Single-Port Robotic Transanal Minimally Invasive Surgery for Rectal Cancer: A Novel Approach With FishBowl-Early Case Series

Background: Transanal minimally invasive surgery (TAMIS) emerged as a validated technique for local excision of rectal adenomas and early-stage adenocarcinomas. In organ preservation protocols, TAMIS is increasingly used for mid- and low-rectal cancers, achieving complete or major clinical response (cCR/cMR) following neoadjuvant chemoradiotherapy, complementing Watch-and-Wait strategies with low morbidity and favorable outcomes. Robotic platforms, particularly the Da Vinci SP, have improved surgical dexterity and visualization in confined pelvic spaces. Despite CE approval and encouraging feasibility data, widespread adoption of SP-TAMIS remains limited due to docking constraints. This study reports the first European series of rectal cancer cases treated with SP-TAMIS (SPrTAMIS) using a novel small FishBowl docking system and evaluates its feasibility, safety, and short-term outcomes. Materials and Methods: Five patients with rectal adenocarcinoma, selected based on organ preservation criteria, underwent SPrTAMIS using the Da Vinci SP system. Preoperative assessment included endoscopy, MRI, CT, and bowel preparation. Procedures were performed under general anesthesia with CO 2 pneumorectum (12 mm Hg) and robotic instrumentation via the FishBowl docking system. Data collected included tumor characteristics, surgical duration, estimated blood loss (EBL), morbidity, mortality, length of stay (LOS), and functional outcomes (LARS and MSKCC scores). Results: All procedures were completed robotically without conversion. The mean lesion size was 8.8 mm, located 50 mm from the anal verge and 16 mm from the anorectal junction. Mean operative time was 85 minutes. No intraoperative complications or mortality occurred. GI function resumed by postoperative day (POD) 1; all patients were discharged by POD 2. One minor, asymptomatic suture dehiscence was observed. Histology confirmed complete excision with negative margins. The median follow-up was 68 days, and functional and quality-of-life outcomes were favorable. Conclusions: SPrTAMIS using Da Vinci SP and the FishBowl system is feasible and safe for rectal excision, offering ergonomic advantages and minimal anal canal trauma. Further studies are warranted to assess long-term oncologic and functional outcomes.