Aplasia or hypoplasia of the pancreatic uncinate process: Comparison in patients with and patients without intestinal nonrotation

PURPOSE: To investigate whether the pancreatic uncinate process is hypoplastic in patients with intestinal nonrotation, and to evaluate the association of hypoplasia or aplasia of the uncinate process with mesenteric vascular inversion. MATERIALS AND METHODS: Computed tomographic (CT) scans of the pancreas in five patients with intestinal nonrotation and in 101 patients with normal intestinal rotation were reviewed to assess the morphology of the uncinate process. The transverse diameter of the uncinate process was measured, and the relationship with the superior mesenteric artery and vein was defined. RESULTS: The uncinate process was absent in three and unusually small in two of the five patients with nonrotation. The uncinate process was clearly present in all patients with normal rotation. The mean transverse diameter (2.60 mm +/- 2.61 [standard deviation]) of the uncinate process in patients with nonrotation was significantly smaller than that (15.1 mm +/- 5.0) in the patients with normal rotation (P < .001). Four of the five patients with nonrotation had mesenteric vascular inversion, and three of these patients had no uncinate process. None of the patients with normal rotation had mesenteric vascular inversion. CONCLUSION: The uncinate process was aplastic or hypoplastic in patients with nonrotation, which may have been associated with incomplete rotation of the ventral bud of the pancreatic primordium, as well as mesenteric vascular inversion.