Intervillous and uteroplacental circulation in normal early pregnancy and early pregnancy loss assessed by 3-dimensional power Doppler angiography

Objective
To assess intervillous and uteroplacental circulation in early normal pregnancies and miscarriages.

Study design
One hundred normal pregnancies and 46 delayed miscarriages were evaluated by 3-dimensional vaginal ultrasound and power Doppler angiography. Volumes of the early placenta and the subplacental area were obtained between 5 and 12.6 weeks' gestation. The placental volume, vascularization index, flow index, and vascularization flow index was calculated.

Results
Intraclass correlation coefficients ranged from 0.961 for placental volume to 0.885 for intervillous flow index. Intervillous power Doppler signals were not detected before the sixth week. Placental volume (R(2) = 0.68), intervillous vascularization index (R(2) = 0.30), flow index (R(2) = 0.33) and vascularization flow index (R(2) = 0.35), uteroplacental flow index (R(2) = 0.34), and vascularization flow index (R(2) = 0.17) increase significantly (P < .001) throughout the first trimester of normal pregnancies. Uteroplacental vascularization index was not significantly related to gestational age. Intervillous vasculariztion index, flow index, and vascularization flow index were significantly raised in miscarriages, but there were no significant differences for uteroplacental vascularization index, flow index, or vascularization flow index.

Conclusions
Intervillous and uteroplacental blood flow increases throughout the first trimester of normal pregnancies. Intervillous circulation is abnormally increased when a miscarriage is diagnosed.

CITATION  Am J Obstet Gynecol. 2009 Mar;200(3):315.e1-8. Epub 2008 Dec 27.