EP208 - Robotic-assisted surgery for rectal cancer with situsinversus totalis: A case report

Purpose/Background: Situs Inversus Totalis (SIT) is a rare congenital anomaly in which thoracoabdominal organs are mirror-reversed, occurring in approximately 1 in 10,000-20,000 individuals. This reversal alters normal anatomy, complicating surgical procedures and requiring high technical adaptability, such as reversing dominant-hand functions. Reported SIT cases are uncommon, with most describing successful laparoscopic resections and few addressing robotic approaches. Given the proven safety and efficacy of the Da Vinci system in rectal cancer, we anticipate similarly favorable outcomes for SIT patients undergoing robotic surgery.

Methods/Interventions: Case Presentation

A 74-year-old man presented with a two-month history of hematochezia and was diagnosed with rectal cancer and situs inversus totalis (SIT). CT confirmed complete mirror reversal of thoracic and abdominal organs without metastasis. Colonoscopy biopsy showed high-grade intraepithelial neoplasia, suggesting adenocarcinoma. MRI revealed no distant disease. Endoscopy identified a large polypoid lesion with central ulceration 13-18 cm from the anus, marked by nano-carbon injection. Laboratory tests showed mild anemia (RBC 4.27 × 10¹²/L) and elevated CA72-4 (8.42 U/mL). As endoscopic resection was infeasible, robotic-assisted rectal resection was chosen.

Surgical Technique

Under general anesthesia and lithotomy position, trocars were placed in a mirrored configuration due to SIT. Pneumoperitoneum was established 1 cm above and left of the umbilicus. Robotic arms and assistant ports were arranged symmetrically. Exploration confirmed complete situs inversus without metastasis. The tumor was located 5 cm above the peritoneal reflection. After mobilizing the bowel, dissection of the inferior mesenteric artery with nerve and lymph node preservation was performed. Rectal resection and sigmoid-rectal anastomosis were completed. Pathology revealed villous tubular adenoma with high-grade intraepithelial neoplasia.

Results/Outcomes: The rarity of SIT limits clinical experience and requires modifications to standard techniques, increasing surgical difficulty. Open surgery provides direct visualization but offers no prognostic advantage over minimally invasive methods and adds greater trauma. Laparoscopic rectal resection is less invasive with faster recovery but poses unique challenges in SIT cases-assistants must adapt to reversed anatomy, coordinate movements in a two-dimensional view, and surgeons must operate from unconventional positions. Robotic systems retain laparoscopic benefits while providing greater flexibility, overcoming reversed handedness, and enabling precise pelvic manipulation. Proper preoperative port planning remains crucial to ensure smooth intraoperative navigation.

Conclusion/Discussion: For patients with SIT and low rectal cancer, Da Vinci robotic-assisted surgery overcomes many challenges posed by reversed anatomy. Based on existing literature and our experience, we conclude that the robotic system is a feasible option for this patient group.

Appropriate port placement and arm positioning significantly improve surgical success rates.

We anticipate that this approach will become increasingly important in clinical practice. However, thorough preoperative planning and a skilled surgical team remain crucial for achieving successful outcomes.

Figure1
MRI and Endoscopic image
Figure2
Surgery and the Pathology