A 74-year-old man presents to the emergency room with abdominal pain. He reports acute onset of left lower quadrant abdominal pain and nausea three hours prior to presentation. The pain is severe, constant, and non-radiating. He has had two maroon-colored bowel movements since the pain started. His past medical history is notable for hypertension, hyperlipidemia, atrial fibrillation, insulin-dependent diabetes mellitus, and rheumatoid arthritis. He takes lisinopril, hydrochlorothiazide, atorvastatin, dabigatran, methotrexate. He has a 60 pack-year smoking history and drinks 1-2 beers per day. He admits to missing some of his medications recently because he was on vacation in Hawaii. His last colonoscopy was 4 years ago which showed diverticular disease in the descending colon and multiple sessile polyps in the sigmoid colon which were removed. His temperature is 100.1°F (37.8°C), blood pressure is 145/85 mmHg, pulse is 100/min, and respirations are 20/min. On exam, he has notable abdominal distention and is exquisitely tender to palpation in all four abdominal quadrants. Bowel sounds are absent. Which of the following is the most likely cause of this patient’s condition?

Perforated intestinal mucosal herniation

A 23-year-old female presents with a seven-day history of abdominal pain, and now bloody diarrhea that brings her to her primary care physician. Review of systems is notable for a 12-pound unintentional weight loss and intermittent loose stools. She has a family history notable for a father with CAD and a mother with primary sclerosing cholangitis. Upon further workup, she is found to have the following on colonoscopy and biopsy, Figures A and B respectively. Serum perinuclear antineutrophil cytoplasmic antibodies (P-ANCA) is positive. This patient's disease is likely to also include which of the following features?

Continuous progression beginning in the rectum

Worse disease severity near the ileocecal valve

Fistulae and stricture formation

A 25-year-old man presents to the emergency department for severe abdominal pain. The patient states that for the past week he has felt fatigued and had a fever. He states that he has had crampy lower abdominal pain and has experienced several bouts of diarrhea. The patient states that his pain is somewhat relieved by defecation. The patient returned from a camping trip 2 weeks ago in the Rocky Mountains. He is concerned that consuming undercooked meats on his trip may have caused this. He admits to consuming beef and chicken cooked over a fire pit. The patient is started on IV fluids and morphine. His temperature is 99.5°F (37.5°C), blood pressure is 130/77 mmHg, pulse is 90/min, respirations are 12/min, and oxygen saturation is 98% on room air. Laboratory studies are ordered and are seen below. Hemoglobin: 10 g/dL Hematocrit: 28% Leukocyte count: 11,500 cells/mm^3 with normal differential Platelet count: 445,000/mm^3 Serum: Na+: 140 mEq/L Cl-: 102 mEq/L K+: 4.1 mEq/L HCO3-: 24 mEq/L BUN: 24 mg/dL Glucose: 145 mg/dL Creatinine: 1.4 mg/dL Ca2+: 9.6 mg/dL Erythrocyte sedimentation rate (ESR): 75 mm/hour Physical exam is notable for a patient who appears to be uncomfortable. Gastrointestinal (GI) exam is notable for abdominal pain upon palpation. Ear, nose, and throat exam is notable for multiple painful shallow ulcers in the patient's mouth. Inspection of the patient's lower extremities reveals a pruritic ring-like lesion. Cardiac and pulmonary exams are within normal limits. Which of the following best describes this patient's underlying condition?

Transmural granulomas in the bowel

p-ANCA positive autoimmune bowel disease

Gram-negative microaerophilic organism

A 33-year-old African-American female presents to her physician with complaints of a persistent, dry cough. She states that the cough has gone on for some time now. Three weeks ago, during her last general checkup, she was started on lisinopril and metformin for concerns regarding an elevated blood pressure and fasting blood glucose. Past medical history is notable for eczema, asthma, and seasonal allergies. At this visit the patient has other non-specific complaints such as fatigue and joint pain as well as a burning sensation in her sternum when she eats large meals. Her physical exam is only notable for painful bumps on her lower extremities (figure A) which the patient attributes to "bumping her shins," during exercise, and an obese habitus. Which of the following is most likely true for this patient's chief concern?

Non-caseating granulomas are found on biopsy of mediastinal lymph nodes

Omeprazole is an appropriate next step in management

Loratadine would best treat her chief complaint

Serum levels of bradykinin will be elevated

Beta agonists would relieve this patient's symptoms

Extraintestinal manifestations for USMLE Step 1: High-Yield Internal Medicine Lessons

EIMs - IBD's Traveling Circus

Extraintestinal manifestations (EIMs) occur in ~25-40% of IBD patients. Their clinical course can either parallel IBD activity or be independent of it.

Activity-Related: Mnemonic 📌 "PEA" - Peripheral arthritis, Erythema nodosum, Aphthous ulcers. Also includes episcleritis. Treatment of IBD flare typically resolves these.
Activity-Independent: Course is unrelated to IBD flare activity. Includes uveitis, pyoderma gangrenosum, axial arthropathies (e.g., ankylosing spondylitis), and PSC.

⭐ Primary Sclerosing Cholangitis (PSC) has a strong association with Ulcerative Colitis (~70-80% of PSC patients have UC), but its clinical course is independent of colonic inflammation.

Achy Joints - The Body's Complaint Dept.

Most common EIM of IBD, affecting up to 30% of patients. Two main types: peripheral and axial.
Peripheral Arthritis:
- Asymmetric, non-erosive, and often migratory.
- Pauciarticular (<5 joints) is more common than polyarticular.
- Large joints (knees, ankles, wrists) are typically affected.
- Activity often parallels IBD activity ("flares with the gut").
Axial Arthropathy (Spondyloarthropathy):
- Includes sacroiliitis and ankylosing spondylitis.
- Presents as inflammatory low back pain and stiffness.
- Strongly associated with HLA-B27.

⭐ Exam Favorite: Axial spondyloarthropathy activity is independent of IBD activity, unlike peripheral arthritis. Symptoms can persist even when IBD is in remission.

Skin & Sight - Surface-Level Clues

Skin:
- Erythema Nodosum (EN): Tender red nodules on shins, often parallels Crohn's flares.
- Pyoderma Gangrenosum (PG): Starts as pustule → painful ulcer with purple borders. More common in UC.
- Aphthous Ulcers: Canker-sore-like lesions in the mouth.
Eyes:
- Uveitis: Presents with pain, photophobia, blurry vision. An ophthalmologic emergency.
- Episcleritis: Localized redness and mild irritation.
General Management: Typically responds to systemic steroids and treating the underlying IBD.

⭐ Pathergy-the development of new skin lesions like Pyoderma Gangrenosum at sites of minor trauma (e.g., needle stick)-is a key diagnostic clue.

Erythema Nodosum on Shins

Liver & Clots - Deeper Dangers

Primary Sclerosing Cholangitis (PSC): Chronic cholestasis from inflammation and fibrosis of intra/extrahepatic bile ducts. Strongly associated with Ulcerative Colitis.
- Features: ↑ALP, p-ANCA positive (~80%).
- Imaging: MRCP/ERCP reveals multifocal strictures and dilatations, creating a classic “beads on a string” appearance.

ERCP: Beaded bile ducts in Primary Sclerosing Cholangitis

⭐ PSC activity is independent of IBD activity; colectomy is not curative.

Thromboembolism (VTE): IBD induces a hypercoagulable state, ↑ risk of DVT/PE, particularly during active flares.

High‑Yield Points - ⚡ Biggest Takeaways

Arthritis, both peripheral and axial (ankylosing spondylitis), is the most common extraintestinal manifestation.

Dermatologic findings include painful erythema nodosum on the shins and deep, purulent ulcers of pyoderma gangrenosum.

Ocular complications like uveitis and episcleritis can threaten vision.

Primary Sclerosing Cholangitis (PSC), a major risk for cholangiocarcinoma, is strongly linked to Ulcerative Colitis.

IBD creates a hypercoagulable state, increasing the risk for DVT/PE.

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