Intestinal malrotation is a defect that occurs at the 10th week of gestation. During this stage of development, the intestines normally migrate back into the abdominal cavity following a brief period where they are temporarily located at the base of the umbilical cord. As the intestine returns to the abdomen, it makes two rotations and becomes fixed into its normal position, with the small bowel centrally located in the abdomen and the colon (large intestine) draping around the top and sides of the small intestine. When rotation is incomplete and intestinal fixation does not occur, this creates a defect known as intestinal malrotation.
With intestinal malrotation, the large intestine is located to the right of the abdomen, while the small intestine is on the left of the abdomen. The cecum (beginning of large intestine) and the appendix, which are normally attached to the right lower abdominal wall, are unattached and located in the upper abdomen. In many cases, abnormal tissue referred to as Ladd's bands attaches the cecum to the duodenum (beginning of small intestine) and may create a blockage in the duodenum.
In patients with malrotation, the blood supply to the intestine is channeled through a very narrow supportive structure (mesentery). Since the intestine is not properly fixated, the bowel may twist on its own blood supply; this condition is termed volvulus. When volvulus involves the entire small bowel, it is referred to as mid-gut volvulus. This can result in the loss of most of the intestine. In some case, it may also result in death.
Intestinal malrotation occurs in 1 of every 500 live births in North America. Up to 40% of patients with malrotation show signs of the disease within the first week of life. By 1 month of age, 50 to 60% are diagnosed. Seventy-five to 90% of patients are diagnosed by age 1. The remaining cases are diagnosed after age 1 and into adulthood. While more boys exhibit symptoms during the first month of life, malrotation occurs equally in boys and girls.
Up to 70% of children with intestinal malrotation also have another defect that is present at birth (congenital), including:
A number of other acute and chronic signs of disease are related to intestinal malrotation and lack of fixation. These include:
In some people with malrotation, symptoms never occur and a diagnosis is never made. In others, symptoms may develop at any age. When the intestine is obstructed by Ladd's bands or when the blood supply is twisted, symptoms may include:
Malrotation of the intestine is usually not evident until the intestine becomes twisted or obstructed by Ladd's bands, resulting in symptoms. Since all of the functional intestine can die with a volvulus, this is considered life threatening.
Surgical repair is performed as soon as possible. The bowel is untwisted and checked carefully for damage. Ideally, circulation to the intestine is restored after it is untwisted, allowing it to regain its pink coloration. If the intestine is healthy, an operation called the Ladd's procedure is performed to repair the malrotation. Since the appendix is not in the correct location, and it would be difficult to diagnose a future appendicitis, it is usually removed at this time.
If the blood supply to the intestine remains in question after untwisting, another operation is usually performed within 24 to 48 hours to re-evaluate it and determine the extent of bowel necrosis (death). If it appears that a section of intestine is severely damaged beyond recovery, this damaged portion is removed. This sometimes necessitates surgically creating a small bowel stoma (opening) through the abdominal wall to the skin. This diverts body waste into a collection bag, allowing the small bowel to heal. After several weeks, an operation may be performed to restore normal intestinal function.
When surgical repair is performed before intestinal damage occurs, there are generally no long-term problems. However, removal of a large portion of intestine due to intestinal injury can severely affect the digestive process. With this operation, the normal intestinal process of absorbing nutrients and fluids cannot occur. Nutrition may need to be supplemented with long-term intravenous high-calorie solutions. This type of supplemental feeding is referred to as total parenteral nutrition (TPN). If the bowel does not recover its function and long-term TPN is necessary, children are at risk for developing chronic liver disease.
Mortality rates substantially increase with the presence of necrotic (dead) bowel at surgery and the presence of other co-existing abnormalities. However, they decrease with age, with the average mortality in infants varying from 5 to 10%.