Disease Information for Small Intestine Volvulus (Midgut): Definition

Author: Janet R Reid, MD, Midgut volvulus is a condition in which the intestine has become twisted as a result of malrotation of the intestine during fetal development; Malrotation of the intestine occurs when the normal embryologic sequence of bowel development and fixation is interrupted; Midgut volvulus: The close proximity of the cecum to the duodenum is associated with a narrow stalk of mesentery around which the gut may twist, resulting in midgut volvulus (see Image 1); Accompanying superior mesenteric vascular compromise (first venous, followed by arterial) can lead to life-threatening ischemia of the small bowel and gangrenous necrosis; Mortality associated with midgut volvulus is at least 15%, and there is a high incidence of short gut syndrome, total parenteral nutrition dependence, and resultant cirrhosis;

No racial predilection is seen;No gender predilection is seen; In approximately 60% of patients, malrotation presents by 1 month of age; Another 20-30% of patients present at 1-12 months of age; Malrotation may remain clinically "silent" for some time and can present at any age; Anatomy: In malrotation, the following relationships may be observed in the gut: The DJJ is low and to the right of the normal location ; The proximal small bowel (jejunum) is in the right upper quadrant; The cecum is in the upper and/or left abdomen; The large bowel is in the left abdomen; Other associated anomalies are seen around the ampulla of Vater;

Clinical Details

In neonates, malrotation with midgut volvulus classically presents with bilious vomiting and high intestinal obstruction (see Image 2); While most neonates with bilious vomiting do not have midgut volvulus, this diagnosis must be ruled out; Older children with malrotation may manifest a failure to thrive, chronic recurrent abdominal pain, malabsorption, or other vague presentations; The older the child is, the less readily identifiable is the clinical presentation; Nonrotation of the intestine may be asymptomatic and is an incidental finding on upper GI series performed for other reasons;

Associated anomalies are seen in approximately 60% of patients and include congenital heart disease with heterotaxy (abnormal positioning and arrangement of the abdominal organs);Malrotation is almost always present in patients with congenital diaphragmatic hernia and abdominal wall defects, such as omphalocele and gastroschisis; Also, malrotation is more common with imperforate anus, duodenal atresia, duodenal web, stenosis, preduodenal portal vein, annular pancreas, and biliary atresia;

Preferred Examination:The diagnostic test of choice in a child with possible malrotation, with or without midgut volvulus, is an upper GI series; Limitations of Techniques

In most patients with malrotation, an upper GI series is easy to perform and, in experienced hands, is easy to interpret, with the following exceptions:

With complete duodenal obstruction, an upper GI series does not differentiate between the causes of proximal intestinal obstruction; In such cases, surgical exploration is indicated;

DIFFERENTIAL DDX: Duodenal Atresia, Gastroesophageal Reflux, Hypertrophic Pyloric Stenosis, Necrotizing Enterocolitis, Malrotation without midgut volvulus,

Duodenal stenosis, Duodenal web, Annular pancreas: Abdominal radiographs are frequently performed in children with abdominal symptoms; In cases of simple malrotation, radiographs may appear normal;

the findings of a malrotation on upper GI series include the following:The DJJ is displaced downward and to the right on frontal view; The duodenum has an abnormal course on lateral view; Abnormal positioning of the jejunum (lying on right side of abdomen) should alert the physician to the possibility of a malrotation, but this finding should not be relied upon to either make or exclude the diagnosis;In malrotation with midgut volvulus, the findings also include the following:A dilated, fluid-filled duodenum, A proximal small bowel obstruction, "corkscrew" pattern ,Mural edema and thick folds

Ultrasonography and CT may suggest the diagnosis of malrotation; however, their sensitivities and specificities are low compared to those of an upper GI series; An upper GI examination is mandatory to confirm the diagnosis, if it is suspected on CT or ultrasonography; [Emedicine Online 2007 Adapted]

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