<p>The nonocclusive diseases ischemic colitis (IC) and pseudomembranous/<i>Clostridioides difficile</i> colitis (CDC) usually present with diarrhea. While IC involves bloody diarrhea and is more likely to affect older patients, the diarrhea in CDC is like other infectious diarrheal diseases and can affect any age group, although it also often affects older patients and especially hospitalized patients after antibiotic treatment. The surgeon is more likely to see clinically acute and fulminant cases. The differential diagnosis can be difficult and a consistent diagnostic algorithm should be followed. Surgically, cases at risk of short-term or long-term complications or recurrences should be filtered out. The differential diagnoses of diarrheal diseases or acute abdominal complaints should be known. After taking a medical history, the clinical examination is the key. If the abdomen is inconspicuous and the cardiovascular system is stable, there is time for the diagnostics. If the opposite is the case, the diagnostics and intervention must be quickly carried out.</p>