What is the most likely cause of lower abdominal pain and bloody diarrhea in an elderly patient with a history of peripheral artery disease?

In an elderly patient, especially one with a history of peripheral artery disease, ischemic colitis is a likely cause of lower abdominal pain and bloody diarrhea. This condition arises when blood flow to a part of the colon is reduced or compromised, which can occur in patients with vascular disease, such as peripheral artery disease.

The symptoms of ischemic colitis typically include sudden abdominal pain, often accompanied by diarrhea that may contain blood. The elderly are particularly vulnerable to this condition due to age-related changes in blood circulation and potential comorbidities that affect vascular health.

While conditions like colon cancer, diverticulitis, and infectious gastroenteritis can also produce similar symptoms, the history of peripheral artery disease increases the likelihood that reduced blood flow is contributing to colonic ischemia, thus making ischemic colitis the most plausible explanation for the symptoms presented in this case.