Impact of Ultrasound Cervical Length Assessment on Duration of Hospital Stay in the Clinical Management of Threatened Preterm Labor

Abstract

Although women with symptoms of preterm labor usually are hospitalized, only 10% to 30% of those admitted to the hospital because of premature contractions deliver before term. Monitoring of contractions and digital examination do not have good predictive value. As a result, the hospital stay may be unnecessarily prolonged when the risk of preterm delivery is actually very low. This prospective study, enrolling 294 women with threatened preterm labor at 3 hospital units, was an attempt to learn whether ultrasound measurements of cervical length have greater predictive value. Patients in preterm labor reportedly are at very low risk when the cervical length is 15 mm or greater. In the initial phase of the study, cervical length was measured by transvaginal ultrasonography and the managing physicians were blinded to the results. In a second phase, physicians at 1 of the 3 units (group A) remained blinded, whereas those at the other 2 units (groups B and C) were able to incorporate the findings into their management plan. Early discharge was considered in group B women if the cervix measured 25 mm or more within 24 hours of admission. Group C women had a repeat scan after 24 to 48 hours and were considered for discharge when cervical length was unchanged. Women in all 3 groups were similar in age, Bishop scores, and ultrasonographic cervical length at admission. Nulliparous women were more frequent in group A than in the other groups. Hospital time averaged 6.1 days overall. In the interventional phase, women in groups B and C had significantly shorter hospital stays than did group A women. Within the same group, hospital time averaged 4.9 days for nulliparas and 5.2 days for parous women. Rates of delivery within 7 days and delivery before 37 weeks gestation were comparable in all units during both phases of the study. There were also no significant group differences in rates of readmission or the use of tocolytic agents. These findings suggest that ultrasound measurements of cervical length may substantially reduce time in the hospital for women with threatened preterm labor. The examination is noninvasive and the findings are reproducible.