Most Common Causes of Lower GI Bleeding in Young Females
In young females, the most common causes of lower GI bleeding differ substantially from older populations and include inflammatory bowel disease (particularly Crohn's disease), anorectal conditions (hemorrhoids and anal fissures), infectious colitis, and small bowel lesions including Dieulafoy's lesions. 1
Age-Dependent Etiology
The etiology of lower GI bleeding is fundamentally age-dependent, which is critical when evaluating young patients:
Younger patients (under 40-50 years) are most likely to have Dieulafoy's lesions and Crohn's disease, while older patients are prone to diverticulosis and vascular lesions. 1
The classic causes of lower GI bleeding in older populations—diverticulosis (21-41% of cases) and angiodysplasia (3-40%)—are uncommon in young patients and increase dramatically with age, showing a >200-fold increase from age 20 to 80 years. 1, 2
The mean age of patients with lower GI bleeding in general populations ranges from 63-77 years, emphasizing that young females represent a distinct clinical entity. 1
Specific Causes in Young Females
Inflammatory Bowel Disease
- IBD, particularly Crohn's disease, is a leading cause in younger patients and should be aggressively investigated. 1
- Inflammatory/infectious colitis collectively accounts for 11-48% of lower GI bleeding cases across all ages, but represents a higher proportion in younger populations. 2
- IBD presents with cramping abdominal pain and mucosal inflammation. 2
Anorectal Conditions
- Hemorrhoids and anal fissures represent 5-28% of lower GI bleeding cases and are particularly common in young females. 2
- Anal fissures cause severe pain with defecation, distinguishing them from painless causes. 2
Infectious Colitis
- Infectious colitis causes cramping pain with diarrhea and fever. 2
- Recent antibiotic use should prompt consideration of Clostridioides difficile colitis. 2
Small Bowel Lesions
- Small bowel tumors are the most common cause of obscure bleeding in patients younger than 50 years, requiring aggressive investigation with capsule endoscopy. 1
- Dieulafoy's lesions are specifically mentioned as occurring in younger patients. 1
Critical Clinical Distinctions
Pain as a Diagnostic Clue
- The presence or absence of pain fundamentally changes the differential diagnosis. 2
- Painless bleeding suggests diverticulosis or angiodysplasia (uncommon in young patients). 2
- Painful bleeding indicates IBD, infectious colitis, ischemic colitis, or anorectal disease. 2
Gender-Specific Considerations
- More women (75) than men (49) experience lower GI bleeding overall. 3
- In premenopausal women with iron deficiency anemia, all patients should be screened for coeliac disease, but other upper and lower GI investigations should be based on clinical judgment. 1
- Menstrual blood loss is the most common cause of iron deficiency anemia in premenopausal women, but GI sources must still be excluded. 1
Common Pitfalls to Avoid
Do not assume all lower GI bleeding is diverticulosis—this is an older patient disease and the presence of pain changes the differential entirely. 2
Remember that 10-15% of patients presenting with hematochezia have an upper GI source, so consider upper endoscopy if lower tract evaluation is unrevealing. 2, 4
Be aggressive in investigating young patients for small bowel tumors and IBD, as early diagnosis significantly impacts outcomes. 1
Do not overlook commonly missed lesions during initial endoscopy, including Cameron's erosions, Dieulafoy's lesions, and angiectasias. 1
Diagnostic Approach
Colonoscopy is the diagnostic and therapeutic procedure of choice for both acute and chronic bleeding. 5
For obscure bleeding with negative colonoscopy and upper endoscopy, capsule endoscopy should be used early to identify small bowel lesions, particularly in young patients where tumors are more common. 1
All premenopausal women with iron deficiency anemia should be screened for coeliac disease. 1