Fetal transcerebellar diameter nomogram in singleton gestations with special emphasis in the third trimester: a comparison with previously published nomograms.
OBJECTIVE
This study was undertaken to construct an institution-specific transverse cerebellar (transcerebellar) diameter nomogram with special emphasis in the third trimester and to compare its ability to predict gestational age with previously published nomograms.


METHODS
A cross-sectional nomogram was constructed using transcerebellar diameter measurements in 24,026 well-dated singleton fetuses by using linear regression models. Third-trimester measurements from 2,010 fetuses were included. The performance of previously established transcerebellar diameter nomograms for predicting gestational age was assessed in our population to determine comparability between nomograms.


RESULTS
Interobserver and intraobserver variabilities in the second and third trimesters were 3.1% to 3.7% and 3.4% to 3.8%, respectively. Between 14 and 27 weeks' gestation, there were no clinically important differences between our nomogram and those previously published in terms of the predicted gestational age. However, predicted gestational age in the third trimester was considerably different by using our nomogram by 1 to 2 weeks from 28 to 30 weeks and by 4 to 6 weeks after 32 weeks.


CONCLUSIONS
Transcerebellar measurements had a similar relationship with gestational age across previously published nomograms before 28 weeks. However, clinically significant differences in predicting gestational age appear later, especially after 32 weeks. These findings suggest that this new nomogram may be particularly useful for accurate dating of pregnancies in the third trimester.
Division of Maternal-Fetal Medicine, Department of Obstetrics, Gynecology and Reproductive Sciences, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School/Saint Peter's University Hospital, New Brunswick, NJ, USA.
Martin R
MR
Chavez
Cande V
CV
Ananth
John C
JC
Smulian
Susan
S
Lashley
Eftichia V
EV
Kontopoulos
Anthony M
AM
Vintzileos
D002531:Cerebellum / Q000196:embryology*; D005260:Female; D005865:Gestational Age; D006801:Humans; D015588:Observer Variation; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011263:Pregnancy Trimester, Third; D012015:Reference Standards