You are in: eMedicine Specialties > Radiology > PEDIATRICS Midgut VolvulusArticle Last Updated: Jul 27, 2007AUTHOR AND EDITOR INFORMATIONSection 1 of 12
  Author: Janet R Reid, MD, FRCP(C), Associate Professor of Radiology, Section Head of Pediatric Radiology, Children's Hospital of Cleveland Clinic Janet R Reid is a member of the following medical societies: American Association for Women Radiologists, American Society of Neuroradiology, Ohio State Medical Association, Radiological Society of North America, Royal College of Physicians and Surgeons of Canada, and Society for Pediatric Radiology Editors: Henrique M Lederman, MD, PhD, Consulting Staff, Department of Radiology, The Children's Hospital of Philadelphia; Professor of Radiology and Pediatric Radiology, Chief, Division of Diagnostic Imaging in Pediatrics, Federal University of Sao Paulo, Brazil; Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand; David A Stringer, BSc, MBBS, FRCR, FRCPC, Professor, National University of Singapore; Head, Diagnostic Imaging, KK Women's and Children's Hospital, Singapore; Robert M Krasny, MD, Consulting Staff, Department of Radiology, The Angeles Clinic and Research Institute; John Karani, MBBS, FRCR, Consulting Staff, Department of Radiology, King's College Hospital, London Author and Editor Disclosure Synonyms and related keywords: malrotation with midgut volvulus, nonrotation, reverse rotation, malrotation INTRODUCTIONSection 2 of 12
  BackgroundMidgut 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. The malrotated bowel is prone to torsion, which can lead to midgut volvulus. PathophysiologyDevelopment of the human gut takes place during the first months of fetal life. In normal embryos, physiologic herniation of the gut through the umbilicus at 6 weeks’ gestation is accompanied by a 270° counterclockwise rotation of the developing intestine around the superior mesenteric artery (SMA). By 10-12 weeks, the intestine returns to the abdomen and assumes its normal adult anatomic position. Normal small bowel mesentery has a broad attachment stretching diagonally from the duodenojejunal junction (DJJ), in the left upper quadrant, to the cecum, in the right lower quadrant. This point of attachment at the DJJ is called the ligament of Treitz. Malrotation is most commonly caused by incomplete rotation of the intestine (<270° of counterclockwise rotation, occurring in weeks 5-12). Malrotation disorders can be divided into 3 categories:
The small bowel may be in the right abdomen; however, this finding is not reliable. Often, the large bowel is in the left abdomen. Malrotation predisposes patients to 2 problems: midgut volvulus and small bowel obstruction. FrequencyUnited StatesAlthough malrotation is estimated to occur in 1 in 500 live births, the actual frequency of malrotation is unknown because many asymptomatic patients probably never present to a physician. InternationalIncidence is the same as in the United States. Mortality/Morbidity
RaceNo racial predilection is seen. SexNo gender predilection is seen. AgeIn 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. AnatomyIn malrotation, the following relationships may be observed in the gut:
Clinical DetailsIn 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, such as the spleen, liver, and major blood vessels; right-sided or left-sided isomerism) (see Image 7). 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 ExaminationThe diagnostic test of choice in a child with possible malrotation, with or without midgut volvulus, is an upper GI series. Limitations of TechniquesIn most patients with malrotation, an upper GI series is easy to perform and, in experienced hands, is easy to interpret, with the following exceptions:
DIFFERENTIALSSection 3 of 12
Duodenal Atresia Gastroesophageal Reflux Hypertrophic Pyloric Stenosis Necrotizing Enterocolitis Other Problems to Be ConsideredMalrotation without midgut volvulus
RADIOGRAPHSection 4 of 12
FindingsAbdominal radiographs are frequently performed in children with abdominal symptoms. In cases of simple malrotation, radiographs may appear normal. In midgut volvulus, the classic radiographic finding is a partial duodenal obstruction (dilation of both the stomach and proximal duodenum, with a small amount of distal bowel gas). Complete obstruction of the duodenum may also be found. Less frequent, but more ominous, signs are a gasless abdomen, ileus, or a distal small bowel obstruction with multiple dilated loops and air-fluid levels. A normal abdominal film does not exclude malrotation. An upper GI series is the preferred diagnostic test for malrotation with midgut volvulus and must be performed, unless a delay in surgical treatment will compromise outcome (as in the case of a moribund child). The upper GI series is performed with barium administered either orally or through a nasogastric tube. The normal DJJ lies to the left of the left-sided spinal pedicle at the level of the duodenal bulb on a true frontal view. The duodenal C-sweep courses posteriorly, inferiorly, anteriorly, and then superiorly. The findings of a malrotation on upper GI series include the following:
In malrotation with midgut volvulus, the findings also include the following:
Degree of ConfidenceIn malrotation without midgut volvulus, the degree of confidence on plain radiographs is low. Radiographs are rarely normal in malrotation with midgut volvulus, increasing the degree of confidence in this clinical scenario. An upper GI series provides a high degree of confidence in the diagnosis of malrotation with midgut volvulus. False Positives/NegativesRadiographic false negatives: Radiographic false positives:
CT SCANSection 5 of 12
FindingsSee Ultrasound. MRISection 6 of 12
FindingsDiagnosis of malrotation with midgut volvulus on fetal magnetic resonance imaging (MRI) has been reported.1 In practice, this is a difficult diagnosis to make, and MRI is not recommended in infants suspected of having malrotation with midgut volvulus. ULTRASOUNDSection 7 of 12
FindingsUltrasonography 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. If the superior mesenteric vein (SMV) lies to the left of or posterior to the SMA, malrotation is suggested; however, normal vascular positioning (the SMV being slightly ventral and to the right of SMA) can be seen in approximately 30% of patients with malrotation. The "whirlpool sign" on color Doppler ultrasonography shows mesentery and flow within the SMV wrapping around the SMA (in a clockwise direction), suggesting, but not entirely specific for, malrotation with midgut volvulus (see Image 8). A dilated, fluid-filled duodenum is frequently seen in patients who have obstruction without volvulus. Degree of ConfidenceThe moderate-to-low degree of confidence associated with ultrasonography and CT necessitates an upper GI series to confirm the diagnosis. False Positives/NegativesUltrasonography and CT have false-negative rates of approximately 30% and false-positive rates as high as 20%. NUCLEAR MEDICINESection 8 of 12
FindingsNuclear medicine techniques do not provide sufficient resolution to confidently diagnose midgut volvulus; therefore, nuclear medicine is not a recommended imaging modality for the diagnosis this condition. ANGIOGRAPHYSection 9 of 12
FindingsAngiographic abnormalities with chronic volvulus have been well described, and they include proximal occlusion of the SMA, a "barber-pole sign" (whirling SMA and its branches), extensive collateral vessels, and thickening of the small bowel folds. Angiography is not used to diagnose acute midgut volvulus. Degree of ConfidenceThe degree of confidence is high, but this examination is rarely indicated. False Positives/NegativesFew false positives or false negatives are seen with angiography. INTERVENTIONSection 10 of 12
Medical/Legal Pitfalls
MULTIMEDIASection 11 of 12
REFERENCESSection 12 of 12
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