Other frequent congenital problems include duodenal atresia, pyloric stenosis, Meckel diverticulum, and imperforate anus. This is due to congenital hypertrophy of the pyloric sphincter. It is used to treat hypertrophic pyloric stenosis. Intravenous and oral atropine may be used to treat pyloric stenosis. It is located immediately distal to the Pyloric sphincter. The cause of pyloric stenosis is unclear. In infants the use of erythromycin has been associated with pyloric stenosis. The orifice is surrounded by a sphincter, a band of muscle, called the "pyloric sphincter". The pyloric glands contain mucus-secreting cells. Pyloric stenosis refers to a pylorus that is narrow. Ghrelin cells are found in oxyntic glands (20% of cells), pyloric glands, and small intestine. Here, digestive enzymes are secreted and a pyloric gland adds further secretions. These are the fundic glands, the cardiac glands, and the pyloric glands. Some waste may also be excreted by the pyloric glands and voided with the faeces. Gastrin is a hormone produced by enteroendocrine G cells in the pyloric glands.