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

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 ÷ 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