From the Guidelines
Pyloric stenosis in a premature infant should be diagnosed using point of care ultrasound (POCUS) to detect hypertrophic pyloric stenosis, as recommended by the European Society of Paediatric and Neonatal Intensive Care (ESPNC) 1. The diagnosis of pyloric stenosis is suspected when a premature infant presents with non-bilious projectile vomiting, visible peristaltic waves across the abdomen, and a palpable "olive-shaped" mass in the right upper quadrant. Laboratory tests often reveal hypochloremic, hypokalemic metabolic alkalosis due to loss of gastric acid.
Key Diagnostic Features
- Non-bilious projectile vomiting
- Visible peristaltic waves across the abdomen
- Palpable "olive-shaped" mass in the right upper quadrant
- Hypochloremic, hypokalemic metabolic alkalosis
Diagnostic Approach
- POCUS is helpful to recognise hypertrophic pyloric stenosis 1, although for a definitive diagnosis, a detailed assessment should be performed by a paediatric radiologist.
- Ultrasound findings of pyloric muscle thickness ≥3mm and pyloric channel length ≥14mm confirm the diagnosis.
Treatment Approach
- Fluid resuscitation and electrolyte correction using IV fluids containing sodium chloride and potassium chloride
- Definitive treatment is surgical pyloromyotomy, which involves cutting the hypertrophied pyloric muscle down to the submucosa without entering the gastric lumen
- Feeding is typically resumed 4-6 hours post-surgery, starting with small amounts of clear fluids and gradually advancing to full feeds within 24-48 hours
- Premature infants may require more careful monitoring post-operatively due to their increased vulnerability to complications such as respiratory distress and temperature instability.
From the Research
Diagnosis of Pyloric Stenosis in Premature Infants
- Pyloric stenosis is a common condition seen in the first 1 to 3 months after birth, characterized by nonbilious projectile emesis after feeds, which may result in hypokalemic, hypochloremic metabolic alkalosis 2.
- The diagnosis of pyloric stenosis can be made using ultrasonography, with criteria including pyloric muscle thickness (PMT) ≥ 3 mm and pyloric muscle length (PML) ≥ 17 mm 3.
- Premature infants may have a lower mean PML than term infants, but this difference is not significant, and the same ultrasound criteria can be applied irrespective of prematurity, age, or weight 3.
Treatment Approach for Pyloric Stenosis
- The mainstay of treatment for pyloric stenosis is pyloromyotomy, which can be performed using open or laparoscopic approaches 4, 2.
- Laparoscopic pyloromyotomy is a safe and effective treatment option, but may result in a small increase in mucosal perforation compared to open pyloromyotomy 5.
- Prior to surgery, patients should be hydrated and serum electrolyte concentrations normalized to prevent complications 2.
- Postoperative care includes monitoring for complications such as wound infections or abscess formations, and reassurance to parents that postoperative emesis is normal 2.
Alternative Treatment Options
- Endoscopic pyloromyotomy is a new concept of minimally invasive surgery for pyloric stenosis, which has been shown to be technically feasible and effective in animal models 6.
- However, further studies are needed to confirm the safety and efficacy of this approach in human patients, including premature infants.