Biparietal diameter: a comparison of real time and conventional B scan techniques

Real time multitransducer B scanners can greatly facilitate obstetrical ultrasound examination. To assess the accuracy and reproducibility of biparietal diameter (BPD) measurement with the real time scanner, we compared the BPD using the real time scanner with the results obtained by conventional bistable leading edge and gray scale measurements. The results show that 73 to 90 per cent of the results with the real time scanner are within 1 mm of the other measurement and 94 per cent are within 2 mm. The variance of measurements on each case with the real time scanner is not significantly greater than the variance using the other two methods. We feel that the real time scanner can be a useful tool for obstetrical examinations and is accurate in the measurement of the biparietal diameter.