medical Definition of subcostal vein
: either of two veins:
a
: one that arises on the right side of the anterior abdominal wall, follows a course along the lower margin of the twelfth rib, and joins in the formation of the azygos vein — called also
right subcostal vein
b
: one on the left side of the body that usually empties into the hemiazygos vein — called also
left subcostal vein
