Essential update: Risk stratification model may significantly reduce CT use in Crohn disease patientsA risk-stratification model based on C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR), which are significantly associated with complications in Crohn disease, could reduce the use of computed tomography (CT) scans in patients reporting to the emergency room by 43%, while missing only 0.8% of emergencies, according to a recent retrospective analysis of 613 adult patients. Researchers used logistic regression to model associations between these laboratory values and perforation, abscess, or other serious complications. Further validation studies of the models need to be performed.[1] Signs and symptomsThe characteristic presentation in Crohn disease is abdominal pain and diarrhea, which may be complicated by intestinal fistulization or obstruction. Unpredictable flares and remissions characterize the long-term course.[2, 3, 4] Other signs and symptoms in Crohn disease may include the following: Rectal bleeding Fever Weight loss, anorexia Nausea, vomiting Malnutrition, vitamin deficiencies Generalized fatigability Bone loss Psychosocial issues (eg, depression, anxiety, and coping difficulty); pediatric patients may also experience psychological issues regarding quality of life and body image[5, 6] Growth failure in pediatric patients: May precede gastrointestinal symptoms by yearsSee Clinical Presentation for more detail.DiagnosisExamination for Crohn disease includes the following: Vital signs: Normal, but possible presence of tachycardia in anemic or dehydrated patients; possible chronic intermittent fever Gastrointestinal: May vary from normal to those of an acute abdomen; assess for rectal sphincter tone, gross rectal mucosa abnormalities, presence of hematochezia Genitourinary: May include presence of skin tags, fistulae, ulcers, abscesses, and scarring in perianal region; nephrolithiasis, hydronephrosis, and enterovesical fistulae Musculoskeletal: Possible arthritis and arthralgia, particularly in large joints[7] Dermatologic: May show pallor or jaundice, mucocutaneous or aphthous ulcers, erythema nodosum, and pyoderma gangrenosum Ophthalmologic: May reveal episcleritis; possible uveitis Growth delay: Decreased growth velocity (eg, height), pubertal delay Hematologic: Hypercoagulable stateLaboratory TestsAlthough laboratory results for Crohn disease are nonspecific and are of value principally for facilitating disease management, they may also be used as surrogate markers for inflammation and nutritional status and to screen for deficiencies of vitamins and minerals. Routine laboratory studies include the following: CBC count Chemistry panel Liver function tests Inflammatory markers Stool studies Serologic testsImaging studiesImaging modalities used for Crohn disease include the following: Plain abdominal radiography Barium contrast studies (eg, small bowel follow-through, barium enema, enteroclysis) CT scanning of the abdomen CT enterography or magnetic resonance enterography: Replacing small bowel follow-through studies MRI of the pelvis Abdominal and/or endoscopic ultrasonography Nuclear imaging (eg, technetium-99m hexamethyl propylene amine oxime, indium-111) Fluorine-18-2-fluoro-2-deoxy-D-glucose scanning combined with positron emission tomography or CT scanningProceduresThe following procedures may help in the evaluation of Crohn disease: Endoscopic visualization and biopsy (eg, upper gastrointestinal endoscopy, esophagogastroduodenoscopy, endoscopic retrograde cholangiopancreatography) Colonoscopy, ileocolonoscopy Small bowel enteroscopy Interventional radiology: For percutaneous drainages of abscessesSee Workup for more detail.ManagementPharmacotherapyMedications used in the treatment of Crohn disease include the following: 5-Aminosalicylic acid derivative agents (eg, mesalamine rectal, mesalamine, sulfasalazine, balsalazide) Corticosteroids (eg, prednisone, methylprednisolone, budesonide, hydrocortisone, prednisolone) Immunosuppressive agents (eg, mercaptopurine, methotrexate, tacrolimus) Monoclonal antibodies (eg, infliximab, adalimumab, certolizumab pegol, natalizumab, vedolizumab) Antibiotics (eg, metronidazole, ciprofloxacin) Antidiarrheal agents (eg, loperamide, diphenoxylate-atropine) Bile acid sequestrants (eg, cholestyramine, colestipol) Anticholinergic agents (eg, dicyclomine, hyoscyamine, propantheline)SurgeryUnlike ulcerative colitis, Crohn disease has no surgical cure. Most patients with Crohn disease require surgical intervention during their lifetime. Surgical management of the terminal ileum, ileocolon, and/or upper gastrointestinal tract may include the following[8] : Resection of the affected bowel Ileocolostomy or proximal loop ileostomy Drainage of any septic foci with later definitive resection Strictureplasty Bypass Endoscopic dilatation of symptomatic, accessible stricturesSurgical management of the colon may include the following[8] : Subtotal or total colectomy with end ileostomy (laparoscopic or open approach) Segmental or total colectomy with or without primary anastomosis Total proctocolectomy or proctectomy with stoma creation