Re: outcome of pregnancy in chromosomally normal fetuses with increased nuchal translucency in the first trimester

Pregnancy outcome of euploid fetuses with increased nuchal translucency: how bad is the news?

AIMS

The number of fetuses with an abnormal increased first trimester nuchal translucency (NT), but confirmed normal karyotype and anatomy is relatively small and therefore a challenge for prenatal counseling. Universal guidelines are still needed for a systematic work-up, how to decide on the rewarding cut-off for this policy as well as how to counsel patients with an increased NT but with euploid fetuses. The current review aims to address some of these issues.

RESULTS

Eleven studies reporting on the pregnancy outcome of 2,128 euploid fetuses with increased NT (>or=3 mm or >or=95 centile) were retrieved by our previously reported literature search. 2.2-10.6% of the fetuses has miscarried and 0.5-15.8% ended in perinatal death. There was an overall rate of 0.5-13% neurodevelopmental problems, and 2-8% of the malformations were undiagnosed before birth, the most common being cardiac anomalies. Nevertheless, 70-90% fetuses had normal outcomes.

CONCLUSION

For those euploid fetuses with increased NT>2 MoM or >or=1.5 mm delta NT we recommend a detailed two-step anomaly scan including midgestation fetal echocardiography. Maternal age as well as data on relevant family history and persistence of nuchal edema provides additional relevant information for counseling and planning pregnancy management.

The clinical evaluation and pregnancy outcome of euploid fetuses with increased nuchal translucency

This review aims to address the systematic work-up and counseling throughout pregnancies with increased nuchal translucency (NT) in euploid fetuses. Original articles from peer-reviewed English-language journals between 1997 and 2003 were studied. They all included descriptions of pregnancy outcomes of euploid fetuses with increased NT. Eleven studies reporting on the pregnancy outcome of 2128 euploid fetuses with increased NT (> or = 3 mm or > or = 95 centile) were retrieved by our literature search. A statistical analysis was conducted for assessing the consistency of effects across studies. The chi2 tests were applied to verify the homogeneity of the results from different series. A significant difference was found between the studies even when the results were analyzed separately according to various NT cutoff levels (i.e. > or = 3 mm, > or = 3.5-4 mm, and > or = 95 centile). These discrepancies suggest that those studies are significantly different and therefore, cannot be combined for meta-analysis. Of all the reported series, 2.2-10.6% of the fetuses have miscarried and 0.5-15.8% ended in perinatal death. There was an overall rate of 0.5-12.7% neurodevelopmental problems, and 2.1-7.6% of the malformations which were undiagnosed before birth. Importantly, 70-90% fetuses had normal outcomes. A detailed two-step anomaly scan including midgestation fetal echocardiography should be part of perinatal management of pregnancies with increased fetal NT. Data on relevant family history and persistence of nuchal edema provide additional relevant information for planning pregnancy management.

Comparison of pregnancy outcome of euploid fetuses with increased nuchal translucency (NT) expressed in NT MoM or delta-NT

OBJECTIVE

To evaluate the outcome of euploid fetuses with increased nuchal translucency thickness (NT) expressed in multiples of the median (MoM) or delta-NT.

METHODS

Included in the study were euploid fetuses with increased NT >or= 95(th) centile, for which information about pregnancy outcome was available. The following parameters were defined as an adverse outcome: miscarriage, structural anomalies justifying termination of pregnancy, and structural anomalies, genetic syndromes and neurodevelopmental problems diagnosed postnatally. Fetal outcome according to NT MoM and delta-NT was calculated using different cut-off values. Calculations of the odds ratio for adverse outcome were performed using either NT MoM or delta-NT as a predictor in logistic regression models.

RESULTS

The study comprised 168 euploid fetuses. Of these, 38 (23%) had an adverse outcome: 11 (6%) had miscarriages, 14 (8%) were terminated because of fetal abnormalities detected on the prenatal scan and 13 (7%) were found postnatally to have abnormalities. The incidence of cases exhibiting an adverse outcome was 5.3%, 19.2% and 58.5% for NT values of 1.6-1.9, 2.0-3.0 and >3.0 MoM, respectively (P < 0.0001, chi(2) test), and 3.9%, 16.7% and 62.8% for delta-NT values of 1.0-1.4, 1.5-2.5 and >2.5 mm, respectively (P < 0.0001, chi(2) test). Using cut-offs of 2.0 MoM and delta-NT of 1.5 mm, the odds ratios for adverse outcome were 10.2 (95% CI, 3.4-30.4) and 15.4 (95% CI, 4.2-43.6), respectively.

CONCLUSION

Both the NT MoM and delta-NT approaches may be used to determine cases which require additional antenatal investigation as well as fetal karyotyping. For this purpose we suggest using a cut-off of either 2.0 MoM or a delta-NT of 1.5 mm.