Gastroenterology · Inflammatory Bowel Disease
The facts most likely to be tested
Ulcerative colitis is characterized by continuous mucosal inflammation starting in the rectum and extending proximally to involve the colon.
Patients typically present with bloody diarrhea, tenesmus, and abdominal pain localized to the left lower quadrant.
Colonoscopy reveals friable mucosa, pseudopolyps, and loss of haustral markings known as the lead pipe sign on barium enema.
Histopathology demonstrates crypt abscesses and crypt distortion limited strictly to the mucosa and submucosa.
Patients are at significantly increased risk for colorectal cancer, necessitating surveillance colonoscopy starting 8 years after diagnosis.
Toxic megacolon is a life-threatening complication characterized by colonic dilation >6 cm and systemic toxicity, which is a contraindication for colonoscopy.
Primary sclerosing cholangitis is the most common extraintestinal manifestation associated with ulcerative colitis, often presenting with elevated alkaline phosphatase.
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A 28-year-old male presents with a 3-month history of bloody diarrhea, urgency, and tenesmus. He reports recent joint pain in his knees and an elevated alkaline phosphatase on routine labs. Colonoscopy shows continuous erythema and friability starting at the anal verge and extending to the splenic flexure. Biopsy reveals crypt abscesses with inflammation confined to the mucosa.
What is the most likely diagnosis and the most appropriate next step in management for his liver-related findings?
Ulcerative colitis; obtain an MRCP to evaluate for primary sclerosing cholangitis.
The patient's continuous mucosal inflammation and bloody diarrhea are classic for ulcerative colitis, while the elevated alkaline phosphatase and joint pain suggest the associated extraintestinal manifestation of primary sclerosing cholangitis.
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Etiology / Epidemiology
Bimodal distribution (15-30, 50-80) with smoking being protective. Associated with HLA-B27 and p-ANCA.
Clinical Manifestations
Presents with bloody diarrhea, tenesmus, and abdominal pain. Lead pipe sign on imaging.
Diagnosis
Colonoscopy with biopsy is the gold standard. Avoid colonoscopy in acute toxic megacolon.
Treatment
Mesalamine is first-line for mild-moderate disease. Avoid anti-motility agents in acute flares.
Prognosis
Increased risk of colorectal cancer; requires annual surveillance colonoscopy after 8 years of disease.
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Epidemiology & Etiology
UC is an idiopathic inflammatory bowel disease with a peak incidence in the second to third decade. It is strongly associated with p-ANCA positivity and has a genetic predisposition linked to HLA-B27. Interestingly, smoking is paradoxically protective against the development of UC.
Pertinent Anatomy
Inflammation is limited to the mucosa and submucosa and always involves the rectum. It spreads in a continuous, proximal fashion without skip lesions.
Pathophysiology
Dysregulated immune response to commensal flora leads to chronic mucosal inflammation. This results in crypt abscesses and depletion of goblet cells. Over time, the loss of haustra leads to the classic lead pipe sign on barium enema.
Clinical Manifestations
Patients present with bloody diarrhea, urgency, and tenesmus. Physical exam may reveal abdominal tenderness. Toxic megacolon is a life-threatening complication characterized by fever, tachycardia, and colonic dilation > 6 cm.
Diagnosis
Colonoscopy with biopsy is the gold standard for diagnosis. Avoid colonoscopy during severe acute flares due to the risk of perforation. Biopsy findings typically show crypt abscesses and inflammatory infiltrates.
Treatment
Mesalamine (5-ASA) is the first-line therapy for induction and maintenance of mild-moderate disease. Corticosteroids are used for acute flares but are not for maintenance. Avoid anti-motility agents (e.g., loperamide) in acute flares as they precipitate toxic megacolon.
Prognosis
Patients face a significantly increased risk of colorectal cancer. Surveillance colonoscopy is mandatory starting 8 years after diagnosis. Total proctocolectomy is curative for refractory disease.
Differential Diagnosis
Crohn's Disease: transmural inflammation with skip lesions
Infectious Colitis: acute onset, usually self-limiting
Ischemic Colitis: elderly patients, pain out of proportion to exam
Irritable Bowel Syndrome: diagnosis of exclusion, no blood in stool
Radiation Colitis: history of pelvic radiation therapy