Right ovarian vein syndrome is revealed in pregnancy by right lumbar pains, and even by nephritic colics. It results from a congenital malposition of the right ovarian vein, which presses the right ureter on the external iliac artery. Diagnosis is by intravenous urography and retrograde ureteral pyelography. If pain persists despite treatment by analgesics, it may be necessary to place a double-J catheter, and to operate after delivery to ligate the ovarian vein.