: the use of a single-port access port, precise full-thickness excision, and primary repair facilitated by the wristed instrumentation. Final pathology confirmed benign tubulovillous adenoma without high grade dysplasia or invasive carcinoma and all margins negative.

Conclusion/Discussion: This case illustrates the vital role of transanal ultrasound in resolving a staging discrepancies between MRI and histopathology, especially when MRI is performed before confirming invasive disease. MRI remains valuable for assessing mesorectal involvement and surgical planning in confirmed carcinomas, while ultrasound offers accuracy of local depth assessment in early or indeterminate lesions. For appropriately selected rectal lesions, SP Robot with SP access port provides a highly effective minimally invasive approach. The enhanced dexterity and visualization of the single-port robot is particularly advantageous for precise full-thickness excision and watertight closure in the narrow confines of the distal rectum.