What are the differential diagnoses and required investigations for a pediatric patient presenting with blood-stained stools?

Blood-Stained Stools in Pediatric Patients: Differential Diagnoses and Investigations

Age-Specific Differential Diagnoses

Neonates and Young Infants (<3 months)

The most common causes in this age group are benign and self-limiting, including anal fissures, infections, and allergies, though serious conditions must be excluded urgently 1.

• Necrotizing enterocolitis (NEC): Life-threatening condition requiring immediate recognition, particularly in premature infants 1
• Vitamin K deficiency bleeding: Consider in infants who did not receive prophylaxis or have malabsorption 2
• Cow's milk protein allergy: Common benign cause presenting with blood-streaked stools 1
• Anal fissures: Most common benign cause across all pediatric ages 1
• Infectious colitis: Including bacterial pathogens and viral gastroenteritis 1, 3
• Hirschsprung enterocolitis: Presents with ill appearance, abdominal distension 3
• Volvulus/malrotation: Surgical emergency requiring urgent imaging 4, 3

Infants and Toddlers (3 months - 2 years)

Intussusception is the critical diagnosis to exclude in this age group, as it presents with life-threatening complications if delayed 5, 3.

• Intussusception: Peak incidence 6-18 months; presents with episodic irritability, vomiting, and "currant jelly" stools 5, 3
• Meckel's diverticulum: Often presents with painless, life-threatening bleeding 3
• Infectious colitis: Most common overall cause in Indian children 3
• Juvenile polyps: Common cause of painless bright red bleeding 3
• Anal fissures: Remain common across all ages 1
• Food protein-induced proctocolitis: Typically resolves with dietary modification 1

Older Children (>2 years)

Inflammatory bowel disease becomes increasingly important in the differential as age increases, particularly in children over 10 years 6.

• Inflammatory bowel disease (IBD): Crohn's disease more common than ulcerative colitis in first decade; younger children have more colitis and less ileitis 6
• Juvenile polyps: Most common cause of painless rectal bleeding in this age group 3
• Infectious colitis: Including typhoid fever, Salmonella, Shigella, Campylobacter, and C. difficile 6, 3
• Henoch-Schönlein purpura: Vasculitis presenting with abdominal pain, rash, and bloody stools 3
• Hemorrhoids: Rare in children unless underlying portal hypertension 6
• Anorectal varices: Consider in children with known liver disease 6

Critical Initial Assessment

Immediate Hemodynamic Evaluation

All children with significant rectal bleeding require rapid cardiopulmonary assessment and hemodynamic stabilization before diagnostic workup 3.

• Vital signs assessment: Check for tachycardia, tachypnea, hypotension indicating significant blood loss 6, 3
• Rapid IV access: Establish in all hemodynamically unstable patients 3
• Volume resuscitation: Normal saline 20 ml/kg bolus for signs of shock 3

Focused History

The history must specifically address timing, character of bleeding, associated symptoms, and risk factors for serious pathology 6, 4.

• Character of blood: Bright red vs. dark/maroon vs. "currant jelly" appearance 6, 3
• Timing and pattern: Acute vs. chronic, intermittent vs. continuous 6
• Associated symptoms: Fever, vomiting, abdominal pain, diarrhea, weight loss, rash, joint pain 6
• Recent infections: Streptococcal pharyngitis (suggesting post-infectious glomerulonephritis), gastroenteritis 6
• Dietary history: Recent formula changes, cow's milk introduction, food allergies 1
• Medication exposure: NSAIDs, antibiotics, immunosuppressants 6
• Travel history: Endemic areas for parasites 6
• Family history: IBD, coagulation disorders, familial polyposis 6
• Trauma history: Including possibility of abuse 6

Physical Examination Priorities

A thorough physical examination must include digital rectal examination and inspection for extraintestinal manifestations 6, 4.

• General appearance: Lethargy, irritability, pallor, jaundice 4, 2
• Abdominal examination: Masses (intussusception), distension, tenderness, peritoneal signs 4, 5
• Perianal inspection: Fissures, skin tags, fistulas (suggesting Crohn's disease) 6
• Digital rectal examination: Mandatory to assess for masses, fissures, and obtain stool sample 6
• Extraintestinal signs: Rash (HSP, IBD), arthritis, oral ulcers, perianal disease 6

Laboratory Investigations

Initial Screening Tests (All Patients)

Complete blood count, inflammatory markers, and stool studies form the foundation of the diagnostic workup 6, 7, 3.

• Complete blood count (CBC): Assess for anemia, thrombocytopenia, leukocytosis 7, 2, 3
• Hemoglobin/hematocrit: Determine severity of blood loss 6, 3
• Coagulation studies: PT/INR, PTT, especially in neonates and those with liver disease 6, 2, 3
• C-reactive protein (CRP) or ESR: Screen for inflammatory conditions 6, 7
• Stool occult blood testing: Confirms presence of blood when not grossly visible 8, 7, 5
• Stool culture: Bacterial pathogens including Salmonella, Shigella, Campylobacter, E. coli O157:H7 6, 3
• C. difficile testing: Particularly important in IBD patients; use glutamate dehydrogenase antigen and toxin A/B assays or nucleic acid amplification 6

Age-Specific Laboratory Testing

Neonates

• Coagulation profile: Essential to exclude vitamin K deficiency bleeding 2
• Blood type and cross-match: For potential transfusion 6, 3
• Electrolytes: Assess for dehydration and metabolic abnormalities 2
• Vitamin K administration: 5-10 mg IV if coagulopathy present 3

Infants and Children with Suspected IBD

Fecal calprotectin is the single most useful non-invasive test to differentiate IBD from functional disorders in children under 45 years 6, 9, 7.

• Fecal calprotectin: Screen for IBD in children with diarrhea; elevated levels require colonoscopy 6, 9, 7
• Celiac serology: Anti-tissue transglutaminase IgA with total IgA level 9, 7
• Albumin: Low levels suggest chronic inflammation or protein-losing enteropathy 7
• Liver function tests: Assess for associated hepatobiliary disease 3

Parasitic Infection Screening (Based on Risk Factors)

• Stool ova, cysts, and parasites: Three separate samples if travel to endemic areas 6, 9
• Giardia antigen testing: Specific testing recommended over routine O&P 9
• Strongyloides serology: If travel history suggestive before immunosuppression 6

Imaging and Endoscopic Investigations

First-Line Imaging

Plain Abdominal Radiography

Plain films are inconsistent and can be normal even in serious conditions like intussusception and malrotation, but remain useful for initial assessment 4.

• Indications: Suspected obstruction, perforation, or NEC 4, 2
• Limitations: Can miss intussusception, early volvulus, and other serious pathology 4

Ultrasound

Ultrasound is the first-line imaging modality for suspected intussusception and has excellent sensitivity without radiation exposure 6, 3.

• Abdominal ultrasound: First-line for suspected intussusception (target sign), Meckel's diverticulum, masses 3
• Doppler ultrasound: Assess bowel wall vascularity in suspected ischemia 6
• Renal ultrasound: If hematuria present to assess kidney size and structure 6

Advanced Imaging (When Initial Workup Non-Diagnostic)

Contrast Studies

• Air or contrast enema: Both diagnostic and therapeutic for intussusception 5, 3
• Upper GI series with small bowel follow-through: Evaluate for malrotation, Meckel's diverticulum 4

Cross-Sectional Imaging

• CT enterography: For suspected complications, abscess, or when ultrasound non-diagnostic 6
• MR enterography: Preferred in IBD for disease extent without radiation 6

Nuclear Medicine

• Technetium-99m pertechnetate (Meckel's) scan: Detects ectopic gastric mucosa in Meckel's diverticulum 3
• Technetium-99m RBC scan: Localize active bleeding when source obscure 3

Endoscopic Evaluation

Indications for Urgent Endoscopy

Endoscopy should be performed within 24 hours in hemodynamically significant bleeding or when diagnosis remains unclear after initial workup 6, 3.

• Proctosigmoidoscopy/flexible sigmoidoscopy: First-line endoscopic procedure; reveals majority of etiologies 6, 3
• Colonoscopy: Required for complete evaluation when lower endoscopy non-diagnostic or IBD suspected 6
• Upper endoscopy: Perform nasogastric lavage first to exclude upper GI source 3

Pediatric IBD-Specific Endoscopy Protocol

In children with suspected IBD, both upper and lower endoscopy with multiple biopsies are essential, as pediatric Crohn's disease frequently involves upper GI tract 6.

• Esophagogastroduodenoscopy (EGD): Mandatory in pediatric IBD workup; granulomas found in 42% of children only on upper tract biopsies 6
• Ileocolonoscopy with terminal ileum intubation: Complete examination with multiple biopsies from all segments, including normal-appearing areas 6
• Biopsy protocol: Minimum 2 biopsies from 5 sites (terminal ileum, ascending, transverse, descending, sigmoid colon, rectum) 6
• Granuloma detection: More frequent in pediatric CD (67% at initial colonoscopy) compared to adults 6

Diagnostic Algorithm by Clinical Presentation

Hemodynamically Unstable Child

1. Immediate resuscitation: IV access, fluid bolus 20 ml/kg, oxygen 3
2. Blood sampling: CBC, type and cross-match, coagulation studies 6, 3
3. Nasogastric lavage: Rule out upper GI bleeding 3
4. Urgent surgical consultation: For suspected volvulus, NEC, or massive bleeding 3
5. Imaging: Ultrasound or CT based on suspected diagnosis 3

Well-Appearing Infant with Streaky Blood

1. Careful perianal examination: Identify anal fissures 1
2. Dietary history: Recent formula changes, maternal diet if breastfed 1
3. Trial of cow's milk protein elimination: If suspected allergy 1
4. Stool culture and occult blood: Rule out infection 1
5. Observation: Most cases self-limiting 1

Child with Episodic Irritability and Bloody Stools

Intussusception must be excluded urgently, as stool occult blood testing is positive in 75% of cases without gross blood 5.

1. Abdominal examination: Palpate for mass (sensitivity low but specific) 5
2. Stool occult blood test: Significantly associated with intussusception (P<0.002) 5
3. Abdominal ultrasound: First-line imaging for intussusception 3
4. Air or contrast enema: Both diagnostic and therapeutic 5, 3

Child with Chronic Bloody Diarrhea and Weight Loss

This presentation mandates evaluation for IBD with fecal calprotectin as the initial screening test 6, 9.

1. Fecal calprotectin: Elevated levels (>50 μg/g) require colonoscopy 6, 9
2. CBC, CRP/ESR, albumin: Assess inflammation and nutritional status 6, 7
3. Celiac serology: Anti-tTG IgA with total IgA 9, 7
4. Stool studies: Culture, C. difficile, ova and parasites 6
5. Colonoscopy with EGD: If fecal calprotectin elevated or high clinical suspicion 6

Critical Pitfalls to Avoid

Diagnostic Errors

• Never attribute positive fecal occult blood to hemorrhoids without complete colonic evaluation 8
• Do not rely on normal abdominal radiographs to exclude intussusception or malrotation 4
• Avoid dismissing episodic symptoms in intussusception; children can appear playful between episodes 4
• Do not assume lethargy or poor feeding in infants is benign; consider appendicitis and intussusception 4
• Never skip upper endoscopy in pediatric IBD workup; 42% of granulomas found only in upper tract 6
• Do not attribute anemia to hemorrhoids; this is extremely rare (0.5/100,000 population) 8

Investigation Errors

• Avoid performing colonoscopy in young patients (<45 years) with typical IBS symptoms and no alarm features 9
• Do not order routine ultrasound; it detects incidental findings unrelated to symptoms 9
• Never skip C. difficile testing in immunosuppressed patients or those with steroid-resistant colitis 6
• Avoid attributing symptoms to food intolerances without objective testing 9

Management Errors

• Do not delay surgical consultation in ill-appearing infants with bloody stools 3
• Avoid starting immunosuppression before excluding CMV in steroid-resistant UC 6
• Do not perform incision and drainage for thrombosed hemorrhoids; excision or conservative management preferred 6