Special Surgery 28. Symptomatics, Causes, and Treatments of Lower-Gastrointestinal Bleeding

I. Definition and Symptomatics

Definition

• LGIB: bleeding distal to ligament of Treitz
• Typical source: colon, rectum, anus; sometimes small bowel
• First question: stable or unstable?
• Important trap: brisk UGIB can present as hematochezia

Main Symptoms

• Hematochezia: bright red / maroon blood per rectum

• Bright red on paper/bowl → anorectal source likely
• Maroon blood/clots → proximal colon or brisk bleeding
• Mixed with stool → colonic source more likely

• Melena: less common → proximal colon, small bowel, or UGIB
• Anemia/hypovolemia: fatigue, dizziness, dyspnea, pallor, tachycardia, hypotension
• Abdominal cramps + bloody diarrhea → ischemic / inflammatory / infectious colitis
• Painless bleeding → diverticulosis, angiodysplasia, hemorrhoids

II. Causes

Common Causes

1. Diverticulosis: most common severe LGIB in older adults

• Painless, intermittent hematochezia; can be massive
• Diverticular neck vessel erosion → arterial bleeding

2. Angiodysplasia

• Right colon dilated vessels → painless occult/overt bleeding
• Risk: age, aortic stenosis, CKD

3. Hemorrhoids / anal fissure

• Hemorrhoids: painless bright red bleeding after stool
• Fissure: severe defecation pain + small fresh bleeding

4. Colorectal cancer / polyps

• Occult bleeding, iron-deficiency anemia, visible bleeding
• Alarm signs: weight loss, change in bowel habit, narrow stool

5. IBD / infectious colitis

• Bloody diarrhea, urgency, fever, systemic symptoms
• UC commonly causes rectal bleeding

6. Ischemic colitis

• Elderly / vascular disease / low-flow state
• Crampy abdominal pain → bloody diarrhea

III. Diagnosis

Initial Assessment

• ABCDE + vital signs → hemodynamic status
• DRE: confirm blood, stool color, rectal mass, fissure/hemorrhoids
• Abdominal exam: tenderness, peritonitis, colitis signs
• History: amount/color of bleeding, pain, diarrhea, fever, weight loss

• NSAIDs, aspirin, anticoagulants
• Diverticulosis, IBD, cancer, vascular disease
• Hematemesis/melena/shock → consider UGIB

Laboratory Tests

• CBC: Hb/Hct, platelets
• Coagulation: INR/PT, aPTT
• Renal function/electrolytes: dehydration, CKD, bowel-prep safety
• CRP/WBC + stool tests if colitis/infection suspected
• Type and screen / crossmatch if major bleeding possible

Diagnostic Tools

• Stable patient → bowel prep → colonoscopy

• Main diagnostic + therapeutic test
• Routine urgent colonoscopy within 24 h is not required for all patients

• Unstable or ongoing severe bleeding → CT angiography first

• Localizes active bleeding → angiographic embolization / targeted therapy

• Negative colonoscopy + ongoing bleeding → consider EGD or small bowel evaluation

• Capsule endoscopy / balloon enteroscopy for obscure small bowel source

IV. Treatment

1. Initial Stabilization

1. ABC → oxygen/airway support if shock or altered consciousness
2. Two large-bore IV lines → fluids → crossmatch blood
3. Transfuse if needed; usually Hb <7 g/dL, higher threshold in cardiovascular disease/shock
4. NPO in major bleeding; monitor vitals, urine output, repeated Hb
5. Hold anticoagulants in major bleeding; reverse only severe/life-threatening bleeding

2. Endoscopic Treatment

• Active bleeding / visible vessel / adherent clot → endoscopic hemostasis
• Methods: clips, thermal coagulation, injection + definitive therapy
• Angiodysplasia → argon plasma coagulation / coagulation therapy
• Polyps/cancer/colitis → biopsy, resection/staging or disease-specific treatment

3. Radiologic and Surgical Treatment

• Persistent severe bleeding + positive CTA → catheter angiography + embolization
• Surgery: rare, last-line

• Massive ongoing bleeding despite endoscopy/embolization
• Peritonitis, perforation, gangrenous ischemic bowel
• Bleeding tumor requiring resection
• Localized source → segmental colectomy; avoid blind segmental resection