[Frequency and importance of fetomaternal hemorrhages through early amniocentesis]

Amniocentesis is a technic to which it is now made more and more reference, even when feto-maternal incompatibility is not involved, for many various indications and at variable chronology along pregnancy. Our study concerns the risk developing Rh immunization among Rh negative women, undergoing amniocentesis early in pregnancy. 233 women had 243 amniocentesis between 16 and 21 weeks of pregnancy. Fetal cells in the maternal circulation were searched for using the Kleihauer's acid elution technic. In 154 cases, the Kleihauer's method was also used just before the amniocentesis, in order to run out a spontaneous foeto-maternal haemorrhage and to correlate the 25 (16,2%) transplacental haemorrhage reported to amniocentesis. When ever the result was positive, we observed a feto-maternal ratio varying from 1/20 000 to 100/20 000 but it is very difficult at this early period of fetal life to assure a precise volume of blood from this ratio. Placental localization preceeding amniocentesis does not seem minimizing the risk of bleeding. Althrough the occurence of a fetal bleeding seems to be more frequent in cases where blood can be demonstrated in the amniotic fluid (8/25 = 32%) than in cases it is not, the estimated volume of the foeto-maternal haemorrhage is not related to the presence or absence of blood in the amniotic cavity. In 3 cases the intra-amniotic blood was tested by the Kleihauer's method. In two instances there was a mixture of adult and fetal cells. In the 3rd case only fetal cells were present. In this last case, as in 17/25 bloody amniotic fluid (68%) no feto-maternal haemorrhage could be demonstrated. The risk of Rh immunization commands prophylaxis. In such Rh negative women, we inject intravenously a 85 mug dose of anti-D immunoglobulin, soon after performing amniocentesis, what ever the result of Kleihauer test is positive or negative.