eMedicine Specialties > Emergency Medicine > Pediatric

Pediatrics, Pyloric Stenosis

Author: Jagvir Singh, MD, Director, Division of Pediatric Emergency Medicine, Lutheran General Hospital of Park Ridge
Coauthor(s): 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
Contributor Information and Disclosures

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.

More on Pediatrics, Pyloric Stenosis

Overview: Pediatrics, Pyloric Stenosis
Differential Diagnoses & Workup: Pediatrics, Pyloric Stenosis
Treatment & Medication: Pediatrics, Pyloric Stenosis
Follow-up: Pediatrics, Pyloric Stenosis
Multimedia: Pediatrics, Pyloric Stenosis
References
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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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  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].

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Further Reading

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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

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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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