The value of fetal trans cerebellar diameter in detecting GA in different fetal growth patterns in Egyptian fetuses

Table 3: Doppler ultrasound velocimetry indices of UA and MCA in included women.

TABLE 4 demonstrated that from 60 women, 4 (6.6%) had fetal Dandy-Walker Malformation, 1 (3.3%) had echogenic foci in right and left lateral ventricles and 1 (3.3%) had mild bilateral hydronephrosis (TABLE 5 and FIGURE 1).The case with Dandy-Walker malformation was excluded from subsequent analyses.

Table 4: Rates of IUGR and macrosomia in included women.

Table 5: Congenital malformation in included women.

TABLE 6 shows differences between discrepancies between menstrual gestational age and sonographic estimation of gestational age using different fetal biometry in included women.

Table 6: Sonographic fetal biometry in included women.

The IQR of the discrepancy between menstrual and sonographic gestational ages was the least when TCD, in comparison to BPD, HC, AC and FL (0.43 mm, 1.27 mm, 1.0 mm, 1.56 mm and 1.28 mm, respectively). The difference, however, was statistically significant only when compared to that using AC.

TABLE 7 shows the correlation between fetal biometry, gestational age and Doppler ultrasound velocimetry indices of UA and MCA.

Table 7: Correlation between fetal biometry, gestational age and Doppler ultrasound velocimetry indices in included women.

TCD was significantly positively correlated to menstrual gestational age, but not to any of the measured Doppler velocimetry indices of UA and MCA.

Discussion

Previous research studies that are performed on TCD measurements evaluation, clearly displayed and showed that TCD was a reliable trusted tool of measurement to calculate the fetal gestational age, it is widely believed to be superior in reliability than HC, FL, BPD and AC when comes to precision of calculating fetal gestational age. It could be even to considered an accurate, dependable and reliable tool of measurement assisting formulas used to settle on fetal gestational age in both singleton and twin gestation [20,21].

The IQR of the discrepancy between menstrual and sonographic gestational ages was the least when TCD, in comparison to BPD, HC, AC and FL [(0.43 mm, 1.27 mm, 1.0 mm, 1.56 mm and 1.28 mm, respectively). The diversity of measurements, however, was statistically significant only when correlated to that using AC [10].

So, from our research results and data obtained, we settled and concluded that the most, reliable, precise showing superiority in accurate analysis and assessment of fetal gestational age was the TCD followed by the HC then the BPD followed by the FL and the least precise tool of calculating fetal gestational age was AC this finding is similar to other research studies which strengthens and augments our research study findings and results reliability [11,14].

Previous research uncovers the linkage between GA and TCD to evaluate predictability of GA by TCD causing increased clinical reliability and trust to use TCD measurements.

TCD was obtained from a total of two hundred and twenty one fetuses with a defined GA. The research showed that TCD matched with GA and expected the GA to ± 2.33 weeks [15,16].

Another research applied on 50 patients made from the start of the 2^nd trimester till term of pregnancy. TCD measurement was done to determine the gestational age. The regression analysis indicated a significant relationship between TCD and GA, concluding that TCD is a useful and a precise tool for the estimation of GA [3].

Another study stated that there was a slight fluctuations and variability in the normal growth curves of the fetal cerebellum, denoting multiple conditions that would result in difficulties in measuring the TCD in late gestations, so we also analyzed the data at the 31 and 36 weeks of gestation. This explores and uncovers the outstanding value of our study in which cerebellar fetal growth is restricted in the study in a limited gestational age period of 5 weeks among Egyptian population .Thereby reducing confounding variables caused by ethnic and racial differences.

Another group of researchers observed and conducted a research study to precisely evaluate and explore clinical reliability and precision to reflect in a professional means the accuracy of fetal transcerebellar diameter normogram in the evaluation and sonographic assessment for guidance and prediction of gestational age in singleton gestation at the second and the third trimesters of singleton pregnancy. Revealing that the TCD measurement appears to be an accurate measurement aiding in calculation of the fetal gestational age, even in the third trimester of pregnancy. It is was recommended to use TCD as a biometric parameter in normal singleton for the prediction of gestational age [15,16].

A retrospective, cross-sectional analytic study of normally developing fetuses in the from 17 to 34 weeks and 73 fetuses with IUGR between 24 and 34 weeks gestation was done, researchers found that the TCD measurements are spared in cases of IUGR [14].

Another study conducted to expose the significance of fetal transverse cerebellar diameter measurement for the prediction of gestational age in growth restricted fetuses. The study sample size was applied on 100 mothers in the third trimester fulfilling the eligibility criteria, 50 were fetuses with normal fetal growth and fifty fetuses with IUGR. The data extracted from this research study demonstrated that the mean transverse cerebellar diameter in the fetuses showing normal growth was not statistically different from the mean transverse cerebellar diameter of that in the growth restricted fetus. They stated that fetal TCD measurements seem to link well with the gestational age in both normal and growth restricted fetuses as there was no statistically considerable difference in TCD measurements in normal and growth restricted fetuses. Transverse cerebellar diameter measurement could be used reliably for accurate calculation of gestational age in growth restricted fetuses [10].

Another group of researchers stated that TCD measurement was both reliable and accurate in determining gestational age even in extremes of fetal growth. While majority of data suggests that the TCD is extremely valuable when the gestational age is unknown or IUGR is suspected [3].

Another study displayed that the TCD was within two standard deviations in only 40% of IUGR cases, nevertheless they included only 44 IUGR fetuses and symmetrical IUGR were not excluded [3].

Some studies stated that the TCD was a useful sonographic measurement aiding in calculation and predicton of gestational age for fetuses with asymmetric but not symmetric growth retardation [6].

Previous research has uncovered a close correlation between cerebellar dimensions and GA using fetal growth parameters including BPD, head circumference, FL, and estimated fetal weight, this relationship had been found to be independent on fetal gender [7-16].

Correlation of the cerebellar circumference and area with GA and illustration of its usefulness in cases of unilateral cerebellar agenesis and hypoplasia was established in a study done in 2007. Accordingly, measurement of cerebellar dimensions, including the TCD might be a useful guidance in detecting cerebellar malformations, if nomograms of TCD were accessible for a selected population [5].

In our present research study, our results obtained displayed that the transcerebellar diameter is the nearly the most precise measurement in accurately detecting the GA in all means during gestation (in uncomplicated pregnancies, in hypertension with pregnancy and in pre-eclamsia associated with either symmetrical or a symmetrical IUGR, also in pregnant diabetic women with fetuses showing macrosomia in which all parameters of fetal biometry obtained are above the normal average range of measurements for gestational age (i.e., above the 95th percentile for GA) and in pregnancies having morphological abnormalities other than cerebellar anomalies. The only exceptional situation in the accuracy of transcerebellar diameter measurement in which TCD is not considered precise with low value of accuracy as it has a value less than average in cases of structural abnormalities of the cerebellum (e.g. Dandy Walker malformation).

All our data and findings were fulfilled by the Doppler study of the umbilical and Middle cerebral artery formulas that deep-rooted normal uteroplacental circulation that displayed and clearly revealed normal PI and RI numerical values of umbilical and MCA Doppler or uteroplacental insufficiency in clinical situations of pregnancy induced hypertension, preeclampsia and IUGR that showed amplified PI and RI numerical values of umbilical artery Doppler above the 95th percentile for gestational age and showed pathologically reduced PI and RI values of MCA Doppler below the 5th centile for GA.

Conclusion

From our Research we concluded that (TCD) measurement is a precise parameter in accurately calculating fetal gestational age as it comes in preference to other fetal biometric measurements (BPD, HC, AC, FL) which are classically used in pregnant women with no medical disorders and also our research revealed the high value and precision superiority of the TCD measurement in cases where other biometric parameters are altered causing false sonographic estimation of the GA as in hypertensive gestations that have IUGR fetuses, diabetic mothers with macrosomic fetuses and in fetuses with congenital abnormalities but the only drawback of TCD measurement is in presence of cerebellar abnormalities as it becomes pathologically small and not a precise tool for calculation and estimation of fetal gestational age.

Therefore after conducting the present research we concluded that TCD is the most accurate biometric measurement in both uncomplicated pregnancies and in complicated pregnancies with medical disorders such as D.M and hypertension especially when associated with macrosomic or IUGR fetuses and in structural abnormalities affecting organs other than cerebellum as the cerebellar growth is not affected by these circumstances. Moreover, dating of pregnancy can be made depending on the TCD in pregnant women with unsure of their dates as it is not affected by hypertension or diabetes mellitus or any growth disturbances. But the only pitfall of TCD measurement expected before beginning the study is in existence of cerebellar abnormalities as it becomes small and not accurate with GA.

State of Declaration

All authors declare that there are no any financial and personal relationships with other people or organizations that could inappropriately influence (bias) their work.

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