What are the possible causes of intestinal bleeding in a 15-year-old male?

Causes of Intestinal Bleeding in a 15-Year-Old Male

In a 15-year-old male presenting with intestinal bleeding, the most likely causes include inflammatory bowel disease (particularly Crohn's disease and ulcerative colitis), infectious gastroenteritis (especially Shiga toxin-producing E. coli, Salmonella, Shigella, Campylobacter, and Yersinia), peptic ulcer disease, and Meckel's diverticulum, with the diagnostic approach prioritizing immediate assessment of hemodynamic stability followed by endoscopic evaluation.

Primary Differential Diagnoses

Inflammatory Bowel Disease (IBD)

• Crohn's disease typically presents with focal erosion into intestinal vessels and can involve any segment of the GI tract including the small bowel, making it a critical consideration in adolescents 1
• Ulcerative colitis causes bleeding from diffuse areas of mucosal ulceration, typically in patients with pancolitis 1
• IBD-related bleeding is common but massive, life-threatening hemorrhage occurs in less than 6% of cases 1
• A documented case of recurrent intestinal ulcer with bloody stool for over 10 years in a 15-year-old male highlights that chronic bleeding patterns can occur in this age group 2

Infectious Gastroenteritis

• The American Academy of Pediatrics recommends testing for Shiga toxin-producing organisms (STEC), Salmonella, Shigella, Campylobacter, and Yersinia in patients with bloody diarrhea 3
• STEC, particularly those producing Shiga toxin 2, carry the highest risk of hemolytic uremic syndrome (HUS) development 3
• Critical pitfall: Never administer antibiotics if STEC is suspected or confirmed, as this dramatically increases HUS risk 3

Peptic Ulcer Disease

• Peptic ulcer disease remains a significant cause of upper GI bleeding even in adolescents, particularly with NSAID use or Helicobacter pylori infection 1
• Can present with melena (black, tarry, sticky stool with distinctive odor) indicating upper GI source 4

Other Important Causes in Adolescents

• Meckel's diverticulum: A congenital anomaly that can present with painless rectal bleeding in adolescents
• Vascular malformations (angiodysplasias): Less common in this age group but possible 5
• Dietary-induced ulceration: Long-term consumption of barbecued spicy food and carbonated drinks has been documented as a cause of recurrent intestinal ulcers in a 15-year-old 2

Immediate Clinical Assessment Algorithm

Step 1: Hemodynamic Evaluation

• Calculate shock index (heart rate ÷ systolic blood pressure) immediately—a value >1 indicates hemodynamic instability and predicts poor outcomes 4, 6
• Check for orthostatic hypotension (BP drop >20 mmHg or HR increase >20 bpm when standing), which indicates significant blood loss 4, 6
• Perform digital rectal examination to confirm blood presence and character (melena vs. hematochezia) 4, 6

Step 2: Risk Stratification

• High-risk features requiring aggressive management include: hemodynamic instability, shock, altered mental status, severe lethargy, and persistent or worsening bloody diarrhea 3, 4
• For hemodynamically stable patients, calculate the Oakland score (includes age, gender, previous lower GI bleeding admission, digital rectal findings, heart rate, systolic BP, and hemoglobin) 4, 6

Step 3: Resuscitation (If Needed)

• Initiate IV fluid resuscitation immediately with goal of normalizing blood pressure and heart rate before endoscopic evaluation 4, 6
• Use restrictive transfusion thresholds: maintain hemoglobin >7 g/dL for patients without cardiovascular disease 1, 4
• Packed red blood cells should be transfused to maintain hemoglobin above 7 g/dL, with a threshold of 9 g/dL considered in patients with massive bleeding 1

Diagnostic Approach Based on Presentation

For Hemodynamically Unstable Patients

• Perform CT angiography immediately to localize active bleeding 4, 6
• Following positive CTA, proceed to catheter angiography with embolization within 60 minutes 6
• Emergency surgery is indicated in unstable patients with hemorrhagic shock non-responsive to resuscitation 1

For Hemodynamically Stable Patients

• Upper and lower GI endoscopy should be the initial diagnostic procedure for nearly all stable patients 1, 7
• If melena is present, perform esophagogastroduodenoscopy (EGD) first to rule out upper GI bleeding 1, 4, 6
• If lower GI source is suspected, perform sigmoidoscopy or colonoscopy after adequate bowel preparation 1, 5
• Endoscopy should preferably be performed within 24 hours from the acute event 7, 8

For Suspected Infectious Etiology

• Obtain stool testing for STEC (using tests that detect Shiga toxin or genes encoding them), Salmonella, Shigella, Campylobacter, and Yersinia 3
• Visual examination of stool to confirm blood presence 3
• Measure fecal lactoferrin and calprotectin as markers of inflammation 1
• Hold antibiotics until pathogen identification, except for confirmed Salmonella, Shigella, or Campylobacter after susceptibility testing 3

Critical Pitfalls to Avoid

• Never delay endoscopy in stable patients—it serves both diagnostic and therapeutic purposes and should occur within 24 hours 7, 8
• Do not assume lower GI source based solely on age—upper GI bleeding can present with hematochezia in brisk bleeding, and EGD should be performed first if patient is unstable 1, 4
• Avoid antidiarrheal agents (loperamide, kaolin-pectin, antimotility drugs) in patients with gastroenteritis, as these can worsen outcomes 3
• Never give antibiotics empirically for bloody diarrhea before ruling out STEC, as this increases HUS risk 3
• Monitor for HUS development in any patient with bloody diarrhea, especially if STEC is identified—watch for hemolytic anemia, thrombocytopenia, and acute kidney injury 3

Special Considerations for Adolescents

• IBD often presents in adolescence, making Crohn's disease and ulcerative colitis high on the differential 1
• Dietary history is crucial—chronic consumption of spicy foods and carbonated drinks has been documented as a reversible cause of intestinal ulceration in this age group 2
• Meckel's diverticulum should be considered if other causes are excluded, particularly with painless bleeding
• Mortality in GI bleeding relates more to comorbidities than exsanguination, though adolescents typically have fewer comorbidities than older adults 4, 6