The Collaborative International Dictionary of English v.0.48:

Omphalomesenteric \Om`pha*lo*mes`en*ter"ic\, a. [Omphalo- +
   mesenteric.] (Anat.)
   Of or pertaining to the umbilicus and mesentery;
   omphalomesaraic; as, the omphalomesenteric arteries and veins
   of a fetus.
   [1913 Webster]