Lower Gastrointestinal Bleeding

Aka: Lower Gastrointestinal Bleeding, Lower GI Bleed, Lower Gastrointestinal Hemorrhage, Rectal Bleeding, Anal Bleeding, Rectal Hemorrhage

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II. Definitions

  1. Lower Gastrointestinal Bleeding
    1. Bleeding distal to the ligament of treitz (suspends the distal duodenum) at the duodenojejunal flexure

III. Epidemiology

  1. Incidence: 20 to 30 per 100,000 patients
  2. Hospital admission rate: 20 to 30 (up to 80) per 100,000 patients
  3. Lower GI Tract account for 20-30% of Gastrointestinal Bleeding sources
    1. Two thirds of Lower GI Bleeds originate in the colon, Rectum or anus (remainder from the Small Bowel)

IV. Causes: Adults with Acute Massive Rectal Bleeding

  1. Precaution: Consider Upper Gastrointestinal Bleeding source
  2. Diverticular Bleeding (10-20%, up to 40% of cases in some studies, most common cause)
    1. Acute, severe painless bleeding, especially with known Diverticular Disease (approaches 50% in over age 60 years)
    2. Increased risk with advancing age and comorbidities (e.g. CAD, CKD, DM, Cirrhosis, cancer)
    3. Increased risk with NSAIDs, Aspirin and other antiplatelet agents (e.g. Plavix)
    4. Bleeding spontaneously ceases in 75%, recurs in 38%
    5. Recurrence is 9% at one year and 25% at 4 years
  3. Angiodysplasia, angioectasias or Arteriovenous Malformations (3-12%)
    1. Recurrent painless bleeding, especially in over age over 60 years
    2. Self resolves in 40-45% of cases, and persistent cases are treated with endoscopic coagulation or electrocautery
  4. Colon Cancer (2-26%)
    1. Slow chronic blood loss with change in bowel habits (esp. age >60 years old, positive Family History)
    2. May be associated with weight loss, chronic Anemia, incomplete emptying
  5. Inflammatory Bowel Disease (10%)
    1. Bloody Diarrhea with recurrent crampy Abdominal Pain and weight loss
    2. Bleeding is more common with Ulcerative Colitis than with Crohns Disease
  6. Ischemic Colitis (16 to 24%)
    1. Self-limited bloody Diarrhea, followed by acute, recurrent lower Abdominal Pain and weight loss
    2. Seen in cardiovascular disease patients (including Aortic Stenosis)
    3. May be foretold by prior hypotensive event
    4. Ischemic Colitis is missed as Hematochezia cause in up to 80% of patients ultimately diagnosed with the condition
  7. Rectal ulcer
    1. Hard stool induced Pressure Ulcers
    2. More common in Immunocompromised patients and with Sexually Transmitted Infections
  8. Acute Infectious Colitis
    1. Bloody Diarrhea with fever (Inflammatory Diarrhea or Dysentery), and travel history or food exposures
    2. Causes include Campylobacter jejuni (most common Bacteria), Salmonella, Shigella, Shiga-toxin producing E. coli
    3. Other inflammatory causes include Clostridium difficile, Entamoeba histolytica and Yersinia
  9. Pseudomembranous colitis (or other Infectious Diarrhea or Dysentery)
    1. Bloody Diarrhea with fever and risk factors (recent Antibiotics, suspect oral intakes)
  10. Radiation Colitis
    1. May be delayed 3 years after Radiation Therapy
  11. Post-polypectomy bleeding
    1. Self-limited bleeding, usually follows polypectomy or other bowel procedure within 30 days
    2. Associated with restarting NSAID or Aspirin too soon after Colonoscopy with polypectomy
  12. Aortoenteric Fistula (Aortic Graft-Enteric Fistula)
    1. Occurs in those with aortic surgery history
    2. Requires immediate emergency management (untreated cases have mortality rates approaching 100%)
  13. Internal Hemorrhoid (<10%)
    1. External Hemorrhoids may also cause bleeding, but are painful and with obvious source unlike Internal Hemorrhoids
    2. See evaluation below regarding precautions in attributing Gastrointestinal Bleeding to Hemorrhoids
    3. More common at ages 45-65 years old

V. Causes: Adults with chronic intermittent GI Bleeding

  1. Hemorrhoids (Up to 59%, includes external and Internal Hemorrhoids)
  2. Colorectal polyps (38 to 52%)
  3. Diverticulosis (34 to 51%)
  4. Colorectal Cancer (up to 8%)
  5. Ulcerative Colitis
  6. Arteriovenous Malformations
  7. Colonic stricture

VI. Causes: Adults - most commonly missed lower GI sources

  1. Arteriovenous Malformations
  2. Neoplasms in colon

VII. Causes: Children

  1. Anal Fissure
  2. Infectious Colitis
  3. Inflammatory Bowel Disease
  4. Colonic Polyps
  5. Intussusception
  6. Gastrointestinal Foreign Body (e.g. Button Battery)
  7. Arteriovenous Malformation
  8. Meckel's Diverticulum (Ileal Diverticulum)
    1. Most common congenital GI abnormality
    2. Strongly consider in children with Lower GI Bleeding (esp. age <10 years old, or with intussception)
    3. Consider Technetium 99m Scan
  9. Blood Mimics
    1. Ingestion of berries, beets or red Food Dye
    2. Cefdinir (melana-like stools)

VIII. Causes: Newborns and Infants

  1. Anal Fissure
  2. Cow's Milk Protein Sensitivity
  3. Soy Protein Allergy
  4. Necrotizing Enterocolitis
  5. References
    1. Claudius, Seiden and Sacchetti (2025) GI Bleed, EM:Rap 5/19/2025

IX. History

  1. See Gastrointestinal Bleeding
  2. Distinguishing severe from mild lower intestinal bleeding may be difficult on initial presentation
    1. Ask to see photos of home output if available
  3. Findings that may suggest more severe bleeding
    1. Blood clots
    2. Bloody rectal output without stool (may also be distal rectal source, e.g. Hemorrhoids)
    3. Continuous bloody output

X. Signs

  1. Hematochezia (bright red blood in stool)
    1. Upper Gastrointestinal Bleeding source in 5-11% of patients
  2. Normal Bowel Sounds
  3. Hemodynamic status is typically more stable than in Upper GI Bleed
    1. Orthostasis may however be seen in one third of patients
    2. Brisk, life-threatening bleeding may still occur in Lower GI Bleeding (e.g. Diverticular Bleeding)
  4. Nasogastric lavage and aspirate is clear except for bile
    1. Not typically recommended to differentiate upper from lower GI source (poor efficacy)
    2. Nasogastric aspirate is in contrast positive in Upper Gastrointestinal Bleeding
  5. Rectal Exam
    1. Perform in all Hematochezia patients, but often nondiagnostic (may miss severe intermittent GI Bleed)

XI. Labs

  1. Serum Electrolytes
    1. BUN to Creatinine ratio >33 suggests Upper Gastrointestinal Bleeding source
    2. Normal Renal Function tests (BUN to Creatinine ratio normal) is typically normal in Lower Gastrointestinal Bleeding
      1. However, prerenal Azotemia may also occur in Dehydration (e.g. Acute Inflammatory Diarrhea)
  2. Complete Blood Count
    1. Hemoglobin or Hematocrit decreased in 50% of patients
      1. Usually less depressed than in Upper Gastrointestinal Bleeding
  3. Coaulation Studies
    1. Partial Thromboplastin Time (PTT)
    2. Prothrombin Time (PT/INR)
  4. Preparation for Blood Transfusion
    1. Consent for Blood Products
    2. Type and Crossmatch for Packed Red Blood Cells (pRBC)
  5. Assessment of comorbidity and secondary complications
    1. Electrocardiogram (EKG)
    2. Troponin
  6. Other diagnostic tests
    1. Fecal Calprotectin
      1. Indicated in the evaluation of Inflammatory Bowel Disease (positive if >250 mcg/g)
    2. Acute Inflammatory Diarrhea Causes
      1. Enteric Bacteria stool PCR testing
      2. Clostridium difficile Toxin (if recent Antibiotics)
      3. Entamoeba histolytica (travel to tropical Africa, Asia or Latin America)

XII. Evaluation: Hemodynamically Unstable (Tachycardia, Hypotension)

  1. See stabilization in management below
  2. Criteria
    1. Heart Rate >100
    2. Systolic Blood Pressure <115 mmHg
    3. Capillary Refill >3 seconds
    4. Two or more comorbid conditions
    5. Shock Index (HeartRate/SystolicBP) >1

XIII. Evaluation: Hemodynamically Stable

  1. Painful Bleeding
    1. Fever, Diarrhea and possible exposures (food, recent travel)
      1. Infectious Colitis (Dysentery) evaluation with Stool Culture or Enteric Bacteria and virus PCR panel
    2. Vascular disease risk factors in an older patient with pain out-of-proportion and symptoms recurrent with eating
      1. Ischemic Bowel disease evaluation with CT Abdomen with contrast, Colonoscopy
    3. Intermittent Abdominal Pain, weight loss in a younger patient
      1. Inflammatory Bowel Disease evaluation with Fecal Calprotectin and Colonoscopy
    4. Pruritus Ani with bleeding occurs after stooling
      1. Evaluate for Hemorrhoids with Anoscopy (and ask patient to perform valsalva during exam)
      2. Anemia is rare with Hemorrhoidal bleeding
      3. Precaution: Bleeding Hemorrhoids may be concurrent with a more proximal, serious bleeding source
        1. Colonoscopy is not typically needed in suspected Hemorrhoids in age <40 without red flags
        2. Red flags include weight loss, fever, Anemia, colon cancer Family History, refractory course
  2. Painless Bleeding
    1. Intermittent bleeding with weight loss and changes in bowel habits
      1. Colon Cancer evaluation with Colonoscopy
    2. Acute painless bleeding with history of Diverticular Disease
      1. Diverticular Bleeding evaluation with Colonoscopy
    3. Polypectomy in the last 30 days
      1. Post-polypectomy bleeding evaluation with Colonoscopy
  3. Tools
    1. Oakland Score for Safe Discharge After Lower Gastrointestinal Bleeding
      1. https://www.mdcalc.com/calc/10042/oakland-score-safe-discharge-lower-gi-bleed

XIV. Management: Acute Gastrointestinal Bleeding

  1. Precaution
    1. Brisk persistent bleeding occurs in up to 19% of cases
    2. Severe Hematochezia leads to a >=2 g Hemoglobin decrease in 24 hours, or >=2 unit pRBC required
  2. Initial Stabilization
    1. Obtain early Consultation with Gastroenterology or General Surgery for brisk Gastrointestinal Bleeding
    2. ABC Management
    3. Oxygen Supplementation
    4. Obtain two large bore peripheral IVs (14-16 gauge)
    5. Obtain acute labs as above
    6. Stabilize with crystalloid (e.g. Normal Saline) as needed for hemodynamic instability while Blood Products pending
      1. However, blood is far preferred as soon as it is available
      2. Avoid excessive crystalloid prior to transfusion
    7. Telemetry monitoring with Heart Rate, Oxygen Saturation and Blood Pressure Monitoring
      1. May also obtain Orthostatic Blood Pressure and Pulse if able (but poor efficacy)
    8. Transfuse Packed Red Blood Cells
      1. pRBC transfusion indicated for severe Anemia (Hemoglobin <7 g/dl, restrictive strategy)
      2. pRBC transfusion Indications for Hemoglobin <8 g/dl
        1. Symptomatic Anemia
        2. Continued heavy bleeding
        3. Ischemic cardiovascular disease or other affected significant comorbidity
    9. Consider Coagulopathy management
      1. See Emergent Reversal of Anticoagulation
      2. Indicated in hemodynamic instability despite other Resuscitation
      3. Available agents
        1. Prothrombin Complex Concentrate (PCC 4)
        2. Fresh Frozen Plasma (FFP)
        3. Platelet Transfusion (for Platelet Count <30,000, or for endoscopy, 50,000)
        4. Tranexamic Acid (NOT recommended, lacks evidence of benefit)
    10. Antiplatelet agent management
      1. Continuing low dose Aspirin (e.g. 81 mg) has both risks and benefits
        1. Those with significant cardiovascular disease risk may continue Aspirin 81 mg daily
          1. Cardiovascular disease patients have fewer serious cardiovascular events on low dose Aspirin
        2. Low dose Aspirin is associated with increased risk of rebleeding after initial GI Bleeding event
        3. Low dose Aspirin use prior to endoscopy is associated with increased mortality in GI Bleeding
          1. However, Platelet function only improves 10%/day after stopping Aspirin
          2. Full return of Platelet function occurs at 10 days (Platelet lifetime) after stopping Aspirin
      2. Discontinue Dual Antiplatelet Therapy
        1. Continue low dose Aspirin
        2. Hold nonaspirin Antiplatelet Therapy for 1 to 7 days
    11. Other medications to consider
      1. Octreotide
        1. Augments Platelet aggregation, decreases splanchnic perfusion and decreases Angiogenesis
        2. Consider in Small BowelHemorrhage and Angiodysplasia
  3. Obtain endoscopy (Colonoscopy and possible upper endoscopy if unclear source)
    1. See Colonoscopy in GI Bleeding
    2. Obtain Colonoscopy when patient is hemodynamically stable and with adequate Colonoscopy preparation
      1. Preparation with Polyethylene Glycol 4 to 6 Liters over 3-4 hours until output without stool or blood
      2. Goal endoscopy timing is within 24 hours of significant acute Lower Gastrointestinal Bleeding
      3. Endoscopy is safe when INR <=2.5 and Platelet Count >50,000
      4. Hemostasis may be achieved with hemostatic clips, Epinephrine injections and coagulation
    3. Avoid tests without adequate yield in acute bleeding
      1. Avoid Flexible Sigmoidoscopy
      2. Avoid Barium Enema
    4. Consider Upper Gastrointestinal Bleeding source
      1. Upper GI Bleed with Hematochezia is always considered unstable
      2. BUN to Creatinine ratio increased >30-36 in Upper Gastrointestinal Bleeding (controversial reliability)
      3. Nasogastric lavage and aspirate is not typically recommended to differentiate source (low efficacy)
  4. Bleeding ceases spontaneously (occurs in 50% of cases)
    1. See Colonoscopy in GI Bleeding
    2. Evaluation may proceed outpatient in stable patient
    3. Colonoscopy negative: Consider Upper GI Bleed
  5. Brisk GI Bleeding obscures source on Colonoscopy (or too unstable for endoscopy)
    1. See Angiography in GI Bleeding
    2. CT Angiography WITHOUT Oral Contrast (preferred)
      1. See CT Angiography in Gastrointestinal Bleeding
      2. May be test of choice in heavy Lower GI Bleeding in which endoscopy cannot be performed
      3. May direct exploratory laparotomy (identifying source)
      4. Typically performed as triple phase scan (CT non-contrast, CTA arterial phase, CT venous phase)
    3. Percutaneous catheter arteriography and embolization
      1. Consider as second-line test if bleeding persists and source not identified
      2. Highest yield study and allows for directed embolization
      3. Complications include acute bowel ischemia, contrast nephropathy
    4. Radionuclide Red Cell Scan (Technetium Tc 99m-labeled RBC Scintigraphy)
      1. Less accurate, older procedure that is rarely performed now, and not typically recommended
      2. May be considered in hemodynamically stable patients in whom other methods are nondiagnostic
      3. More useful in slower bleeding (<0.4 ml/minute) but requires a minimum of 0.1 ml/min
      4. Immediate blush identifies high risk bleeding
        1. Ng (1997) Dis Colon Rectum 40:471-7 [PubMed]
  6. Slow continuous or recurrent bleeding
    1. See Colonoscopy in GI Bleeding
    2. No source on Colonoscopy
      1. Radionuclide Red Cell Scan: Positive
        1. See Angiography in GI Bleeding
        2. Consider repeat Colonoscopy in GI Bleeding
          1. Guided by red cell scan results
        3. Consider exploratory laparotomy
          1. See below for indications
      2. Radionuclide Red Cell Scan: Negative
        1. Consider Upper Endoscopy
          1. Evaluate for Hematochezia due to Upper GI Bleed
          2. These cases are always hemodynamically unstable
        2. Consider Small Intestinal Bleeding
  7. Exploratory laparotomy
    1. Adjunctive intraoperative measures
      1. Intraoperative Colonoscopy
      2. Intraoperative angiography
      3. Subtotal colectomy is a a procedure of last resort
        1. Indicated only in uncontrolled Massive Hemorrhage where no alternative management exists
        2. High morbidity and mortality associated with emergent subtotal colectomy
    2. Indications
      1. Transfusion >4 units in 24 hours
      2. Transfusion >10 units total
      3. Recurrent bleeding episodes
      4. Comorbid conditions significantly affected
  8. Disposition
    1. Several established tools may help with risk stratification to outpatient management
    2. Oakland Score for Safe Discharge After Lower Gastrointestinal Bleeding
      1. https://www.mdcalc.com/calc/10042/oakland-score-safe-discharge-lower-gi-bleed
      2. Score <=8 is consistent with safe discharge and outpatient follow-up

XV. Management: Asymptomatic mild Rectal Bleeding (clinic)

  1. Age over 35 years: Colonoscopy
  2. Age 25 to 35 years: Diagnostics based on risk factors
  3. Age under 25 years: Anoscopy, Flexible Sigmoidoscopy
  4. Lewis (2002) Ann Intern Med 136:99-110 [PubMed]

XVI. Prognosis

  1. Overall mortality 4%
  2. Mortality may approach 20% if admitted for comorbidity

XVII. Resources

  1. Oakland Score for Safe Discharge After Lower Gastrointestinal Bleeding
    1. https://www.mdcalc.com/calc/10042/oakland-score-safe-discharge-lower-gi-bleed

XVIII. References

  1. Rodgers (2024) Crit Dec Emerg Med 38(11): 4-11
  2. Morris (2020) Crit Dec Emerg Med 34(8): 9
  3. Demarkles (1993) Med Clin North Am 77(5):1085-100 [PubMed]
  4. Fallah (2000) Med Clin North Am 84(5):1183-208 [PubMed]
  5. Hawks (2020) Am Fam Physician 101(4): 206-12 [PubMed]
  6. Manten (1995) Postgrad Med 97(4):154-7 [PubMed]
  7. Peter (1999) Emerg Med Clin North Am 17(1):239-61 [PubMed]
  8. Sengupta (2023) Am J Gastroenterol 118(2): 208-31 [PubMed]
  9. Zuckerman (2000) Gastroenterology 118:201-21 [PubMed]

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