The position of the duodenojejunal junction: the wrong horse to bet on in diagnosing or excluding malrotation.

PURPOSE: The purpose of this communication is to highlight the shortcomings of all currently used imaging criteria in diagnosing or excluding malrotation and offer ultrasound demonstration of the 3(rd) portion of the duodenum (D3) between the AO and the SMA in transverse and sagittal plains as the most reliable diagnostic method.

BACKGROUND: Although UGI is currently considered to be the imaging modality of choice in diagnosis of malrotations, numerous publications indicate that in certain patients, false positives and negatives can be encountered.

MATERIALS AND METHODS: The material consists of more than 10 years experience in university settings, during which the author has used US as the definitive imaging modality for the work-up of malrotation. High resolution linear transducers (5-17 MHz) are the transducers of choice. Imaging plains: A. Transverse. With gradual grading compression, the following landmarks are illustrated in cehaplocaudad directions in the following order. The junction of splenic vein with the SMV portal vein. The cross sections of SMA and SMV that may either be situated in midline, or to the right or the left of the midline. Left renal vein crossing the spine from left to right between the AO and the SMA. The jejunal vein, often coming from left, transversing between the AO and the SMA. The transverse portion of the duodenum, D3, between the AO & the SMA. B. Sagittal. D3 between vertically oriented SMA-SMV and the AO. If SMA is not aligned with the AO by slight compression on the right or the left side of the abdomen, it will be aligned (depending on leftward or rightward position of SMA-SMV in axial plain). Vertical orientation of SMA and SMV if they have an anteroposterior orientation. C. Coronal. Side by side orientation of SMA and SMV if they don't have an anteroposterior orientation.

RESULTS: In overwhelming majority of cases, by illustrating a retromesenteric D3 malrotation and, therefore, midgut volvulus were excluded.

DISCUSSION: None of the current imaging criteria addresses the following most fundamental anatomic and embryologic facts regarding the gut rotation and fixation. In first trimester, the D3 is secured in retroperitoneal space after the embryologic journey comes to an end, making the duodenum immune of midgut volvulus. The surgical pathology of malrotation-midgut volvulus indicates that D3 is always Intraperitoneal and has not reached its final embryologic destination in retroperitoneal space. Demonstrating a retromesenteric D3, therefore, indicates that the embryologic journey is completed and the patient does not have malrotation. Excluding malrotation excludes the likelihood of midgut volvus.

CONCLUSION: The position of the DJJ, the configuration of the duodenal sweep, the orientation of the mesenteric vessels are all wrong horses to bet on because none of them addresses the fundamental anatomic and embryologic facts. Only the cross-sectional imaging, US, CT and MRI can prove that the D3 is retromesenteric, therefore, excluding malrotation and volvulus. Therefore, demonstrating a retromesenteric duodenum is the reference standard of imaging in the work-up of malrotation, not any other previously published criteria. The US imaging is the most acceptable imaging method for malrotation work-up, in the spirit of ALARA principle and "Image Gently" campaign.