A 32-year-old man comes to the emergency department because of recurrent episodes of vomiting for 1 day. He has had over 15 episodes of bilious vomiting. During this period he has had cramping abdominal pain but has not had a bowel movement or passed flatus. He does not have fever or diarrhea. He was diagnosed with Crohn disease at the age of 28 years which has been well controlled with oral mesalamine. He underwent a partial small bowel resection for midgut volvulus at birth. His other medications include vitamin B12, folic acid, loperamide, ferrous sulfate, and vitamin D3. He appears uncomfortable and his lips are parched. His temperature is 37.1°C (99.3°F), pulse is 103/min, and blood pressure is 104/70 mm Hg. The abdomen is distended, tympanitic, and tender to palpation over the periumbilical area and the right lower quadrant. Rectal examination is unremarkable. A CT scan of the abdomen shows multiple dilated loops of small bowel with a transition zone in the mid to distal ileum. After 24 hours of conservative management with IV fluid resuscitation, nasogastric bowel decompression, promethazine, and analgesia, his condition does not improve and a laparotomy is scheduled. During the laparotomy, two discrete strictures are noted in the mid-ileum, around 20 cm apart. Which of the following is the most appropriate next step in management?

Strictureplasty of individual strictures

Small bowel resection with ileostomy

Abdominal closure and start palliative care

Small bowel resection and primary anastomosis

A 22-year-old woman presents to the emergency department with a 3-day history of fever and abdominal pain. She says that the pain is located in the left lower quadrant of the abdomen and feels crampy in nature. The pain has been associated with bloody diarrhea and joint tenderness. She has no past medical history but says that she returned 2 weeks ago from vacation in Asia where she tried many new foods. Her family history is significant for multiple cancers in close relatives. Physical exam reveals swollen ulcers on her legs, and colonoscopy reveals contiguous ulcerations from the rectum through the descending colon. Which of the following is associated with the most likely cause of this patient's symptoms?

Perinuclear anti-neutrophil cytoplasmic antibodies

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 22-year-old Caucasian female presents with severe right lower quadrant pain, malaise, and diarrhea. The physician performs an endoscopy and finds disease involvement in the terminal ileum, noting that the disease process is patchy with normal intervening mucosa. The entire wall of the region is thickened and inflamed, which may directly lead to formation of:

Widening of the intestinal lumen

A 32-year-old woman presents to her family physician with a long history of depression, irritability, and, more recently, personality changes. As her partner comments, she has stopped engaging in activities she used to enjoy like dancing, drumming lessons, and yoga. The patient denies changes in skin pigmentation and assures she keeps a balanced diet low in fat and carbohydrates. During the physical examination, jaundice and dark rings encircling the iris of the eye are noted, as well as hepatomegaly and gait disturbances. For a follow-up visit, the patient brings a battery of laboratory tests that includes a complete blood count showing normocytic normochromic anemia, a negative Coombs, normal iron levels, normal fasting glucose levels, elevated aminotransferases from the liver biochemical tests, bilirubin, and decreased serum ceruloplasmin levels. Antinuclear antibodies are negative. What is the most likely diagnosis?

Nonalcoholic fatty liver disease

IBD-related complications for USMLE Step 3: High-Yield Internal Medicine Lessons

Intestinal Complications - Gut Punch Problems

Strictures: Narrowing of the intestinal lumen due to fibrosis (common in CD) or inflammation. Can cause obstruction.
Fistulas & Abscesses: Abnormal connections between bowel and other structures (enteroenteric, enterovesical) or walled-off infections. Primarily in CD. 📌 Mnemonic: Some Fellas Always Make Cancer (Stricture, Fistula, Abscess, Megacolon, Cancer).
Colorectal Cancer (CRC) Risk: Significantly ↑ with disease duration and extent. Surveillance colonoscopy recommended every 1-2 years starting >8-10 years after diagnosis.

⭐ Toxic megacolon is a life-threatening complication characterized by acute colonic dilation (>6cm on imaging), more commonly seen in Ulcerative Colitis.

MSK & Skin Manifestations - Achy Joints, Itchy Spots

Arthritis: Most common extraintestinal complication.
- Peripheral: Asymmetric, non-deforming, pauciarticular (<5 joints) or polyarticular. Activity often parallels IBD activity.
- Axial: Spondyloarthritis (Ankylosing Spondylitis) & Sacroiliitis. Associated with HLA-B27. Activity is independent of IBD activity.
Erythema Nodosum (EN): Painful, red nodules on anterior shins. Typically mirrors IBD activity.
Pyoderma Gangrenosum (PG): Deep, ulcerative lesions with purulent base and violaceous borders. Course is independent of IBD activity.

Cutaneous Manifestations of Inflammatory Bowel Disease

⭐ High-Yield: Erythema nodosum activity typically parallels IBD flares, whereas pyoderma gangrenosum and axial arthropathies (e.g., sacroiliitis, ankylosing spondylitis) often follow a course independent of intestinal inflammation.

Hepatobiliary & Systemic - Beyond the Bowel

Hepatobiliary
- Primary Sclerosing Cholangitis (PSC): Inflammation & fibrosis of intra- and extrahepatic bile ducts. Strongly linked to UC. Associated with p-ANCA.
- Gallstones: Increased risk, especially in Crohn's disease due to bile salt malabsorption.
- Hepatic Steatosis (Fatty Liver).
Ocular Manifestations
- Uveitis, episcleritis. Can be painful with vision changes.
Other Systemic Issues
- Hematologic: Anemia of chronic disease, iron deficiency.
- Thromboembolism: Hypercoagulable state leads to ↑ risk of DVT/PE.
- Nephrolithiasis: Calcium oxalate stones in Crohn's (fat malabsorption → enteric hyperoxaluria).

Cholangiogram: Beaded Bile Ducts in PSC

⭐ Primary Sclerosing Cholangitis (PSC) is strongly associated with Ulcerative Colitis (~70% of PSC patients have UC) and significantly increases the risk for cholangiocarcinoma.

High‑Yield Points - ⚡ Biggest Takeaways

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

Colorectal cancer (CRC) risk increases with disease duration and extent, mandating regular surveillance colonoscopies.

Toxic megacolon, more common in UC, presents as colonic dilation >6 cm with signs of systemic toxicity.

Crohn's disease is defined by transmural inflammation, leading to fistulas, strictures, and abscesses.

Erythema nodosum and pyoderma gangrenosum are classic extra-intestinal skin manifestations.

Axial arthritis (spondylitis, sacroiliitis) is an HLA-B27-associated complication independent of bowel disease activity.

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