Congenital hypertrophic pyloric stenosis is a condition in neonates caused by hypertrophy and thickening of the pylorus, leading to mechanical obstruction. It is one of the most common causes of organic vomiting in neonates, with a male-to-female ratio of 4:1. The exact etiology remains unclear, but it may be associated with the absence of intermuscular nerve plexuses in the pyloric muscle layer, elevated blood levels of gastrin, and sustained tension of the pyloric muscle.
Pathology
Macroscopically, the pyloric region appears olive-shaped, approximately 2–2.5 cm in length and 0.5–1.0 cm in diameter, with a firm, cartilage-like texture and a smooth, pink or pale surface that is elastic. Hypertrophy of the circular muscle layer in the pylorus is observed, with the thickness reaching 0.4–0.6 cm. The pyloric canal becomes elongated and narrowed due to compression by the muscle layer, distinctly separated from the duodenum. Microscopically, mucosal congestion, edema, thickened muscle fibers, smooth muscle hyperplasia, and disorganized fiber arrangement can be identified.
Clinical Manifestations
Typical signs and symptoms generally appear 1–3 weeks after birth. Vomiting occurs within minutes after feeding, involving bile-free gastric contents. Initially, regurgitation is present, which progresses to projectile vomiting. The frequency and intensity of vomiting progressively worsen. Visible gastric peristaltic waves in the upper abdomen and the palpation of an olive-shaped hypertrophic pylorus located between the xiphoid process and the umbilicus are characteristic physical findings. Dehydration, hypokalemic alkalosis, weight loss, and eventually malnutrition can develop in affected infants.
Diagnosis and Differential Diagnosis
The diagnosis is typically based on the characteristic features of projectile vomiting, visible gastric peristaltic waves, and the palpation of a pyloric mass.
Ultrasound findings of a pyloric muscle thickness ≥4 mm, pyloric canal length ≥16 mm, and pyloric canal diameter ≥14 mm strongly suggest this condition. Barium study findings on X-ray may reveal gastric enlargement, enhanced peristalsis, an elongated, narrow pyloric canal, and a "beak-like" appearance at the pyloric opening, with delayed gastric emptying due to obstruction.
Differential diagnosis includes other causes of vomiting in infants, such as improper feeding, infections, increased intracranial pressure, and gastroenteritis. Neonates with pylorospasm may also exhibit intermittent projectile vomiting, but a pyloric mass is not palpable in such cases. Barium studies can help distinguish conditions such as intestinal malrotation, bowel obstruction, and esophageal hiatal hernia.
Treatment
Pyloromyotomy is the primary treatment approach for this condition, which can be performed via open surgery or laparoscopic techniques. Preoperative management involves correcting dehydration and electrolyte imbalances. Parenteral nutrition may be provided in cases of malnutrition to improve the infant's overall condition.