Anatomical factors causing oedema of the lower limb during pregnancy.

BACKGROUND The objective of this study was to investigate the morphology of the common iliac artery and vein (CIA&V) comparing right and left sides in females versus males. Pregnant women favour lying on one side at rest and during sleep. The reason for this may be due to the morphology and orientation between the CIA&V. Virtually all women during their pregnancy suffer from lower limb swelling. This study provides an anatomical explanation for the propensity to lie consistently on one side, for lower limb swelling, and offers prevention measures. MATERIALS AND METHODS A literature search was conducted on anatomical texts, atlases, journals, and websites regarding the morphology and orientation of the right and left CIA&V, lower limb oedema, and sleeping positions during pregnancy. Measurements from 15 dissected cadavers were conducted on the right and left CIA&V. RESULTS The literature search revealed very limited studies on the morphology and orientation of the right and left CIA&V with no studies relating this orientation to lower limb oedema or sleeping positions during pregnancy. Cadaver dissection revealed a relatively direct anterior to posterior orientation left CIA&V and an oblique lateral to medial right CIA&V. CONCLUSIONS This study suggests an explanation of why women lie on their left side when resting and sleeping during the third trimester due to the clinically relevant anatomy between the CIA&V.