Toxic megacolon differential diagnosis

Differentiating Toxic Megacolon from other Diseases

• Toxic megacolon must be differentiated from other diseases that cause abdominal pain, fever,diarrhea such as acute appendicitis, acute diverticulitis, inflammatory bowel disease, whipple's disease, tropical sprue, infective colitis, viral hepatitis (hepatitis A and hepatitis E), liver abscess, spontaneous bacterial peritonitis, mesenteric ischemia, and acute ischemic colitis.

Preferred Table

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

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 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 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 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 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 Disease 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 Comments 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 Disease 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 Comments 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