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, or computed tomography. 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. Immunosuppressive 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.

	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
Disease	Clinical manifestations													Diagnosis		Comments
	Symptoms									Signs				Diagnosis
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