Post-Colonoscopy Appendicitis: A Rare but Concerning Entity

Abstract

Appendicitis following colonoscopy is an exceedingly rare event with an absolute risk of 1 per 56,000 cases. However, with the percentage of the screened population increasing, the incidence of this complication is expected to rise. Thus, maintaining a high index of suspicion during the early post-procedural period when the incidence is greatest can aid in timely diagnosis. Herein, we present a case of post-colonoscopy appendicitis in a patient who presented with diffuse abdominal pain 48 hours after colonoscopy. A 40-year-old woman underwent a colonoscopy for evaluation of anemia and a suspected occult bleed. Labs revealed Hgb 9.6 g/dL and MCV 71 fL. Following an uneventful bowel preparation, the procedure was performed without any intra-procedural complications. No polyps, diverticula, ulcers, erosions, arteriovenous malformations or masses were found. The colonoscope was advanced to the cecum without difficulty and location was confirmed by visualization of the appendiceal orifice. The patient was asymptomatic post-procedure but presented to the ED with diffuse abdominal pain and rebound tenderness 2 days later. CT abdomen with IV contrast revealed acute appendicitis with appendicoliths measuring up to 15 mm, a fluid-filled lumen, and multiple foci of gas (Image 1). The patient subsequently underwent laparoscopic appendectomy with biopsy results confirming acute gangrenous appendicitis. An estimated 15 million colonoscopies were performed in 2012. Coupled with a 2014 national campaign to promote colorectal cancer screening, we expect the number of colonoscopies and the incidence of their complications to rise significantly. One such complication is appendicitis, which has been shown to be at least 4 times more likely in the first week following colonoscopy. Proposed mechanisms for post-colonoscopy appendicitis include advancement of fecal material into the appendiceal lumen, changes in gut microbiota after bowel preparation, over-insufflation, intubation of the appendiceal lumen, and exacerbation of pre-existing subclinical disease. In our patient, the gas pattern was highly unusual with gas evidenced both proximal and distal to the appendicolith (Image 2), which was suggestive of local disruption. In the absence of preceding local disease, a suggestive temporal relationship, and radiologic evidence of local disruption, colonoscopy was most likely the etiology for her appendicitis.1548_A Figure 1 No Caption available.1548_B Figure 2 No Caption available.