Residency · Residency · Medicine Pediatrics
Acute Abdomen: Surgical Decision-Making in Children and Adults
Introduction
The acute abdomen is a common clinical scenario requiring rapid assessment and decision-making. The differential diagnosis varies significantly by age, and the med-peds physician must recognize age-specific surgical emergencies while avoiding unnecessary interventions. This lecture covers the systematic approach to abdominal pain from infancy through adulthood with emphasis on surgical versus medical management.
Age-Specific Differential Diagnosis
Neonates (0-28 days)
Necrotizing enterocolitis (NEC): Primarily in premature infants; feeding intolerance, bloody stools, pneumatosis intestinalis. Malrotation with midgut volvulus: Bilious emesis is a surgical emergency until proven otherwise. Hirschsprung disease: Failure to pass meconium in first 48 hours. Intestinal atresia.
Infants (1-12 months)
Intussusception: Colicky pain, currant jelly stools, sausage-shaped mass; peak 6-36 months. Incarcerated inguinal hernia. Pyloric stenosis: Projectile nonbilious vomiting at 3-6 weeks.
Children (1-12 years)
Appendicitis: Most common surgical emergency in children. Meckel diverticulum: Painless rectal bleeding, or may present like appendicitis; Mesenteric lymphadenitis; Constipation (most common cause of abdominal pain in children).
Adolescents and Adults
Appendicitis: Remains most common surgical emergency. Cholecystitis and cholelithiasis; Small bowel obstruction (adhesive disease, hernias); Perforated peptic ulcer; Diverticulitis (typically age >40); Ovarian torsion, ectopic pregnancy (reproductive-age females); Mesenteric ischemia (elderly; "pain out of proportion to exam").
Clinical Assessment
History
Onset, location, character, radiation, severity of pain; Associated symptoms: vomiting (bilious vs. nonbilious), fever, diarrhea, anorexia. Last bowel movement, urinary symptoms; Menstrual history and pregnancy status in reproductive-age females; Surgical history (adhesive obstruction risk).
Physical Examination
Inspection: Distension, visible peristalsis, surgical scars. Auscultation: Absent bowel sounds (ileus/peritonitis), high-pitched tinkling (obstruction) Palpation: Rebound tenderness, guarding, rigidity (peritoneal signs) Special signs: McBurney point tenderness, Rovsing sign, psoas sign, obturator sign (appendicitis); Murphy sign (cholecystitis) Pediatric considerations: Exam may be unreliable in young children; observe gait, positioning, and facial expressions.
Red Flags Requiring Urgent Surgical Consultation
Bilious vomiting in a neonate (malrotation until proven otherwise); Peritoneal signs (rigid abdomen, rebound, guarding); Hemodynamic instability with abdominal pain; Evidence of bowel ischemia or perforation on imaging; Signs of incarcerated hernia.
Diagnostic Workup
Laboratory Studies
CBC with differential, CRP; BMP, lipase, liver function tests; Urinalysis (rule out UTI, nephrolithiasis); Beta-hCG in all reproductive-age females; Lactate if mesenteric ischemia or sepsis is suspected; Type and screen if surgical intervention anticipated.
Imaging
| Modality | Pediatric Indications | Adult Indications |
|---|---|---|
| Ultrasound | First-line for appendicitis, intussusception, pyloric stenosis, ovarian pathology | Cholecystitis, appendicitis (initial), ovarian torsion |
| CT abdomen/pelvis | Used if US equivocal; limit radiation exposure | Gold standard for appendicitis, diverticulitis, SBO, perforation |
| X-ray (KUB) | Free air, obstruction, NEC (pneumatosis) | Free air, obstruction pattern, foreign body |
| MRI | Appendicitis in pregnancy; complex cases | Appendicitis in pregnancy; equivocal cases |
Pediatric principle: Ultrasound first to minimize radiation (ALARA principle) Adult principle: CT with IV contrast is the workhorse for acute abdominal imaging.
Appendicitis: The Prototype Surgical Emergency
Pediatric Appendicitis
Perforation rate higher in young children (up to 80% in children <5 years) Atypical presentations common in young children. Pediatric Appendicitis Score (PAS) or Alvarado Score for risk stratification. Ultrasound first; CT if US is equivocal. Appendectomy (laparoscopic) is standard treatment. Non-operative management with antibiotics is an emerging option for uncomplicated cases.
Adult Appendicitis
Classic presentation: periumbilical pain migrating to RLQ, anorexia, fever. Alvarado score or AIR score for risk stratification. CT abdomen/pelvis with IV contrast is the primary imaging modality. Laparoscopic appendectomy remains standard of care. CODA trial: Antibiotics alone are a reasonable alternative for uncomplicated appendicitis in adults.
Surgical Decision-Making Principles
Operate early when clinical and imaging findings are clear. Observe and reassess when diagnosis is uncertain; serial abdominal exams are valuable. Avoid unnecessary surgery in conditions managed medically (mesenteric lymphadenitis, constipation, pancreatitis) Understand the role of interventional radiology for percutaneous drainage of abscesses. Multidisciplinary communication between surgery, radiology, and primary team is essential.
Clinical Pearls
Bilious vomiting in a neonate is malrotation with volvulus until proven otherwise; this is a true surgical emergency. Ultrasound is the first-line imaging modality for pediatric abdominal pain; limit CT use to minimize radiation exposure. Always obtain a pregnancy test in reproductive-age females with abdominal pain before any imaging or intervention. Perforated appendicitis rates are highest in the very young and the elderly due to delayed or atypical presentations. The med-peds physician should maintain a low threshold for surgical consultation when peritoneal signs are present, regardless of age.
References
- CODA Collaborative. A randomized trial comparing antibiotics with appendectomy for appendicitis. N Engl J Med. 2020;383(20):1907-1919.
- Kharbanda AB, Vazquez-Benitez G, Ballard DW, et al. Development and validation of a novel pediatric appendicitis risk calculator (pARC). Pediatrics. 2018;141(4):e20172699.
- Di Saverio S, Podda M, De Simone B, et al. Diagnosis and treatment of acute appendicitis: 2020 update of the WSES Jerusalem guidelines. World J Emerg Surg. 2020;15(1):27.
- Leung AK, Sigalet DL. Acute abdominal pain in children. Am Fam Physician. 2003;67(11):2321-2326.