Updated: 12/15/2021

Crohn Disease

Review Topic
  • Snapshot
    • A 16-year-old girl presents to her gastroenterologist with severe, crampy, abdominal pain and intermittent nonbloody diarrhea. She has also had unexpected weight loss over the past few months. She also reports having irritating sores in her mouth. On exam, she is noted to have aphthous sores on the bucca mucosal, and skin tags around the anus. A colonoscopy a week later shows cobblestone mucosa and non-contiguous involvement of the small intestine, suggesting a diagnosis of Crohn disease.
  • Introduction
    • Overview
      • Crohn disease is an inflammatory bowel disease that can affect any part of the gastrointestinal (GI) tract, including the mouth and the anus
        • characterized by abdominal pain and nonbloody diarrhea
        • classically associated with non-contiguous involvement, or “skip lesions”, along GI tract
  • Epidemiology
    • Demographics
      • onset 15-30 or 60-70s years of age
    • Risk factors
      • family history
    • Pathogenesis
      • mechanism
        • chronic Th1-mediated inflammation
          • starts as focal inflammatory infiltrates around crypts, evolves into transmural inflammation and noncaseating granulomas
  • Presentation
    • Symptoms
      • GI symptoms
        • results from transmural involvement
        • abdominal pain
        • bloody or nonbloody diarrhea
        • abscess
        • fistulas
        • strictures
        • malnutrition
      • extraintestinal manifestations
        • arthralgias
        • kidney stones
          • calcium oxalate
        • ankylosing spondylitis
      • systemic symptoms
        • chronic intermittent fever
        • weight loss
        • fatigue
    • Physical exam
      • skin and mucosal findings
        • pyoderma gangrenosum
        • erythema nodosum
        • aphthous stomatitis
        • perianal region
          • skin tags
          • scarring
      • ocular finding
        • episcleritis
        • uveitis
  • Imaging
    • Abdominal radiograph
      • indications
        • assess for bowel obstruction
    • CT of abdomen
      • indications
        • evaluation for obstruction, fistulas, or abscesses
  • Studies
    • Serum labs
      • serology used when endoscopic studies and barium studies are inconclusive
        • anti-Saccharomyces cerevisiae positive
        • anti-neutrophil cytoplasmic antibody negative
      • complete blood cell count
      • elevated inflammatory markers
    • Invasive studies
      • colonoscopy or esophagogastroduodenoscopy
        • indication
          • diagnostic
        • findings
          • cobblestone mucosa
          • transmural inflammation
          • skip lesions
          • bowel wall thickening
          • ulcers
          • fissures
    • Histology
      • noncaseating granulomas
      • lymphoid aggregates
  • Differential
    • Ulcerative colitis
      • key distinguishing factors
        • bloody diarrhea
        • disease affecting colon and always the rectum
        • mucosal and submucosal inflammation only
  • Treatment
    • Medical
      • 5-aminosalicylic acid agents
        • indications
          • mild disease
          • initial therapy
        • drugs
          • mesalamine
            • best initial therapy
          • sulfasalazine
      • corticosteroids
        • indications
          • for flares
      • immunosuppressive agents
        • drugs
          • infliximab
            • good for those with fistula formation
          • azathioprine
            • recurrent symptoms off steroids
      • antibiotics
        • drugs
          • metronidazole/ciprofloxacin
            • perianal involvement
      • anti-diarrheal medications
        • drugs
          • loperamide
      • replace fat soluble vitamins
        • vitamin D
          • can lead to hypocalcemia, hypophosphatemia, and secondary hyperparathyroidism
    • Surgical
      • surgical resection of affected area
        • indications
          • not curative
  • Complications
    • Fistula formation
    • Colorectal cancer
    • Abscesses
    • Strictures
  • Prognosis
    • Unpredictable course of relapses and remissions

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(M2.GI.15.4672) A 25-year-old woman presents to her primary care physician complaining of several months of diarrhea. She has also had crampy abdominal pain. She has tried modifying her diet without improvement. She has many watery, non-bloody bowel movements per day. She also reports feeling fatigued. The patient has not recently traveled outside of the country. She has lost 10 pounds since her visit last year, and her BMI is now 20. On exam, she has skin tags and an anal fissure. Which of the following would most likely be seen on endoscopy and biopsy?

QID: 107179

Diffuse, non-focal ulcerations with granuloma



Diffuse, non-focal ulcerations without granuloma



Pseudopolyps and continuous mucosal involvement



Focal ulcerations with granuloma



Friable mucosa with pinpoint hemorrhages



M 6 E

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(M2.GI.15.4672) A 42-year-old female presents to her primary care provider complaining of numbness and tingling bilaterally in her hands for the past month. She has a past medical history of Crohn’s disease and underwent ileal resection 2 years ago. Previously, laboratory studies demonstrated glucose intolerance, which has been managed with lifestyle modifications. The patient’s vital signs are T 98.7 F, HR 98, BP 128/76, and O2 Sat 98%. CBC demonstrates a WBC 7.0, Hgb 10.8, Hct 31.1, and MCV 110. The patient’s Hgb A1c is 5.6%. MRI spine is performed, which shows the following finding (Figure A). What is the most likely cause of the patient’s presentation?

QID: 107181

Long-term poorly managed diabetes mellitus



New onset of multiple sclerosis



Manifestation of a previously untreated syphilis infection



Consequence of ileal resection



Autoimmune destruction of gastric parietal cells



M 6 C

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(M2.GI.14.5) A 27-year-old man presents to the emergency department for weakness and fatigue. His symptoms started 3 days ago and have been gradually worsening. The patient has a history of poorly managed Crohn disease and currently has a complication being managed by his surgeon. This past month, he has had 4 episodes of severe abdominal pain requiring admission. His temperature is 97.6°F (36.4°C), blood pressure is 114/64 mmHg, pulse is 120/min, respirations are 12/min, and oxygen saturation is 98% on room air. Physical exam is notable for the finding in Figure A which is suctioned and cleaned. His abdomen is nontender. Laboratory studies are ordered as seen below.

Na+: 139 mEq/L
Cl-: 100 mEq/L
K+: 3.3 mEq/L
HCO3-: 25 mEq/L
BUN: 20 mg/dL
Glucose: 90 mg/dL
Creatinine: 1.4 mg/dL
Ca2+: 10.2 mg/dL

Which of the following is the most appropriate initial step in management?

QID: 105615

Abdominal ultrasound






CT abdomen






Ringer lactate



M 7 E

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Evidence (7)
Private Note