BACKGROUND AND INDICATIONS
Pyloric stenosis remains the most frequent surgical cause of vomiting in infancy since its original description more than 100 years ago. The etiology of this disease is still uncertain, but it most commonly presents between 2 and 8 weeks of age and rarely up to 3 months. The typical presentation consists of repeated, nonbilious emesis that can become projectile in nature. The presence of bilious emesis dictates a different workup, as this is almost never pyloric stenosis. Diagnosis is made most frequently with ultrasound. A pylorus that measures greater than 3 mm thick and 17 mm long and does not open to allow the passage of food into the duodenum is diagnostic for pyloric stenosis. Diagnosis can also be made on exam by palpating for the classic “olive” in the right upper quadrant. This can be facilitated by placement of a nasogastric tube and gastric decompression.
Mortality for this disease remained unacceptably high until a muscle-splitting extramucosal pyloromyotomy was perfected and eventually led to an almost 100% survival rate. This technique has since been adapted to a minimally invasive procedure that accomplishes the same operation using smaller incisions.
Once the diagnosis of pyloric stenosis has been established, a careful analysis of the infant’s fluid and electrolyte status is important. Electrolyte disturbances, especially hyponatremia, hypokalemia, and hypochloremia in the face of a metabolic alkalosis, are not uncommon and should be corrected prior to surgery. Placement of an IV catheter and administration of normal saline boluses and maintenance fluid should be given until the electrolytes normalize and the infant is making at least 1 mL of urine per hour. The placement of a nasogastric tube is not always necessary during the fluid resuscitation phase, but prior to induction of anesthesia the stomach should be suctioned to help prevent aspiration.
After the induction of general anesthesia, the infant is positioned across the middle of the OR table with the head turned facing the anesthesiologist. If not already present, an orogastric tube is placed. A large syringe is attached to the tube for later insufflation of the stomach. The infant’s legs should be placed frog legged on the table so they do not dangle over the edge (Figure 1). The infant is prepped and draped and the operators stand at the feet of the infant. A 3-mm trocar can be easily placed through the middle of the umbilicus. Once the trocar has been placed, the abdomen is insufflated to 8 to 10 mm Hg pressure. A 3-mm nontraumatic bowel grasper is placed laterally in the right upper quadrant just below the liver edge. The instrument can be placed directly through the abdominal wall, and a trocar is usually not necessary. A third 3-mm incision is made through the abdominal wall directly over the pylorus (Figure 2).