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Overview
What Is Pyloric Stenosis?
Pyloric stenosis is a condition in which the muscle around the pyloric sphincter becomes unusually thick. This pyloric narrowing reduces the opening between the stomach and the small intestine, making it harder for milk or formula to pass through the pyloric valve. It most often affects young infants, commonly during the first weeks of life. The condition is also called hypertrophic pyloric stenosis.
Symptoms
Pyloric Stenosis Symptoms
- Forceful vomiting (projectile vomiting) after feeding.
- Vomiting that becomes more frequent or forceful over time.
- Hunger soon after vomiting.
- Poor weight gain or weight loss.
- Fewer wet diapers than usual.
- Signs of dehydration such as a dry mouth or unusual sleepiness.
- Visible wave-like stomach contractions after feeding.
Act promptly
When symptoms need urgent attention
Repeated forceful vomiting in a young infant needs prompt medical assessment. Seek urgent advice if the infant cannot keep feeds down or has fewer wet diapers, as dehydration can develop quickly.
Causes
Causes of Pyloric Stenosis
Hypertrophic pyloric stenosis develops when the pyloric muscle becomes abnormally thick, narrowing the outlet from the pyloric stomach to the small intestine. The narrowed passage can obstruct the movement of milk or formula and lead to repeated vomiting. The precise cause is uncertain and may involve a combination of genetic and developmental factors. This condition is different from an acquired pyloric stricture, in which scarring or another illness narrows the outlet after it was previously normal.
Risk Factors
Risk Factors for Pyloric Stenosis
- Age of about 2 to 8 weeks, with risk generally lower outside early infancy.
- Male sex, particularly in firstborn boys.
- A parent or sibling with a history of pyloric stenosis.
- Being a firstborn infant.
- Premature birth.
- Certain early-life medication or environmental exposures, when applicable and confirmed by the infant’s clinician.
Complications
Complications of Pyloric Stenosis
- Dehydration from repeated vomiting and reduced fluid absorption.
- Abnormal blood electrolyte or acid-base levels.
- Poor weight gain or weight loss.
- Nutritional deficiencies when obstruction persists.
- Breathing problems if vomit enters the airways.
Why prompt care matters
Complications can develop quickly
Repeated vomiting, unusual sleepiness, or reduced urination can signal dehydration or other complications. Infants with these signs need urgent medical evaluation because pyloric narrowing can worsen the loss of fluids and nutrients.
Diagnosis
How Pyloric Stenosis Is Diagnosed
Clinicians review the vomiting pattern, feeding history, and the infant’s growth, then examine the abdomen and assess hydration. A pyloric stenosis ultrasound is usually the main confirmation test and can show thickening of the pyloric muscle and narrowing of the passage. Blood tests evaluate dehydration, electrolyte changes, and acid-base balance. If the ultrasound is unclear, additional imaging may be considered to look for other causes of vomiting.
| Test or assessment | What it evaluates | Typical role |
|---|---|---|
| Physical examination | Hydration, weight, abdominal findings, and feeding history | Initial clinical assessment |
| Ultrasound | Thickness and length of the pyloric muscle and passage narrowing | Common confirmatory test |
| Blood tests | Electrolytes, hydration, and acid-base balance | Identifies complications and guides stabilization |
| Additional imaging | Other causes of infant vomiting when needed | Used when the diagnosis remains uncertain |
Treatment & Management
Treatment and Management of Pyloric Stenosis
Stabilization Before Surgery
Before pyloric stenosis surgery, the medical team gives intravenous fluids and corrects dehydration or electrolyte and acid-base abnormalities. Once the infant is medically stable, the usual treatment is a pyloromyotomy, a surgical procedure that splits the thickened pyloric muscle to open the passage. The stomach outlet is not removed. This pyloric stenosis surgical procedure treats the obstruction rather than simply managing the vomiting.
- Feeds are usually restarted and increased gradually after surgery.
- Small amounts of vomiting can occur briefly during recovery, but persistent or worsening vomiting needs medical review.
- Caregivers receive instructions for incision care, pain relief, and warning signs.
- Follow-up confirms feeding progress, hydration, and weight gain.
Outlook and Prognosis
Outlook and Prognosis for Pyloric Stenosis
Pyloric stenosis is highly treatable, and most infants resume feeding and gain weight normally after treatment. Long-term problems are uncommon when dehydration and the obstruction are addressed promptly. Follow-up helps confirm that feeding, hydration, and growth are progressing as expected.
When Should You See a Doctor
When Should You See a Doctor?
Seek medical care
Do not wait with repeated forceful vomiting
Seek immediate medical evaluation for repeated projectile vomiting, green or bloody vomit, inability to keep feeds down, a swollen or very tender abdomen, marked sleepiness, breathing difficulty, or significantly fewer wet diapers. These pyloric stenosis symptoms can indicate obstruction, dehydration, or another urgent problem.
Branches
3 topics
Pyloric Stenosis
Gastroenterology
Pyloric Stenosis
Pediatric Surgery
Pyloric Stenosis
Pediatrics
Symptoms
2 topics
