II. Epidemiology

  1. Ages 3-6 weeks old (mean 3 weeks, up to 12 weeks of age)

III. Pathophysiology

  1. Hypertrophy of pylorus of the Stomach causing a gastric outlet obstruction

IV. Risk factors

  1. Family History of Pyloric Stenosis (especially northern european)
  2. Male gender (4 times more common than in girls)
  3. Other possible risk factors
    1. Bottle Feeding (Formula Feeding)
    2. Prematurity
    3. Maternal Tobacco Abuse
    4. Maternal Hyperthyroidism
    5. Macrolide antibiotic use in the first 2 weeks of life

V. Symptoms: Vomiting

  1. Non-Bilious Vomiting that is more forceful than Spitting Up
  2. Starts intermittently
  3. Progressively increases in frequency and severity
  4. Infant remains hungry despite Vomiting
  5. Projectile Vomiting in up to 70% of cases

VI. Signs

  1. Typically, otherwise well appearing infant with benign Abdomen
  2. Palpable swelling ("olive") present in >60% of cases in past when delayed presentation was common
    1. In 2016 olive is rare due to early presentations
    2. Inferior to xiphoid process and inferior or deep to left liver edge

VII. Labs

  1. Basic metabolic panel
    1. Hypochloremic hypokalemic Metabolic Alkalosis
      1. Rarely seen due to early presentations in U.S.
    2. Other findings
      1. Hyponatremia
      2. Hypoglycemia
      3. Increased Renal Function tests (Serum Creatinine, Blood Urea Nitrogen)

VIII. Imaging: Pyloric Ultrasound

  1. Technique
    1. Linear probe in subxiphoid location, horizontal probe
    2. Look for gastric rugae, smooth outer serosal surface, slightly thicker wall
    3. Trace the outer surface of the Stomach down to the pylorus and duodenum
      1. Duodenal wall is much thinner than pylorus
  2. Diagnosis
    1. Thickened and elongated pylorus
      1. Pylorus wall thickness >3 mm
      2. Pylorus diameter >13 mm
      3. Pylorus length >15 mm (variable)
    2. No relaxation
    3. No fluid passage within channel
      1. May see very minimal flow (string sign)
  3. Efficacy
    1. Test Sensitivity and Test Specificity approach 100%

X. Complications

  1. Pediatric Dehydration
  2. Hypochloremic hypokalemic Metabolic Alkalosis
    1. Rarely seen due to early presentations in U.S.

XI. Management

  1. Correct fluid and Electrolyte abnormalities
    1. Risk of postoperative apnea if not corrected
  2. Surgery (pyloromyotomy)
    1. Loosens pyloric Muscle

XII. Resources

  1. Pyloric Stenosis Ultrasound
    1. https://vimeo.com/156797541

XIII. References

  1. Bukata (2013) Pediatric Emergencies, EM Bootcamp, CEME
  2. Nazer (2013) Pediatric Hypertrophic Pyloric Stenosis, EMedicine
    1. http://emedicine.medscape.com/article/929829-overview#showall
  3. Nirappil (2021) Crit Dec Emerg Med 35(8):12-3

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Related Studies

Ontology: Pyloric Stenosis (C0034194)

Definition (NCI) Narrowing of the pyloric lumen caused either by hypertrophy of the surrounding muscles or tissue scarring due to a chronic peptic ulcer.
Definition (MSH) Narrowing of the pyloric canal with varied etiology. A common form is due to muscle hypertrophy (PYLORIC STENOSIS, HYPERTROPHIC) seen in infants.
Concepts Finding (T033)
MSH D011707
ICD10 K31.1
SnomedCT 367403001
English Pyloric Stenosis, PYLORIC STENOSIS, pyloric stenosis (diagnosis), pyloric stenosis, Pyloric Stenosis [Disease/Finding], gastric outflow obstruction, pyloric stenoses, pyloric stenosi, gastric outlet obstruction, pyloric obstruction, Gastric Outlet Obstruction, Pylorus--Stenosis, Pyloric stenosis, PS - Pyloric stenosis, Pyloric stenosis (disorder), pylorus; stenosis, pylorus; stricture, stenosis; pylorus, stricture; pylorus, Stenosis, Pyloric, Pyloric stenosis NOS, Stenosis pyloric
Portuguese ESTENOSE PILORICA, Estenose pilórica, Estenose pilórica NE, Estenose Pilórica
Spanish ESTENOSIS PILORICA, Estenosis pilórica, Estenosis pilórica NEOM, estenosis pilórica (trastorno), estenosis pilórica, Estenosis Pilórica
German PYLORUSSTENOSE, Pylorusstenose NNB, Pylorusstenose
Dutch pylorusstenose, stenose pylorus, pylorusstenose NAO, pylorus; stenose, pylorus; strictuur, stenose; pylorus, strictuur; pylorus, Pylorusstenose, Stenose, pylorus-
Italian Stenosi del piloro, Stenosi del piloro NAS, Stenosi pilorica
French Sténose du pylore SAI, STENOSE DU PYLORE, Sténose pylorique, Sténose du pylore
Japanese 幽門狭窄NOS, ユウモンキョウサクNOS, ユウモンキョウサク, 幽門狭窄, 幽門狭窄症
Swedish Pylorusförträngning
Czech pylorus - stenóza, Pylorostenóza, Pylorostenóza NOS
Finnish Mahanportin ahtauma
Polish Zwężenie odźwiernika
Hungarian Pylorus stenosis k.m.n., Stenosis pylorikus, Pylorus stenosis
Norwegian Pylorusstenose, Magemunnsforsnevring

Ontology: Pyloric Stenosis, Hypertrophic (C0700639)

Definition (NCI) An abnormality characterized by thickening of the muscle in the wall of the pylorus. It results in the narrowing of the pyloric channel. The overlying mucosa may appear hypertrophic as well. Clinical signs and symptoms appear early in life and include projectile vomiting and dehydration.
Definition (MSH) Narrowing of the pyloric canal due to HYPERTROPHY of the surrounding circular muscle. It is usually seen in infants or young children.
Concepts Congenital Abnormality (T019) , Disease or Syndrome (T047)
MSH D046248
ICD9 750.5
ICD10 Q40.0
SnomedCT 48644003
English Cong hypertroph pylor stenosis, Pyloric stenosis, hypertrophic, Cong pyloric stenosis, Pyloric Stenosis, Hypertrophic [Disease/Finding], hypertrophic pyloric stenosis, pyloric hypertrophic stenosis, Hypertrophic pyloric stenosis, Congenital hypertrophic pyloric stenosis, Congenital hypertrophic pyloric stenosis (disorder), hypertrophy; pylorus, infantile, infantile; pyloric obstruction, pylorus; hypertrophy, infantile, Hypertrophic Pyloric Stenosis, Pyloric Stenosis, Hypertrophic, Stenosis, Hypertrophic Pyloric, Stenosis pyloric hypertrophic congenital, Congenital or infantile constriction of pylorus, Congenital or infantile hypertrophy of pylorus, Congenital or infantile stenosis of pylorus, Congenital or infantile stricture of pylorus
Dutch congenitale hypertrofe pylorusstenose, hypertrofie; pylorus, infantiel, infantiel; pylorusobstructie, pylorus; hypertrofie, infantiel, Congenitale hypertrofische pylorusstenose, Hypertrofische pylorusstenose, Pylorusstenose, hypertrofische, Stenose, hypertrofische pylorus-
French Sténose hypertrophique congénitale du pylore, Sténose pylorique hypertrophique congénitale, Sténose hypertrophique du pylore, Sténose pylorique hypertrophique
German Pylorusstenose hypertrophisch kongenital, kongenitale hypertrophische Pylorusstenose, Angeborene hypertrophische Pylorusstenose, Hypertrophische Pylorusstenose, Pylorusstenose, hypertrophische, Stenose des Pylorus, hypertrophische
Italian Stenosi ipertrofica congenita del piloro, Stenosi pilorica ipertrofica congenita, Stenosi pilorica ipertrofica
Portuguese Estenose congénita hipertrófica do piloro, Estenose hipertrófica congénita do piloro, Estenose Pilórica Hipertrófica
Spanish Estenosis hipertrófica del píloro congénita, Estenosis pilórica hipertrófica congénita, estenosis hipertrófica del píloro congénita (trastorno), estenosis hipertrófica del píloro congénita, estenosis pilórica hipertrófica congénita, Estenosis Hipertrofica de Piloro
Japanese 先天性肥厚性幽門狭窄症, センテンセイヒコウセイユウモンキョウサクショウ, 肥厚性幽門狭窄症, 幽門狭窄症-肥厚性
Swedish Pylorusstenos, hypertrofisk
Czech pylorus - stenóza hypertrofická, Kongenitální hypertrofická pylorostenóza, Vrozená hypertrofická stenóza pyloru
Finnish Hypertrofinen mahanportin ahtauma
Korean 선천 비대성 날문협착(유문협착)
Polish Zwężenie odźwiernika przerostowe
Hungarian Veleszületett stenosis pylorikus hypertrophiás, Veleszületett hypertrophiás pylorikus szűkület
Norwegian Hypertrofisk pylorusstenose