- Publication date : 2017-10-04
Drouin O, Johnson JA, Chaemsaithong P, Metcalfe A, Huber J, Schwarzenberger J, Winters E, Stavness L, Tse AWT, Lu J, Lim WT, Leung TY, Bujold E, Sahota D, Poon LC. The transverse technique; a complementary approach to the measurement of first-trimester uterine artery Doppler. Ultrasound Obstet Gynecol. 2017;:. doi: 10.1002/uog.18917. PubMed PMID: 28976627.
The objectives of this study were to 1) define the protocol for the first-trimester assessment of the uterine artery pulsatility index (UtA-PI) using the new transverse technique, 2) evaluate UtA-PI measured by the transverse approach versus that obtained by the conventional sagittal approach, and 3) determine if accelerated onsite training (both methods) of inexperienced sonographers can achieve reproducible UtA-PI measurements compared to that measured by an experienced sonographer.The study consists of 2 parts conducted in 2 centers (Part 1, Calgary, Canada and Part 2, Hong Kong). Part 1 Prospective observational study of women with singleton pregnancies between 11-13+6 weeks' gestation. UtA-PI measurements were performed using the 2 techniques (4 sonographers trained in both methods, 10 cases each) and measurement indices (PI), time required and subjective difficulty to obtain satisfactory measurements were compared. One sample t-test and Wilcoxon rank sign test was used when appropriate. Bland-Altman difference plots were used to assess measurement agreement, and intra-class correlation (ICC) was used to evaluate measurement reliability. A target plot was used to assess measures of central tendency and dispersion. Part 2 One experienced and three inexperienced sonographers prospectively measured the UtA-PI at 11-13+6 weeks' gestation in two groups of women (42 and 35, respectively), with singleton pregnancies using both approaches. Inexperienced sonographers underwent accelerated on-site training by the experienced sonographer. Measurement approach and sonographer order were on a random basis. ICC, Bland-Altman and Passing-Bablok analyses were performed to assess measurement agreement, reliability and effect of accelerated training.Part 1 We observed no difference in the mean time to acquire the measurements (Sagittal: 118 seconds vs Transverse: 106 seconds, p=0.38). The 4 sonographers reported the transverse technique was subjectively easier to perform (p=0.04). The bias (95% LOA) and the ICC between sagittal and transverse measurements was -0.05 (-0.48 to 0.37) and 0.94 for the mean UtA-PIs respectively. Measurements obtained using the transverse technique after correcting for gestation were significantly closer to the expected distribution than the sagittal technique. Part 2 There were no significant differences in the median UtA-PI measurements using the different approaches for both experienced and inexperienced sonographers (p>0.05 for all sonographers). Mean UtA-PI measurement reliability between approaches was high for the experienced (ICC=0.92) and inexperienced sonographers (ICC>0.81). UtA-PI measurement approaches did not deviate from linearity whilst biases ranged from -0.10 to 0.07. Median time required was similar (sagittal vs. transverse: 56.11 sec vs. 49.29 sec; p=0.054).This novel transverse approach for the measurement of UtA-PI in the first-trimester appears comparable to the sagittal approach and can be used in first-trimester preeclampsia screening. Providing accelerated onsite training can be helpful to improve UtA-PI measurement reliability and could potentially facilitate the broad implementation of first-trimester preeclampsia screening.