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Pediatrics, Pyloric Stenosis

Jagvir Singh, MD, Director, Division of Pediatric Emergency Medicine, Lutheran General Hospital of Park Ridge
Dara A Kass, MD, Clinical Assistant Instructor, Department of Emergency Medicine, State University of New York Downstate Medical Center, Kings County Hospital; Richard H Sinert, DO, Associate Professor of Emergency Medicine, Clinical Assistant Professor of Medicine, Research Director, State University of New York College of Medicine; Consulting Staff, Department of Emergency Medicine, Kings County Hospital Center

Updated: Dec 16, 2009

Introduction

Background

Pyloric stenosis, also known as infantile hypertrophic pyloric stenosis (IHPS), is the most common cause of intestinal obstruction in infancy. IHPS occurs secondary to hypertrophy and hyperplasia of the muscular layers of the pylorus, causing a functional gastric outlet obstruction.

In 1717, Blair first reported autopsy findings of pyloric stenosis. Although the description of the signs and symptoms of infantile hypertrophic pyloric stenosis can be found in the 17th century, the clinical picture and pathology were not accurately described until 1887 by the Danish pediatrician, Hirschsprung. Prior to 1912, early successful surgical procedures included gastroenterostomy, pyloroplasty, and forcible dilatation via gastrostomy. In 1912, Ramstedt observed an uneventful recovery in a patient following pyloroplasty, where sutures used in reapproximating the seromuscular layer had disrupted. Following this observation, he began leaving the split muscle layer unsutured in all subsequent repairs. The Ramstedt pyloromyotomy remains the standard procedure for pyloric stenosis today.

Pathophysiology

Marked hypertrophy and hyperplasia of the 2 (circular and longitudinal) muscular layers of the pylorus occurs, leading to narrowing of the gastric antrum. The pyloric canal becomes lengthened, and the whole pylorus becomes thickened. The mucosa is usually edematous and thickened. In advanced cases, the stomach becomes markedly dilated in response to near-complete obstruction.

The causes of infantile hypertrophic pyloric stenosis are multifactorial.[1 ]Both environmental factors and hereditary factors are believed to be contributory. Possible etiologic factors include deficiency of nitric oxide synthase containing neurons, abnormal myenteric plexus innervation, infantile hypergastrinemia, and exposure to macrolide antibiotics.

Nitric oxide has been demonstrated as a major inhibitory nonadrenergic, noncholinergic neurotransmitter in the GI tract, causing relaxation of smooth muscle of the myenteric plexus upon its release. Impairment of this neuronal nitric oxide synthase (nNOS) synthesis has been implicated in infantile hypertrophic pyloric stenosis, in addition to achalasia, diabetic gastroparesis, and Hirschsprung disease.

Rogers has suggested, that persisting duodenal hyperacidity, secondary due to a high parietal cell mass (PCM) and loss of gastrin control, produces pyloric stenosis from repeated pyloric contraction in response to hyperacidity.[2 ]

No specific pattern of inheritance exists. It is more common in first-born white males of northern European ancestry and more concordant in monozygotic than dizygotic twins. It also has predominance in children of affected parents (as many as 7%).

Frequency

United States

The incidence of infantile hypertrophic pyloric stenosis is 2-4 per 1000 live births.

Mortality/Morbidity

Death from infantile hypertrophic pyloric stenosis is rare and unexpected. The reported mortality rate is very low and usually results from delays in diagnosis with eventual dehydration and shock.

Race

Infantile hypertrophic pyloric stenosis is more common in whites than Hispanics, blacks, or Asians. The incidence is 2.4 per 1000 live births in whites, 1.8 in Hispanics, 0.7 in blacks, and 0.6 in Asians. It is also less common amongst children of mixed race parents.

Sex

Infantile hypertrophic pyloric stenosis has a male-to-female predominance of 4:1, with 30% of patients with infantile hypertrophic pyloric stenosis being first-born males.

Age

The usual age of presentation is approximately 3 weeks of life (1-18 wk). Approximately 95% of infantile hypertrophic pyloric stenosis cases are diagnosed in those aged 3-12 weeks. Infantile hypertrophic pyloric stenosis is rare in premature infants. In addition, premature infants have a delayed diagnosis secondary to low birth weight and atypical presentation.

Clinical

History

  • Classically, the infant with pyloric stenosis has nonbilious vomiting or regurgitation, which may become projectile (in as many as 70% of cases), after which the infant is still hungry.[3 ]
  • Emesis may be intermittent or occur after each feeding.
  • The emesis may become brown or coffee color due to blood secondary to gastritis or a Mallory-Weiss tear at the gastroesophageal junction.
  • The infant begins to show signs of dehydration and malnutrition, such as poor weight gain, weight loss, marasmus, decreased urinary output, lethargy, and shock.
  • The infant may develop jaundice, which is corrected upon correction of the disease.

Physical

  • In as many as 60-80% of the infants with infantile hypertrophic pyloric stenosis (IHPS), a firm, nontender, and mobile hard pylorus that is 1-2 cm in diameter, described as an "olive," may be present in the right upper quadrant at the lateral edge of the rectus abdominus muscle. This is best palpated after the infant has vomited and when calm, or when the gastric contents have been removed via nasogastric tube.
  • Clinicians may also observe gastric peristalsis just prior to emesis as the peristaltic waves try to overcome the obstruction.
  • Signs of dehydration include depressed fontanelles, dry mucous membranes, decreased tearing, poor skin turgor, and lethargy.
  • The classic signs of infantile hypertrophic pyloric stenosis are becoming less common. The mean age of presentation is getting significantly younger, and infants are not developing the physical signs or electrolyte abnormalities they were 20 years ago. Additionally, the availability of diagnostic imaging is allowing clinicians to make this diagnosis before other clinical manifestations appear.

Causes

  • The etiology of infantile hypertrophic pyloric stenosis is unknown and is probably multifactorial.

Differential Diagnoses

Adrenal Insufficiency and Adrenal Crisis
Pediatrics, Urinary Tract Infections and Pyelonephritis
Gastroenteritis
Renal Failure, Acute
Pediatrics, Dehydration
Pediatrics, Gastroenteritis
Pediatrics, Inborn Errors of Metabolism

Other Problems to Be Considered

Malrotation
Gastroesophageal reflux
Pyloric atresia
Pyloric antral web
Pyloric diaphragm
Poor feeding practices
Hiatal hernia
Congenital adrenal hyperplasia (CAH)

Workup

Laboratory Studies

  • Electrolytes, pH, BUN, and creatinine levels should be obtained at the same time as intravenous access in patients with pyloric stenosis.
    • Hypochloremic, hypokalemic metabolic alkalosis is the classic electrolyte and acid-base imbalance of pyloric stenosis. Persistent emesis causes progressive loss of fluids rich in hydrochloric acid, which causes the kidneys to retain hydrogen ions in favor of potassium. Electrolyte abnormalities depend on the duration of symptoms in the affected infant.
    • The dehydration may result in hypernatremia or hyponatremia and may result in prerenal renal failure.
  • Elevated unconjugated bilirubin levels may be present.

Imaging Studies

  • If the clinical presentation is typical and an olive is felt, the diagnosis is confirmed and further imaging is not warranted.
  • Ultrasonography is the imaging modality of choice when evaluating a child for infantile hypertrophic pyloric stenosis (IHPS).[4 ]It is both highly sensitive (90-99%) and specific (97-100%) in the hands of a qualified sonographer. The pylorus is viewed in longitudinal and transverse planes. The sonographic hallmark of infantile hypertrophic pyloric stenosis is the thickened pyloric muscle.
  • Criteria for making the diagnosis include pyloric muscle thickness greater than 4 mm. The length of the pyloric canal is variable and may range from 14 mm to 20 mm. The pyloric diameter may range from 10-14 mm.
    • Infantile hypertrophic pyloric stenosis may be falsely diagnosed in infants who have pylorospasm. Ultrasonography also allows for observation of peristaltic activity, differentiating between pylorospasm and true infantile hypertrophic pyloric stenosis.
    • Upper GI imaging (UGI) can help to confirm the diagnosis of infantile hypertrophic pyloric stenosis but is not routinely performed unless ultrasonography is nondiagnostic.
  • The "shoulder" sign is a collection of barium in the dilated prepyloric antrum and may be seen in the infant with infantile hypertrophic pyloric stenosis. The "double track" sign (ie, 2 thin tracks of barium compressed between thickened pyloric mucosa), once thought to be pathognomonic of infantile hypertrophic pyloric stenosis, has recently been identified in multiple cases of sonographically confirmed pylorospasm and is shown in the image below.

  • Lateral view from an upper GI study demonstrates ...

    Lateral view from an upper GI study demonstrates the double-track sign.


Procedures

  • Upper GI endoscopy has been used as an adjunct diagnostic tool in select cases of infantile hypertrophic pyloric stenosis when other imaging tests are inconclusive or when the infant presents with atypical clinical features.

Treatment

Prehospital Care

  • As with all pediatric resuscitations, prehospital care in patients with pyloric stenosis should be consistent with pediatric advanced life support (PALS) recommendations for infants who are dehydrated or in shock.
  • Immediate treatment requires correction of fluid loss, electrolytes, and acid-base imbalance. Once intravenous access is obtained, the dehydrated infant should receive an initial bolus (20 mL/kg) of crystalloid fluid. The infant should remain nothing by mouth (NPO).

Emergency Department Care

  • Infantile hypertrophic pyloric stenosis (IHPS) is a medical emergency.
  • Immediate treatment requires correction of fluid loss, electrolytes, and acid-base imbalance. Once intravenous access is obtained, an initial fluid bolus (20 mL/kg) of crystalloids should be infused immediately if the infant is dehydrated.
  • More than 60% of infants present to the ED with normal electrolyte values or are not in clinical shock. These infants should receive 1.5-2 times maintenance intravenous fluid: 5% dextrose in 0.25% or 0.33% sodium chloride with 2-4 mEq KCl per 100 mL replacement. The infant's fluid status should be continuously reassessed with special attention to acid-base status and urine output.
  • The definitive treatment for infantile hypertrophic pyloric stenosis is corrective surgery.
  • The Ramstedt pyloromyotomy is the procedure of choice, during which underlying antro-pyloric mass is split leaving the mucosal layer intact.
    • Traditionally, the pyloromyotomy was performed through a right upper quadrant transverse incision. Recent studies have compared the operative time, cost, and hospital stay associated with the traditional incision, a circumbilical incision (believed to have improved cosmesis), and a laparoscopic procedure. The laparoscopic pyloromyotomy has been found to be safe and effective, with shorter operative times and hospital stay.
    • A study from the United Kingdom observed less time to full feedings, less analgesia, less emesis, and faster discharge in the laparoscopic group compared with the traditional approach.[5 ]
    • A study from France showed that laparoscopic pyloromyotomy does not decrease the incidence of postoperative vomiting and may lead to a risk of inadequate pyloromyotomy.[6 ]
    • Pyloromyotomy performed in specialized centers in pediatric surgery and a general surgery teaching hospital had similar complication rates in a study from the Netherlands.[7 ]
    • Recently, various surgical approaches, such as the supraumbilical skin-fold incision and umbilical incision, have been used with easy access, and these approaches have better cosmetic results. Also, a study from Montreal showed superior cosmesis with the supraumbilical (SU) approach than with the right upper quadrant (RUQ) approach.[8 ]
  • Nonsurgical treatment for infantile hypertrophic pyloric stenosis with atropine sulfate, both intravenous and oral, has shown encouraging results. In one study, infants were given 21 days of atropine via nasogastric tube and regression of pyloric hypertrophy was monitored sonographically. One patient needed intravenous atropine, as nasogastric tube feedings were not tolerated for the first 2 days, but the patient did well subsequently. In this study, all 12 patients were successfully treated nonsurgically without complication.
  • Surgical correction is considered the standard of care for all patients with infantile hypertrophic pyloric stenosis; therefore, medical management should be reserved for patients who are poor surgical candidates or whose parents are opposed to surgery.

Consultations

  • A surgeon comfortable with neonatal care should be consulted as soon as the diagnosis of infantile hypertrophic pyloric stenosis is entertained.

Medication

  • Surgical correction is considered the standard of care for infantile hypertrophic pyloric stenosis (IHPS).
  • Limited data are available for nonsurgical treatment (see Treatment).

Follow-up

Further Inpatient Care

The infant with pyloric stenosis should continue to receive intravenous fluid until feeding is resumed. Feeding can be initiated 4-8 hours after recovery from anesthesia, although earlier feeding has been studied. Infants who are fed earlier than 4 hours do not have a worse total clinical outcome; however, they do vomit more frequently and more severely, leading to significant discomfort for the patient and anxiety for the parents.

  • As many as 80% of patients continue to regurgitate after surgery; however, patients who continue to vomit 5 days after surgery may warrant further radiologic investigation.
  • Patients should be observed for surgical complications (eg, incomplete pyloromyotomy, mucosal perforation, bleeding) and may be discharged home when adequately hydrated and tolerating feedings well.
  • A study from the Children's Hospital of Philadelphia showed that infants fed ad libitum were able to tolerate full feedings sooner after laparoscopic pyloromyotomy, and the standardized feeding regimen had no advantage over ad libitum feedings.[9 ]

Prognosis

  • Surgery is curative with minimal mortality.
  • The prognosis is very good, with complete recovery and catch-up growth if detected in a timely fashion.

Miscellaneous

Medicolegal Pitfalls

  • For infants presenting with the classic picture, the diagnosis should be considered early.
  • Overreliance on imaging tools, rather than the clinical presentation, should be avoided.
  • The infant may present with severe fluid and electrolyte imbalance and may succumb if the diagnosis is not considered for a prolonged period.

Multimedia

Lateral view from an upper GI study demonstrates ...

Media file 1: Lateral view from an upper GI study demonstrates the double-track sign.

References

  1. Panteli C. New insights into the pathogenesis of infantile pyloric stenosis. Pediatr Surg Int. Sep 16 2009;[Medline].

  2. Rogers IM. The true cause of pyloric stenosis is hyperacidity. Acta Paediatr. Feb 2006;95(2):132-6. [Medline].

  3. [Guideline] Cincinnati Children's Hospital Medical Center. Evidence based clinical practice guideline for hypertrophic pyloric stenosis. Cincinnati (OH): Cincinnati Children's Hospital Medical Center; 2007 Nov 14. [Full Text].

  4. Maheshwari P, Abograra A, Shamam O. Sonographic evaluation of gastrointestinal obstruction in infants: a pictorial essay. J Pediatr Surg. Oct 2009;44(10):2037-42. [Medline].

  5. Aldridge RD, MacKinlay GA, Aldridge RB. Choice of incision: the experience and evolution of surgical management of infantile hypertrophic pyloric stenosis. J Laparoendosc Adv Surg Tech A. Feb 2007;17(1):131-6. [Medline].

  6. Leclair MD, Plattner V, Mirallie E, Lejus C, Nguyen JM, Podevin G. Laparoscopic pyloromyotomy for hypertrophic pyloric stenosis: a prospective, randomized controlled trial. J Pediatr Surg. Apr 2007;42(4):692-8. [Medline].

  7. van den Ende ED, Allema JH, Hazebroek FW, Breslau PJ. Can pyloromyotomy for infantile hypertrophic pyloric stenosis be performed in any hospital? Results from two teaching hospitals. Eur J Pediatr. Jun 2007;166(6):553-7. [Medline].

  8. Taqi E, Boutros J, Emil S, Dube S, Puligandla P, Flageole H. Evaluation of surgical approaches to pyloromyotomy: a single-center experience. J Pediatr Surg. May 2007;42(5):865-8. [Medline].

  9. Adibe OO, Nichol PF, Lim FY, Mattei P. Ad libitum feeds after laparoscopic pyloromyotomy: a retrospective comparison with a standardized feeding regimen in 227 infants. J Laparoendosc Adv Surg Tech A. Apr 2007;17(2):235-7. [Medline].

  10. Cohen HL, Blumer SL, Zucconi WB. The sonographic double-track sign: not pathognomonic for hypertrophic pyloric stenosis; can be seen in pylorospasm. J Ultrasound Med. May 2004;23(5):641-6. [Medline].

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  12. Godbole P, Sprigg A, Dickson JA. Ultrasound compared with clinical examination in infantile hypertrophic pyloric stenosis. Arch Dis Child. Oct 1996;75(4):335-7. [Medline].

  13. Hernanz-Schulman M. Infantile hypertrophic pyloric stenosis. Radiology. May 2003;227(2):319-31. [Medline].

  14. Hernanz-Schulman M, Sells LL, Ambrosino MM. Hypertrophic pyloric stenosis in the infant without a palpable olive: accuracy of sonographic diagnosis. Radiology. Dec 1994;193(3):771-6. [Medline].

  15. Huang YC, Su BH. Medical treatment with atropine sulfate for hypertrophic pyloric stenosis. Acta Paediatr Taiwan. May-Jun 2004;45(3):136-40. [Medline].

  16. Irish MS, Pearl RH, Caty MG, Glick PL. The approach to common abdominal diagnosis in infants and children. Pediatr Clin North Am. Aug 1998;45(4):729-72. [Medline].

  17. Kim SS, Lau ST, Lee SL. Pyloromyotomy: a comparison of laparoscopic, circumumbilical, and right upper quadrant operative techniques. J Am Coll Surg. Jul 2005;201(1):66-70. [Medline].

  18. Liacouras CA, Cook-Sather SD, Schreiner MS, Bellah RD. Endoscopic findings in hypertrophic pyloric stenosis: appearance in classic and evolving disease. Gastrointest Endosc. May 1997;45(5):371-4. [Medline].

  19. Nagita A, Yamaguchi J, Amemoto K, et al. Management and ultrasonographic appearance of infantile hypertrophic pyloric stenosis with intravenous atropine sulfate. J Pediatr Gastroenterol Nutr. Aug 1996;23(2):172-7. [Medline].

  20. Schechter R, Torfs CP, Bateson TF. The epidemiology of infantile hypertrophic pyloric stenosis. Paediatr Perinat Epidemiol. Oct 1997;11(4):407-27. [Medline].

  21. Sorensen HT, Skriver MV, Pedersen L. Risk of infantile hypertrophic pyloric stenosis after maternal postnatal use of macrolides. Scand J Infect Dis. 2003;35(2):104-6. [Medline].

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Keywords

pyloric stenosis in children, pyloric stenosis in infants, pyloric stenosis, intestinal obstruction in children, gastric outlet obstruction, infantile hypertrophic pyloric stenosis, IHPS, treatment, diagnosis, symptoms

Contributor Information and Disclosures

Author

Jagvir Singh, MD, Director, Division of Pediatric Emergency Medicine, Lutheran General Hospital of Park Ridge
Jagvir Singh, MD is a member of the following medical societies: American Academy of Pediatrics
Disclosure: Nothing to disclose.

Coauthor(s)

Dara A Kass, MD, Clinical Assistant Instructor, Department of Emergency Medicine, State University of New York Downstate Medical Center, Kings County Hospital
Dara A Kass, MD is a member of the following medical societies: American College of Emergency Physicians, Emergency Medicine Residents Association, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Richard H Sinert, DO, Associate Professor of Emergency Medicine, Clinical Assistant Professor of Medicine, Research Director, State University of New York College of Medicine; Consulting Staff, Department of Emergency Medicine, Kings County Hospital Center
Richard H Sinert, DO is a member of the following medical societies: American College of Physicians and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Medical Editor

Garry Wilkes, MBBS, FACEM, Director of Emergency Medicine, Bunbury Hospital, Western Australia; Medical Director, St John Ambulance, WA Ambulance Service; Adjunct Associate Professor, Edith Cowan University; Clinical Associate Professor, Rural Clinical School, University of Western Australia, Australia.
Disclosure: Nothing to disclose.

Pharmacy Editor

Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Grace M Young, MD, Associate Professor, Department of Pediatrics, University of Maryland Medical Center
Grace M Young, MD is a member of the following medical societies: American Academy of Pediatrics and American College of Emergency Physicians
Disclosure: Nothing to disclose.

CME Editor

John D Halamka, MD, MS, Associate Professor of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center; Chief Information Officer, CareGroup Healthcare System and Harvard Medical School; Attending Physician, Division of Emergency Medicine, Beth Israel Deaconess Medical Center
John D Halamka, MD, MS is a member of the following medical societies: American College of Emergency Physicians, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Chief Editor

Richard G Bachur, MD, Associate Professor of Pediatrics, Harvard Medical School; Associate Chief and Fellowship Director, Attending Physician, Division of Emergency Medicine, Children's Hospital of Boston
Richard G Bachur, MD is a member of the following medical societies: American Academy of Pediatrics, Society for Academic Emergency Medicine, and Society for Pediatric Research
Disclosure: Nothing to disclose.

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