Second-trimester soft markers: relation to first-trimester nuchal translucency in unaffected pregnancies
Article first published online: 10 FEB 2012
Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.
Ultrasound in Obstetrics & Gynecology
Volume 39, Issue 3, pages 274–278, March 2012
How to Cite
Miguelez, J., De Lourdes Brizot, M., Liao, A. W., De Carvalho, M. H. B. and Zugaib, M. (2012), Second-trimester soft markers: relation to first-trimester nuchal translucency in unaffected pregnancies. Ultrasound Obstet Gynecol, 39: 274–278. doi: 10.1002/uog.9024
- Issue published online: 27 FEB 2012
- Article first published online: 10 FEB 2012
- Accepted manuscript online: 12 APR 2011 03:53AM EST
- Manuscript Accepted: 1 APR 2011
- Down syndrome;
- nuchal translucency;
- sequential screening;
Genetic sonography following first-trimester combined screening appears to increase substantially detection rates for Down syndrome but it relies on the unproved assumption of independence between these tests. In this study we aimed to investigate the relationship between first-trimester nuchal translucency (NT) and a series of second-trimester soft markers and structural defects in unaffected pregnancies.
NT measurement in the first trimester was followed by second-trimester scan (18 to 23 + 6 weeks) including examination for three categorical markers (intracardiac echogenic foci, hyperechogenic bowel and structural defects) and measurement of nasal bone length, nuchal-fold thickness, femur length, humerus length, renal pelvis diameter and prenasal thickness. All continuous variables were expressed in multiples of the median (MoM) for gestation and correlation coefficients between log-transformed NT and second-trimester variables were calculated. In addition, frequencies of soft markers and structural defects in cases with increased NT were compared to those with normal NT, using MoM cut-offs.
In a dataset of 1970 cases, NT was significantly correlated (P < 0.05) with all second-trimester continuous variables, the correlation being strongest for nuchal-fold thickness (r = 0.10). There was a higher frequency of cases with second-trimester nuchal-fold thickness above the 97.5th centile (10.7 vs. 2.2%) and hyperechogenic bowel (2.4 vs. 0.1%) in cases with increased NT.
Straightforward reassessment of risk using likelihood ratios derived from the second-trimester genetic sonogram might lead to inaccurate estimates. Multivariate models using continuous second-trimester variables might be preferable in sequential screening strategies. Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.