A patient presents with change in bowel habits and weight loss; which diagnosis is most consistent?

• A. Hemorrhoids
• B. Colorectal carcinoma
• C. Acute diverticulitis
• D. Fistula-in-ano

Answer: (B)

Unexplained weight loss with a change in bowel habits points most strongly to a malignant process in the colon or rectum. Colorectal carcinoma often presents with progressive alterations in stooling—diarrhea, constipation, or a mix of both—and can cause a change in stool caliber as the tumor narrows the lumen. Weight loss reflects systemic cancer-related effects, such as cachexia, even when other symptoms are mild.

Hemorrhoids typically cause painless rectal bleeding and itching without a sustained change in bowel habit or weight loss. Acute diverticulitis usually presents with localized abdominal pain (often left lower quadrant), fever, and an inflammatory response, not a persistent change in bowel patterns with weight loss. Fistula-in-ano causes chronic drainage and irritation around the anal area rather than systemic weight loss and a persistent alteration in bowel habits.

Together, the combination of bowel habit change plus weight loss is most consistent with colorectal carcinoma.