The comparison of vessels in elective and spontaneous abortion decidua in first trimester pregnancies: importance of vascular changes in early pregnancy losses.

BACKGROUND

To determine whether adequate trophoblastic migration and maternal placental perfusion occurs in cases of early pregnancy loss, we compared vessels in elective abortion decidua with those in spontaneous abortion decidua.

METHODS

Elective abortion decidua at 5-11 weeks (n = 40) were compared with spontaneous abortion decidua at 5-12 weeks (n = 25). Also normal late secretory endometrial biopsy specimens (n = 10) were examined. The cross-sections of veins and arteries were counted in 25 elective and 15 spontaneous abortion materials. The number of the veins that contain trophoblastic fragments and the number of the spiral arteries converted by trophoblasts were determined. Statistical significance by Mann-Whitney U and Spearman's correlation test was p < 0.05.

RESULTS

All sets of decidua had dilated veins, but no secretory endometrium did. The ratio of converted spiral arteries to nonconverted arteries was much more in elective abortion decidua (113/938, 12.04%) than in spontaneous abortion decidua (11/511, 2.15%) (p < 0.001).

CONCLUSIONS

The presence of converted arteries, dilated veins, and intravenous trophoblastic fragments in decidual specimens were evidence of intervillous circulation and placental perfusion by maternal circulation in the first trimester. Also the insufficient conversion of the arteries in spontaneous abortions might be responsible for many cases of early pregnancy loss.