Undifferentiated lower gastrointestinal bleeding

Background

Gasterointestinal anatomy.

Layers of the Alimentary Canal. The wall of the alimentary canal has four basic tissue layers: the mucosa, submucosa, muscularis, and serosa.

• Loss of blood from the gastrointestinal tract distal to the ligament of Treitz
  • Majority of cases originate distally to ileocecal valve, rather than small intestines
• Diverticulosis cause majority, other conditions include colitis, polyps, colorectal cancer, hemorrhoids, anal fissures, inflammatory bowel disease
  • Consider recent procedures such as abdominal surgeries or colonoscopies/polypectomies
  • Must consider upper GI bleed (especially rapid transit) as a source, as a significant number of lower GI bleeds have a concurrent upper GI bleed, brisk or not
• Cause of bleeding found in <50% of cases^{[citation needed]}
• 80% of lower GI bleeding will resolve spontaneously

Medication Risk Factors

• Obtain a thorough medication history to assess for new antiplatelets or anticoagulants
  • Salicylates
  • NSAIDs
  • Warfarin and Clopidogrel
  • Apixaban and Rivaroxaban

Clinical Features

Type of blood

• Hematochezia
  • Usually represents lower GI bleeding
  • Left colonic bleeding tends to be bright red, whereas right colonic is usually maroon and mixed with stool
  • May represent upper GI source if bleeding is brisk
    • Usually accompanied by hematemesis and hemodynamic instability
• Melena
  • Usually represents bleeding from upper GI source (see upper GI bleed)
  • May represent slow bleeding or slow stool transit from lower GI source

Differential Diagnosis

Undifferentiated lower gastrointestinal bleeding

• Upper GI Bleeding
• Diverticular disease
  • Diverticulosis
  • Diverticulitis
• Vascular ectasia / angiodysplasia
• Inflammatory bowel disease
• Infectious colitis
• Mesenteric Ischemia / ischemic colitis
• Meckel's diverticulum
• Colorectal cancer / polyps
• Hemorrhoids
  • Internal hemorrhoid
  • External hemorrhoid
• Aortoenteric fistula
  • Nearly 100% mortality if untreated
  • Consider in patients with gastrointestinal bleeding and known abdominal aortic aneurysms or aortic grafts
• Rectal foreign body
• Rectal ulcer (HIV, Syphilis, STI)
• Anal fissure

Evaluation

Fecal Occult Blood Test showing positive (A) and positive control (B).

• Digital rectal exam for guaiac or assessment of anorectal structural abnormalities
• Consider chart review to search for prior colonoscopy/endoscopy results

Workup

• CBC
  • Consider q3-12hr serial Hgb, depending on suspected severity of bleed
  • Initial Hgb may be normal if bleeding is acute
• CMP
  • BUN may be elevated if bleeding occurs from site high in GI tract, due to heme digestion to nitrogenous substances reflected in BUN
• Coags
• Type and screen/cross
• Consider:
  • ECG (if concern for silent ischemia in patients likely to have CAD)
  • Fibrinogen
  • CTA
    • Requires brisk bleeding rate (0.5 cc/min) for detection^{[citation needed]}
  • Tagged red blood cell scan (not typically an emergency study)

Definitive studies

• Consider:
  • Anoscopy if source of bleeding cannot be identified on external exam
  • Proctoscopy (22cm from anal verge)
  • Sigmoidoscopy (60cm from anal verge)

False Positive Guaiac

• Red meat
• Red jello
• Fruit and vegetables
  • Melon, broccoli, radish, beets
• Iron (causes GI bleed by irritation)

Management

• NPO, if there is foreseeable endoscopy or surgery
• Fluid resuscitation for all

Categorize as stable versus unstable using shock index: <1 stable; >1 unstable or suspect active bleeding

• Unstable
  • CT angiography is preferred for hemodynamically unstable patients due to speed
  • Consider transfusing pRBCs/platelets for unstable patients or with very low hemoglobin (<7). with cardiovascular disease use trigger of 8 and target of 10 hemoglobin.
    • Base decision to transfuse on individual clinical factors. Active bleeding and tachycardia may call for transfusion despite normal Hgb
  • Consider withholding and DOACs; consult with a specialist or the physician who prescribed the medication especially if high-risk cardiac pathology is present
  • Consult GI for emergent sigmoidoscopy/colonoscopy (next 24 hours); upper endoscopy may be needed if CTA does not reveal source of GI bleeding
  • Consult interventional radiology for embolization if an extravasating lesion is identified on CTA
  • Consult surgery if endoscopy fails or not available
• Stable
  • Calculate risk score to determine disposition
    • Oakland score
    • Glasgow-Blatchford Bleeding Score

Major Bleed and Supratherapeutic INR

• Correct coagulopathy
  • Vitamin K 10mg IV (best bioavailability in critical patient)
  • PCC or FFP

Special situations

• Marathon runners - 16% will have hematochezia within 24-48 hrs of race and 85% will be guaiac positive
  • Non-actionable unless abdominal pain present

Disposition

Discharge

• Oakland score can help determine if outpatient management is feasible
• Bleeding from hemorrhoids, anal fissures, or known IBD (hemodynamically stable)
• No gross blood on rectal exam (hemodynamically stable)
• Minor, self-terminating bleed with no other indication for admission (shock index >1; low risk score calculated)

Admission

• Melena
• Significant anemia
• Hemodynamic instability

See Also

Gastrointestinal Bleeding Pages

• Adults
  • Upper GI bleeding
    • Balloon tamponade for massive GI bleeding
    • Upper GI bleeding guidelines
    • EBQ:Omeprazole in Bleeding Peptic Ulcers
  • Lower GI bleeding
• Pediatrics
  • Gastrointestinal bleeding (peds)