Infantile Hypertrophic Pyloric Stenosis: Review of Pathophysiology, Clinical Presentation, Treatment and Outcomes

Infantile hypertrophic pyloric stenosis (IHPS) is considered one of the most common pediatric surgical conditions. Presentation is most common between the ages of 2 to 12 weeks with a mean and median age of 5 weeks. IHPS has been reported to be more common in males than females (5:1) and in first-born children (30-40%). Throughout history, the etiology of this condition has been studied, discovering multiple genetic and environmental factors, such as newborns with increased acid secretion, nitric oxide synthase deficiency, poor innervation of the pyloric muscle, smoking during pregnancy, neonatal use of macrolides and cesarean section; however, the exact cause remains uncertain. The classic clinical presentation begins with a recent history of severe, nonbilious projectile vomiting immediately after feeding and a strong, persistent appetite. During abdominal examination, palpation of the "pyloric olive" in the epigastrium by an experienced doctor is considered a pathognomonic sign. Laboratory tests may show low chloride, potassium, and hydrogen ion levels, leading to metabolic alkalosis due to persistent vomiting. Ultrasound is the gold standard imaging study if history and physical examination are insufficient to diagnose IHPS with a reported sensitivity and specificity of up to 98% and 100% by allowing evaluation of pyloric morphology and behavior. Pyloromyotomy is considered the definitive treatment for infantile hypertrophic pyloric stenosis, but should not be performed until the baby is adequately resuscitated. Patients typically experience positive outcomes after pyloromyotomy, with low morbidity and mortality rates. Most cases recover quickly and without complications.