Pyloric Stenosis

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Basics

Description

  • Progressive narrowing of the pyloric canal, occurring in infancy
  • Synonym(s): infantile hypertrophic pyloric stenosis (IHPS)

Epidemiology

  • Onset almost always between 2 and 12 weeks of age
  • Considered the most common condition requiring surgical intervention in the 1st year of life
  • A recent decline in incidence has been reported in a number of countries.
  • Predominant sex: male > female (4 to 5:1)

Incidence
In Caucasian population, 2 to 5:1,000 babies; less common in African American and Asian populations

Prevalence
National prevalence level is 1 to 2:1,000 infants, ranging from 0.5 to 4.21:1,000 live births.

Etiology and Pathophysiology

  • Abnormal relaxation of the pyloric muscles leads to hypertrophy.
  • Redundant mucosa fills the pyloric canal.
  • Gastric outflow is obstructed, leading to gastric distension and vomiting.
  • The exact cause remains unknown, but multiple genetic and environmental factors have been implicated.
  • Increased vasoactive intestinal peptide in breast milk may mediate pyloric relaxation and increase gastric emptying, protecting from pyloric stenosis
  • Formula feeding may cause higher serum levels associated with pylorospasm, increasing rates of pyloric stenosis (1)[C].

Genetics
Recent studies have identified linkage to chromosomes 3, 5, 11, and 19.

Risk Factors

  • 5 times increased risk with affected first-degree relative
  • Strong familial aggregation and >80% heritability
  • Multiple gestation
    • 200-fold increased risk if monozygotic twin affected
    • 20-fold increased risk if dizygotic twin affected
  • Perinatal risk factors include C-section, preterm infant, and first born
  • Breastfeeding is protective whereas formula feeding increases risk

Commonly Associated Conditions

Associated anomalies present in ~4–7% of infants with pyloric stenosis

  • Hiatal and inguinal hernias (most common)
  • Other anomalies include the following:
    • Congenital heart disease
    • Esophageal atresia
    • Tracheoesophageal fistula
    • Renal abnormalities
    • Turner syndrome and trisomy 18
    • Cornelia de Lange syndrome
    • Smith-Lemli-Opitz syndrome

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Basics

Description

  • Progressive narrowing of the pyloric canal, occurring in infancy
  • Synonym(s): infantile hypertrophic pyloric stenosis (IHPS)

Epidemiology

  • Onset almost always between 2 and 12 weeks of age
  • Considered the most common condition requiring surgical intervention in the 1st year of life
  • A recent decline in incidence has been reported in a number of countries.
  • Predominant sex: male > female (4 to 5:1)

Incidence
In Caucasian population, 2 to 5:1,000 babies; less common in African American and Asian populations

Prevalence
National prevalence level is 1 to 2:1,000 infants, ranging from 0.5 to 4.21:1,000 live births.

Etiology and Pathophysiology

  • Abnormal relaxation of the pyloric muscles leads to hypertrophy.
  • Redundant mucosa fills the pyloric canal.
  • Gastric outflow is obstructed, leading to gastric distension and vomiting.
  • The exact cause remains unknown, but multiple genetic and environmental factors have been implicated.
  • Increased vasoactive intestinal peptide in breast milk may mediate pyloric relaxation and increase gastric emptying, protecting from pyloric stenosis
  • Formula feeding may cause higher serum levels associated with pylorospasm, increasing rates of pyloric stenosis (1)[C].

Genetics
Recent studies have identified linkage to chromosomes 3, 5, 11, and 19.

Risk Factors

  • 5 times increased risk with affected first-degree relative
  • Strong familial aggregation and >80% heritability
  • Multiple gestation
    • 200-fold increased risk if monozygotic twin affected
    • 20-fold increased risk if dizygotic twin affected
  • Perinatal risk factors include C-section, preterm infant, and first born
  • Breastfeeding is protective whereas formula feeding increases risk

Commonly Associated Conditions

Associated anomalies present in ~4–7% of infants with pyloric stenosis

  • Hiatal and inguinal hernias (most common)
  • Other anomalies include the following:
    • Congenital heart disease
    • Esophageal atresia
    • Tracheoesophageal fistula
    • Renal abnormalities
    • Turner syndrome and trisomy 18
    • Cornelia de Lange syndrome
    • Smith-Lemli-Opitz syndrome

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