Bloody Diarrhea

A combination of abdominal pain, cramping, and stools mixed with blood and mucus suggest that a patient has colitis but does not distinguish infectious colitis from idiopathic, inflammatory, or other causes.

 

DDx:

· Infectious:

o Bacterial: E. Coli 0157:H7, Salmonella, Shigella, Campylobacter, Yersinia , C. difficile (less often bloody), Vibrio parahemolyticus, Aeromonas

o Viruses: CMV

o Parasites: entamoeba histolytica, schistosomiasis

o Helminths

· Ischemic Colitis

· GI bleeding (AVMs, diverticulosis, brisk UGI bleeds etc.)

· Medications: NSAIDs, 5-FU, chemotherapy

· Inflammatory Bowel Disease

· Diverticulitis

· Cancer

· Radiation

 

 

Relevant history in a pt with bloody diarrhea:

Bowel symptoms:

· Duration

· Character of stool: loose, formed, mixed with mucus

· Stool caliber and volume

· Character of blood: hematochezia, melena, clots, mixed with stool

· Bleeding intermittent or with every stool

· Bleeding in relation to defecation

· Frequency of bowel movements

Abdominal pain

· Location, radiation

· Character: cramping, dull ache

· Persistent or intermittent, intensity

Rectal pain

Fever (high fever w Shigella, often none with STEC)

First or previous similar episode

Health status, comorbid conditions

 

 

Medications

· Antimicrobial use within preceding month

· Anticoagulants

· NSAIDs

· Chemotherapy

 

 

Travel history

Food consumption

· Raw shellfish

· Raw milk

 

 

Social history

· Congregate living: dormitory, assisted living, nursing home

 

 

Diagnostic Testing:

· Stool cultures should be obtained, specifically to evaluate for the bacterial etiologies identified above, you often must specify for EHEC testing (not a part of routine culture for all labs)

· C. diff toxin

· Stool O&P if relevant travel history or if bacterial cultures negative

· Fecal leukocytes less helpful

· Abdominal CT (with contrast—get stool studies first as po contrast can decrease sensitivity)

· Colonoscopy: useful if non-infectious causes are higher on the differential; often deferred for several days due to risk of perforation

 

 

Empiric treatment for infectious diarrhea:  see link to IDSA guidelines, but generally speaking:

· Quinolones for Shigella, Salmonella

· Macrolide for Campylobacter

· Metronidazole or po vancomycin for C. Diff

· Avoid abx if suspect EHEC

See attached review article on approach to bloody diarrhea in children and adults.

 

 

Overview of  E coli O157:H7 infection:

· Enterohemorrhagic strains of E. Coli (EHEC) are capable of producing Shiga toxin—0157:H7 is a particular strain of EHEC (also known as STEC for Shiga toxin producing E. Coli)

· Incubation period is typically 3-4 days

· Hemolytic uremic syndrome complicates up to 10% of cases of EHEC: of acute renal failure, microangiopathic hemolytic anemia and thrombocytopenia (typically 5 to 10 days after the onset of diarrhea)

 

 

Clinical features:

· Nonbloody diarrhea that becomes bloody after 1–3 days.

· No fever on initial presentation to medical care.

· Tender abdomen.

· More than 5 stools in the past 24 hours.

· Pain is worse on defecation.

· No, few, or moderate fecal leukocytes

· Diarrhea, and especially bloody diarrhea, persists during first 8 hours in hospital.

· There is no relative bandemia in the differential white cell count

 

 

Diagnosis:

· As above, not always checked on routine stool culture, needs to be sent on sorbitol-MacConkey (SMAC) agar

· Highest yield in first 6 days of symptoms

 

 

Treatment:

· Supportive care, monitoring for signs of HUS

· Avoidance of antimotiility agents

· Antibiotics are controversial: some concern that they can precipiate HUS and there is no evidence that they will reduce duration of symptoms .  Generally NOT recommended when clinical suspicion of EHEC is high, especially in children

 

See link to IDSA guidelines for more info on infectious diarrhea: http://sfx.stanford.edu.laneproxy.stanford.edu/local?sid=Entrez:PubMed&id=pmid:11170940

 

 

(Victoria Kelly MD, 5/3/11)