Pyloric Stenosis
BASICS
- Definition: Acquired narrowing of the pyloric canal due to progressive hypertrophy of the pyloric muscle, leading to gastric outflow obstruction.
EPIDEMIOLOGY
- Age: Presents most commonly between 2–8 weeks (median 6 weeks)
- Most common surgical condition in the first year of life
- Incidence: 1.56 per 1,000 live births; higher in first-born males, Caucasians, and Hispanic children
ETIOLOGY & PATHOPHYSIOLOGY
- Impaired relaxation → muscle hypertrophy → outflow obstruction
- Gastric distension → projectile, postprandial, nonbilious vomiting
RISK FACTORS
- Maternal smoking
- C-section delivery
- Prematurity
- Formula feeding
- Postnatal macrolide antibiotics (esp. in first 2 weeks)
- Multiple gestation (esp. monozygotic twins)
PREVENTION
- Breast milk (contains vasoactive intestinal peptides) may help prevent pylorospasm
COMMON ASSOCIATED CONDITIONS
- Hiatal and inguinal hernias
DIAGNOSIS
History
- Nonbilious projectile vomiting after feeding, increasing in frequency/severity
- Hunger, irritability, weight loss
- Median symptom duration: 10 days
Physical Exam
- Firm "olive-like" mass in right upper quadrant
- Visible peristalsis after feeding
- Late: dehydration (dry mucosa, poor turgor), tachycardia, irritability
- Rare: jaundice (elevated indirect bilirubin from starvation)
Differential Diagnosis
- Inappropriate feeding
- GERD
- Gastritis
- Adrenal crisis
- Antral/gastric web
Diagnostics
- Labs: Hypokalemic, hypochloremic, metabolic alkalosis
- Pyloric ultrasound (study of choice):
- Muscle thickness ≥3 mm, length ≥15 mm, diameter ≥11 mm, volume ≥12 mL
- Key factor: muscle thickness
- Upper GI series: Rarely needed; "string sign" or "double-tract sign" if performed
TREATMENT
General Measures
- Medical emergency, not surgical emergency
- Restore hydration and correct electrolytes pre-op (esp. alkalosis)
Definitive Treatment
- Surgical pyloromyotomy (Ramstedt procedure): Curative
- Laparoscopic approach: less pain, shorter stay, faster recovery, fewer complications
Medical Therapy (Alternative)
- Atropine (for those who cannot undergo surgery):
- Oral: start 0.05 mg/kg/day, up to 0.1 mg/kg/day
- IV: start 0.1 mg/kg/day, increase until vomiting ceases, then convert to oral at double the IV dose
- Slower resolution (vomiting usually stops in 7 days; pyloric muscle normalizes in 5–15 months)
- Lower success rates and longer hospital stay vs. surgery
ADMISSION & INPATIENT CONSIDERATIONS
- Fluid resuscitation: ≥1 20 mL/kg bolus, D5 ½ NS + 20 mEq KCl, 1.5–2× maintenance fluids
- Correct electrolytes before anesthesia (alkalosis can reduce inspiratory drive/post-op apnea)
ONGOING CARE
- Discharge after tolerating 2–3 full feeds
- Monitor for pain, emesis, apnea
- If persistent emesis after 1–2 weeks: upper GI to rule out incomplete pyloromyotomy or duodenal leak
DIET
- Ad-lib feeding after pyloromyotomy is recommended (decreases length of stay)
- Early feeding = more emesis, but does not affect LOS
PATIENT EDUCATION
- Caregivers: Signs of dehydration, infection, expected postoperative emesis
PROGNOSIS
COMPLICATIONS
- Dehydration, failure to thrive, jaundice
- Chronic abdominal pain, functional GI disorders post-op
- Incomplete pyloromyotomy, mucosal perforation
ICD-10 Codes
- Q40.0 Congenital hypertrophic pyloric stenosis
CLINICAL PEARLS
- Most common surgical condition in 1st year of life
- Presents 1–5 months, with projectile vomiting and a palpable RUQ mass
- Abdominal US is diagnostic study of choice
- Laparoscopic pyloromyotomy is preferred and curative; medical management with atropine is effective for select cases