Inflammatory bowel disease

Inflammatory Bowel Disease Main page
Patient Information
Overview
Causes
Classification Crohn's disease Ulcerative colitis
Differential Diagnosis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] ; Associate Editor(s)-in-Chief: Aditya Ganti M.B.B.S. [2]
Synonyms and keywords: IBD ;

Overview

Inflammatory bowel disease (IBD) is a chronic inflammatory disease of the gastrointestinal tract that represents 2 distinctive disorders, Crohn's disease and ulcerative colitis. Both disorders are characterized by unpredictable exacerbations and remissions. Genetic and environmental factors are believed to play a key role in the pathogenesis of IBD. A dysregulated immune response to environmental factors in a genetically susceptible host results in activation of cytokines, triggering a cascade of reactions ultimately bowel inflammation. Common symptoms of inflammatory bowel disease include persistent diarrhea, abdominal pain, rectal bleeding/bloody stools, weight loss and fatigue. IBD can be diagnosed using a combination of endoscopy for Crohn’s disease or colonoscopy for ulcerative colitis and imaging studies, such as contrast radiography, magnetic resonance imaging (MRI), or computed tomography (CT). The goal of medical therapy is to induce remission initially with medications, followed by the administration of maintenance medications to prevent a relapse of the disease. Sulfasalazine along with steroids are the main stay of treatment for IBD. Immunosuppresive agents such as infliximab or 6-mercaptopurine and azathioprine are recommended alternatives to steroids.

Causes

While the causes of inflammatory bowel disease is unknown, several possibly interrelated studies have been suggested following causes:

Common causes

Genetic factors

• Mutations in the CARD15 gene (also known as the NOD2 gene) are associated with Crohn's disease.
• Mutations of the transporter proteins such as OCTN1 and OCTN2 and scaffolding proteins such as the MAGUK family are believed to cause ulcerative colitis.

Environmental factors

• Alterations in normal bacterial flora of the intestinal tract is responsible for Crohn's disease.
• Smoking: Unlike Crohn's disease, ulcerative colitis has a lesser prevalence in smokers than non-smokers.
• Use of NSAIDs
• Stress
• Red meat consumption

Rare causes

• Hemolytic uremic syndrome
• Connective tissue disease
• Vasculitis
• Radiation therapy to the prostate or pelvic area
• Chemical or physical trauma to anorectal area
• Amyloidosis
• Behçet syndrome
• Chronic lymphocytic leukemia
• Lymphoma
• Lipid proctocolitis
• Tuberculosis
• Syphilis
• Infection with Entamoeba histolytica or Giardia lamblia, most often seen in patients with acquired immune deficiency syndrome.
• Infection with C difficile

Classification

Inflammatory bowel disease can be classified into Crohn's disease and ulcerative colitis.

Inflammatory Bowel Disease

Crohn's Disease

Ulcerative colitis

Based on Region involved

Based on Severity

Ileocolic Crohn's disease

Crohn's ileitis

Crohn's colitis

Stricturing disease

Penetrating disease

Inflammatory disease

Based on Region involved

Based on Severity

Distal UC

Proximal UC

Mild

Moderate

Severe

Flumiant

Differential diagnosis

Inflammatory bowel disease must be differentiated from other diseases that present with abdominal pain, fever and diarrhea which include appendicitis, diverticulitis, Whipple's disease, mesenteric ischemia, Tropical sprue, hepatitis and spontaneous bacterial peritonitis.

Disease Clinical manifestations Diagnosis Comments Symptoms Signs Abdominal Pain Fever Rigors and chills Nausea or vomiting Jaundice Constipation Diarrhea Weight loss GI bleeding Hypo- tension Guarding Rebound Tenderness Bowel sounds Lab Findings Imaging Inflammatory bowel disease Diffuse ± − − ± − + + + − − − Normal or hyperactive Anti-neutrophil cytoplasmic antibody (P-ANCA) in Ulcerative colitis Anti saccharomyces cerevisiae antibodies (ASCA) in Crohn's disease String sign on abdominal x-ray in Crohn's disease Extra intestinal findings: Uveitis Arthritis Acute appendicitis Starts in epigastrium, migrates to RLQ + Positive in pyogenic appendicitis + − − ± − − Positive in perforated appendicitis + + Hypoactive Leukocytosis Ct scan Ultrasound Positive Rovsing sign Positive Obturator sign Positive Iliopsoas sign Acute diverticulitis LLQ + ± + − + ± − + Positive in perforated diverticulitis + + Hypoactive Leukocytosis CT scan Ultrasound History of constipation Whipple's disease Diffuse ± − − ± − + + − ± − − N Thrombocytopenia Hypoalbuminemia Small intestinal biopsy for Tropheryma whipplei Endoscopy is used to confirm diagnosis. Images used to find complications Chest and joint x-ray CT MRI Echocardiography Extra intestinal findings: Uveitis Endocarditis Encephalitis Dementia Hepatosplenomegaly Arthritis Ascites Toxic megacolon Diffuse + − − − − + − − + ± + Hypoactive Anemia Leukocytosis especially in patients with Clostridium difficile infection Hypoalbuminemia Metabolic alkalosis associated with a poor prognosis Metabolic acidosis secondary to ischemic colitis CT and Ultrasound shows: Loss of colonic haustration Hypoechoic and thickened bowel walls with irregular internal margins in the sigmoid and descending colon Prominent dilation of the transverse colon (>6 cm) Insignificant dilation of ileal bowel loops (diameter >18 mm) with increased intraluminal gas and fluid Tropical sprue Diffuse + − − − − + + − − − − N Fat soluble vitamin deficiency Hypoalbuminemia Fecal stool test Barium studies: Dilation and edema of mucosal folds Steatorrhea- 10-40 g/day (Normal=5 g/day) Infective colitis Diffuse + − ± − − + − + Positive in fulminant colitis ± ± Hyperactive Stool culture and studies Shiga toxin in bloody diarrhea PCR CT scan Bowel wall thickening Edema Viral hepatitis RUQ + − + + − Positive in Hep A and E + − Positive in fulminant hepatitis Positive in acute + N Abnormal LFTs Viral serology US Hep A and E have fecal-oral route of transmission Hep B and C transmits via blood transfusion and sexual contact. Liver abscess RUQ + + + + − ± + − + + ± Normal or hypoactive CBC Blood cultures Abnormal liver function tests US CT Spontaneous bacterial peritonitis Diffuse + − − Positive in cirrhotic patients − + − − ± + + Hypoactive Ascitic fluid PMN>250 cells/mm³ Culture: Positive for single organism Ultrasound for evaluation of liver cirrhosis Mesenteric ischemia Periumbilical Positive if bowel becomes gangrenous − + − − + + + Positive if bowel becomes gangrenous Positive if bowel becomes gangrenous − Hyperactive to absent Leukocytosis and lactic acidosis Amylase levels D-dimer CT angiography SMA or SMV thrombosis Also known as abdominal angina that worsens with eating Acute ischemic colitis Diffuse + ± + − − + + + + + + Hyperactive then absent Leukocytosis Abdominal x-ray Distension and pneumatosis CT scan Double halo appearance, thumbprinting Thickening of bowel May lead to shock

Abbreviations: RUQ= Right upper quadrant of the abdomen, LUQ= Left upper quadrant, LLQ= Left lower quadrant, RLQ= Right lower quadrant, LFT= Liver function test, SIRS= Systemic inflammatory response syndrome, ERCP= Endoscopic retrograde cholangiopancreatography, IV= Intravenous, N= Normal, AMA= Anti mitochondrial antibodies, LDH= Lactate dehydrogenase, GI= Gastrointestinal, CXR= Chest X ray, IgA= Immunoglobulin A, IgG= Immunoglobulin G, IgM= Immunoglobulin M, CT= Computed tomography, PMN= Polymorphonuclear cells, ESR= Erythrocyte sedimentation rate, CRP= C-reactive protein, TS= Transferrin saturation, SF= Serum Ferritin, SMA= Superior mesenteric artery, SMV= Superior mesenteric vein, ECG= Electrocardiogram