A Rare Finding of Retroperitoneal Sepsis Following Robot-Assisted Transanal Minimally Invasive Surgery (TAMIS): A...

Robot-assisted transanal minimally invasive surgery (TAMIS) is a safe and effective platform for the local excision of early rectal lesions. While postoperative complications such as bleeding or contained perforation are recognized, rapidly progressive retroperitoneal sepsis remains an exceedingly rare occurrence. A 56-year-old male underwent robot-assisted TAMIS for a pT1 grade 1 rectal neuroendocrine tumor (NET). Despite successful circumferential excision and defect closure with sutures, the patient developed fever, hypotension, and rising lactaemia within 24 hours. Computed tomography demonstrated localized gas in the total mesorectal excision (TME) plane. Due to hemodynamic instability and suspected retroperitoneal sepsis, a diagnostic laparotomy was performed, revealing purulent peritonitis and pneumoretroperitoneum. Concurrent flexible sigmoidoscopy revealed a healthy-appearing TAMIS site. Management involved an end colostomy, laparostomy, and broad-spectrum antibiotics after intra-operative swabs grew extended-spectrum beta-lactamase (ESBL) E. coli. The patient was eventually discharged 15 days post return to theater. This case highlights that retroperitoneal sepsis can develop after robotic TAMIS despite no local macroscopic evidence of perforation or necrosis. Clinicians should maintain a high index of suspicion for this condition in patients who deteriorate suddenly with septic shock, particularly when abdominal examination findings do not reflect the severity of systemic toxicity. Early surgical intervention with diversion and aggressive sepsis control is critical.