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Assessment of Gestational Age in the Third Trimester of Pregnancy: Comparison of Symphysio-Fundal Height Measurements with Ultrasonic Methods


Oluwafemi Kuti
Bamidele O. Osinusi
Oladosu A. Ojengbede

Abstract

Context: Despite its cost and loss of accuracy, ultrasound is still employed by most obstetricians when faced with the problem of uncertain dates in the third trimester of pregnancy. There are, however, cheaper methods of estimating gestational age in the third trimester.


Objective: To compare the accuracy of symphysio-fundal height measurement (SFH) with ultrasonic measurement of biparietal diameter (BPD) and femur length (FL) in assessing gestational age in the third trimester of pregnancy.


Subjects and Methods:Women carrying singleton uncomplicated pregnancies in the third trimester who were attending antenatal clinic at the University College Hospital (UCH), Ibadan between January 1991 and May 1991 had SFH measurements, and ultrasonic BPD and FL determination. The measurements were used to obtain the corresponding estimated gestational ages from local growth charts. The gestational age of each patient on the day measurements were taken was calculated retrospectively from the Dubowitz Gestational Age Assessment at birth. This was used to determine the accuracy of the estimated gestational ages.


Results: Of the 105 patients studied, SFH correctly assessed gestational age in 59.1% compared to 62.5% for BPD (p = 0.71), 62.8% for FL (p = 0.72) and 69.8% for BPD combined with FL (p = 0.14). Among the patients who delivered at term, 70% delivered within two weeks of the date predicted by SFH compared to 69.6% for BPD (p = 0.916), 72.8% for FL (p = 0.77) and 78% for BPD combined with FL (p = 0.26).


Conclusion: There was no significant difference between SFH measurement and ultrasound parameters in determining gestational age in the third trimester of pregnancy.


Key Words: Ultrasonography, Gestational Age, Biparietal Diameter, Femur Length, Symphysio-Fundal Height.


[Trop J Obstet Gynaecol, 2003, 20: 123-126]

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eISSN: 0189-5117