EP953 - Robotic Intrersphincteric Resection for Low Rectal GIST

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Purpose/Background: Gastrointestinal stromal tumors (GISTs) of the rectum are rare and pose unique surgical challenges [1]. Intersphincteric resection (ISR) is an anus-preserving surgical technique for treating low rectal cancer, providing a safe alternative to abdominoperineal resection (APR). Since its introduction by Schiessel in 1994, ISR indications have expanded due to the widespread use of total mesorectal excision (TME), standardized neoadjuvant chemoradiotherapy (nCRT), and minimally invasive approaches, achieving anus-preservation rates up to 98.8% [2]. Robotic ISR (RISR), though studied mainly in East Asia, offers enhanced precision through the da Vinci Surgical System, which improves ergonomics, eliminates tremors, and provides a 3D stereoscopic view with increased dexterity [3]. While Schiessel’s original ISR technique is traditionally performed with a hand-sewn coloanal anastomosis, stapled anastomosis has also proven to be feasible [4]. This video presentation highlights the successful execution of RISR with stapler coloanal anastomosis for a rectal GIST.

Methods/Interventions: The patient is a 44-year-old female with no significant past medical history who presented with tenesmus and pelvic pain. She did not exhibit obstructive symptoms and denied associated rectal bleeding, pain, changes in bowel habits, or systemic symptoms such as weight loss or fatigue.
During a digital rectal examination, a large, very low rectal mass was identified, of which the patient was previously unaware. The mass was located posteriorly, approximately 2 cm from the anal verge. It was extraluminal, mobile, and measured 9 x 6 cm.
Following this finding, the patient was referred to gastroenterology for further evaluation, including endoscopic assessment, imaging, and biopsy. MRI revealed a large, right posterior-lateral lower rectal mass measuring 9.7 x 8.5 x 6.7 cm.
Endoscopy showed a large submucosal rectal mass. A tru-cut biopsy was performed, revealing a spindle cell neoplasm, most suggestive of a gastrointestinal stromal tumor (GIST) with a low histologic grade (5 mitoses/50 HPF) and KIT gene mutation detected.
The patient subsequently received neoadjuvant Imatinib for 6 months, which resulted in a significant response. A follow-up pelvic MRI showed a decrease in the size of the mass, now measuring 5.3 x 4.2 x 7.2 cm.

Results/Outcomes: A robotic intersphincteric resection with a diverting loop ileostomy was then performed. The stepwise approach of this procedure will be described in detail in the accompanying video

Conclusion/Discussion: The robotic intersphincteric resection (ISR) provided several key advantages. The robotic platform offered enhanced visualization, precise hemostasis during the levator-sphincter dissection, and improved traction, enabling meticulous pelvic dissections. These factors contributed to a safe and efficient surgical approach in this complex case.