[Involution-induced changes in arterial uterine blood flow].

The change of resistance in the uterine arteries was studied in 20 patients showing a normal involution on five consecutive days. A uterine artery was examined by Doppler sonography, the Doppler profile evaluated, and the quotient, Fmean, resistance index, and pulsatility index were calculated from the systole and diastole. These parameters, which provided information on vascular resistance independently of the angle between the Doppler beam and the vessel, indicated a continuous increase during the puerperium; the differences in values for different days were significant. The changes in the Doppler profiles in the puerperial period pointed to an increasing vascular resistance. In one-half of the patients this was shown only by an increasing slope to the systolic peak, a sharp drop to early diastole, and a clear distinction between systole and diastole. In the other half of the patients the Doppler curves were like those found in pregnant patients with EPH gestosis. This indicated that the pathologic mechanisms leading to increased resistance in the uterine vessels were the same in both groups. One cause of this may be contraction and compression of the blood vessels, the other, and probably principal, cause was reduction of the vascular system due to histolysis, as in the puerperium, or insufficient development of the vascular system, as in EPH gestosis. That is to say, functional and morphological changes occur in both cases. No decrease in resistance in the uterine vascular bed was detected in cases of puerperial subinvolution of the uterus.