Congenital hypertrophic pyloric stenosis (CHPS) is a common, treatable condition affecting young infants. It involves a blockage at the exit of the stomach, preventing food from passing into the small intestine. Symptoms typically appear between two and eight weeks of age. This gastric outlet obstruction is one of the most frequent reasons for surgery in newborns and young babies. The condition involves the progressive enlargement of a muscle that becomes problematic shortly after birth.
Understanding the Obstruction
The pylorus is the muscular valve at the lower end of the stomach, controlling the flow of food into the small intestine (duodenum). In CHPS, the circular muscle fibers of this valve become abnormally thickened and enlarged (hypertrophy). This thickening reduces the open channel, resulting in a narrowing (stenosis) that obstructs the passage of milk or formula from the stomach.
The exact cause of this muscular overgrowth is not fully understood, but it involves genetic and environmental influences. The condition primarily affects male infants, with a ratio of about five boys for every one girl, especially firstborn males. Exposure to certain macrolide antibiotics, such as erythromycin, early in life is also associated with an increased risk. Although the predisposition is present from birth, the progressive muscle thickening means the obstruction only causes severe symptoms weeks later.
Key Indicators for Parents to Watch For
The most recognizable sign of pyloric obstruction is forceful, or projectile, vomiting. This differs distinctly from regular infant spit-up, as the vomit can be launched several feet away and typically occurs shortly after feeding. The vomitus is usually non-bilious (white or curdled), indicating it has not passed beyond the stomach.
Vomiting often begins as occasional episodes but rapidly increases in frequency and intensity. Despite expelling their entire meal, infants with CHPS remain persistently hungry and eagerly attempt to feed again immediately after vomiting. This combination of forceful vomiting and a ravenous appetite strongly indicates a physical blockage.
Another sign is the appearance of visible peristaltic waves across the upper abdomen right after feeding. These waves are the stomach muscles contracting vigorously, attempting to push contents past the narrowed pylorus. Over time, the repeated loss of fluids and nutrients leads to dehydration.
Signs of dehydration include lethargy, dry mouth, or fewer wet diapers than normal. If unaddressed, the infant will fail to gain weight or experience significant weight loss. These indicators prompt immediate medical attention to prevent severe dehydration and electrolyte imbalance.
Medical Confirmation and Pre-Operative Stabilization
When an infant presents with symptoms suggestive of CHPS, the medical team focuses on confirmation and stabilization. During a physical examination, a skilled clinician may palpate the thickened pylorus muscle in the upper right abdomen. This mass is often described as feeling like a firm, movable “olive.”
The primary diagnostic tool is an abdominal ultrasound. This non-invasive imaging test uses sound waves to visualize the pylorus and measure the thickness and length of the muscle wall. A pyloric muscle thickness of three millimeters or more, along with an elongated pyloric channel, confirms the diagnosis.
Before surgery, the infant must be medically stabilized, as persistent vomiting causes serious metabolic complications. The repeated loss of stomach acid leads to hypochloremic, hypokalemic metabolic alkalosis, where the body’s pH balance becomes too alkaline. Intravenous (IV) fluids are immediately initiated to correct dehydration and restore the balance of electrolytes, particularly chloride and potassium.
Blood tests regularly monitor the normalization of these electrolyte and acid-base disturbances. Surgery is a semi-urgent procedure postponed until the infant’s metabolic status is corrected, which often takes 12 to 48 hours. Proper preoperative stabilization significantly reduces the risks associated with general anesthesia and the procedure.
The Pyloromyotomy Procedure and Post-Surgical Outlook
The definitive treatment for CHPS is a surgical procedure called a pyloromyotomy, or the Ramstedt procedure. This operation relieves the obstruction by cutting through the thickened outer muscle layer of the pylorus. The surgeon makes a longitudinal incision through the hypertrophied muscle down to the submucosa, carefully avoiding the inner mucosal lining of the stomach.
Splitting the muscle fibers releases pressure, allowing the inner mucosal layer to bulge outward and create a wider channel for food passage. The procedure can be performed using an open incision or, more commonly, a minimally invasive laparoscopic approach, which allows for smaller incisions and faster recovery. The procedure typically takes less than an hour and is highly successful at permanently resolving the obstruction.
Following the pyloromyotomy, infants are closely monitored and gradually reintroduced to feeding via a specific post-operative protocol. This involves starting with small, frequent amounts of clear fluids or diluted formula, then slowly progressing back to full-strength breast milk or formula. Some spitting up may occur in the first day or two as the stomach adjusts, but projectile vomiting rapidly resolves.
The hospital stay is short, often lasting one to three days once the infant tolerates full feeds without significant vomiting. The long-term prognosis after a successful pyloromyotomy is excellent. Recurrence is rare, and patients recover completely with no lasting digestive issues.