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Signs of pyloric stenosis usually appear within three to five weeks after birth. Pyloric stenosis is rare in babies older than age 3 months.

Watch for these signs and symptoms:

• Projectile vomiting. Pyloric stenosis often causes projectile vomiting — the forceful ejection of milk or formula up to several feet away — within 30 minutes after your baby eats. Vomiting may be mild at first and gradually become more severe. The vomit may sometimes contain blood.
• Persistent hunger. Babies who have pyloric stenosis often want to eat soon after vomiting.
• Stomach contractions. You may notice wave-like contractions that move across your baby's upper abdomen (peristalsis) soon after feeding but before vomiting. This is caused by stomach muscles trying to force food past the outlet of the pylorus.
• Dehydration. Your baby may cry without tears or become lethargic. You may find yourself changing fewer wet diapers or diapers that aren't as wet as you expect.
• Changes in bowel movements. Since pyloric stenosis prevents food from reaching the intestines, babies with this condition may be constipated.
• Weight problems. Pyloric stenosis can prevent a baby from gaining weight, and can sometimes even cause weight loss.

When to see a doctor
Contact your baby's doctor if your baby is:

• Frequently vomiting after feeding
• Projectile vomiting
• Less active or seems unusually irritable
• Urinating much less frequently or is having noticeably fewer bowel movements
• Isn't gaining weight, or seems to be losing weight

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The causes of pyloric stenosis are unknown, but genetic factors may play a role.

©1998-2012 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.
Read this article on Mayoclinic.com.

Risk factors for pyloric stenosis include:

• Sex. Pyloric stenosis occurs more often in males than in females.
• Birth order. About one-third of babies affected by pyloric stenosis are firstborns.
• Family history. More than 1 in 10 babies with pyloric stenosis has a family member who had the disorder.
• Early antibiotic use. Babies given certain antibiotics, such as erythromycin, in the first weeks of life for whooping cough (pertussis) have an increased risk of pyloric stenosis. In addition, babies born to mothers who were given certain antibiotics in late pregnancy also may have an increased risk of pyloric stenosis.

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Pyloric stenosis can lead to:

• An electrolyte imbalance. Electrolytes are minerals, such as chloride and potassium, that circulate in the body's fluids to help regulate many vital functions, such as heartbeat. When a baby vomits every time he or she eats, dehydration and an imbalance of electrolytes eventually occurs.
• Stomach irritation. Repeated vomiting can irritate your baby's stomach. This irritation may even cause mild bleeding.
• Jaundice. Rarely, infants who have pyloric stenosis develop jaundice — a yellowish discoloration of the skin and eyes caused by a buildup of a substance secreted by the liver called bilirubin.

©1998-2012 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.
Read this article on Mayoclinic.com.

If you suspect that your child has pyloric stenosis, you're likely to start by seeing your child's pediatrician. However, you may then be referred to a doctor who specializes in treating digestive disorders (gastroenterologist).

Here's some information to help you get ready for your appointment, and what to expect from your doctor.

What you can do

• Write down any symptoms you've noticed in your baby, including any that may seem unrelated to the reason for which you scheduled the appointment. Try to keep track of the times your baby vomits. Is it always after eating? Note if the amount of vomit appears to be most or just part of what the baby has eaten, and if the vomit is forcefully projected.
• Write down questions to ask your doctor.

Your time with your doctor is limited, so preparing a list of questions can help you make the most of your time together. For pyloric stenosis, some basic questions to ask your doctor include:

• What's the most likely cause of my baby's symptoms?
• What kinds of tests does my baby need? Do these tests require any special preparation?
• Will surgery stop the symptoms permanently?
• Is surgery the only treatment?
• What are the risks associated with surgery?
• What are the risks associated with the general anesthesia needed for the surgery?
• Will there be any dietary restrictions after surgery?
• Are there any brochures or other printed material that I can take with me? What websites do you recommend?

What to expect from your doctor
Your doctor is likely to ask you a number of questions. Being ready to answer them may reserve time to go over points you want to spend more time on. Your doctor may ask:

• When did your baby first begin experiencing symptoms?
• Have the symptoms been continuous, or occasional? Do they occur only after eating?
• Does your baby seem hungry after vomiting?
• Does the vomit come out forcefully?
• What was your baby's last recorded weight?

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Signs and symptoms of pyloric stenosis can mimic those of other conditions that cause infant vomiting, including gastroesophageal reflux disease (GERD). Your baby's doctor may use various steps to make the diagnosis:

• Physical exam. Your baby's doctor may feel an olive-shaped lump — the enlarged pyloric muscle — when examining your baby's abdomen.
• Blood tests. The loss of electrolytes — such as sodium, potassium, magnesium and calcium — may be a sign of continual vomiting and dehydration.
• Ultrasound. This test uses sound waves to create an image of your baby's stomach.
• Contrast X-ray. For this test, your baby swallows a small amount of a liquid that coats the stomach. This contrast material helps any abnormalities show up more clearly on an X-ray.

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Pyloric stenosis is typically treated with a surgical procedure known as pyloromyotomy (pie-lor-oh-my-OT-uh-me). Surgery is often scheduled on the same day as the diagnosis. If your baby is dehydrated or has an electrolyte imbalance, surgery will be scheduled as soon as possible after these problems have been treated with fluid replacement.

Pyloromyotomy is done under general anesthesia. Traditionally, the procedure was done through a small incision in the baby's right upper abdomen or around the baby's navel. Today, however, pyloromyotomy is often done laparoscopically. With laparoscopic surgery, a slender viewing instrument (laparoscope) is inserted through a small incision near your baby's navel. The laparoscope is equipped with a laser and small surgical instruments. Recovery from the laparoscopic procedure is quicker than is recovery from a traditional open surgery, and the procedure leaves a smaller scar.

Before surgery, your baby may be given intravenous (IV) fluids to treat dehydration and restore electrolytes. During the procedure, the surgeon cuts and spreads apart the outside layer of the thickened pyloric muscles. The inside lining of the pylorus is left intact. After surgery, your baby may receive IV fluids for a few hours or until he or she can eat. Rarely, some vomiting occurs for a few days after surgery, however.

Potential complications of surgery include bleeding and infection. If the pyloric muscles aren't cut completely, your baby's signs and symptoms may return. Pyloromyotomy doesn't increase the risk of future stomach or intestinal problems.

Most infants return home within 48 hours. Your baby's doctor may request a follow-up visit after surgery to check on your baby's recovery.

©1998-2012 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.
Read this article on Mayoclinic.com.