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Suitability of obstetric ultrasonographic parameters in determining gestational age derived by last menstrual period.

TT Marchie
E Ogbeide


Objective: A prospective study aimed at assessing the suitability of Biparietal Diameter (BPD), Femoral Length (FL), Transverse abdominal Diameter (TAD) and Composite value by ultrasonography, in determining foetal or gestational age derived by last menstrual period (LMP) in our environment was undertaken. METHOD: Random sample selection of consenting 360 pregnant women attending the antenatal clinic of NNPC Warri referred for routine ultrasonography between July 2004 and May 2006 were scanned. Those women with adverse health conditions were excluded. Data obtained were LMP, BPD, FL, CRL and TAD. Foetal age was calculated from each of the parameters singly and in combinations as composite value. Composite value consisted of BPD, FL, and TAD. The following percentage frequency; BPD (90.90%), FL (33.23%), TAD (53.33%), and Composite value (71.41%) were gestational values within two-week variation from what was obtained with LMP. The data showed significant variation in comparison to the values obtained from LMP. An analysis suggested that BPD and Composite value were more comparable to the values from LMP than the other assessed obstetric ultrasonographic parameter. In conclusion BPD and Composite value are better parameters for ultrasonic assessment of gestational age in mid to third trimester pregnancy in our environment.