Second trimester transvaginal ultrasound measurement of cervical length for prediction of preterm birth: a blinded prospective multicentre diagnostic accuracy study.

ABSTRACT:

Objective

To estimate the diagnostic performance of sonographic cervical length for prediction of preterm birth (PTB).

Design

Prospective observational multicentre study.

Setting

Seven Swedish ultrasound centres. Sample 11456 asymptomatic women with a singleton pregnancy.

Methods

Cervical length was measured with transvaginal ultrasound at 18 to 20 weeks (Cx1) and at 21 to 23 weeks (Cx2; optional). Staff and participants were blinded to results.

Main outcome measures

Area under receiver operating characteristic curve (AUC), sensitivity, specificity, positive and negative predictive values (PPV, NPV), positive and negative likelihood ratios (LR+, LR-), number of false positive results per true positive result (FP/TP), number needed to screen to detect one PTB (NNS), prevalence of "short" cervix.

Results

Spontaneous PTB (sPTB) <33 weeks occurred in 56/11072 (0.5%) women in the Cx1 population (89% white ethnicity) and in 26/6288 (0.4%) in the Cx2 population (92% white ethnicity). The discriminative ability of shortest endocervical length was better the earlier the sPTB occurred and better at Cx2 than at Cx1 (AUC to predict sPTB <33 weeks 0.76 versus 0.65, difference in AUC 0.11, 95% CI 0.01 to 0.23). At Cx2, shortest endocervical length ?25 mm (prevalence 4.4%) predicted sPTB <33 weeks with sensitivity 38.5% (10/26), specificity 95.8% (5998/6262), PPV 3.6% (10/274), NPV 99.7% (5988/6014), LR+ 9.1, LR- 0.64, 26 FP/TP, 629 NNS.

Conclusion

Second trimester sonographic cervical length can identify women at high risk of sPTB. In a population of mainly white women and low prevalence of sPTB its diagnostic performance is at best moderate.

SUBMITTER: Kuusela P 

PROVIDER: S-EPMC7821210 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature