EP376 - Long term complications of conservatively managed anastomotic sinus tracts after LAR

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Purpose/Background: The development of chronic sinus tracts at the colorectal anastomosis is a rare complication of LAR. Healing of these tracts after one year is unlikely (Shung 2011). However, these tracts can be successfully managed by ensuring drainage from the cavity back into the rectum. We report here two cases of late progression of a presacral cavity years after successful management of an anastomotic sinus.

Methods/Interventions: Patient 1 is a 67-year-old man diagnosed with low rectal cancer in 2014. He underwent neoadjuvant chemoradiation followed by laparoscopic low anterior resection with colorectal anastomosis and diverting loop ileostomy in 2015. The patient underwent ileostomy closure in late 2015. A chronic sinus tract had been identified at the colorectal anastomosis; this was noted to become smaller with adequate drainage into the rectum before stoma closure. Eventually the sinus was marsupialized with an endoscopic stapler. He remained asymptomatic until September 2024 when he fell onto his coccyx, after which he developed persistent coccygeal pain and night sweats. CT scan of the pelvis demonstrated a large abscess within the right gluteus that communicated with the distal posterior rectum. Flexible sigmoidoscopy revealed disruption of the posterior colorectal anastomosis without evidence of cancer recurrence. He underwent laparoscopic diverting colostomy and was treated with a long course of antibiotics with resolution of symptoms.

Patient 2 is a 44-year-old man who underwent neoadjuvant chemoradiation and low anterior resection with diverting loop ileostomy in 2010 for rectal cancer followed by adjuvant chemotherapy. A persistent sinus tract was identified at the posterior aspect of the coloanal anastomosis and was surveilled with endoscopic and radiographic means. The patient remained asymptomatic and desired stoma closure, and the patient’s ileostomy was closed in 2015. He remained asymptomatic until presenting to clinic in 2024 with new onset fecal incontinence. Flexible sigmoidoscopy demonstrated dehiscence at the anastomosis. Biopsy of the previous anastomosis site showed no evidence of malignancy recurrence. Patient is awaiting discussion regarding definitive management.

Results/Outcomes: Patient 1 underwent laparoscopic diverting colostomy with resolution of symptoms.

Patient 2 is awaiting discussion regarding definitive management.

Conclusion/Discussion: The development of a chronic sinus tract at the colorectal anastomosis, while rare, can be difficult to manage, and can have significant consequences. There are reports of these sinus tracts being amenable to endoscopic intervention (Badia-Closa 2024). While the majority are managed conservatively, and successfully so, the potential exists for these sinus tracts to progress to dehiscence of the anastomosis and/or increasingly symptomatic presacral/pelvic abscesses ten years or more after their initial identification. Risk factors for progression of the sinus may include the therapeutic modalities used in neoadjuvant and adjuvant management of low rectal cancers, and cancer recurrence must always be considered. Further investigation regarding this entity is warranted.