Pediatric Hypertrophic Pyloric Stenosis Surgery Treatment & Management

Although medical treatment has been used to manage pyloric stenosis, pyloromyotomy has been firmly established as the treatment of choice for this condition. Medical management of pyloric stenosis, however, remains important. Early assessment and treatment of fluid, electrolyte, and acid-base disturbances are paramount. Urgent resuscitation, rather than emergent surgical intervention, is the rule. Once the diagnosis is made, fluid resuscitation is begun. Clinical and biochemical assessments are made and repeated to guide appropriate fluid repletion.

Nonsurgical management was described originally in Europe using a low-curd feeding of dextrose or breast milk; however, this treatment reportedly took months to complete and was associated with significant morbidity. Reports from Sweden showed that using intravenous nutrition alone also usually failed. Additionally, a biochemical approach of giving atropine or scopolamine was used to compensate for the lack of nitric oxide synthase in the pylorus, which is thought to cause the hypertrophy. These anticholinergics were thought to decrease pyloric contractions; however, early success was lacking and, until recently, was thought to be only of historical interest.

In 1996, Nagita et al, in a Japanese study, reported successfully treating 21 of 23 infants (91%) with pyloric stenosis using intravenous atropine, administered at a dosage of 0.04-0.11 mg/kg/d until vomiting ceased, followed by oral atropine for 2 weeks.^[11]

Another Japanese study, by Kawahara et al (2005), reported a success rate of 87% in 52 patients treated with intravenous and oral atropine. Manometric studies were used to find the level of atropine that decreased tonic and phasic contractions in the pylorus. The dosing regimen of atropine was 0.01 mg/kg IV 6 times a day before feedings (median time, 1 wk) followed by 0.02 mg/kg orally after vomiting stopped and infants could tolerate formula in the amount of 150 mL/kg (median time, 44 d). Hospital stays ranged from 6-36 days (median, 13 d); however, despite the longer hospital stay, the costs for the medical group were similar to those for the surgical group, without the inherent risks of general anesthesia and surgery. Regarding general outcomes, the 2 groups showed no difference in weight at age 1 year. Applying medical treatment for pyloric stenosis could prove useful to patients without sufficient access to surgical care or when surgery would be too risky.^[12]

The authors of the study concluded that this medical treatment of pyloric stenosis is an effective alternative to pyloromyotomy if the length of hospitalization and the necessity of continuing oral atropine are accepted. Long-term studies have yet to be conducted to address recurrence rates, hospital costs in other countries, and caregiver compliance for atropine-treated patients with pyloric stenosis. In the United States, the Ramstedt pyloromyotomy remains the optimal treatment for pyloric stenosis.

Pyloric stenosis is not a surgical emergency. Urgent resuscitation, rather than emergent surgical intervention, is the rule. The preoperative medical management of patients with pyloric stenosis is paramount for safe general anesthesia. Once the diagnosis is made, fluid resuscitation is begun to treat dehydration and electrolyte and acid-base disturbances. Clinical and biochemical assessments are made and repeated to guide appropriate fluid repletion.

Intravenous therapy consists of 5% dextrose in one-half isotonic sodium chloride solution (0.45% NaCl/D5W) at 1.5 times the maintenance rate. Although children with severe dehydration should receive deficit fluid therapy with isotonic sodium chloride solution (20 mL/kg) initially, ongoing resuscitation should be performed with 0.45% NaCl/D5W to prevent rapid changes in volume and electrolyte levels, which can result in seizures. When urine output has been demonstrated, potassium chloride (10-20 mEq/L) can be added to the fluids.

In some patients with severe volume abnormalities (>20%) and electrolyte abnormalities (Cl^- < 80 mEq/dL; HCO₃^- >35; Na⁺ < 120 mEq/L), resuscitation may take 48-72 hours. With serum bicarbonate levels exceeding 30 mEq/dL, the potential exists for myocardial dysfunction and respiratory depression. The patients should therefore be monitored for signs of apnea; if such signs are present, the patient may need to be intubated and mechanically ventilated until surgery is performed.

An alternative preoperative stabilization treatment has been proposed for severely alkalemic patients in order to decrease the preoperative hospital stay. In a report of 16 infants with a pH level exceeding 7.60, 4 patients received standard resuscitation for 4 days and then cimetidine at 10 mg/kg, while 12 received intravenous cimetidine upon admittance until the pH level dropped below 7.50. In all 16 infants, the pH level reached the goal the same day cimetidine therapy was initiated, and all underwent pyloromyotomy that day. No complications associated with the use of cimetidine were reported. Thus, this type of prompt preoperative resuscitation may be a significant approach to decreasing hospital length of stay and overall costs in infants with severe metabolic alkalosis.^[13]

Once the diagnosis of pyloric stenosis has been confirmed, adequate ongoing preoperative fluid resuscitation must be maintained by establishing adequate urine output (1 mL/kg/h) and correcting acid-base disorders and electrolyte abnormalities. Regarding anesthetic induction for infants with pyloric stenosis, tracheal intubation with muscle paralysis seems to be superior to awake intubation, as the former reduces the risk of desaturation and bradycardia due to multiple attempts at intubation.

Pyloromyotomy may be performed either as an open procedure, via a right-upper-quadrant horizontal incision or an umbilical incision (Tan-Bianchi operation), or a laparoscopic procedure (see the images below).

In 1986, a Tan-Bianchi approach was described in which a pyloromyotomy was performed through a supraumbilical incision that afforded superior cosmesis.^[14] Blumer et al (2004) compared the umbilical approach with the right-upper-quadrant approach in 237 patients and found that the umbilical approach took 3.1 minutes longer (28.5 min vs 31.6 min; P < .025). This difference was clinically irrelevant, however, as there were no significant differences regarding length of hospital stay, mucosal perforations, or wound infections. Blumer et al also concluded that the umbilical approach provided a superior cosmetic outcome.^[15]

In 2004, Alberti et al reported modifying the Tan-Bianchi approach with a right semicircular umbilical incision, thus keeping all the incisions in the same axis, allowing for delivery of a larger pylorus, and decreasing the amount of retractor strain on the wound.^[16] This approach resulted in a lower rate of hematoma formation and lower wound infection rates (0%) than supraumbilical incisions (16%), despite the use of prophylactic antibiotics with the semicircular umbilical approach. In this modified Tan-Bianchi operation, after the pyloric channel is delivered from the abdomen, a seromuscular incision is made along the anterior border of the hypertrophied pylorus from 1-2 mm proximal to the duodenum to the distal antrum just proximal to the pylorus. Great care must be taken not to incise or perforate the underlying mucosa. An alternative superficial V-shaped extension can be made at the duodenal end of the myotomy to reduce the risk of duodenal mucosal injury.

Other variations of the open abdominal approach include a technique reported by Yokomori et al (2006) in which a semi-circumumbilical incision was used to create a 1.5-cm sliding window with an 8-cm subcutaneous space. This space was then slid 3-4 cm toward the right upper quadrant. The abdomen was entered and the pyloromyotomy performed intracorporeally within the window. This type of incision can afford an uneventful postoperative course, along with a good cosmetic outcome.

One study compared an umbilical approach using a transverse muscle cutting incision and a vertical linea alba incision and found no difference in terms of postoperative morbidity.^[17] In addition, a double-Y or Alalayet pyloromyotomy may be superior to the Ramstedt technique in decreasing postoperative vomiting and increasing weight gain in the first week following surgery.

Another consideration with pyloromyotomy may be the presence of foveolar cell hyperplasia (FCH), a type of redundant mucosa, which may be evident ultrasonographically in 12% of infantile hypertrophic pyloric stenosis cases. In patients diagnosed with FCH, an extended pyloromyotomy may decrease postoperative vomiting and reduce the need for gastric foveolar fold excision due to persistent postoperative vomiting.

A laparoscopic pyloromyotomy follows the same principles as an open procedure. First described by Alain et al in 1991,^[18] the laparoscopic approach has been demonstrated as a safe alternative to exteriorizing the pylorus and improving cosmetic results. The authors' approach entails creating a 5-mm camera port at the umbilicus. A 3-mm atraumatic, locking, grasping instrument is inserted in the right upper quadrant, over the duodenum. The grasping instrument is used to stabilize the pyloric channel. A 3-mm incision is made in the midepigastrium, over the pyloric olive, through which a sheathed arthrotome is passed (without a trocar). The pylorus is then incised in the same fashion as with the open procedure. A laparoscopic pyloric spreader is then used to bluntly split the hypertrophied muscle.

Crystalloid resuscitation is continued postoperatively until the patient returns to full feeding. Recent data suggest that infants with pyloric stenosis have an increased incidence of postoperative apnea and bradycardia. These infants should be placed on an apnea and cardiac monitor for 24 hours following the operation.

A decrease in the number of hospital days after operation depends to a certain degree on how rapidly feeding is started and advanced. In one study, Michalsky et al (2002) reported that having a clinical pathway decreased surgeon variability by advancing the diet to oral feedings within 5 hours after operation. Additionally, the length of hospital stay was significantly reduced (41.8 ± 9.7 h vs 57.8 ± 11.7 h; P < .001), as well as hospital costs ($4555 ± $464 vs $5400 ± $1017; P < .001).^[19]

In contrast, Puapong et al (2002) showed that feeding ad libitum after the patient is awake resulted in a significantly faster return to full-strength feeding than a controlled feeding regimen (29.1 h vs 5.1 h; P < .05), along with a shorter hospital stay (38.8 d ± 16.6 d vs 25.1 d ± 10.9 d; P < .05) and a significant decrease in cost per patient ($3560 vs $2290; P < .05).^[20] Both studies found that early initiation of feeding leads to better recovery and to cost savings.

The author has found the following feeding regimen to be safe and adequate.

1. Give the patient nothing by mouth (NPO) for 6 hours in the recovery room.
2. Then, on demand, give 15 mL of Pedialyte every 2-3 hours for 2 feedings.
3. If 15 mL is tolerated, advance to 30 mL of Pedialyte every 2-3 hours for 2 feedings.
4. If 30 mL is tolerated, advance to 30 mL of full-strength formula every 2-3 hours for 2 feedings.
5. If full-strength formula is tolerated, advance to spontaneous feedings.
6. If vomiting occurs, repeat the step at which vomiting occurs and advance when tolerated.
7. If the patient is being breastfed and the mother has bottled milk, follow the above schedule.

If the patient is being breastfed and no bottled milk is available, follow the schedule below:

• Follow steps 1, 2, and 3 above.
• Have the patient breastfeed on each side for 5 minutes every 2 hours for 2 feedings.
• Have the patient breastfeed on each side for 10 minutes every 2 hours for 2 feedings.
• Have the patient breastfeed spontaneously.

Slow feeding and gentle burping help prevent wet burps postoperatively. Intermittent vomiting persisting through the first postoperative week is sometimes observed in patients with a protracted course of emesis and severe dehydration preoperatively. Vomiting lasting longer than 7 days postoperatively should alert the physician to the possibility of an incomplete pyloromyotomy. A UGI study may be obtained but is useful only for demonstrating gastroesophageal reflux, as the radiographic appearances of pyloric stenosis may persist for several months following complete pyloromyotomy.

The follow-up care regimen involves a routine postoperative visit at 1 week to check wounds and to ensure that the patient is once again gaining weight.

Although pyloromyotomy is safe and curative and performed virtually without operative mortality (< 0.5%) and morbidity (< 10%), it is not without potential complications. Potential intraoperative and postoperative complications include bleeding, perforation, and wound infection. Duodenal or gastric perforation, the most serious complication, rarely occurs; however, if it goes unrecognized before wound closure, devastating or lethal consequences are possible. The infant with an enteric leak develops pain, distention, fever, and peritonitis. Ongoing fluid requirements, generalized sepsis, vascular collapse, and death follow if the enteric leak is not recognized and treated. Suspected perforation postoperatively requires immediate reexploration. Recognition of this complication at the time of surgery is important.

Mucosal perforation most commonly results from extending the myotomy beyond the pyloric-duodenal junction. If perforation occurs, the mucosal defect should be repaired and the myotomy completed. An omental patch may be sutured to the perforation site, and a paraduodenal drain may be considered. If any question exists about the success of the closure, a UGI study can be obtained before feedings are initiated. The patient should continue to receive antibiotics until feedings are resumed.

Bleeding is a rare complication of pyloromyotomy. Other complications that are more common but less serious include superficial wound infections (usually Staphylococcus aureus) and postoperative vomiting. Patients with wound erythema, drainage, or both undergo wound opening and debridement and antibiotic therapy. Incomplete myotomy results in ongoing gastric outlet obstruction and requires reoperation. However, ongoing emesis after pyloromyotomy does not mean an incomplete myotomy was performed. Patients with prolonged preoperative obstruction develop gastric distention and dysmotility, which may cause postoperative emesis for up to 1 week after an adequate pyloromyotomy.

Pyloromyotomy that is adequately performed is curative of pyloric stenosis. There have been reports of recurrent pyloric stenosis despite performance of an adequate pyloromyotomy, but recurrence is considered to be a rare exception after incomplete pyloromyotomy has been ruled out.

Yoshizawa et al (2001) has demonstrated in ultrasonography studies that, after pyloromyotomy, the pylorus changes significantly within 3 days postoperatively and returns to normal within 5 months.^[21] Specific changes are provided below:

• The dorsal pyloric aspect temporarily thickens from 5.1 mm ± 0.8 mm to 6.0 mm ± 0.3 mm within 3 days postoperatively (P < .5) and thins out to 2.8 mm ± 0.2 mm within 5 months.
• The pyloric length decreases from 20.1 mm ± 2.9 mm preoperatively to 16.9 mm ± 2.7 mm (P < .5) within 3 days postoperatively and to less than 15 mm within 4 months.
• The change in pyloric diameter is comparable to the change in pyloric length
• The transverse muscle thickness of the incision site changes from 4.3 mm ± 0.4 mm to 4.6 mm ± 0.4 mm (P < .5) within 3 days postoperatively and to 2.1 mm ± 0.9 mm (P < .5) within 7 days (normal, < 3 mm).

Several studies have focused on patient outcomes with respect to advanced training and experience of surgeons. Pranikoff et al (2002) reported that pediatric surgeons performing pyloromyotomy had a mucosal perforation rate of 0.5%, compared with a 2.9% rate for general surgeons (P = .0015), and that this difference in rate of mucosal perforation correlated with a decrease in total hospital charges ($4806 ± $79 vs $6592 ± $492; P = .002) and a shorter hospital stay (2.7 d ± 0.1 d vs 3.1 d ± 0.1 d; P = 0.01).^[22]

In a study of 11,003 patients with pyloric stenosis, Safford et al (2005) stratified patient outcomes based on surgeon volume and hospital volume of pyloric stenosis cases. For surgeons, low volume was considered less than 1 procedure per year; intermediate, 1-5 procedures per year; and high, more than 5 procedures per year. For hospitals, low volume was considered fewer than 5 procedures per year; intermediate, 5-15 procedures per year; and, high, more than 15 procedures per year.

They reported that patients operated on by low- and intermediate-volume surgeons were more likely to have complications than patients operated on by high-volume surgeons (95% CI, 1.25-3.78 and 1.25-2.69, respectively). Patients operated on at low-volume hospitals were 1.6 times more likely to have complications than patients operated on at intermediate- or high-volume hospitals (95% CI, 1.19-2.20). Procedures performed at high-volume hospitals were less expensive than those done at intermediate-volume hospitals, by a margin of $910 (95% CI, $443-$1377). High-volume surgeons were more expensive than low-volume surgeons, by a margin of $511 (95% CI, $25-$962). Low-volume surgeons at low-volume hospitals had mucosal perforation rates 4-6.7 times higher than high-volume surgeons at high-volume hospitals.^[23]

It is important to note that, between 1994 and 2000, the frequency of laparoscopic pyloromyotomy was likely increasing; however, the rates of open pyloromyotomy and laparoscopic pyloromyotomy were not included in procedure coding. The data have shown that, for pyloromyotomy procedures, complication rates are lower and cost savings greater with high-volume surgeons operating at high-volume hospitals.

Laparoscopic pyloromyotomy has a significant learning curve. Hendrickson et al (2005) reported an initial operative time of 70 minutes at a teaching hospital, with operative times decreasing to 15 minutes after 25 procedures. A conversion rate of 8% from the laparoscopic to the open procedure was reported.^[24] Similar learning curves have been reported at other centers. Yagmurlu et al (2004) compared open pyloromyotomy (n = 225) with laparoscopic pyloromyotomy (n = 232) and found the overall complication rates to be 4.4% for the open procedure and 5.6% for the laparoscopic procedure. The open approach resulted in a higher rate of mucosal perforation (3.6% vs 0.4%; P = .016), and laparoscopy had a higher rate of postoperative complications, such as incomplete pyloromyotomy (0% for open vs 2.2% for laparoscopic; P = 0.027).^[25]

Campbell et al (2002), in a retrospective study, reported on 117 patients showing a trend toward significantly higher complications with laparoscopic pyloromyotomy than with the open procedure (18% vs 12%; P = .31). Additionally, significantly higher hospital costs were associated with the laparoscopic approach.^[26] The International Pediatric Endosurgery Group (2002) has reported that laparoscopic pyloromyotomy provides cost savings, decreases operating room time, reduces tissue trauma, and improves cosmetic outcome.^[27] Oomen et al concluded that laparoscopy might be acknowledged as the standard of care if the major postoperative complication rate is low. To achieve this, this procedure should performed by pediatric surgeons with expertise in this procedure.^[28]

Outcome studies comparing open versus laparoscopic approaches to pyloromyotomy are becoming more numerous overall as the trend toward more minimally invasive procedures is becoming more important to the public. In one survey, cosmetic outcome was valued such that up to 88% of parents were willing to pay additional expenses for their children to have smaller scars.^[29]

With a higher public demand for minimally invasive surgery, it is important to note the changing trends in surgical resident training. Cosper et al reported that 93% of surgeons agreed that residents need to perform at least 4 open pyloromyotomies in order to become competent in the procedure; however, 44% reported that their residents performed fewer than 4, explained partly by the increased use of laparoscopic approach and partly by a decreased opportunity for residents in the operating room to acquire the necessary skills.^[30]

The rate of complications associated with laparoscopic pyloromyotomy when a general surgery resident participates in the procedure is increased 5.4-fold compared with the rate associated with performance by a pediatric resident, despite close attending supervision. However, because of the fact that more surgical residents are specializing, combined with the possibility of fewer general surgeons who are comfortable performing pyloromyotomies, patients with pyloric stenosis may eventually experience a healthcare access problem. The need for parents to travel longer distances to a larger center that offers this procedure (or that has a high volume of these procedures performed) may result in further attempts at other modalities for treating pyloric stenosis.

For example, in an alternative approach used to address the pylorus externally, Zhang et al (2008) reported 9 successful applications of endoscopic pyloromyotomy in resolving infantile hypertrophic pyloric stenosis. After transabdominal ultrasonography was used to assess the wall thickness, a 5.9-mm gastroscope was used to create a 2- to 3-mm incision (if the wall was 4-6 mm) or 3- to 4-mm incision (if the wall was >6 mm thick). There were no complications of hemorrhage or perforation; however, one patient developed vomiting after one month. A repeat procedure resolved her symptoms.^[31] With further research, this may prove to be a safer, more effective, and simpler alternative to the current standard of care.