Arielle Kanters and Todd Ponsky

Introduction

Pyloric stenosis occurs in approximately 3 of every 1000 births in the United States and is a common cause of gastric outlet obstruction in infants. First described in 1911, the Ramstedt approach to pyloric stenosis repair (extramucosal pyloromyotomy) has been the surgical standard of care until recently. This technique involves splitting the antropyloric mass while leaving the mucosa intact. Morbidity of the Ramstedt procedure is less than 10% and the mortality rate is less than 0.5%. The laparoscopic modification of the Ramstedt procedure has gained great support in recent years, and some argue that it has improved morbidity and mortality rates compared with the traditional open approach.

Pyloric stenosis results from hypertrophy of the musculature surrounding the pylorus, but the etiology is currently unknown. Possible causes include compensatory work hypertrophy from increased gastric mucosa, neurologic degeneration, and aberrant endocrine signaling. Strong evidence exists for many of these theories, indicating a multifactorial etiology. Risk factors for pyloric stenosis include gender, race, family history, maternal age, birth order, and maternal feeding patterns.

Clinical Presentation and Diagnosis of Pyloric Stenosis

A diagnosis of pyloric stenosis depends on both patient history and physical examination. Most patients will initially be seen with progressive, nonbilious projectile vomiting at 2 to 8 weeks of age. Patients may show signs of metabolic alkalosis, dehydration, and malnutrition, depending on duration of symptoms. On examination, visible peristaltic waves at the epigastrium and a palpable mass in the left upper quadrant may be present when the abdominal wall is relaxed. The mass is typically olive shaped, smooth, hard, and about 1 to 2 cm in size (Fig. 10-1). The hypertrophied pylorus can also be appreciated using ultrasonography or an upper gastrointestinal (GI) contrast study.

Preoperative Imaging of Pyloric Stenosis

The ultrasonographic criteria for pyloric stenosis include an elongated pyloric channel (14 to 20 mm), an enlarged pyloric diameter (>12 mm), and a thickened muscle wall (>3 mm) (Fig. 10-2, A). A contrast study will demonstrate a distended stomach with a narrowed and elongated pyloric channel. These findings are often referred to as the “string” sign or “double track” sign. Upper GI studies can also show “shoulders” at the proximal end of the pylorus, indicating the hypertrophied muscle bulging into the gastric lumen, and a pyloric “beak” at the pyloric entrance to the antrum (Fig. 10-2, B).

Principles of Pyloromyotomy

Before surgical intervention can be considered, it is important to assess and treat any signs of dehydration, metabolic alkalosis, or malnutrition, which can result from prolonged emesis. Although pyloric stenosis can be self-limiting, the standard of care in the United States is pyloromyotomy, performed as an open or laparoscopic procedure. The Ramstedt extramucosal pyloromyotomy is the classic open approach and can be performed through a number of incisions, including transverse right upper quadrant, Robertson gridiron, or circumbilical. Of the three, the circumbilical incision offers superior cosmetic results and decreased perioperative morbidity.

First described by Alain in 1991, the laparoscopic approach has been widely supported and has gained significant popularity in recent years. Proponents of minimally invasive surgery cite many benefits, including faster recovery time, decreased postoperative pain, sooner return to feeding, and earlier discharge from the hospital. Advocates of the open approach argue that the two approaches have comparable recovery time, and that the laparoscopic approach has a greater complication rate, including mucosal injury, incomplete myotomy, increased operative time, and increased expense to the patient.

Open Surgical Approach

The open pyloromyotomy can be performed through a small, right upper quadrant incision. Alternatively, the surgeon may choose to enter the abdomen through a circumbilical incision. With this technique, an omega-shaped incision is made in a supraumbilical skin fold, through which the midline fascia is identified and exposed one-third to one-half the distance from the umbilicus to the xiphoid. To visualize the pylorus, the omentum must first be mobilized using gentle traction, thereby exposing the transverse colon. With the transverse colon displaced caudally, the gastric antrum is visible (Fig. 10-3, A).

Gently grasping the greater curvature of the stomach with a sponge, the surgeon brings the pylorus into the wound by inferior and lateral traction on the stomach. The surgeon identifies the gastroduodenal junction by the prepyloric vein (Fig. 10-3, B). The surgeon secures the duodenal portion of the pylorus with the index finger of the nondominant hand and makes a 1- to 2-cm longitudinal incision along the plane of the transverse muscle fibers, from the proximal thickening of the muscle to within 3 mm of the antrum. The incision is taken through the serosal and muscle layers using blunt dissection, then widened using a Benson spreader until the submucosa bulges into the cleft (Fig. 10-3, C). Care should be taken to avoid injury to the distal pylorus, because the duodenal mucosa is fragile.

On completion of the myotomy, the two sides of the hypertrophied pylorus should move independently. Before closing the peritoneum and fascia of the transversalis muscle, the surgeon assesses the pylorus for leaks by filling the stomach with 60 to 100 mL of air. The air is then gently milked toward the antrum while the duodenum is sealed off with compression. Bubbles or bile-stained fluid would indicate leakage and thus mucosal injury. Any mucosal disruption must be repaired immediately and can be closed with fine nonabsorbable sutures. The fascial layers and skin are closed routinely.

Laparoscopic Approach

The infant is placed in the supine position on the operating table with folded towels under the head and back to maintain reverse Trendelenburg position, allowing the intestines to fall away from the upper abdomen.

The umbilicus is entered bluntly with a fine mosquito clamp. A 3-mm, 4-mm, or 5-mm trocar, followed by a 30-degree telescope, is inserted through the umbilicus, and two 3-mm stab incisions are created in the left and right epigastrium (Fig. 10-4). A knife blade exposed to no more than 3 mm, or an extended-length, insulated Bovie electrocautery device with 3 mm of exposed blade, is placed in the left upper quadrant incision, while a pyloric grasper is inserted into the right upper quadrant incision. The grasper is used to secure the distal pylorus, and an incision is made along the anterior surface of the pylorus, extending from the prepyloric vein to the antrum of the stomach. The blunt blade of the knife or cautery blade is pushed into the myotomy incision, then rotated 60 to 90 degrees, thereby breaking down the muscular wall. As the incision is made deeper, the knife is replaced by the pyloric spreader. The myotomy is complete when the two cut edges move independently (Fig. 10-4).

As with the Ramstedt approach, the stomach is inflated with air while the duodenum is obstructed to test for injury to the mucosa. This approach also confirms that air can pass smoothly from the antrum to the stomach. If present, damage to the mucosa can be repaired with a single layer of nonabsorbable suture at the site of injury and covered with an omental patch. The incisions are closed routinely.

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