Summary
Hypertrophic pyloric stenosis is the most common cause of gastric outlet obstruction in infants. The condition manifests with postprandial nonbilious projectile vomiting, and symptom onset is typically between 2 and 6 weeks of age. On examination, an olive-shaped mass may be palpable in the epigastrium. The diagnosis is confirmed with abdominal ultrasound. Rehydration and correction of electrolyte derangements are required before definitive treatment with pyloromyotomy.
Epidemiology
- Incidence: 0.5–5:1000 live births (considered to be the most common cause of gastric outlet obstruction in infants) [1]
- Sex: ♂ > ♀ (∼ 5:1)
- More common in firstborn children
- The incidence is higher in White populations. [2]
Epidemiological data refers to the US, unless otherwise specified.
Etiology
- Environmental factors
- Genetic factors: Patients with affected relatives have an increased risk of hypertrophic pyloric stenosis.
- Macrolide antibiotics: Erythromycin and azithromycin are associated with an increased risk of hypertrophic pyloric stenosis, especially when administered within 2 weeks after birth.
Clinical features
- Onset: typically between 2 and 6 weeks of age (rarely after 12 weeks of age) [4][5]
-
Symptoms [4]
- Frequent regurgitation that progresses to projectile and nonbilious vomiting after feeding
- Continued hunger after vomiting
- Late stage: dehydration, poor weight gain, failure to thrive
-
Physical examination [4]
- Enlarged, thickened, nontender pylorus on palpitation (described as olive-like)
- Visible peristaltic waves in the epigastrium
Diagnosis
Hypertrophic pyloric stenosis is suspected based on history and physical examination; imaging (e.g., abdominal ultrasound) is required for confirmation. [5]
Ultrasound abdomen [4][6]
- Indication: first-line for suspected hypertrophic pyloric stenosis [4][6]
- Findings [6]
Upper GI series [6]
-
Indications [6]
- Concern for bowel obstruction (e.g., midgut volvulus)
- May be indicated for patients with suspected pyloric stenosis with nondiagnostic ultrasound
- Findings [6]
Laboratory studies [4][5]
Assess for electrolyte derangements and dehydration with a BMP. The following findings are common in late-stage disease and uncommon in early disease:
-
Hypochloremic, hypokalemic metabolic alkalosis
- Loss of gastric hydrochloric acid due to emesis results in increased bicarbonate and decreased chloride concentrations in the blood.
- Hypokalemia usually occurs in infants who have been vomiting for many days or even weeks.
- Hyponatremia or hypernatremia
Hypertrophic pyloric stenosis is now usually diagnosed early, and infants generally do not present with significant electrolyte imbalances.
Differential diagnoses
Differential diagnosis of newborn vomiting | |
---|---|
Condition | Findings |
Hypertrophic pyloric stenosis |
|
Midgut volvulus and intestinal malrotation |
|
Gastroesophageal reflux in infants |
|
Gastroesophageal reflux disease in infants |
|
Gastroenteritis | |
Congenital adrenal hyperplasia with salt loss |
|
Cyclical vomiting syndrome [7] |
|
Gastroesophageal reflux in infants [8][9]
- Definition: the movement of stomach contents into the esophagus with or without spitting up and regurgitation due to transient lower esophageal sphincter relaxation
- Epidemiology: physiological process in infants; typically occurs shortly after feeding
-
Etiology
- Esophageal sphincter: transient lower relaxation due to frequent, large-volume feedings
- Esophagus: short length and/or supine position
-
Clinical features
- Spitting up or regurgitation shortly after feeding
- Normal physical examination and development (normal weight gain, no difficulty feeding)
- Diagnostics: clinical findings
-
Management
- Reassurance of the infant's parents
-
Conservative measures
- Maintain breastfeeding
- Avoiding overfeeding
-
Positioning therapy
- Maintain the infant in an upright position for 20–30 minutes after feeding.
- Avoid sitting.
- Using food thickeners
- Avoid exposure to tobacco smoke. [10]
- Prognosis: : The frequency of episodes decreases with age; usually resolves spontaneously by 12–18 months of age.
Gastroesophageal reflux disease (GERD) [8]
See “Gastroesophageal reflux disease in infants.”
Sandifer syndrome [11]
- Definition: a paroxysmal movement disorder characterized by torticollis and arching of the spine that occurs in association with GERD and hiatal hernia
-
Epidemiology
- Unknown incidence and prevalence
- Associated with GERD in children
-
Clinical features
- Torticollis and arching of the spine (opisthotonic posturing) lasting 1–3 minutes and often associated with ingestion of food
- Vomiting, poor feeding, epigastric discomfort
- Diagnosis: based on clinical findings (association with GERD and a normal neurological examination)
- Treatment: treatment of GERD
The differential diagnoses listed here are not exhaustive.
Treatment
Initial management [4][5]
- Establish NPO status.
- Initiate IV fluid resuscitation and/or IV maintenance fluids.
- Replete electrolytes (e.g., potassium repletion) as indicated.
- Consult surgery for pyloromyotomy.
- Admit for surgical management.
Pyloromyotomy [4][5]
- Definition: : a surgical procedure in which a longitudinal incision is made through the muscular layers of the hypertrophic pylorus to widen its lumen
- Indications: hypertrophic pyloric stenosis
- Contraindications: inadequate fluid resuscitation and electrolyte repletion
-
Techniques
- Laparoscopic pyloromyotomy (preferred)
- Open Ramstedt pyloromyotomy
-
Complications
- Gastrointestinal perforation
- Incomplete pyloromyotomy
Infants with uncorrected metabolic alkalosis are at increased risk of postoperative apnea and prolonged intubation. [5]
Prognosis
- Very good prognosis
- Mortality rate: < 1% [12]