This has implication for prenatal diagnosis in Nigeria.
Keywords: Crown-rump length; dating; gestational age How to cite this URL: Oboro VO, Bello TO, Oyeniran AO.
To achieve this we conducted a retrospective cross-sectional study at the obstetrics unit of our institution.
The hospital records of 322 pregnant women who presented for early booking in the first trimester were reviewed.
The accuracy of the formula was compared with that of existing formula in another data set of 88 fetuses.
Results: The scatter plot yielded a best-fit equation for the estimation of GA (in weeks) from CRL (in mm) as GA=−0.0008 (CRL2) 0.168 CRL 5.397, (R2=0.8017).
The three established formulae referenced were Korean (GA = 51.008 0.6 × CRL).
The performance of our best-fit model and derived formula was then tested against those of the three published CRL dating formulae in the new set of patients which are as follows: The menstrual age for each fetus was compared with the GA calculated using the three established formulae and the locally derived formula, and the mean difference in estimated GA was used to quantify the systematic prediction error (the error that could be expected in the best "point" estimate of GA for a given CRL).
The long axis of the fetus in mid-sagittal position was measured from the crown of the head to the end of the trunk (rump) with the aid of the onscreen callipers.
We performed a polynomial linear regression to study the relationship between the Expected Gestatational Age (EGA) (in weeks) and CRL (in mm), and derived a mathematical formula for predicting the EGA in weeks from the CRL.
This formula is: GA = −0.0008 (CRL) = 0.8017) [Figure 1].
The scatter plot of the raw data for the best-fit fractional polynomial regression model showing the estimated GA by CRL expressed in days and mm, respectively, for the first group of 322 subjects is shown in [Figure 1].
The best-fit equation for the estimate of GA for a given CRL was GA = -0.0008 (CRL) = 0.8017).