Pyloric Stenosis
Pyloric stenosis is a common cause of gastric outlet obstruction in infants, caused by hypertrophy and spasm of the pyloric muscle. This condition typically presents in a previously well infant between 2 and 8 weeks of age. It is more common in first-born males. Early diagnosis and management are crucial to prevent severe dehydration and electrolyte abnormalities.
Clinical Presentation
Vomiting: The hallmark symptom is progressive, projectile, non-bilious vomiting. The vomiting is described as “effortless” and becomes more forceful over time. The vomit may contain streaks of blood due to irritation.
Feeding: Infants remain hungry and willing to feed despite the vomiting. However, as the condition progresses, they lose weight and become lethargic and dehydrated.
Constipation: Due to a lack of food reaching the intestines, infants often become constipated, and their nappies are dry.
Examination
Weight: Check the infant’s weight, as weight loss is a key sign.
Signs of Dehydration: Look for signs of dehydration such as reduced skin turgor, a sunken fontanelle, and dry mucous membranes.
Abdomen: A key finding is a palpable, olive-sized mass in the epigastric region, which is the hypertrophied pylorus. Visible peristaltic waves may also be seen travelling from the left to the right upper abdomen during or after a feed.
Investigations
Blood Tests: Prolonged vomiting of gastric contents, which are rich in acid, leads to metabolic derangement.
Urea and Electrolytes: Dehydration, hypokalaemia (), and hypochloraemia () are common.
Blood Gas: This will show a hypochloraemic metabolic alkalosis.
Ultrasound: An abdominal ultrasound is the gold standard for diagnosis. It confirms the diagnosis by measuring the thickened and elongated pyloric muscle. The classic ultrasound findings are a pyloric muscle thickness of mm and a pyloric channel length of mm.
Management
Resuscitation: The immediate priority is to correct dehydration and electrolyte abnormalities. This involves the administration of intravenous fluids, specifically 0.9% sodium chloride, to correct the hypochloraemic alkalosis. This step is critical before any surgical intervention.
Surgical Intervention: The definitive treatment is a surgical procedure called Ramstedt’s pyloromyotomy. In this procedure, the surgeon makes a longitudinal incision through the anterior pyloric muscle down to the submucosa, releasing the obstruction. This is a simple and highly effective procedure with a good prognosis.
Post-Operative Care: Post-surgery, feeding can be gradually re-introduced, and the child’s electrolytes and hydration status are monitored until they are stable and feeding well.