Surgical anatomy of the mesocaval shunt.

Having encountered wide variations in the surgical trunk of the superior mesenteric vein and its arterial relationships during the performance of mesocaval shunts, we believed it would be rewarding to evaluate this vessel in a series of 36 cadavers. In two of these 36 instances, we determined that the anatomic findings precluded the performance of a mesocaval shunt. In ten other instances, even though a shunt could be performed, a knowledge of these variations could prevent operative complications. The most common variation was a bifurcation of the superior mesenteric vein at or proximal to the site of the surgical trunk. Another variation which could cause operative difficulties was unusual positions of the superior mesenteric artery and its major branches in relation to the vein at the level of the surgical trunk. A knowledge of these variations in the surgical anatomy of the superior mesenteric vein should make mesocaval shunts easier and safer to perform.