Malrotation

Embryology

To distinguish normal from abnormal and properly diagnose malrotation, a review of the intestinal development is helpful. Development of the gut is a complex process.1, 2, 3, 4 Frazer and Robbins first described three stages of development.¹ In Stage 1, from week 5 to week 10, midgut herniates into the umbilical cord. In Stage 2, at weeks 10 to 11, midgut returns to the abdomen. In Stage 3, from the conclusion of stage 2 until birth, the gut undergoes fixation. While visualization of the three

Maldevelopment

Errors in development can occur at any point in the complex process of midgut development.3, 4, 5, 7 Timing of the error will affect the resultant defect and its potential morbidity. The resultant errors are termed “malrotation.” Malrotation thus is not a single entity, but rather a spectrum of abnormalities. Malrotation, in itself, simply implies that the bowel is abnormal in location. Abnormal location may not be problematic; however, malrotated bowel is also malfixated. It is lack of proper

Clinical Presentation

The classic presentation of malrotation is a newborn infant with bilious vomiting. The vomiting is bilious as the point of obstruction is distal to the ampulla of Vater. Approximately 80% of patients who present with malrotation do so in the first month of age.10, 11, 12 Most do so in the first week of life. While bilious vomiting appropriately raises concern for malrotation, any congenital or acquired obstruction distal to the ampulla of Vater may cause bilious vomiting. Moreover, most infants

Radiography

Imaging evaluation of the infant or child with suspected malrotation begins with radiographs, particularly in the infant. Radiographs aid in excluding other diagnoses, namely more distal obstructions in the neonate.

A variety of radiographic appearances may be seen with malrotation, but, unfortunately, the most common radiographic appearance of malrotation and malrotation with volvulus is that of a “normal bowel gas pattern.” A normal radiograph therefore should not preclude additional workup as

Upper GI

A fluoroscopic upper GI study is the preferred method of diagnosing malrotation or excluding the diagnosis. For greatest accuracy, the upper GI examination must be performed with careful attention to the anatomy of the duodenum. As a rule, unless previously documented, every upper GI examination performed in a child should include documentation of duodenal anatomy. Barium is utilized, unless the infant is critically ill or perforation is suspected. In such cases, nonionic water-soluble contrast

Cecal Position

The normally rotated cecum is in the right lower quadrant of the abdomen, often descending into the right hemipelvis. The malrotated cecum may be found at varied locations throughout the abdomen.

Up to 20% of patients with malrotation have a normally located cecum.16, 27, 31 A contrast enema is therefore not the preferred method of diagnosing malrotation as it will fail to make the diagnosis in too many patients. In young infants, the cecum is often slightly high in position; thus, the contrast

Cross-Sectional Imaging

Increasing utilization of cross-sectional imaging modalities has led to the increased incidence of the diagnosis of malrotation by modalities other than fluoroscopic study. Cross-sectional imaging findings of malrotation include dilation of the proximal duodenum, absence of the crossing duodenum posterior to the SMA, malposition of small and/or large bowel, and inversion of the normal SMA/superior mesenteric vein (SMV) relationship.4, 32, 33, 34

Normally, the SMA is to the left of the SMV. If

Conclusion

If not promptly diagnosed and treated, malrotation with volvulus may be fatal to the affected child. Unfortunately, and despite the best efforts of frontline physicians (pediatricians and emergency room doctors), radiologists, and pediatric surgeons, fatal cases of malrotation with volvulus are occasionally seen. Fortunately, an overwhelming majority of affected children are promptly diagnosed and treated and do survive without significant sequelae. The role of the radiologist is paramount to