Pyloric Stenosis

Key Features

• Postnatal muscular hypertrophy of the pylorus

• Progressive gastric outlet obstruction, nonbilious vomiting, dehydration, and alkalosis in infants younger than 12 weeks

• Upper GI contrast radiographs or abdominal ultrasound are diagnostic

• Cause is unknown.

• Incidence is 1–8 per 1000 births, with a 4:1 male predominance

• Studies suggest that erythromycin given in the neonatal period is associated with a higher incidence of pyloric stenosis

Clinical Findings

• Onset of symptoms may be delayed in preterm infants

• Vomiting starts at birth in about 10% of cases

• Projectile postprandial vomiting

  • Usually begins between 2 and 4 weeks of age

  • May start as late as 12 weeks

• Vomitus is rarely bilious but may be blood-streaked

• Infants are usually hungry and nurse avidly

• Upper abdomen may be distended after feeding

• Prominent gastric peristaltic waves from left to right may be seen

• An oval mass can be felt on deep palpation in the right upper abdomen, especially after vomiting

  • Measures 5–15 mm in longest dimension

  • However, only present in 13.6% of patients studied

Diagnosis

• Hypochloremic alkalosis with potassium depletion is classic metabolic finding

• Dehydration causes elevated hemoglobin and hematocrit

• Mild unconjugated bilirubinemia occurs in 2–5% of cases

• Ultrasonography shows a hypoechoic muscle ring greater than 4 mm thickness with a hyperdense center and a pyloric channel length > 15 mm

• Barium upper GI series

  • Reveals retention of contrast in the stomach and a long narrow pyloric channel with a double track of barium

  • Postoperative radiograph remains abnormal for many months despite relief of symptoms

Treatment

• Treat dehydration and electrolyte imbalance before surgery, even if it takes 24–48 hours

• Ramstedt pyloromyotomy

  • Treatment of choice

  • Consists of incision down to the mucosa along the pyloric length

  • Can be performed laparoscopically, with similar efficacy

• Outlook after surgery is excellent