Introduction
Lower gastrointestinal (GI) bleeding is a common yet often misunderstood condition. It may appear suddenly as bright red blood in the stool or be hidden and chronic. This guide walks you through the causes, warning signs, diagnostic workup, and treatments.
What is Lower GI Bleeding?
- Defined as bleeding from any GI site distal to the ligament of Treitz (jejunum, ileum, colon, rectum, anus)
- Most common presentation: haematochezia (bright red rectal bleeding)
- May also present as dark red or occult bleeding
Key Clinical Presentations
1. Bright Red Blood Per Rectum (Haematochezia)
- Usually anorectal or sigmoid source
- Seen during or after defecation
2. Mixed Blood with Stool
- Indicates proximal source (e.g., right colon, small bowel)
3. Occult Bleeding
- Hidden blood, detected by fecal occult blood test (FOBT)
- May present with anemia, fatigue
Causes of Lower GI Bleeding by Location
A. Anorectal Region
- Haemorrhoids – bright red bleeding, painless
- Fissure-in-ano – pain on defecation, small volumes
- Carcinoma of the anus – elderly, bloody discharge, ulceration
B. Rectum
- Proctitis – bloody mucus, purulent discharge, perianal pain
- Solitary rectal ulcer – post-defecation bleeding, mucus
- Carcinoma/polyp
C. Colon
- Angiodysplasia – proximal colon, painless, large bleeds
- Diverticular disease – common cause, painless, large volume
- Polyps/carcinoma – bright red or dark mixed blood
- Ulcerative colitis – chronic inflammation, bloody diarrhea
D. Small Intestine
- Meckel’s diverticulum – painless red bleeding in children, young adults
- Crohn’s disease – chronic inflammation, diarrhea, weight loss
- Enteritis (infective, radiation, IBD)
- Ischemia – severe abdominal pain, bloody diarrhea, shock
- Intussusception (children) – red jelly-like stool, colicky pain
- Tumors (leiomyoma, lymphoma) – rare
Age-wise Differential Diagnosis
| Age Group | Likely Causes |
|---|---|
| Children | Meckel’s diverticulum, intussusception, fissure |
| Young Adults | Fissure, IBD, Meckel’s diverticulum |
| Elderly | Carcinoma, diverticular bleed, angiodysplasia, ischemic colitis |
Important Red Flags
- Age >55 with new rectal bleed → assume malignancy until proven otherwise
- Persistent bleeding, weight loss, anemia
- Severe pain + PR bleeding = ischemia or serious colitis
Diagnostic Workup
1. Clinical Evaluation
- History: volume, color, timing
- PR exam: local pathology
- Vitals: shock, instability
2. Lab Tests
- FBC – anemia
- Coagulation profile – clotting issues
- FOB testing – occult blood
3. Imaging & Endoscopy
- PR exam & proctoscopy
- Flexible sigmoidoscopy – colitis, hemorrhoids, polyps
- Colonoscopy – full bowel inspection
- CT Angiography – for active, large volume bleeds
- Technetium scan – Meckel’s diverticulum, angiodysplasia
- Small bowel enema, capsule endoscopy – for obscure bleeds
Emergency Management of Lower GI Bleeding
Step 1: Resuscitation
- PR exam + rigid sigmoidoscopy
- IV fluids, crossmatch blood
- Monitor vitals, urine output
Step 2: Identify Source
- Major PR bleed → CT angiography + intervention
- Stable → colonoscopy (prepped/unprepped)
Step 3: Targeted Management
- Diverticular bleed – often self-limiting
- Angiodysplasia – endoscopic coagulation or angiographic embolization
- Polyps/cancer – polypectomy or surgery
- Meckel’s diverticulum – surgical resection
- Ischemia – fluids, antibiotics, surgery if infarcted
- Hemorrhoids/fissure – local measures, dietary fiber, topical agents
Surgical Management Options
- Laparotomy for uncontrolled bleeding
- Resection for tumors, ischemia
- On-table colonoscopy in acute setting
- Split colostomy if life-threatening & unstable
FAQs About Lower GI Bleeding
Is bright red blood in stool always serious?
Not always. It could be from hemorrhoids—but if you're over 55 or have other symptoms, get evaluated.
What is the most common cause of lower GI bleeding?
Diverticular disease in elderly, hemorrhoids in young adults.
Can colon cancer cause rectal bleeding?
Yes, especially in the elderly. Always investigate rectal bleeding >55.
How is the source of bleeding found?
Via colonoscopy, CT angiography, and nuclear scans.
Can bleeding stop on its own?
Yes, especially if due to hemorrhoids or diverticular disease. But always investigate the first occurrence.
Conclusion
Lower GI bleeding can range from mild and harmless to life-threatening. Prompt assessment using clinical clues, age-appropriate differential diagnosis, and targeted imaging and intervention is crucial for optimal outcomes.
