The effects of maternal and fetal parameters on the quality of nuchal translucency measurement

United States' experience in nuchal translucency measurement: variation according to provider characteristics in over five million ultrasound examinations

OBJECTIVE

The Nuchal Translucency Quality Review (NTQR) program has provided standardized education, credentialing and epidemiological monitoring of nuchal translucency (NT) measurements since 2005. Our aim was to review the effect on NT measurement of provider characteristics since the program's inception.

METHODS

We evaluated the distribution of NT measurements performed between January 2005 and December 2019, for each of the three primary performance indicators of NT measurement (NT median multiples of the median (MoM), SD of log₁₀ NT MoM and slope of NT with respect to crown-rump length (CRL)) for all providers within the NTQR program with more than 30 paired NT/CRL results. Provider characteristics explored as potential sources of variability included: number of NT ultrasound examinations performed annually (annual scan volume of the provider), duration of participation in the NTQR program, initial credentialing by an alternative pathway, provider type (physician vs sonographer) and number of NT-credentialed providers within the practice (size of practice). Each of these provider characteristics was evaluated for its effect on NT median MoM and geometric mean of the NT median MoM weighted for the number of ultrasound scans, and multiple regression was performed across all variables to control for potential confounders.

RESULTS

Of 5 216 663 NT measurements from 9340 providers at 3319 sites, the majority (75%) of providers had an NT median MoM within the acceptable range of 0.9-1.1 and 85.5% had NT median MoM not statistically significantly outside this range. Provider characteristics associated with measurement within the expected range of performance included higher volume of NT scans performed annually, practice at a site with larger numbers of other NT-credentialed providers, longer duration of participation in the NTQR program and alternative initial credentialing pathway.

CONCLUSIONS

Annual scan volume, duration of participation in the NTQR program, alternative initial credentialing pathway and number of other NT-credentialed providers within the practice are all associated with outcome metrics indicating quality of performance. It is critical that providers participate in ongoing quality assessment of NT measurement to maintain consistency and precision. Ongoing assessment programs with continuous feedback and education are necessary to maintain quality care. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Fetal heart assessment in the first trimester of pregnancy: influence of crown-rump length and maternal body mass index

OBJECTIVE

To evaluate the influence of the crown-rump length and body mass index on sonographic evaluation of the fetal heart using abdominal and vaginal routes in the first trimester of pregnancy.

METHODS

We conducted a cross-sectional study with 57 pregnant women between 12-14 weeks (CRL< 84 mm). We evaluated the following fetal cardiac plans using the abdominal and vaginal routes: four-chamber view, right ventricle outflow tract, left ventricle outflow tract and aortic arch. We used the B-mode, color Doppler and four-dimensional ultrasonography (spatio-temporal image correlation). To evaluate the influence of crown-rump length and body mass index in the assessment of fetal cardiac planes, we used the t test unpaired.

RESULTS

There were no statistically significant differences in the rates of success and failure between abdominal and vaginal routes in relation to body mass index, however, there was a higher failure rate in vaginal assessment using B mode associated with color Doppler (P<0.01).

CONCLUSION

The crown-rump length and body mass index had no interference in fetal cardiac assessment in the first trimester of pregnancy.

Quality of nuchal translucency measurements in multifetal pregnancies

OBJECTIVE

A prospective comparative study was conducted to investigate the effect of multifetal pregnancies on the quality of nuchal translucency measurements using an image scoring method.

METHODS

The study sample included 72 consecutive multiple gestations (164 fetuses) and 195 singleton gestations (control) matched for maternal age and fetal crown-rump length. Nuchal translucency ultrasound was performed similarly in singleton and multiple pregnancies. A single sonographer scored an elected ultrasound image of each fetus according to a nuchal translucency image scoring method and the mean image score was compared between the whole singleton and multiple gestation groups and between subgroups defined by fetal distance from the abdominal wall.

RESULTS

There was no significant difference in mean image score between the multiple and singleton gestation groups (6.60 +/- 1.3 and 6.69 +/- 1.5, respectively; p = 0.595). Within the multiple gestation group, there was a significant difference in mean score between fetuses positioned proximal to the abdominal wall (n = 72) (3.7 +/- 1.1) and both the middle fetuses (6.2 +/- 1.4; p < 0.01) and distal fetuses (5.7 +/- 1.06; p < 0.008). There was no difference between the proximal fetuses and controls.

CONCLUSIONS

The fetuses in multiple pregnancies that are located further from the abdominal wall have a poorer image score.

Optimal crown-rump length for measuring the nuchal translucency

PURPOSE

To determine the optimal crown-rump length (CRL) for obtaining nuchal translucency (NT) measurements.

METHODS

Women undergoing NT measurements by NT-certified sonographers within a combined screening program over an 18-month period were included in the study if they had a living fetus with a CRL of 45-84 mm. NT measurement success and screen-positive rates, transvaginal sonography (TVUS) use, and reasons for failed NT measurements were compared in 3 groups by CRL corresponding to 11-0/7 to 11-6/7 weeks (45-54 mm), 12-0/7 to 12-6/7 weeks (55-66 mm), and 13-0/7 to 13-6/7 weeks (67-84 mm).

RESULTS

Eight hundred thirty-seven women aged 34.9 +/- 4.9 years underwent 1 to 3 NT measurements at a mean CRL of 59.8 +/- 25.0 mm. NT measurements were more successful at 11 and 12 weeks (81.8% and 84.4%) than at 13 weeks (66.9%) (p < 0.001). Screen-positive and TVUS rates, and reasons for failed NT measurements did not vary by CRL.

CONCLUSION

NT measurements are most successful at CRL 45-66 mm corresponding to sonographically determined gestational ages of 11-0/7 to 12-6/7 weeks.