eP589 - Rectal Ischemia in the Setting of Biologic Therapy: A Case Report

Purpose/Background: Rectal ischemia is rare, largely due to the rich blood supply of the rectum. The exact incidence of isolated rectal ischemia is unknown; however, rectal involvement of acute colonic ischemia is estimated to be 2-5%. Risk factors seem to include advanced age, hemodynamic instability, cardiovascular disease, history of aortic surgery, and fecal impaction. Treatment is usually non-operative with bowel rest and antibiotics, with surgical management typically reserved for refractory cases or patient instability.Methods/Interventions: A 36-year-old female with recurrent cervical adenosquamous carcinoma presented with diarrhea and bleeding per rectum. She had previously been treated with cisplatin, radiation, and brachytherapy, and at the time was undergoing treatment with bevacizumab, carboplatin, paclitaxel, and pembrolizumab. Physical exam revealed lower abdominal tenderness to palpation and gross blood on digital rectal examination. Laboratory testing revealed a hemoglobin of 6 g/dL. Computed tomography was remarkable for inflammatory changes in the rectum and sigmoid colon with findings concerning for superior rectal perforation with an adjacent 4 cm air collection. A flexible sigmoidoscopy was performed to determine the cause of her proctitis and this revealed diffuse rectal ischemia. The patient underwent a laparoscopic diverting loop sigmoid colostomy and drainage of abdominopelvic abscess.Results/Outcomes: Biopsies taken at the time of initial flexible sigmoidoscopy showed necrotic tissue and fibrin. After a prolonged hospital course requiring antibiotics and total parenteral nutrition, the patient was ultimately discharged home. A repeat flexible sigmoidoscopy at 4 weeks demonstrated minimal improvement of rectal ischemia, as well as a rectovaginal fistula. The patient remains stable at most recent follow up and is currently being considered for resumption of systemic chemotherapy.Conclusion/

Discussion: The above case of rectal ischemia was likely multifactorial, due to acute on chronic anemia and toxicity from chemoradiation and biologic therapy, specifically pembrolizumab. Pembrolizumab is an anti-programmed death 1 (PD-1) receptor monoclonal antibody that ultimately prevents tumor cells from evading the host’s immune system. Immune-mediated colitis from anti-PD-1 agents is a known entity, with incidence found to be 0.7%–1.6%. We hypothesize that pembrolizumab played a significant role in this case of rectal ischemia. This case demonstrates that rectal ischemia, although rare, should remain on the differential of proctitis, especially in the setting of immunotherapy. It remains controversial whether emergency abdominoperineal resection is needed, fecal diversion alone was sufficient in this case to mitigate the patient’s sepsis."Computed Tomography Of Rectum

Computed tomography scan showing diffuse rectal inflammation with adjacent extra-luminal air
Initial Flexible Sigmoidoscopy

Flexible sigmoidoscopy image showing diffuse ischemic proctitis. "