Valor predictivo de la longitud cervical medida después de las 24 semanas para el parto prematuro espontáneo:...

This study aimed to investigate the differences in transvaginal cervical length (TVCL) after 24⁺⁰ weeks of gestation between women with spontaneous preterm birth (SPTB) and term birth and the predictive accuracy of third trimester TVCL in the prediction of SPTB among asymptomatic women.

A systematic search of published literature was performed in PubMed, MEDLINE, and the Cochrane Library through June 2025. There was no language restriction.

Cohort or cross-sectional studies reporting on TVCL measurements after 24⁺⁰ week of gestation in asymptomatic women with both SPTB and term births that allowed the construction of 2 x 2 contingency tables were included. We excluded abstracts, studies with duplicated data, symptomatic women, twin pregnancies, or transabdominal cervical length measurement. (PROSPERO registration number: CRD42024538449) Study appraisal and synthesis methods: T.S.T.A. and T.Y.P.C searched for and selected studies independently. Newcastle-Ottawa Scale was used to evaluate the quality of the included studies. Mean differences in TVCL measurements between SPTB and term populations were calculated using the inverse variance method with the random-effects model. Subgroup analyses on gestational age, TVCL measurement technique, populations and type of cohort studies were performed. Predictive accuracy of various TVCL cut-offs were evaluated using the DerSimonian-Laird random-effects model. Youden index was calculated to identify the optimal TVCL cut-off.

A total of 3641 published articles were identified and 16 studies consisting of 26776 pregnancies met the inclusion criteria. All studies excluded iatrogenic PTB. Women with SPTB had a significantly shorter TVCL at 24⁺⁰ to 28⁺⁶ weeks (<37 weeks: MD=-5.47, 95% CI=-7.52 to -3.43, p<0.001; <34 weeks: MD=-7.85, 95% CI=-10.33 to -5.37, p<0.001) and 27⁺⁰ to 32⁺⁶ weeks (<37 weeks: MD=-4.41, 95% CI=-6.45 to -2.36, p<0.001; <34 weeks: MD=-7.75, 95% CI=-10.55 to -4.94, p<0.001), compared to women with term birth. The TVCL at 31⁺⁰ to 36⁺⁶ was comparable between the two groups (<37 weeks: MD=-4.71, 95% CI=-10.13 to 0.72, p=0.09). These observations were consistently seen among women with or without risk factors of SPTB, and irrespective of the TVCL measurement method. A TVCL cut-off of 25.5-26.0mm after 24⁺⁰ weeks had the highest positive likelihood ratio of 7.75 to predict SPTB, with pooled sensitivity of 0.74, specificity of 0.92, negative likelihood ratio of 0.31 and diagnostic odds ratio of 28.1 CONCLUSIONS: Women with SPTB had a significantly shorter TVCL after 24⁺⁰ weeks of gestation, compared to those who delivered at term. A cut-off of 25.5mm between 24⁺⁰ and 32⁺⁶ weeks may be used to identify women at risk of SPTB.