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

	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
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

Toxic megacolon differential diagnosis

Differentiating Toxic Megacolon from other Diseases

Preferred Table

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