predisposing factors
Last reviewed 01/2018
Congenital:
- absence of valves in the iliac veins
- abnormal vein wall elasticity
- arteriovenous fistulae e.g. Robertson's giant limb
Acquired:
- obesity in women (but not in men)
- prolonged standing
- parity - women are affected six times more often than men, the majority of cases following a second or third pregnancy; important factors may include:
- impaired venous return, due to pressure on the iliac veins from the pregnant uterus
- high level of progesterone which alters collagen structure, sometimes irreversibly, and relaxes smooth muscle
- previous deep vein thrombosis - valves damaged when the veins recanalise