Intestinal malrotation and nonrotation are congenital abnormalities that occur during the 5th to 12th week of fetal development, when the intestines incompletely rotate or do not rotate around the superior mesenteric artery. Without appropriate rotation of the intestines, only a narrow mesenteric base develops and the colon does not fixate to the posterior abdominal wall. Without fixation and having only a narrow mesentery, the intestines can further twist, causing midgut volvulus and bowel ischemia, as the mesentery includes the superior mesenteric artery. Most infants with intestinal malrotation present with vomiting (usually bilious) and abdominal distention before 5 years of age. Depending on the severity, patients may have peritonitis or be in septic shock. Some patients do not develop symptoms until adolescence, with recurrent abdominal pain and postprandial bloating. Plain radiographs are often obtained as the initial study to look for free air in minimally symptomatic patients but will rarely be able to diagnose malrotation. The gold standard test is an upper GI series, as it identifies malrotation and nonrotation in the vast majority of cases, although the findings are sometimes subtle. Treatment for symptomatic cases is surgical with disruption of the Ladd bands and positioning of the intestines in a nonrotated position (as there is not enough mesentery to position them normally), which has a lower risk of volvulus. The procedure will also result in adhesions to further prevent volvulus.
A barium enema (A) is considered an adjunct to an upper GI series in the diagnosis of malrotation and is recommended when there is high suspicion and a negative upper GI due to the high false-positive and false-negative rates. A computed tomography scan (B) will sometimes provide the diagnosis and can be used as the initial test when appropriate to rule out other intra-abdominal causes in severely ill patients, but it is not recommended as the initial screening test and is not considered the gold standard in diagnosis of malrotation. An abdominal ultrasound (C) can identify an abnormal position of the superior mesenteric artery and is sometimes more accessible than an upper GI series. A negative ultrasound, however, cannot exclude malrotation, so it is not the gold standard test.