What is the diagnosis for a patient with profuse, massive per rectal (PR) bleeding and colonoscopy findings of a hyperemic and reddish area in the transverse colon?

Diagnosis: Ulcerative Colitis (UC)

The most likely diagnosis is ulcerative colitis (UC), given the colonoscopic finding of a hyperemic and reddish area in the transverse colon with profuse PR bleeding. 1

Clinical Reasoning

Why UC is the Most Likely Diagnosis

• In UC, bleeding typically occurs in patients with pancolitis from diffuse areas of mucosal ulceration, presenting as hyperemic, reddish, inflamed mucosa on colonoscopy 1
• The colonoscopic description of a "hyperemic and reddish area" is characteristic of the inflammatory changes seen in UC 1
• Massive lower GI bleeding occurs in less than 6% of IBD cases, but when it does occur in UC, it manifests as diffuse mucosal inflammation rather than focal bleeding 1

Why Other Options Are Less Likely

Diverticular bleeding (Option B):

• While diverticulosis is the most common cause of acute lower GI bleeding overall (accounting for 20-41% of cases in older adults), diverticular bleeding does NOT produce hyperemic, reddish areas on colonoscopy 2
• Diverticular bleeding appears as bleeding from a specific diverticulum, not as diffuse mucosal hyperemia 1
• More than 75% of diverticula are found in the left colon, not the transverse colon 1

Crohn's disease (Option C):

• In Crohn's disease, bleeding most often results from focal erosion into an intestinal vessel, not diffuse hyperemic mucosa 1
• Crohn's typically shows segmental disease with skip lesions, not the continuous hyperemic appearance described 1

Aortoenteric fistula (Option A):

• This occurs in the duodenum (3rd/4th parts), not the transverse colon 1
• This option is anatomically incompatible with the colonoscopic findings

Key Diagnostic Pitfall

Always exclude an upper GI source first in patients with massive hematochezia and hemodynamic instability, as 10-15% of patients with severe hematochezia have an upper GI source 1, 2. However, the colonoscopic visualization of the transverse colon lesion in this case confirms a lower GI source.

Management Implications

• Hemodynamically unstable IBD patients with GI bleeding require intravenous fluid/blood product resuscitation prior to endoscopic evaluation 1
• Maintain hemoglobin above 7 g/dL (or 9 g/dL in massive bleeding or cardiovascular disease) 1
• In UC with massive bleeding from diffuse mucosal ulceration, endoscopic hemostasis is rarely possible due to the diffuse nature of inflammation, unlike focal bleeding in Crohn's disease 1