Congenital hypertrophic pyloric stenosis is a condition in infants where the pylorus, a muscular valve connecting the stomach to the small intestine, thickens abnormally. This thickening narrows the opening, obstructing food passage from the stomach. It is a common condition in young babies, often requiring surgical intervention.
Understanding the Condition
The pylorus is a muscular ring at the stomach’s lower end, controlling food flow into the duodenum, the first part of the small intestine. In pyloric stenosis, the pylorus’s muscle layers become abnormally thick and enlarged, a process known as hypertrophy and hyperplasia. This overgrowth creates a significant narrowing, or stenosis, within the pyloric channel.
The narrowed opening prevents food from moving out of the stomach and into the small intestine. The stomach works harder to push contents through, leading to increased pressure. This obstruction leads to difficulties in keeping food down and can cause dehydration.
Recognizing the Signs
Symptoms of pyloric stenosis typically emerge between 3 and 6 weeks of age, though they can appear from 1 week to 5 months. The most noticeable symptom is projectile vomiting, which is forceful and can send breast milk or formula several feet away. This vomiting is usually non-bilious (meaning it does not contain bile) and often occurs shortly after feeding.
Despite frequent vomiting, babies often remain very hungry and eager to feed again. This persistent hunger, combined with the inability to retain food, leads to poor weight gain or even weight loss. Dehydration is a concern, manifesting as fewer wet diapers, dry mouth, crying without tears, and lethargy. Parents might also observe wave-like contractions across their baby’s abdomen, moving from left to right, just before vomiting, indicating the stomach attempting to push food past the obstruction.
Diagnosis and Confirmation
Diagnosis of pyloric stenosis typically begins with a thorough medical history and physical examination. During the exam, a healthcare provider might feel a firm, movable, olive-shaped mass in the baby’s upper abdomen, which is the thickened pylorus. This “olive” can sometimes be more apparent after the infant has consumed formula or breast milk.
The primary diagnostic tool for confirming pyloric stenosis is an abdominal ultrasound. This imaging technique allows visualization of the thickened pyloric muscle. An ultrasound can measure the pyloric wall thickness (typically 3 mm or greater) and the pyloric channel length (often exceeding 15 mm). Blood tests are also performed to check for electrolyte imbalances, such as hypochloremia and hypokalemia, and metabolic alkalosis, which can occur due to the loss of stomach acid from persistent vomiting.
Treatment and Recovery
The treatment for congenital hypertrophic pyloric stenosis is a surgical procedure called pyloromyotomy. This operation involves cutting through the outer layers of the thickened pyloric muscle, allowing it to spread apart and relieve the obstruction, while leaving the inner lining intact. The procedure can be performed through an open incision in the upper abdomen or using a laparoscopic approach with three small incisions. The laparoscopic approach often leads to less pain and faster recovery.
Before surgery, babies often receive intravenous fluids for 24 to 48 hours to correct dehydration and electrolyte imbalances, ensuring a safer anesthetic and surgical experience. After the pyloromyotomy, infants are typically monitored in the hospital for one to two days to ensure they can resume a normal feeding schedule with minimal vomiting. Initial feedings are usually small amounts of water, gradually increasing to breast milk or formula. Mild pain and some continued spitting up are common in the first few days post-surgery. However, the prognosis after a successful pyloromyotomy is excellent, with rapid improvement in feeding and weight gain.
Causes and Risk Factors
The cause of congenital hypertrophic pyloric stenosis is not fully understood, but it is believed to result from genetic and environmental factors. Genetic predisposition plays a role, with siblings of affected infants having a 5 to 20 times increased risk, and a higher concordance rate in identical twins.
Other risk factors include: Male infants are 4 to 6 times more likely to develop the condition than females, especially firstborn males. Caucasian ethnicity is associated with a higher incidence. Maternal factors such as smoking during pregnancy and young maternal age can increase the risk. Exposure to certain macrolide antibiotics, like erythromycin, in the first few weeks of life has been linked to an elevated risk.