Can myometrial thickness/cervical length ratio predict preterm delivery in singleton pregnancies with threatened preterm labor? A prospective study.

Objective: To investigate whether myometrial thickness (MT) to cervical length (CL) ratio could be used in the prediction of preterm birth (PTB) in singleton pregnancies presented with threatened preterm labor (TPL).

Methods: After 48 h of successful tocolysis, MT was measured transabdominally from the fundal, mid-anterior walls and the lower uterine segment (LUS) in 46 pregnancies presented with TPL. MT measurements were divided into CL, individually. The main outcome was PTB before 37 weeks of gestation.

Results: The patients were divided into two groups as women delivered ≥ 37 weeks (38.68 ± 1.01 weeks) (n = 25) and those delivered < 37 weeks (34.28 ± 2.53 weeks) (n = 21). The mean ± SD CL in the preterm delivery group was significantly shorter than the term delivery group (23.77 ± 9.23 vs 29.91 ± 7.03 mm, p < 0.05). Fundal, mid-anterior or LUS MT values were similar in both groups. However, in those who delivered preterm, the ratios of fundal MT-to-CL (p = 0.026) and mid-anterior MT-to-CL (p = 0.0085) were significantly different compared to those delivered at term. The optimal cutoff values for CL, fundal MT-to-CL and mid-anterior MT-to-CL ratios in predicting PTB were calculated as 31.1 mm, 0.19 and 0.20, respectively. Fundal MT-to-CL ratio predicted preterm delivery with 71% sensitivity, 72% specificity, 68% positive and 75% negative predictive values. For mid-anterior MT-to-CL ratio, respective values were 76, 76, 73 and 79%.

Conclusion: Measurement of MT along with CL may offer a promising method in the management of women presented with TPL.