[Localization of the placenta by means of nuclear medical methods]

Accurate localization of the placenta in the cavity of the uterus is indicated prior to transabdominal amniocentesis and in cases where hemorrhages occur during pregnancy. Several nucleo-medical techniques are available for this purpose. Earlier a so-called placentography was performed, a method later replaced by placental scintigraphy. Today the gamma scintillation camera is ideal for localizing the seat of the placenta. In case of a normally embedded placenta, the profile view makes it possible to determine whether the placenta is attached to the anterior or posterior wall. In case of an anterior wall placenta it is possible with a radioactively labelled marker to draw the outline of the placenta on the abdomen of the patient so that the examiner is certain to puncture in an area that does not contain the placenta. Diagnosis of placenta praevia is assured in all cases by use of the gamma scintillation camera. Short-term introduction of an emitter into the posterior fornix vaginae makes it possible to determine the position of the internal orifice of the cervix uteri. If the caudal part of the placenta extends up to this mark, a placenta praevia is likely and all obstetrical precautions indicated have to be taken.