MEDICAL ANIMATION TRANSCRIPT: Pyloric stenosis is a disease in which part of a baby's stomach is blocked or abnormally narrow. Located between the esophagus and small intestine, the stomach stores and begins to digest milk. Some of the main parts of the stomach are the fundus, the body, the pyloric region, which includes the antrum and pyloric canal, and the pylorus. The wall of the stomach contains several layers of muscle. At the end of the pyloric region, the muscle layer forms a thickened ring called the pyloric sphincter. The pyloric sphincter surrounds an opening to the small intestine called the pylorus. The pyloric sphincter is normally contracted just enough to hold milk in the stomach while contractions mix and break down the milk. From time to time, stronger waves of stomach contractions push milk out of the stomach. As the pyloric muscle relaxes, milk passes through the pylorus into the small intestine. For unknown reasons, some babies develop pyloric stenosis, in which abnormally thickened muscle layers in the pyloric sphincter block the pylorus. Stomach contractions can't push milk from the baby's stomach through the blocked pylorus. As a result, milk in the stomach can't pass into the small intestine, which causes the baby to forcefully vomit the milk. The vomiting may cause severe dehydration, a condition in which the body loses too much water. Common symptoms of dehydration include sunken eyes, no tears when the baby cries, a sunken soft spot on the top of the head, and urinating less often, or having brown or dark yellow urine. Fortunately, the dehydration is not immediately life-threatening. After the dehydration is treated, the baby will require an operation called a pyloromyotomy to open the blocked pylorus. This operation will be done a month or two after birth, when the condition is discovered. Before the operation, the baby will be given general anesthesia to put him or her to sleep for the entire operation. A breathing tube will be inserted through the nose or mouth and down the throat to help the baby breathe during the operation. Commonly, the surgeon will make three tiny incisions near or in the belly button and on the right and left sides of the upper abdomen. Then small tubes for a camera and surgical instruments will be inserted through these incisions. The surgeon will carefully locate the thickened pyloric sphincter. An incision will be made along the outside of the pyloric sphincter. The incision will only pass through the muscle layer, leaving the inner tissue lining intact. The surgeon will insert a surgical instrument to widen the incision and spread the muscle fibers apart. This incision, called a pyloromyotomy, will loosen the pyloric sphincter muscle so that stomach contractions will be able to push food through the pylorus into the small intestine. Finally, the surgeon will close the skin incisions with dissolvable sutures and skin closure strips. After the operation, the baby will be taken to the recovery room for monitoring. Pain medication will be given. Feedings will begin shortly after the operation. The baby will be released from the hospital within one to two days, once they can feed normally and stay well hydrated.