Pyloric stenosis refers to a narrowing of the passage between the stomach and the small intestine. The condition, which affects infants during the first several weeks of life, can be corrected effectively with surgery. Pyloric stenosis can be cured with a surgical procedure called a pyloromyotomy. In this operation, the surgeon makes an incision in the baby's abdomen. Then a small cut is made in the thickened muscle of the pylorus and it is spread apart. In this manner, the passage can be widened without removing any tissue.
The main symptom is vomiting after feedings. Other symptoms include increased appetite, weight loss, infrequent bowel movements, belching, and diarrhoea. Due to dehydration, the infant may also have fewer wet diapers. In Norway the statistical analysis of pyloric stenosis was resulted as during the first trimester, 0.4% and 0.7% of control women had used erythromycin and non-erythromycin macrolides, respectively. Compared to non-use during pregnancy, first-trimester exposure to erythromycin was not associated with an increased risk of CHD (OR, 1.3; 95% CI, 0.6–2.6) or PS (OR, 0.9; 95% CI, 0.3–3.0). The corresponding ORs for non-erythromycin macrolides were 0.7 (95% CI, 0.4–1.3) for CHD and 1.7 (95% CI, 0.6–4.6) for PS.