Pediatric Surgical Abdomen: Pyloric Stenosis, Volvulus & Hirschsprung
Comprehensive emergency evaluation and protocolized resuscitation of neonatal surgical abdominal emergencies: Hypertrophic Pyloric Stenosis (non-bilious projectile vomiting, 'olive' mass, hypochloremic hypokalemic metabolic alkalosis, ultrasound criteria, fluid resuscitation before surgery), Midgut Malrotation with Volvulus (sudden bilious vomiting, upper GI series 'corkscrew' sign, Ladd procedure), and Hirschsprung Disease (delayed meconium passage > 48h, explosive blast sign, and toxic enterocolitis).
Resuscitation Quick Actions • First 2 Minutes
Bilious Vomiting Rule
Green or yellow-green vomiting in a neonate is VOLVULUS until proven otherwise; stat emergent pediatric surgery consult + Upper GI series
Pyloric Stenosis Lab Triad
Hypochloremic, hypokalemic, metabolic alkalosis (paradoxical aciduria develops as kidneys conserve Na+ in exchange for H+)
Pyloric Resuscitation First
Pyloromyotomy is NEVER an emergent midnight surgery! Resuscitate first with 0.9% NS + 20 mEq KCl until Cl > 100 and HCO3 < 30
Pyloric Ultrasound Criteria
Muscle thickness >= 3.0 mm (or >= 4 mm) AND pyloric channel length >= 14 mm (the 'pi' rule: 3.14 mm/14 mm)
Hirschsprung Meconium Delay
Failure to pass meconium within 48 hours of birth in a full-term infant; rectosigmoid aganglionosis causes distal functional obstruction
Hirschsprung Enterocolitis
Fever, foul-smelling explosive diarrhea, abdominal distension, septic shock; stat rectal decompression + IV piperacillin-tazobactam
Bottom-Line Clinical Pearl
Bilious (green/yellow-green) vomiting in an infant is a SURGICAL EMERGENCY until Midgut Malrotation with Volvulus is ruled out; intestinal ischemia develops within hours, leading to whole-gut necrosis and death. Obtain an emergent Upper GI contrast series (showing failure of duodenojejunal junction to cross midline and a 'corkscrew' appearance). Conversely, Hypertrophic Pyloric Stenosis presents with non-bilious projectile vomiting in a 2–8 week old infant; it is a MEDICAL, NOT SURGICAL, emergency: the patient must never be taken to surgery until severe hypochloremic, hypokalemic metabolic alkalosis is completely corrected with 0.9% Normal Saline + KCl.
In neonatal emergency medicine, the single most critical triage question regarding vomiting is the color of the emesis: is it bilious (bright spinach-green or dark yellow-green) or non-bilious (clear, milky, or curdled)? Bile enters the gastrointestinal tract at the ampulla of Vater in the second portion of the duodenum. Any obstruction distal to the ampulla produces bilious vomiting, which represents a potential midgut strangulation emergency until proven otherwise.
| Condition & Peak Age | Vomitus Type & Clinical Features | Diagnostic Gold Standard | Definitive Resuscitative Management |
|---|---|---|---|
| Hypertrophic Pyloric Stenosis (2 to 8 weeks; firstborn males) | Non-bilious projectile vomiting immediately after feeds; infant is 'hungry vomiter'; palpable firm, mobile, non-tender olive-shaped mass in epigastrium/RUQ | Abdominal Ultrasound: Pyloric muscle wall thickness $\ge 3.0\text{ to }4.0\text{ mm}$ and channel length $\ge 14\text{ mm}$ (mnemonic: $\pi = 3.14$) | Medical Resuscitation First: Infuse 0.9% Normal Saline at 1.5x maintenance + 20–40 mEq/L KCl. Do NOT operate until serum Cl > 100 mEq/L and HCO3 < 30 mEq/L to prevent postoperative central hypoventilatory apnea. |
| Midgut Malrotation with Volvulus (First month of life, 60% < 1 week) | Sudden onset bilious emesis, abdominal distension, irritability progressing rapidly to peritonitis, hematochezia, and circulatory collapse | Emergent Upper GI Series (UGI): Failure of duodenojejunal junction (ligament of Treitz) to cross left of midline; twisted duodenal loops produce the classic 'corkscrew sign' | Emergent Surgical Laparotomy (Ladd Procedure): NG tube decompression, IV fluid boluses (20 mL/kg), broad-spectrum IV antibiotics (Ampicillin/Gentamicin/Metronidazole), and stat surgical transport. |
| Hirschsprung Disease & Enterocolitis (Neonates & young infants) | Failure to pass meconium within 48h; abdominal distension; bilious emesis; digital rectal exam yields explosive expulsion of stool/flatus ('blast sign') | Rectal Suction Biopsy: Absence of ganglion cells in the submucosal (Meissner) and myenteric (Auerbach) plexuses with hypertrophied nerve trunks | Rectal Decompression & Antibiotics: For Hirschsprung-Associated Enterocolitis (HAEC), perform rectal irrigation via large catheter; IV Piperacillin-Tazobactam; emergent surgical diversion. |
Critical Pitfall / Contraindication
PYLORIC STENOSIS IS A MEDICAL EMERGENCY, NOT A SURGICAL ONE: Administering general anesthesia to an infant with uncorrected hypochloremic, hypokalemic metabolic alkalosis induces life-threatening postoperative central hypoventilation, apnea, and cardiac arrhythmias. Alkalosis suppresses the medullary respiratory center. Always delay pyloromyotomy until serum electrolytes and bicarbonate are fully normalized.
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