AND SummaryIn a busy hospital an attempt was made to locate the placenta by ultrasound in 437 patients suspected of having a placenta praevia. There were three failures to locate the placenta and two dangerous false negative results. Caesarean section was performed in 126 patients of whom 76 had placenta praevia. The placental site was located by ultrasound in 124 patients delivered abdominally and in 98.4 per cent of them a safe diagnosis was obtained (82.2 per cent of diagnoses were anatomically correct, 8 1 per cent overstated or understated the extent of placenta praevia and 8 * 1 per cent were falsely positive). A correlation was found between the frequency of diagnostic problems and gestational age. Ultrasound provided a safe and reliable method of excluding placenta praevia except in the presence of multiple pregnancy.

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