## Distinguishing Normal from Incomplete Rotation ### Embryological Basis During weeks 6–10 of gestation, the midgut herniates, rotates 270° counterclockwise around the SMA, and returns to the abdomen. The duodenojejunal flexure normally rotates to lie **left of the midline** and becomes fixed by the ligament of Treitz (suspensory ligament of Treitz). ### Key Anatomical Landmarks | Feature | Normal Rotation | Incomplete Rotation | |---------|-----------------|---------------------| | **Duodenojejunal flexure position** | Left of midline, fixed by ligament of Treitz | Right of midline or midline; unfixed | | **Cecal position** | Right lower quadrant | Midline, epigastrium, or left side | | **SMA–duodenum relationship** | SMA crosses anterior to 3rd part of duodenum | SMA may not cross properly | | **Clinical significance** | Stable, no obstruction risk | Risk of volvulus, Ladd's bands | **Key Point:** The **fixation of the duodenojejunal flexure at the ligament of Treitz** is the single most reliable anatomical discriminator. In normal rotation, this flexure is anchored left of the midline. In incomplete rotation, it fails to reach this position and remains unfixed, predisposing to midgut volvulus. ### Clinical Pearl Ladd's procedure (the surgical correction for malrotation) involves dividing Ladd's bands, widening the mesenteric base, and positioning the duodenojejunal flexure to the left of the midline—restoring the normal anatomical relationship. **High-Yield:** The ligament of Treitz is the **gold standard landmark** for assessing rotation adequacy on imaging and at surgery. Its absence or rightward position indicates malrotation. 
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