ULTRASONOGRAPHIC MEASUREMENT OF TRANSVERSE CEREBELLAR DIAMETER (TCD) IN ASSESSMENT OF GESTATIONAL AGE COMPARED TO FEMORAL LENGTH (FL) AND BIPARIETAL DIAMETER (BPD)

Dr. Rehana Afshan, Dr. Sabeeha Gul* and Dr. Mir Saiqa Shafi

ABSTRACT

Background: The study was done on pregnant women of gestational age of 16 weeks onwards. Routine antenatal USG scan included FL, BPD, AC, HC was used for estimation of gestational age with exception as in fetuses suffering from skeletal dysplasia or IUGR, which will have deformed appendicular skeleton. In those fetuses estimation of gestational age is not possible by FL, BPD hence TCD was measured. A strong correlation between gestational age estimated by gold standard (FL, BPD) and gestational age estimated by TCD was found. Aim: The study was conducted to measure the transverse cerebellar diameter (TCD) and compare it with femoral length (FL) and Biparietal diameter (BPD) in assessment of Gestational age, done on pregnant women of gestational age of 16 weeks onwards. Methods: We performed a cross sectional study done on 60 pregnant women with normal pregnancy, of normal singleton fetuses, 16 weeks onwards. The statistical method was of regression analysis and It was particularly useful in generating growth and dating curves for various foetal parameters. Differences in the estimation of BPD, TCD, and FL, TCD in prediction of gestational age were compared. At each given gestational age, the measurements were assessed. The difference between estimated measurements at each gestational age versus that of Hadlock was performed. Gestational age was estimated using FL and BPD. Then gestational age was estimated by TCD. All the three gestational age’s were compared separately. Gestational age derived from FL and TCD, gestational age derived from BPD and TCD. Statistical analysis revealed strong correlation between gestational age estimated by gold standard (FL,BPD) and gestational age estimated by TCD. Results: In every patient first Gestational age was calculated by measuring using femur length and biparietal diameter of foetus and then a Gestational age (gold standard method) was calculated by measuring the transverse cerebellar diameter of foetus. (experimental method) in order to determine whether these two methods can be used interchangeably or the new method can replace the established one and the bland altman graph was plotted. At the end the correlation was found out to be significant. Conclusion: TCD is a reliable parameter in estimation of Gestational age, and can be used alternatively in fetuses with IUGR or skeletal dysplasia where FL and BPD cannot give correct Gestational Age.

Keywords: TCD, Gestational age, IUGR, Skeletal dysplasia, FL, BPD.