Sequential cervical length screening in pregnancies after loop excision of the transformation zone conisation: a retrospective analysis

Objective To review our experience with a screening programme that included four sequential cervical length (CL) measurements from 16 to 22 weeks of gestation. Design Historical cohort study. Setting Tertiary‐care centre in a university hospital. Population There were 312 singleton pregnancies in 321 women with a previous large loop excision of the transformation zone (LLETZ), and 62 pregnancies after a second‐trimester miscarriage in a previous pregnancy. Methods The CL measurements were performed by transvaginal ultrasound at 16, 18, 20, and 22 completed weeks of gestation. Main outcome measures Early preterm delivery before 34 completed weeks of gestation. Results Early preterm delivery was found in 7.4%. The CL at 16 completed weeks of gestation was smaller in the LLETZ group (36 mm, interquartile range 30–40 mm) compared with the control group (38 mm, interquartile range 32–42 mm; P = 0.040). For the analysis of risk factors for early preterm delivery after LLETZ, only cases with a complete data set were included (n = 145). In a multivariate analysis, two parameters remained significantly predictive, with CL at 16 completed weeks of gestation being the most significant measure (P