Shorter Cervical Length Tied to Problems in Placenta Previa

Third-trimester cervical length of ≤30 mm associated with higher risk for hemorrhage, preterm birth

WEDNESDAY, Aug. 25 (HealthDay News) -- Shorter cervical length during the third trimester of pregnancy among women with placenta previa is linked to a higher risk of hemorrhage, uterine activity, and preterm delivery, according to a study published in the September issue of Obstetrics & Gynecology.

Irene A. Stafford, M.D., of the University of Texas Southwestern Medical Center in Dallas, and colleagues obtained transvaginal cervical length measurements in singleton pregnancies with placenta previa identified at 24 weeks of gestation or later between October 2007 and May 2009. Cervical length of ≤30 mm was considered short.

The investigators found that 68 of 89 identified women with placenta previa at initial ultrasonography had placenta previa at delivery, and 43 percent of these women had a short cervix. Women with placenta previa and a short cervix were more likely to require delivery for hemorrhage (79 versus 28 percent) and to have a preterm delivery (69 versus 21 percent). Compared to women with a longer cervix, tocodynamometer evidence of regular uterine contractions was more common among women with a short cervix (69 versus 21 percent). However, 64 percent of women with a cervical length >30 mm experienced no bleeding events and carried to term.

"The results of this study showing that hemorrhage resulting from placenta previa occurs in the setting of perceptible uterine contractions plus cervical shortening also suggests that the pathophysiology of bleeding resulting from previa is a result of labor effects on the placenta implanted onto a changing cervix," the authors conclude.

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