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

Abstract

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 < 0.001, OR 0.90, 95% CI 0.83-0.98), followed by conception using IVF treatment (P = 0.031, OR 0.64, 95% CI 1.54-34.80).

Conclusions: Even as early as 16 weeks of gestation, women with early preterm delivery reveal a significantly lower CL than those without. Dynamics in the CL do not add to this information.

Keywords: Cervical length; conisation; loop excision of the transformation zone; prediction; preterm delivery; risk factor.