In weeks 5-10 of pregnancy, the nerve cells from the brain gradually grow downward via the oesophagus, stomach, small intestine and large intestine. Sometimes these nerve cells do not reach the very last part of the intestine. This is the case with Hirschsprung's disease, named after the discoverer, the Danish paediatrician Harald Hirschsprung (1830-1916). Due to the absence of nerve cells, the intestine cannot work the stool outwards. The poop accumulates, causing the intestine to expand. Hirschsprung’s disease can sometimes occur in combination with, for example, Down's syndrome.
Duodenal atresia is the congenital absence or complete closure of a portion of the lumen of the duodenum. It causes increased levels of amniotic fluid during pregnancy (polyhydramnios) and intestinal obstruction in newborn babies. Sometimes there is still a passage to distal, mostly when there is a duodenal web.
Intestinal atresia is a malformation where there is a narrowing or absence of a portion of the intestine. This defect can either occur in the small or large intestine. The different types of intestinal atresia are named after their location: jejunal-, ileal- and colon atresia. The most common cause of non-duodenal intestinal atresia is a vascular accident in utero that leads to decreased intestinal perfusion and ischemia of the respective bowel segment. This leads to narrowing, or in the most severe cases, complete obliteration of the intestinal lumen. In the case that the superior mesenteric artery, or another major intestinal artery, is occluded, large segments of bowel can be entirely underdeveloped. Classically, the affected area of bowel assumes a spiral configuration and is described to have an "apple peel" like appearance; this is accompanied by lack of a dorsal mesentery. Ileal atresia can also result as a complication of meconium ileus.
Necrotizing enterocolitis (NEC) is a medical condition where a portion of the bowel dies. It typically occurs in newborns who are either premature or otherwise unwell. Symptoms may include poor feeding, bloating, decreased activity, blood in the stool, or vomiting of bile. The exact cause is unclear. Risk factors include congenital heart disease, birth asphyxia, exchange transfusion, and prolonged rupture of membranes. The underlying mechanism is believed to involve a combination of poor blood flow and infection of the intestines. Diagnosis is based on symptoms and confirmed with medical imaging.
Prevention includes the use of breast milk and probiotics. Treatment includes bowel rest, orogastric tube, intravenous fluids, and intravenous antibiotics. Surgery is required in those who have free air in the abdomen. A number of other supportive measures may also be required. Complications may include short-bowel syndrome, intestinal strictures, or developmental delay.