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Developing a quality assurance program for transvaginal cervical length measurement at 18-21 weeks' gestation
Casey Filce1, Jon Hyett1, Daljit Sahota2
1Discipline of Obstetrics, Gynaecology and Neonatology, Faculty of Medicine, University of Sydney, Sydney, New South Wales, Australia.
Insights
This study established an Australian reference range for transvaginal cervical length (TVCL) measurements in mid-trimester pregnancies. A quality assurance tool was also validated to ensure accurate ultrasound assessments for predicting preterm birth risk.
Area of Science:
- Obstetrics and Gynecology
- Medical Imaging
- Biostatistics
Background:
- Preterm birth is a leading cause of mortality in children under five.
- Transvaginal cervical length (TVCL) assessment during mid-trimester scans aids in predicting preterm delivery risk.
- Establishing quality standards is crucial for optimizing TVCL as a screening tool.
Purpose of the Study:
- To develop an Australian reference range for TVCL measurements between 18.0 and 21.0 weeks' gestation.
- To establish quality standards for TVCL measurement.
- To create audit mechanisms for ultrasound operators.
Main Methods:
- Retrospective audit of 1031 consecutive patient scans at 18.0-21.0 weeks' gestation.
- Exclusion of images based on defined quality criteria.
- Application of fractional polynomial Bayesian methodology to establish the reference range and a quality assurance audit tool.
Main Results:
- A median TVCL of 36.0 mm (IQR 32.7-40.0 mm) was determined, independent of gestational age.
- The quality audit tool demonstrated efficacy in a validation cohort, with 90.9% of operators showing acceptable central tendency and 86.4% within the appropriate cumulative sum zone.
Conclusions:
- An Australian reference range for TVCL at 18.0-21.0 weeks' gestation has been successfully developed.
- A validated quality assurance audit tool for ultrasound operators has been created to ensure measurement accuracy.
Background:
Preterm birth is the leading cause of death in children under the age of five years. Transvaginal cervical length (TVCL) assessment can be used to predict preterm delivery risk at the mid-trimester scan. To optimise the screening tool, developing and maintaining quality standards is important.
Aims:
To develop an Australian reference range for TVCL at 18.0-21.0 weeks' gestation, quality standards for measurement and audit mechanisms for ultrasound operators.
Materials And Methods:
A retrospective audit was performed of consecutive patients scanned at 18.0-21.0 weeks' gestation. Each TVCL measurement ultrasound image was reviewed, and exclusions were made based on a defined set of quality criteria. Fractional polynomial Bayesian methodology was used to establish a reference range. Central tendency, dispersion plots and cumulative sum charts for operators in the original reference range cohort were created. These plots were then applied to a second validation cohort of operators to establish the efficacy of this quality assurance audit tool.
Results:
Median TVCL from 1031 participants was 36.0 mm (interquartile range 32.7-40.0 mm), which was independent of gestational age. The quality audit tool was applied to 15 operators from the reference cohort with a mean cervix length multiple of the median of 1.01 and a mean SD log10 cervix length multiple of the median of 0.06. Of the 22 operators in the validation cohort, 20 (90.9%) demonstrated ideal or acceptable central tendency results, and 19 (86.4%) remained in the appropriate cumulative sum zone.
Conclusion:
An Australian cervix length measurement reference range at 18.0-21.0 weeks' gestation has been developed along with a validated quality assurance audit tool for ultrasound operators.
