Physical examination should be used to first identify unstable patients who need immediate attention.1 Vital signs and body weight should be measured. Dehydration is common because of diarrhea, which causes fluid and electrolyte losses. Abdominal examination findings can include tenderness, distention, and/or masses.1 An abdominal mass without overt obstruction may be found. Ileocolitis in CD can often mimic appendicitis with right lower quadrant pain and fever. Approximately one-third of patients with CD have perianal findings. An anorectal examination is required and a pelvic examination should be considered because abscesses, fissures, or fistulas are common in CD.
The most common extraintestinal manifestations on physical examination include large joint arthritis, particularly ankylosing spondylitis and sacroiliitis.28 These disorders can present with low back pain. Ocular inflammatory disorders that can cause eye pain, photophobia, visual impairment, and erythema include uveitis, iritis, and episcleritis.29 Erythema nodosum, appearing as tender raised subcutaneous nodules, often occurs on the lower extremities. Common dermatologic disorders include oral aphthous stomatitis, which causes burning erythematous ulcerations on the buccal and labial mucosa.30 Pyoderma gangrenosum may appear as erythematous pustules on extensor surfaces of extremities.31
Diagnostic Studies for Crohn Disease
Laboratory studies can assist in diagnosis, monitoring disease activity, and assessing treatment efficacy. These tests should include complete blood cell count, complete metabolic panel, pregnancy test prior to treatment, C-reactive protein level, erythrocyte sedimentation rate, and stool studies for Clostridium difficile, ova and parasites, and stool culture. Stool studies should also include the fecal neutrophil-derived biomarkers calprotectin and lactoferrin, which can detect intestinal inflammation.32 These biomarkers can be used to differentiate between CD and IBS in adults and children.1,26,33
Anemia and malabsorption are common in patients with CD. Hemoglobin and hematocrit should be monitored periodically along with folate, iron, vitamin B12, and 25-hydroxyvitamin D levels.1,34,35 The most common etiologies for anemia in CD include iron deficiency, anemia of chronic disease, and vitamin B12 deficiency. Involvement of the terminal ileum is particularly associated with vitamin B12 deficiency.34 Holotranscobalamin (holoTC) combined with methylmalonic acid (MMA) is the most accurate method to identify impaired B12 status.34 Renal and hepatic function testing should be performed prior to treatment. Tuberculosis screening and hepatitis B serologic testing should be completed before prescribing biologic agents.32
Endoscopy and imaging studies are essential tools for diagnosing and monitoring CD. Plain abdominal radiograph is a first-line imaging tool for CD and detects bowel dilatation, obstruction, bowel perforation, and bowel wall thickening.18 Endoscopy, including gastroscopy/enteroscopy and colonoscopy, allows direct visualization of the bowel lumen and can identify characteristic lesions, assess treatment efficacy, and screen for colorectal cancer.18
Computed tomography enterography (CTE) and magnetic resonance enterography (MRE) are the preferred imaging studies in IBD.35 Sometimes referred to as enteroclysis, these radiologic studies use contrast material to demonstrate the structure and function of the intestine.1 Enterographic imaging studies complement endoscopy as they can identify extraluminal pathology and examine part of the gastrointestinal tract that is not accessible to endoscopic procedures.36
Small bowel capsule endoscopy (SBCE) can be used for patients if there is still clinical suspicion of CD despite negative ileocolonoscopy and radiologic examinations.1,26 If SBCE is negative along with other testing, it is moderately certain that the patient does not have CD.26
Biopsy can provide a reliable diagnosis of CD. A minimum of 2 biopsies from 5 sites around the colon (including the ileum and rectum) should be obtained.26,36
Primary Care Considerations
Primary care providers play an important role in identifying and managing patients with IBD in partnership with a multidisciplinary team (eg, gastroenterologist, nutritionist, radiologist, and psychologist). The following are important points regarding identification and care of patients with CD:1,35,37,38
- Consider the diagnosis of CD in patients with a history of diarrhea that contains blood and mucus, abdominal pain, poor appetite, anemia, and weight loss. Red flags for CD include perianal lesions other than hemorrhoids, a first-degree relative with inflammatory bowel disease, weight loss in the past 3 months, abdominal pain for longer than 3 months, and nocturnal diarrhea.
- Physical examination may reveal peritoneal signs such as rebound tenderness, abdominal guarding, masses, and distension. Abscess can present as a mass. Right lower quadrant abdominal tenderness can mimic appendicitis. A digital rectal examination should be performed to detect the presence of rectal masses or abscesses. A fecal occult blood test is necessary.
- Fecal calprotectin is a useful test for ruling out CD in adults.
- Crohn disease can affect any area of the gastrointestinal tract and is associated with extraintestinal manifestations such as large joint arthropathies, ocular inflammatory conditions, vitamin D deficiency, and anemias associated with iron deficiency, folic acid deficiency, and vitamin B12 deficiency.
- Ileocolonoscopy with biopsies is the recommended diagnostic procedure. Computed tomography enterography and magnetic resonance enterography may provide additional information and are used for disease surveillance.
- Immunomodulators and biological agents are commonly used to treat CD. Tuberculosis screening and hepatitis B serology are necessary laboratory tests prior to prescription of these agents. Systemic corticosteroids, budesonide or prednisone, are commonly used to induce remission in CD.
- Patients with CD are at increased risk for cancer, osteoporosis, anemia, nutritional deficiencies, depression, and infection. There is a risk for opportunistic infection with use of biologic agents and immunomodulators. Patients often have anxiety about pregnancy and medication use.
- Persons with CD should be up to date on all immunizations, undergo vigilant cancer screening, and should receive bone mineral density testing for osteoporosis. Persons of childbearing age should be counseled about family planning. Laboratory testing is necessary because of potential anemia and myelosuppression associated with specific medications. Smoking cessation is necessary as smokers have more complicated disease (eg, increased flare-ups). Patient education, nutritional counseling, and emotional support are necessary.