Chemoimmunotherapy-related enteritis resulting in a mechanical small bowel obstruction - A case report

Mechanical small bowel obstruction (SBO) is amongst the commonest diagnoses encountered in surgical departments. Although the aetiology is frequently post-surgical adhesions, the condition can arise in a virgin abdomen and we now know several of these cases do not require acute operative management. Here we report one such case where a small bowel obstruction transpired due to enteritis in the setting of chemoimmunotherapy with no prior abdominal surgery.

A 62 year old male presented to our department with 2 days of vomiting and obstipation. This is on a background of metastatic non-small cell lung cancer for which he was due for his 4^th cycle of carboplatin, pemetrexed and pembrolizumab. Computed Tomography (CT) of the abdomen demonstrated a segment of thickened distal small bowel without any mass lesion, along with upstream dilatation. The findings were consistent with a mechanical SBO due to enteritis. Infective causes were excluded. The patient successfully recovered with non-operative intervention in the coming days.

Enteritis is an established adverse effect of various chemoimmunotherapy agents, though a case severe enough to produce a mechanical bowel obstruction is exceptionally rare. We demonstrate through this case that the condition may resolve through conservative measures.

The diagnosis of chemoimmunotherapy-related enteritis producing an SBO although uncommon, should be considered in the relevant population. A non-operative approach may be appropriate under some circumstances.