Obstet Gynecol Sci.  2013 Sep;56(5):307-311.

Simplified protocol of nuchal translucency measurement: Is it still effective?

• Kim SM
• Jun JK

Abstract

OBJECTIVE
Nuchal translucency (NT) is the most powerful screening tool for Down syndrome and congenital cardiac anomaly, therefore strict guidelines were established to get accurate NT values. However, to stick to the guideline in all pregnant women is time-consuming and superfluous in majority of low risk population. We undertook this study to investigate whether the simplified protocol enables to select low risk group and is effective in them even if we skip the suggested NT measurement.
METHODS
NT and crown-rump length (CRL) were measured prospectively. First, CRL was measured in the ordinary view that was mid-sagittal section of fetus in neutral position, and NT was measured at the same frozen screen (first measured value, 1MV). Then, NT was measured again according to the Fetal Medicine Foundation (FMF) guideline (second measured value, 2MV).
RESULTS
There was good correlation between 1MV and 2MV in each case (r = 0.83, P < 0.001). All of the NT values over the 95th percentile in 2MV also belonged to over the 95th percentile in 1MV. NT value of 2 mm in 1MV could be used as a cut-off to obtain over the 95th percentile 2MV by receiver operating characteristic curve (sensitivity 100%, specificity 80.5%). The proportion of 1MV > or = 2 mm was only 23.8% of all cases, namely we had only to measure 2MV in 23.8% patients. Every 95th percentile or more 2MV could be detected with this simplified protocol.
CONCLUSION
If NT is less than 2 mm at ordinary CRL view, we may skip suggested NT measurement according to FMF guideline.

Keyword

Nuchal translucency measurement; Simplification

MeSH Terms

Crown-Rump Length
Down Syndrome
Female
Fetus
Humans
Mass Screening
Nuchal Translucency Measurement
Pregnant Women
Prospective Studies
ROC Curve
Sensitivity and Specificity

Figure

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  Fig. 1 Measurement of the (A) first measured value (1MV) and (B) second measured value (2MV). (A) The 1MV was measured in the ordinary view for measurement of crown rump length. (B) The 2MV was measured according to the Fetal Medicine Foundation guideline.

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  Fig. 2 Receiver operating characteristic curve that describes the performance of the first measured value in the identification of the 95th percentile or more second measured value (area under curve, 0.98; standard error, 0.011; P<0.001).

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