Pyloric Stenosis In Babies: Symptoms, Causes And Treatment

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The narrowing of the pylorus (opening from the stomach into the duodenum) is called pyloric stenosis. Pyloric stenosis in babies occurs due to the thickening of the pylorus muscles, preventing the food from passing through the stomach to the intestines.

The condition may cause vomiting after being fed, increasing the risk of fluid deficiency, nutrient deficiency, and weight loss. Babies with pyloric stenosis may seem hungry all the time, and vomiting may increase their food demand.

Keep reading this post to know about the symptoms, causes, risk factors, diagnosis, treatment, and complications of pyloric stenosis in babies.

Signs And Symptoms Of Pyloric Stenosis

You may notice pyloric stenosis signs and symptoms in your baby within three to five weeks after birth. The onset of pyloric stenosis is rare in infants older than three months.

The signs and symptoms of pyloric stenosis in babies include the following(1).

  • Vomiting: Forceful vomiting that may go several feet across a room is seen after feeding. Some babies may have mild vomiting initially which gradually worsens to projectile vomiting. The vomitus consists of breastmilk or formula and rarely contains blood.
  • Abdominal contractions: A wave-like movement on the upper abdomen may occur due to stomach contractions (peristalsis). This is usually seen after feeding but before vomiting. This is due to stomach muscles trying to move food through the narrow pylorus to the intestine.
  • Hunger: Babies with pyloric stenosis may demand feeding soon after vomiting.
  • Bowel habit changes: Babies may have constipation or fewer bowel movements since less food reaches the intestines.
  • Dehydration: Vomiting may result in dehydration. Dry diapers, fewer wet diapers, crying without tears, and lethargy are the notable signs of dehydration. You must seek immediate medical care in such cases.
  • Poor weight gain: Babies with pyloric stenosis may have weight loss or poor weight gain due to inadequate absorption of nutrients.

Seek medical care if your baby has signs and symptoms of pyloric stenosis. Delaying the care may increase the risk of dehydration and lead to nutritional deficiencies.

Causes And Risk Factors For Pyloric Stenosis

Pyloric stenosis occurs due to the thickening of the pylorus, but the exact cause behind it is unknown (2). Genetic and environmental factors may be involved in the development of this anomaly. Environmental factors could play a significant role since pyloric stenosis may often not be present at birth and usually develops later.

The following factors may increase the risk for pyloric stenosis in some babies (2).

  • Male gender
  • Positive family history
  • Bottle-feeding
  • Antibiotics use, such as erythromycin, in early life

It is not entirely known how these factors increase the risk of pyloric stenosis. Some babies with risk factors may not develop this condition.

Diagnosis Of Pyloric Stenosis

Pediatricians may be able to palpate enlarged pylorus muscle as an olive-shaped lump on the abdomen. Doctors may also ask you to feed your baby and look for abdominal contractions and projectile vomiting.

The following tests are ordered if the symptoms and signs during physical examinations are suggestive of pyloric stenosis (3).

  • Ultrasound could help visualize and examine the narrow pylorus.
  • Abdominal X-ray (barium swallow or upper GI series) are taken to confirm the diagnosis further or if the ultrasound is not clear.
  • Blood tests are also conducted to evaluate dehydration and electrolyte balance that could indicate poor absorption of nutrients.

Pediatricians may refer your baby to a pediatric gastroenterologist or a surgeon to further diagnose and treat pyloric stenosis.

Treatment For Pyloric Stenosis

A surgical procedure called pyloromyotomy is required to treat pyloric stenosis. Thickened pylorus muscle is incised until the inner mucosal layer bulges out, letting the stomach contents pass to the intestines without issues. Pyloromyotomy can be done through traditional open surgery or laparoscopic surgery (4).

Intravenous fluid and electrolytes are given before surgery for dehydrated babies. Your baby may also need IV fluids for a few hours after surgery. Feeding sessions usually begin after 12 to 24 hours of surgery, and you may have to feed your baby more often to meet the nutritional needs. Some babies may have vomiting for a few days after surgery.

Complications Of Pyloric Stenosis

The possible complications of pyloric stenosis may include the following (5).

  • Dehydration and hypovolemic shock may occur due to fluid and electrolyte loss from persistent vomiting.
  • Jaundice is seen in some babies due to reduced liver enzyme levels that itself may occur due to inadequate nutrition.
  • Growth and development failure may be seen in some babies with nutritional deficiencies.
  • Stomach irritation and bleeding due to repeated vomiting may occur in some cases.

Babies usually get well and grow after the surgery (6). Bleeding and infection may happen after surgery in some babies. You may discuss with your doctor the possible post surgery complications and requisite care.

Frequently Asked Questions

1. Do babies still poop with pyloric stenosis?

Babies with pyloric stenosis do pass stools but less frequently. It is because the food does not adequately reach the intestine, and mucus may also be present in stools (1) (7).

2. Is pyloric stenosis painful in infants?

Stomach pain may accompany other symptoms of pyloric stenosis in infants (8).

3. Is pyloric stenosis an emergency?

Pyloric stenosis is an urgent condition that needs immediate treatment. Surgical correction is often advised after diagnosis of the disorder (9)

4. Is pyloric stenosis a congenital disability?

Pyloric stenosis is a congenital disability that is a condition present from birth. This disorder may run in some families but may be multifactorial. It involves both genetic and environmental factors (2).

Pyloric stenosis in babies may be a life-threatening condition since it leads to nutritional and fluid deficiencies. It is believed to be caused by environmental and genetic factors. You may find that the babies affected by pyloric stenosis experience forceful vomiting, excessive hunger, and dehydration. If your baby shows these symptoms, consult a doctor without delay. An abdominal X-ray and blood tests will allow doctors to diagnose the condition. Pyloric stenosis can be successfully treated by a surgical procedure. Babies can usually lead a normal life after the treatment.

Key Pointers

  • Pyloric stenosis is a condition in babies, where the muscle between the stomach and small intestine (pylorus) thickens, preventing the passage of food.
  • This condition leads to persistent vomitings, hunger, dehydration, and bowel changes in babies.
  • It could further lead to complications such as jaundice, bleeding, irritation in the stomach, and developmental delays.
  • Pyloric stenosis can be fixed by surgery.


MomJunction's articles are written after analyzing the research works of expert authors and institutions. Our references consist of resources established by authorities in their respective fields. You can learn more about the authenticity of the information we present in our editorial policy.
1. Pyloric Stenosis; Nationwide Children’s Hospital
2. Pyloric Stenosis; University of Rochester Medical Center (URMC)
3. Pyloric Stenosis in Infants; MedlinePlus; US National Library of Medicine
4. Hypertrophic Pyloric Stenosis (HPS)- Help for Babies with Forceful Vomiting; Healthy children; The American Academy of Pediatrics
5. Pyloric Stenosis; St. Clair Hospital
6. Pyloric Stenosis; Children’s Hospital of Philadelphia
7. Pyloric Stenosis; KidsHealth
8. Pyloric Stenosis; Johns Hopkins Medicine
9. Pyloric Stenosis; Inova Children’s Hospital
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Dr. Dur Afshar Agha

Dr. Dur Afshar Agha is a consultant pediatrician with decades of experience in various medical facilities both in Pakistan and Saudi Arabia. She has headed the Department of Preventive Pediatrics at the prestigious, Children’s Hospital and Institute of Child Health in Pakistan and is a life member of the Pakistan Paediatric Association. She has also completed her Post Graduate Program... more

Dr Bisny T. Joseph

Dr. Bisny T. Joseph is a Georgian Board-certified physician. She has completed her professional graduate degree as a medical doctor from Tbilisi State Medical University, Georgia. She has 3+ years of experience in various sectors of medical affairs as a physician, medical reviewer, medical writer, health coach, and Q&A expert. Her interest in digital medical education and patient education made... more