The Radiological Localisation of the Placental Site—Part II

Abstract

The radiological methods which have been used in the diagnosis of placenta prævia are described. An account is given of a normal X-ray procedure, designed to estimate the thickness of the uterine wall between the presenting part of the fœtus and the brim of the maternal pelvis. Positioning of the patient and interpretation of the films both depend on the fact that the fœtus normally sinks through liquoramnii, owing to its higher specific gravity. Evidence is given to show that the lower uterine segment extends approximately up to the pelvic inlet towards the end of pregnancy so that a substantial thickening of the uterine wall at this level is probably due to implantation on the lower segment. The projections used are chiefly lateral and anteroposterior views of the pelvic region, in erect or reclining positions. By this means, positive radiological evidence was found in 47 of 50 cases with clinical findings of placenta prævia, the erect antero-posterior view not being in use when the three errors were made. Thirty-one of these 50 patients were examined in the period during which the full procedure was in use, and, without exception, X-ray appearances of low implantation were found. Forty-two cases are discussed in which radiological findings of a low-lying placenta were unconfirmed clinically.