Reproducibility of the first trimester uterine artery Doppler indices: comparing the transabdominal and the transvaginal approach.

Reproducibility of first trimester uterine dopplers

Abstract

Purpose: to assess the reproducibility of the uterine Doppler pulsatility index (UA-PI) in the first trimester using the transabdominal (TA) and the transvaginal (TV) approach.

Materials and Methods: prospective study in singleton pregnancies presenting at 11-13 weeks for routine assessment. The UA-PI was measured independently by two experienced sonographers transabdominally and transvaginally according to the ISUOG guidelines. The two techniques were evaluated with the computation of the intra-class correlation coefficients (ICC) for random effects models and the limits of agreement (LOA).

Results: 221 pregnancies were examined. Mean Ut-PI was 1.63 by TA and 1.66 by TV ultrasound scan. No significant paired differences were found between TA and TV measurements (p>0.05) and ICC were over 0.8 in all comparisons (p<0.001) among the two techniques.

The intra-observer ICC ranged from 0.87 to 0.96 and the inter-observerICC ranged from 0.82 to 0.91. ICC for intra and inter-observer variability was not influenced by maternal BMI for TA nor TV measurements. LOA between operators ranged between -0.7 and 0.7.

Conclusion: UA-PI shows moderate to good intra and inter-observer variability which is not influenced by the technique or the maternal characteristics. No significant difference was observed between the TA and TV, indicating that both techniques can be used for screening purposes.