Ultrasound/Imaging
Poster Session 4
Sofie H. Breuking, MD
Amsterdam UMC, location AMC
Amsterdam, Noord-Holland, Netherlands
Charlotte E. van Dijk, MD
Amsterdam UMC, location AMC
Amsterdam, Noord-Holland, Netherlands
Annabelle L. van Gils, MD (she/her/hers)
Amsterdam UMC, location AMC
Amsterdam, Noord-Holland, Netherlands
Maud D. van Zijl, MD
Amsterdam UMC, location AMC
IJsselstein, Utrecht, Netherlands
Brenda M. Kazemier, MD, PhD
Wilhelmina's Children Hospital
Utrecht, Utrecht, Netherlands
Eva Pajkrt, MD, PhD, Prof. (she/her/hers)
Head of Obstetrics
Amsterdam UMC, location AMC
Amsterdam, Noord-Holland, Netherlands
Previous literature demonstrated that the use of a cut-off value may manipulate the distribution of cervical length(CL) measurements and introduce potential selection bias. Therefore, the objective of this study is to assess the distribution of CL using a cut off value for a short CL of ≤35mm.
Study Design:
This is a secondary analysis of the Quadruple P (QP) Screen study; a prospective cohort study that included low-risk women with singleton pregnancies undergoing fetal assessment at 18-22 weeks of gestation with a CL measurement. Women with a short cervix, defined as <35mm, were subsequently counseled for the QP trial; a multicenter randomized controlled trial that compared vaginal progesterone and cervical pessary in the prevention of preterm birth in women with a short cervix.
In this present study, normal distributions for CL were simulated based on mean and standard deviation (SD) of the original data. The Kolmogorov-Smirnov test was used to evaluate the distribution of the CL measurements.
Results:
The total cohort included 19.364 women who underwent CL measurement, with a total mean CL of 43.8mm (±8.1 SD). A total of 2031(10.5%) women had short cervix of ≤35mm. The observed distribution of all CL measurements was not normally distributed(P < 0.001; Figure 1A). When comparing the data to the simulated normal distribution, a decrease in the distribution of CL measurements was seen within the range of 26-35 mm. Conversely, CL measurements at ≤25 mm showed an increase compared to the normal distribution (Figure 1B).
Conclusion:
In line with previous literature, we did find the use of a cut-off value for a short CL influences the CL distribution. The increase in CL measurements at ≤25mm appears to be influenced by the cut-off value for treatment with progestogens, while the measurements ≤35mm is influenced by the cut-off value for study eligibility. This study highlights the risk of selection bias and importance of measuring CL with caution when essential decisions are depending on a specific cut-off value for the CL.