Villus and other chorionic structures found at the peripheral blood of pregnant women: number, size, and a technique for their recovery [Abstract in English]

Aims: To develop a technique to recover, count, identify, and measure chorionic villi and other chorionic structures present in the peripheral blood of pregnant women. Methods: Ten normal pregnant women with gestational age equal or over 37 weeks, admitted to the Hospital Sao Lucas da PUCRS for delivery, were selected for the study. Three milliliters of blood samples in EDTA and 5,000 IU of aprotinine (Trasylol® Bayer) were obtained at a cubital vein from each patient. Samples were immediately fixed in Bouin, embedded in paraffin, sectioned at 3 μm, stained by hematoxylin/eosin, Masson’s trichrome, and with monoclonal antibodies specific to trophoblastic tissues. Each slide was scrutinized over all its surface at 250x magnification, by a linear scrutiny with conventional microscopy and every chorionic structure recognized was counted and measured with a calibrated micrometric ocular. The measures have been presented by mean ± standard error. Results: For each milliliter of maternal blood, 15.4 ± 3.1 syncytiotrophoblastic plaques equal or larger than 100 μm and 5.8 ± 0,9 chorionic villi have been recovered. The mean longitudinal diameter of villi was 289.3 ± 13.6 μm, their mean transverse diameter was 116.3 ± 5.3 μm and their syncytiotrophoblast thickness was 33.4 ± 1.7 μm. In two of the six samples subjected to immunologic studies, a reactivity to monoclonal antibodies specific to trophoblast was obtained on the recovered structures. Conclusions: Immediate fixation of blood samples was presented as a new method to recover chorionic structures from peripheral blood of pregnant women. They have been identified, counted and measured. Their quantity and size were large. The mechanisms that could explain their presence and fate in maternal blood and the significance of their presence, quantity and fate have been discussed. KEY WORDS: PREGNANCY/blood; PREGNANCY/immunology; CHORIONIC VILLI; TROPHOBLASTS; HUMANS.