Sonographic fetal weight estimation in a south-east Asian population.

OBJECTIVES: To determine the optimal sonographic fetal weight estimation formula for a mixed south-east Asian population near term. METHODS: Seventy-eight uncomplicated pregnancies were monitored between January 1996 and January 1997. Biparietal diameter, head circumference, abdominal circumference and femur length were measured and the following formulae were tested: Campbell, Shepherds and Hadlock. The estimated fetal weight was calculated by 12 different methods. The weight estimate was then projected forward to the time of delivery using the gestation-adjusted forward projection method. The weight estimation error was derived from the difference between the projected fetal weight and birth weight, and expressed as a percentage of birth weight. RESULTS: The mean time interval from the time of ultrasound fetal weight estimation to delivery was 4.4 days. The birth weight ranged between 2,330 to 4,215 g. The best performing formula was Hadlock's formula using the head circumference, abdominal circumference and femur, with the perimeters calculated using the ellipse function. The standard deviation of error for this formula was 8.66%. CONCLUSION: Even though the Hadlock formula was originally derived from an American population, it was equally useful in south-east Asian population.

Intrahepatic vein fetal blood sampling: current role in prenatal diagnosis.

OBJECTIVE: To identify the site of fetal blood sampling (FBS) with lesser complications; and also analyses the reasons for targetting the intrahepatic vein (IHV) for FBS. METHODS: Fetal blood sampling (FBS) performed on 382 women over a period of 7 years at the National University Hospital, Singapore was analysed. FBS was performed from 13 weeks of gestational age onwards. In 76.4% (292 of 382) the intrahepatic part of the umbilical vein (IHV) was targetted; in 18.3% (70 of 382) percutaneous umbilical cord sampling (PUBS) was performed; in 5.2% (20 of 382) cardiocentesis was performed to obtain fetal blood. RESULTS: Multivariate analysis showed an increase in odds of fetal loss for umbilical cord and cardiocentesis groups compared with the IHV FBS group. It was statistically significant (p < 0.01) only in the cardiocentesis group for fetal loss at < 2 weeks of performing the procedure.