Faculty Bibliography

OBJECTIVE:To determine whether the acceleration/ejection time ratio of the fetal main pulmonary artery Doppler waveform (PATET) can accurately predict the results of fetal lung maturity testing in amniotic fluid. METHODS:We prospectively studied pregnant women attending our ultrasound unit for clinically indicated fetal lung maturity testing. An ultrasound examination that included measurement of the PATET was performed before the results of the amniocentesis were reported. The results of the PATET and the surfactant/albumin ratio were compared, and a receiver operating characteristic curve was used to determine the PATET cutoff with the optimal sensitivity and specificity for predicting surfactant/albumin ratio results. p < 0.05 was considered statistically significant. RESULTS:Forty-three patients were included in this study. The receiver operating characteristic curve demonstrated that a PATET cutoff of 0.3149 provided a specificity of 93% (95% CI 77-98%), a sensitivity of 73% (95% CI 48-89%), a negative predictive value of 87% (95% CI 70-95%), and a positive predictive value of 85% (95% CI 58-96%) for predicting immature surfactant/albumin ratio results. CONCLUSION/CONCLUSIONS:The PATET may provide a noninvasive means of determining fetal lung maturity with acceptable levels of sensitivity, specificity, and predictive values.

This study was performed to determine if cerclage height is associated with spontaneous preterm birth in patients with a history-indicated cerclage. We performed a retrospective cohort study of women with a history-indicated cerclage. Functional cervical length and the cerclage height (distance from cerclage to the external cervical os) were obtained. The cohort was grouped into thirds, based on cerclage height percentile. Our primary outcome was spontaneous preterm birth <35 weeks. There were 21 women in group 1 (cerclage height <10 mm), 53 in group 2 (cerclage height 10 to 19 mm), and 31 in group 3 (cerclage height ≥20 mm). The rates of spontaneous preterm birth <35 weeks were similar between each group: 24, 17, and 10%, respectively ( P = 0.38). Cerclage height is not associated with a reduction in spontaneous preterm birth for women with a history-indicated cerclage. The association between longer cerclage height and decrease in preterm birth was nonsignificant possibly due to the small sample size.

We estimated the optimal gestational age for placement of a history-indicated cerclage in a retrospective cohort study of pregnancies during the period between 1994 to 2007. Pregnancies were divided into two groups: group 1, cerclage <14 weeks (N = 83), and group 2, cerclage >or=14 weeks (N = 59). The primary outcome was spontaneous preterm birth (SPTB) <35 weeks. Parametric and nonparametric tests were performed where appropriate. One hundred forty-two pregnancies by 130 women were included. Demographic characteristics were similar between groups. The median gestational age at cerclage was 12 weeks (group 1) and 15 weeks (group 2). There was no difference in the primary outcome, incidence of SPTB <35 weeks (17% versus 20%; P = 0.59) between groups 1 and 2, respectively. Likewise, the secondary outcomes, mean gestational age at birth (38 versus 37 weeks; P = 0.96), incidence of low birth weight (28% versus 23%; P = 0.50), and the incidence of preterm premature rupture of membranes (17% versus 18%; P = 0.89) were similar between groups. No other gestational age cutoff was predictive of SPTB <35 weeks using a receiver operator characteristic curve (13 to 17 weeks; area = 0.52; P = 0.64). Gestational age of history-indicated cerclage placement was not associated with a significant effect on preterm birth in high-risk women. The optimal gestational age for placement of a history-indicated cerclage is probably 12 to 14 weeks, after screening for fetal anomalies and aneuploidy.

OBJECTIVE:The purpose of this study was to estimate the time interval between elective cerclage removal and spontaneous delivery. METHODS:Singleton pregnancies with McDonald cerclage were evaluated for the interval between elective cerclage removal (36-37 weeks) and spontaneous delivery. We also compared spontaneous delivery within 48 hours after cerclage removal between women with ultrasound-indicated vs history-indicated cerclage. RESULTS:We identified 141 women with elective cerclage removal. The mean interval between removal and delivery was 14 days. Only 11% of women delivered within 48 hours. Women with ultrasound-indicated cerclage were more likely to deliver within 48 hours, compared with women with history-indicated cerclage (odds ratio, 5.14; 95% confidence interval, 1.10-24.05). CONCLUSION/CONCLUSIONS:The mean interval between elective cerclage removal and spontaneous delivery is 14 days. Women with cerclage who achieved 36-37 weeks should be counseled that their chance of spontaneous delivery within 48 hours after elective cerclage removal is only 11%.