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Hypertrophic Pyloric Stenosis



  • Age
    • Usually manifests at 2-8 weeks of life
  • Clinical
    • Nonbilious projectile vomiting with progression over a period of several weeks after birth (15-20%)
    • Palpable olive-shaped mass (80% sensitive in experienced hands)
  • Positive family history
  • Nasogastric aspirate >10 ml
  • UGI findings
    • Pyloric wall thickness >10 mm
    • Elongation and narrowing of pyloric canal (2-4 cm in length)
    • "Double / triple track sign"
      • Crowding of mucosal folds in pyloric channel
    • "String sign"
      • Passing of small barium streak through pyloric channel
    • Twining recess = "diamond sign"
      • Transient triangular tent-like cleft / niche in midportion of pyloric canal with apex pointing inferiorly secondary to mucosal bulging between two separated hypertrophied muscle bundles on the greater curvature side within pyloric channel
    • "Pyloric teat"
      • Outpouching along lesser curvature due to disruption of antral peristalsis
    • "Antral beaking"
      • Mass impression upon antrum with streak of barium pointing toward pyloric channel

Hypertrophic Pyloric Stenosis

Stomach shows double tracking in region of pyloric canal,
indentation on base of bulb and delayed gastric emptying

  • Kirklin sign = "mushroom sign"
    • Indentation of base of bulb (in 50%)
  • Gastric distension with fluid
  • Active gastric hyperperistalsis
    • "Caterpillar sign"
      • Gastric hyperperistaltic waves
  • US findings
    • "Target sign"
      • Hypoechoic ring of hypertrophied pyloric muscle around echogenic mucosa centrally on cross-section
    • "Cervix sign"
      • Indentation of muscle mass on fluid-filled antrum on longitudinal section
    • "Antral nipple sign"
      • Redundant pyloric channel mucosa protruding into gastric antrum
    • Pyloric volume >1.4 cm3 (= 1/4 รท x [maximum pyloric diameter]2 x pyloric length)
      • Most criteria independent of contracted or relaxed state
    • Pyloric length (mm) + 3.64 x muscle thickness (mm) > 25
    • Pyloric muscle wall thickness >3 mm
    • Pyloric transverse diameter >13 mm with pyloric channel closed
    • Elongated pyloric canal >17 mm in length
    • Exaggerated peristaltic waves
    • Delayed gastric emptying of fluid into duodenum
  • Complications
    • Hypochloremic metabolic alkalosis
  • DDx
    • Infantile pylorospasm
      • Muscle thickness between 1.5 and 3 mm
      • Variable caliber of antral narrowing
      • Antral peristalsis
      • Delayed gastric emptying
      • Elongation of pylorus
      • Prognosis
        • Resolves in several days / ? early stage of evolving pyloric stenosis
      • Treatment
        • Effective with metoclopramide hydrochloride
    • Milk allergy
    • Eosinophilic gastroenteritis