Guidelines For Surgical Treatment Of Infantile Hypertrophic Pyloric Stenosis

Introduction

Infantile hypertrophic pyloric stenosis (IHPS) is a common cause of gastric outlet obstruction in infants and presents as one of the most common surgical conditions of infancy(1). It occurs in 1 to 3 of every 1000 live births(2). The problem is associated with a 4:1 male-to-female ratio. Pyloric stenosis appears to be more common in infants of Caucasian decent and is rare in Asian children(3).   It is an acquired disorder of unknown etiology in which hypertrophy of the muscle fibers of the pylorus occurs, causing a mechanical obstruction of the gastric outlet along with its associated metabolic and electrolyte abnormalities.  This condition has been successfully treated for decades with the open Ramstedt extramucosal pyloromyotomy, which clearly stands as the gold-standard treatment against which all other techniques must be compared(4) .  So highly effective is this simple, elegant, and inexpensive operation that it has been described as 'one of the most easy and gratifying procedures performed by pediatric surgeons"(5)  and 'the most consistently successful operation ever described"(6). Despite the success and popularity of the Ramstedt pyloromyotomy, complications occasionally do occur including prolonged post-operative emesis, wound infection, and duodenal perforation.  In addition, there is a permanent scar, which may negatively impact on the self image of  some children.  To deal with the issue of cosmesis some surgeons have advocated a circumumbilical incision for pyloromyotomy(7). However, it appears that this approach, although an acceptable alternative to Ramstedt's technique, has its own shortcomings including infection, incisional hernia, and prolonged gastroparesis.  The laparoscopic approach to pyloromyotomy obviates many of these concerns.  There is clearly an advantage as far as cosmesis is concerned and the anticipated increased complication rate and costs have not consistently been demonstrated. The technique has evolved over the last decade and appears to be at the very least an acceptable alternative to the time-honored open approach.

Definition

Infantile hypertrophic pyloric stenosis is defined as hypertrophy of the muscles of the pyloric channel, usually occurring in infants 3-10 weeks of age.  The pyloric muscle hypertrophy results in vomiting which can lead to dehydration, weight loss, and severe electrolyte abnormalities characterized by a hypokalemic, hypochloremic metabolic alkalosis.

Diagnosis

Infants suspected of pyloric stenosis usually present with the onset of non-bilious vomiting, beginning at 3-6 weeks of age. The pattern of vomiting varies, but often progresses to the characteristic 'projectile' vomiting.  Often, infants have undergone numerous formula changes before the diagnosis is made.  Severe or neglected cases can result in significant weight loss and failure to thrive.

An examiner may observe gastric peristaltic waves traveling from the infant's left upper abdomen toward the right side and the diagnostic finding is a mobile, ovoid mass, commonly referred to as an 'olive', palpable in the epigastrium or the right upper quadrant. In the absence of a palpable "olive", diagnostic imaging can be helpful.  Plain radiographs of the abdomen may show gastric distention.  An abdominal ultrasound is the most sensitive test for diagnosis and should be performed if the "olive" is not palpable.  The characteristic appearance of pyloric stenosis on ultrasound is that of a "doughnut" or "bulls eye" on cross section of the pyloric channel.  Pyloric dimensions with positive predictive value greater than 90% are muscle thickness greater than 4mm and a pyloric channel length greater than 17mm.  These limits may be lower in infants less than 30 days of age(8). When ultrasound is not available, a contrast upper gastrointestinal study (UGI) will confirm the diagnosis.  The classic radiographic signs are the "string sign" and the "shoulder sign" caused by the hypertrophied muscle protruding into the gastric channel.

Infants with a diagnosis of pyloric stenosis will show characteristically low Cl- and H+ ions as measured in the serum. Due to the loss of K+ and H+ ions in the urine and Cl- in the emesis, the infants will retain HCO3- and a resultant metabolic alkalosis occurs.  In severe cases with diagnostic delay, hypoglycemia and hypoalbuminemia can be observed.

Management

Infants with less than 5% dehydration and no electrolyte imbalance are candidates for surgery without delay.

Infants with electrolyte abnormalities or dehydration require correction of both.  Due to the severity of the dehydration, these infants are typically resuscitated with twice the maintenance volume of normal saline solution until they void.  Then, potassium is added to the intravenous fluids, which are changed to half-normal saline at 1.5 times maintenance.  It may take 48 hours or longer to fully resuscitate an infant and prepare them for surgery.  Lactated Ringers Solution is not to be used as an initial resuscitation fluid.  Nasogastric tubes should be avoided as they further deplete electrolytes.

Once an infant is resuscitated, the pyloric stenosis is treated surgically.

Surgical Treatment of Pyloric Stenosis

Preoperative Work-up

Once the diagnosis is made, the volume status restored (as evidenced by the infant's voiding), and the electrolytes corrected, the infant is ready for surgery unless there are other complicating factors.

Indications for Surgery

Surgical therapy should be considered in infants with documented pyloric stenosis

Surgical Techniques

Since Ramstedt, the treatment has been pyloromyotomy.  This procedure is done under general anesthesia with several incisions described, none of which have any particular advantage.  A circumumbilcal incision is recommended by some to hide the incision. Regardless, the pyloric "tumor" is withdrawn from the wound with gentle traction and a sero-muscular incision is made from the gastric antrum to the junction of the pylorus and the duodenum. This incision is "split" with the back of a knife handle until the two halves of the pyloric ring are separate from each other and move independently.

In the event of a duodenal perforation, the perforation may be closed primarily or the Plylorus closed and a new pyloromyotomy performed.

Laparoscopic Treatment of Pyloric Stenosis

Alain, et al, reported their initial experience in 10 patients in 1991(9).  In the first 2 infants the effectiveness of the laparoscopic procedure was in fact confirmed by an open abdominal incision without exteriorizing the pylorus itself.  All of the patients had an uncomplicated postoperative course, and so the authors were the first to conclude that laparoscopic pyloromyotomy was a sound and technically simple procedure.  Tan and Najmaldin reported their initial experience in 1993(10) . They improved on Alain's technique in that they were able to perform the procedure with 1 assistant rather than 2, and their patients were discharged sooner than those in the earlier series.  Two years later the same authors reported a series of 37 patients, all of whom underwent laparoscopic pyloromyotomy.  They documented the average time of operation (29 minutes), the average time before the initiation of feedings (5.2 hours), and the average time to discharge (28 hours)(11). Furthermore they had no technical failures.  In 1995 Castañón, et al, described the pyloric traumamyoplasty, an entirely new approach to splitting the hypertrophied pylorus(12). In this technique 2 crushing applications of a laparoscopic Babcock clamp were used to rupture the pyloric muscle, thus creating 2 grooves in the muscle and relieving the obstruction.

The further evolution of laparoscopic pyloromyotomy beyond the work of these pioneering individuals has been evident, as several more authors have more recently described their results as well as technical improvements in the procedure.  Rothenberg described his slice and pull technique in 1997(1). In this procedure the duodenum is grasped with a laparoscopic Babcock clamp, and a sheathed arthroscopy blade is used to perform the myotomy.  All 20 patients in this series had an uncomplicated postoperative course.  The average operating time was 13 minutes, and 19 of the 20 patients were discharged in less than 24 hours.  Importantly, he also demonstrated the cost effectiveness of the laparoscopic approach as versatile, reusable instruments were used excepting the inexpensive, disposable blade.  Bufo, et al, described a safer technique in which the stomach rather than the duodenum is grasped and the pyloromyotomy completed from the right with a retractable arthroscopy blade and a laparoscopic pyloric spreader, with grooves on the outside of the clamp(13). Harris and Cywes presented a simple technique in which the only required instruments were an extended-tip cautery device and 2 reusable, laparoscopic pyloric spreaders(14). In their hands the cost of laparoscopic pyloromyotomy was actually less than that for the open technique.

The laparoscopic pyloromyotomy is performed using a peri-umbilical telescope and two stab wounds, one for a grasper and the other for the retractable blade and the pyloric spreader. The surgeon has the choice os whether to grasp the duodenum and incise from duodenum toward the stomach, or to grasp the stomach and incise from the stomach toward the duodenum.  Either way, the pyloric muscle is spread and the adequacy of the operation verified as is described above for the open procedure.

Post-operatively, infants are returned to their wards with maintenance intravenous fluids.  Several hours after operation, feedings are initiated and advanced as tolerated until discharge.

Summary

Infantile hypertrophic pyloric stenosis is a common disorder of infancy.  The diagnosis and treatment have long been established.  Laparoscopic pyloromyotomy is an appropriate option for most patients and in the experience of some proves to offer the advantage of being less costly with a shorter operative time, less tissue trauma, and a better cosmetic appearance(15,16).

References

  1. Schwartz MZ: Hypertrophic pyloric stenosis. In Pediatric Surgery. O'Neill JA, Rowe MI, Grosfeld JL, et al, eds:1111-1117
  2. Grant GA, McAleer JJA: Incidence of infantile hypertrophic pyloric stenosis (letter). Lancet 1:1177, 1984
  3. Klein A, Cremin BJ: Racial significance in pyloric stenosis. S Afr Med J 44:1130-1134, 1970
  4. Ramstedt C: Zur operation der angeborenen pylorus stenose.  Med Klinic 8:1702, 1912
  5. Rothenberg SS: Laparoscopic pyloromyotomy: the slice and pull technique. Pediatric Endosurgery and Innovative Techniques. 1:39-41, 1997
  6. Pollack WF, Norris WJ: Surgical History. Dr. Conrad Ramstedt and pyloromyotomy. Surgery 42:966-970, 1957
  7. Tan KC, Bianchi A: Circumumbilical incision for pyloromyotomy. British Journal of Surgery 73:399, 1986
  8. Lamki N, Athey PA, Round ME, et al: Hypertrophic pyloric stenosis in the neonate ' diagnostic criteria revisited.  Can Assoc Radiol J 44:21-24, 1993
  9. Alain JL, Grousseau D, Terrier G: Extramucosal pyloromyotomy by laparoscopy.  Journal of Pediatric Surgery 26:1191-1192, 1991
  10. Tan HL, Najmaldin A: Laparoscopic pyloromyotomy for infantile hypertrophic pyloric stenosis.  Pediatric Surgery International 8:376-378, 1993
  11. Najmaldin A, Tan HL: Early experience with laparoscopic pyloromyotomy for infantile hypertrophic pyloric stenosis. Journal of Pediatric Surgery 30:37-38, 1995
  12. Castañón J, Portilla E, Rodríguez E, et al: A new technique for laparoscopic repair of hypertrophic pyloric stenosis. Journal of Pediatric Surgery 30:1294-1296, 1995
  13. Bufo AJ, Merry C, Shah R, et al: Laparoscopic pyloromyotomy: a safer technique. Pediatric Surgery International 13:240-242, 1998.
  14. Harris SE, Cywes R: Laparoscopic pyloromyotomy. Pediatric Endosurgery and Innovative Techniques 5:405-410, 2001 15.
  15. Lobe TE: Laparoscopic surgery in children. Current Problems in Surgery 35:859-948, 1998
  16. Scorpio RJ, Tan HL, Hutson JM: Pyloromyotomy: comparison between laparoscopic and open surgical techniques. Journal of Laparoendoscopic Surgery 5:81-84, 1995

This guideline was prepared by the IPEG Guidelines Committee and  was reviewed and approved by the Executive Committee of the International Pediatric Endosurgery Group (IPEG) November, 2002.

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