Key takeaways: Pyloric stenosis is a thickening of the muscle at the outlet of the stomach, blocking food from passing. It usually shows up between about 2 and 8 weeks of age with forceful, projectile vomiting after feeds, and a baby who wants to eat again right away. It’s diagnosed by ultrasound and fixed with a common surgery. Babies can get dehydrated quickly.
Pyloric stenosis is one of the most common reasons young babies need surgery. Knowing the signs helps you get care quickly.
What It Is
The pylorus is the muscle between the stomach and small intestine. In pyloric stenosis, it thickens and narrows, so milk can’t pass easily.
Who Gets It
- Usually babies between about 2 and 8 weeks old.
- More common in boys and in first-born babies.
- More common in babies with a family history.
- Linked to early use of certain antibiotics (erythromycin and azithromycin) in the first weeks of life.
From the author
From First Breath to First Birthday is my month-by-month guide to your baby’s first year, written as a NICU and postpartum nurse. My book covers common first-year illnesses and the warning signs that mean it’s time to call the doctor, explained the way I’d explain them at the bedside.
Signs
- Projectile vomiting: forceful vomiting that shoots out, often after feeds, getting worse over days.
- Hungry after vomiting, wanting to feed again right away.
- Fewer wet and dirty diapers.
- Weight loss or poor weight gain.
- Signs of dehydration: sleepiness, dry mouth, sunken soft spot.
- Sometimes, visible waves across the belly after feeds or a small lump in the upper belly.
The vomit usually isn’t green.
Diagnosis
An ultrasound can measure the pylorus. Blood tests check for dehydration and salt imbalances.
Treatment
- IV fluids to fix dehydration and electrolytes first.
- Pyloromyotomy: surgery to cut the thickened muscle, often done laparoscopically through small incisions.
- Most babies feed normally soon after surgery and recover well.
Call your baby’s doctor right away if your baby: has projectile vomiting, vomits after most feeds, has fewer wet diapers, or seems sleepy or weak. Go to the emergency room for signs of dehydration or green vomit.
The Bottom Line
Projectile vomiting in a young baby needs prompt evaluation. Pyloric stenosis is very treatable, and most babies recover quickly after surgery.
Want more support for your baby’s first year? My book, From First Breath to First Birthday, is available on Amazon.
Related Articles
- Vomiting in Babies: When to Worry
- Spit-Up vs. Reflux vs. GERD: What’s the Difference?
- Intussusception: Warning Signs of a Bowel Emergency
Sources
- Hernanz-Schulman M. Infantile hypertrophic pyloric stenosis. Radiology. 2003;227(2):319-331.
- American Academy of Pediatrics. Pyloric stenosis. HealthyChildren.org. https://www.healthychildren.org
- National Library of Medicine. Pyloric stenosis. MedlinePlus. https://medlineplus.gov
This article is for general education and is not a substitute for individualized medical advice. Always talk with your baby’s health care provider or your own provider about your specific situation. If you think your baby or you may have a medical emergency, call 911.
