Colonic Ischemia in a Young Patient: Who To Blame?

Abstract

Purpose: Case Presentation: A 37 year old female presented to clinic for evaluation of rectal condylomata by colonoscopy. Patient was given bisacodyl and polyethylene glycol bowel prep (halflytely) one day prior to the procedure. Patchy erythema was noted in the sigmoid colon 20 to 30 cm from the anal verge. Biopsy of the affected area was consistent with ischemic colitis (IC). The patient returned in six months for repeat colonoscopy and was given the same bowel preparation. Mucosal changes and histologic biopsies were again consistent with ischemic colitis in the same area. The patient was not on any medication. Additionally, hypercoaguable work up was negative. Discussion: Numerous medications have been shown to cause IC. Evidence linking bisacodyl and polyethylene glycol (PEG) to IC has been suggested yet rarely studied. Though the mechanism of action of bisacodyl is not entirely known, it seems to act at two levels. The first is as a stimulant of peristalsis and the second to promote fluid and ion accumulation in the lumen. Few mechanisms have been proposed linking bisacodyl to IC. Bisacodyl may cause rapid fluid shifts to the gut lumen causing transient hypoperfusion and ischemia. This may also be the mechanism behind IC and PEG. PEG is also believed to be an osmotic agent, though it has been rarely implicated as a cause for IC. One study, however, found patients with IC during PEG interferon alpha and ribavarin therapy. Another case showed a young adult with transient ischemic colitis after PEG and glycerin enema. Alternatively, bisacodyl may cause diminished blood flow to the colon by inducing both increased motility and pressure. This latter mechanism may also be the reason IC has been linked to tegaserod use, lending further credence to the association between promotility agents and IC. Our patient had no known risk factor for IC. Additionally, IC is rare in young adults. It is these factors that favor the assertion that the bowel preparation caused IC in our patient. Conclusion: Bowel preparation may be an under recognized source of IC. This case illustrates that bowel preparations are a plausible risk factor for IC, particularly in the young adult. Large studies are lacking, making this a promising area future research.