Pyloric stenosis | |
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Outline of stomach, showing its anatomical landmarks, including the pylorus. | |
Classification and external resources | |
Specialty | General surgery |
ICD-10 | K31.1, Q40.0 |
ICD-9-CM | 537.0, 750.5 |
DiseasesDB | 11060 29488 |
MedlinePlus | 000970 |
eMedicine | emerg/397 radio/358, article/929829 |
MeSH | D046248 |
Pyloric stenosis or pylorostenosis is narrowing (stenosis) of the opening from the stomach to the first part of the small intestine known as the duodenum, due to enlargement (hypertrophy) of the muscle surrounding this opening (the pylorus, meaning "gate"), which spasms when the stomach empties. This condition causes severe projectile non-bilious vomiting. It most often occurs in the first few months of life, when it may thus be more specifically labeled as infantile hypertrophic pyloric stenosis. The thickened pylorus is felt classically as an olive-shaped mass in the middle upper part or right upper quadrant of the infant's abdomen. In pyloric stenosis, it is uncertain whether there is a true congenital anatomic narrowing or whether there is merely a functional hypertrophy of the pyloric sphincter muscle. This condition typically develops in male babies in the first 2 to 6 weeks of life.
Pyloric stenosis also occurs in adults, where the cause is usually a narrowed pylorus due to scarring from chronic peptic ulceration. This is a different condition from the infantile form.
Babies with this condition usually present any time in the first weeks to months of life with progressively worsening vomiting. The vomiting is often described as non-bile stained ("non bilious") and "projectile vomiting", because it is more forceful than the usual spittiness (gastroesophageal reflux) seen at this age. Some infants present with poor feeding and weight loss but others demonstrate normal weight gain. Dehydration may occur which causes a baby to cry without having tears and to produce less wet or dirty diapers due to not urinating for hours or for a few days. Constant hunger, belching, and colic are other possible signs that the baby is unable to eat properly.
Pyloric stenosis seems to be multifactorial, with some genetic and some environmental components. It is four times more likely to occur in males, and is also more common in the first born. Rarely, infantile pyloric stenosis can occur as an autosomal dominant condition.