Malrotation of the duodenum is a more common cause of duodenal obstruction, typically appearing in the first few weeks of life.
In malrotation, the duodenum is usually coiled to the right, causing obstruction of the duodenum and failure of the stomach contents to pass through to the next portion of small intestine.
Malrotation may also involve the presence of Ladd's bands, abnormal folds or bands of tissue under tension across the lumen of the duodenum.
Malrotation can also occur with duodenal volvulus or volvulus lower in the bowel.
Intestinal malrotation is a more common cause, occurring in one in 500 live births, although only a small percentage of these have duodenal malrotation.