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Pyloric stenosis: causes and treatment

by Josephine Andrews
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Pylorus stenosis (narrowing of the pylorus ) is a mostly congenital narrowing of the stomach outlet. It mainly affects boys in the third to eighth week of life. Typical sign is gushing vomiting. A pyloric stenosis is usually operated on. Read more about the causes, symptoms and treatment options for pyloric stenosis here.

ICD codes for this disease:

ICD codes are internationally valid codes for medical diagnoses. They can be found, for example, in doctor’s letters or on certificates of incapacity for work.

Q40 K31

quick overview

  • Symptoms: Barrage of vomiting shortly after the meal, weight loss, dehydration, restlessness and constant hunger in the baby.
  • Causes and risk factors: permanent spasm and enlargement of the pylorus in the hypertrophic form. Genetic factors are likely, smoking during pregnancy is considered a risk. Acquired pyloric stenosis possible due to foreign bodies, gastric tumor or scar after gastric ulcer.
  • Diagnosis: based on the symptoms, enlarged pylorus in the baby usually palpable, ultrasound examination. In the acquired form (in adults or older children) gastroscopy .
  • Treatment: Usually surgery, in which the pylorus muscle is widened. Rarely treated with drugs only. In the case of acquired form, elimination and treatment of the cause (foreign body, stomach ulcer or tumor).
  • Prognosis: With successful treatment, affected children usually develop normally, and the stenosis usually does not recur. In the case of acquired pyloric stenosis, the prognosis depends on the cause.
  • Prevention: informing the doctor if there is a known family history in order to prevent complications; not smoking during pregnancy.

What is pyloric stenosis (in babies?)

In hypertrophic pyloric stenosis, sometimes also called “pyloric spasm”, the outlet of the stomach (“pyloric nerve”, pylorus) is narrowed by thickened muscles. As a result, ingested food is not transported further into the duodenum. It is therefore typical of pyloric stenosis that the children vomit in surges shortly after eating. About three out of 1000 newborns develop pyloric stenosis. It is therefore not a rare disease and affects boys more often than girls.

Pyloric stenosis is relatively common in people of European descent, but rare in people of Asian and African descent. The symptoms of pyloric stenosis usually develop in the third to sixth week of life of the newborn baby. The full name of the condition is “hypertrophic pyloric stenosis”. The addition hypertrophic describes that the muscle cells of the pylorus enlargement as a result of the permanent spasm and the entire muscle appears larger.

Doctors usually treat pyloric stenosis quickly, since insufficient food intake often leads to serious metabolic problems such as hypoglycaemia or nutrient deficiencies. The treatment is usually a minor surgical procedure in which the constriction is loosened.

In addition to hypertrophic pyloric stenosis, which affects babies in particular, narrowing of the pylorus, for example due to foreign bodies or scarring from a stomach ulcer or tumor, is also referred to as pyloric stenosis.

What are the symptoms of pyloric stenosis?

Pyloric stenosis manifests itself in the form of vomiting, which occurs approximately half an hour after meals. It is characteristic of pyloric stenosis in babies that the child vomits violently and violently at short intervals. The vomit smells strongly sour and in many cases has blood threads running through it due to the stomach irritation.

The thickened exit from the stomach can often be felt from the outside as an olive-shaped structure in the upper right abdomen, especially when the child has just vomited and the stomach is empty. In addition, the movements pronounced of the stomach muscles (stomach peristalsis) can sometimes be observed as a wavy movement in the child’s upper abdomen.

Due to the disturbed emptying of the stomach, the children develop a massive lack of food and liquid after just a few hours. They are therefore very restless and often drink conspicuously greedily. Since stomach acid is also vomited, the pH value (acidity) in the blood shifts to the basic range (metabolic alkalosis). As a result of the pyloric stenosis, the affected children lose a lot of weight.

At the same time, they produce less urine because they hardly absorb the liquid they drink into their bodies. The typical signs of dehydration (exsiccosis) can therefore often be seen in pyloric stenosis: deep circles under the eyes, a sunken fontanelle (gap between the skull bones) and wrinkles on the face are noticeable. The mucous membranes are dry and so-called standing skin folds form.

This means that if you gently grasp the child’s skin with two fingers, it will remain as a fold of skin due to the lack of fluids. Standing skin folds are a serious sign of severe dehydration in the child and should be treated as soon as possible.

The children have severe pain in the upper abdomen due to the repeated vomiting and a visibly distressed facial expression with a wrinkled forehead. Occasionally, children’s skin turns yellow (jaundice, jaundice).

If the children vomit less during the course of the disease, this should not be misinterpreted as an improvement. Rather, it is an expression of the exhaustion and dehydration of the child. The child must be examined and treated by a doctor as soon as possible.

Even with acquired pyloric stenosis caused by foreign bodies or as a result of a gastric ulcer or gastric carcinoma, the symptoms ranging from vomiting to dehydration and emaciation are largely identical to the hypertrophic form.

Causes and risk factors

The pylorus is a ring-shaped muscle between the stomach outlet and the duodenum. It is important for the controlled gradual emptying of the chyme from the stomach into the intestine. In congenital hypertrophic pyloric stenosis, spasms of the circular muscles at the gastric outlet occur repeatedly or continuously for reasons that have not yet been clarified.

After a while, these spasms lead to the circular muscle (hypertrophy) becoming thicker, so that little or no food passes through the stomach outlet. This leads to impaired gastric emptying. The more food content accumulates, the more pressure is created in the stomach, until the child finally vomits all the food it has eaten.

The exact cause of this congenital pyloric stenosis has not yet been clarified. However, various causes are discussed, including a faulty activation of the pylorus muscles by the nerves. Pyloric stenosis may also be hereditary, since the disease tends to run in families. In addition, children with blood groups B and 0 are affected more often than children with other blood groups .

Boys are affected more often than girls. Genetic factors are considered likely because siblings and offspring of those affected are often also affected and, in the case of identical twins, both usually develop the disease. Smoking during pregnancy and possibly also taking certain antibiotics in the first few weeks of life are considered risk factors.

In the acquired form of pyloric stenosis, which can occur at any age, a foreign body blocks the stomach outlet, for example. Such a narrowing of the pylorus is also possible as a result of scarring, as a result of a stomach ulcer or a stomach tumor.

investigations and diagnosis

The doctor confirms the diagnosis of pyloric stenosis based on the typical symptoms and by means of ultrasound . Among other things, the thickened muscle in the hypertrophic form can often already be felt through the abdominal wall.

In the ultrasound, the pylorus muscles (pylorus) appear thickened. In addition, the thickness of the muscles can be measured using ultrasound: A pyloric stenosis is present when the circular muscle (pylorus) is longer than sixteen millimeters in the ultrasound image and the wall thickness is more than four millimeters. For newborns less than a month old and for premature babies, these measurements are slightly smaller.

If a clear diagnosis by ultrasound and the symptoms is not possible, an X-ray contrast agent examination is often also carried out.

A gastroscopy (gastroscopy) is an examination method that is more commonly used in adults in the case of acquired polyrus stenosis.

Diseases resembling pyloric stenosis

Food intolerance, poisoning or errors in nutrition sometimes cause symptoms similar to those of pyloric stenosis. Gastrointestinal infections and reflux disease (backflow of stomach contents into the esophagus) are possible causes of vomiting.

The doctor will also consider metabolic diseases. Paediatricians already identify several congenital metabolic disorders as part of the newborn screening and can therefore usually be ruled out as the cause of the symptoms at an early stage.

Congenital anomalies such as a so-called tracheoesophageal fistula, in which the esophagus is connected to the trachea, sometimes occur together with pyloric stenosis for unknown but probably genetic reasons.

In newborns, the doctor uses the examinations to rule out other possible malformations with similar symptoms, such as a blockage of the duodenum (duodenal atresia).

How is pyloric stenosis treated?

In most cases, the doctor operates on the pyloric stenosis. Before an operation, however, the doctors ensure that the fluid and electrolyte balance of the child is balanced again with infusions. Immediately before the operation, the stomach is also emptied with a gastric tube so that no stomach contents get into the trachea during the operation.

The operation of choice for the hypertrophic form is the so-called Weber-Ramstedt pylorotomy, in which all muscle fibers of the stomach outlet are severed lengthwise with a scalpel without injuring the mucous membrane. This technique increases the diameter of the stomach outlet so that the food pulp can pass through it again.

The operation shows very good results, so that the children usually develop completely normally after the operation. In the initial period after the operation, the child should be fed small, easily digestible meals in the form of mother’s or baby’s milk.

Doctors recommend an early operation, since the general condition of the child is usually still good in the early stages of the disease. A good general condition significantly reduces the risk of the operation. The operation can be performed endoscopically through a small incision (laparoscopy, “keyhole technique”) or through a surgical opening in the upper abdomen ( laparotomy ).

The advantage of the laparoscopic operation is that the children usually have less pain afterwards and vomit less often. Overall, pylorotomy is an established and low-risk procedure. If possible, however, it is carried out in a hospital with a pediatric surgery department.

Hypertrophic pyloric stenosis can also be treated conservatively (without surgery). However, this method is usually tedious. Here you feed the child small meals (about ten to twelve small meals a day) and lie down to sleep with the upper body elevated by 40 degrees.

In addition, it is possible to give drugs such as atropine (parasympatholytic) to relax the pyloric muscles and reverse muscle hypertrophy. This treatment is recommended when surgical treatment is not possible for medical reasons.

In the case of acquired pyloric stenosis, the doctor usually treats the cause. This means that a foreign body may be removed as part of the gastroscopy or, if nothing else is possible, by surgery.

The doctor treats stomach ulcers or stomach cancer as the cause accordingly. If there is a permanent and inoperable blockage, doctors may insert a feeding tube directly into the duodenum or small intestine.

Course of the disease and prognosis

If pyloric stenosis is treated surgically at an early stage, the prognosis is usually good, even in severe cases. After an operation, it is possible to start feeding the child with formula after just two to four hours. If the child vomits again, the meals should first be reduced and then gradually increased. Pyloric stenosis usually does not recur. Thanks to the surgical measures, the mortality rate is now well below one percent.

In acquired cases, the prognosis depends on the cause.

Complications of pyloric stenosis

If the pyloric stenosis is not operated on, there is a risk of death due to the massive metabolic derailments (metabolic alkalosis and dehydration).

With timely diagnosis and treatment, however, serious complications can usually be prevented. The children initially receive infusions to stabilize the fluid and electrolyte balance. Once her condition has stabilized, the pyloric stenosis is treated surgically.


Concrete prevention of hypertrophic pyloric stenosis is not possible because the cause has not been fully elucidated. However, the serious complications can be prevented if the first symptoms, such as sudden vomiting, are examined by a doctor immediately.

In addition, parents should inform the pediatrician or the medical team at the hospital if there is a known family history.

In addition, doctors generally recommend not smoking during pregnancy to reduce the risk of several other diseases, developmental disorders and premature births.

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