The dynamics of glomerular filtration after caesarean section

The objective of this study was to determine whether the glomerular hyperfi ltration of pregnancy is maintained even after Caesarean section and, if so , to define the responsible hemodynamics. The dynamics of glomerular filtra tion were evaluated in 12 healthy women who had just completed an uncomplic ated pregnancy and were delivered by Caesarean section. Age-matched but non -gravid female volunteers (n = 22) serv ed as control subjects. GFR in post partum women was elevated above control values by 41%; 149 +/- 10 versus 10 6 +/- 3 ml/min per 1.73 m(2), respectively (P < 0.001). In contrast, corres ponding renal plasma flow was the same in the two groups, such that the pos tpartum filtration fraction was significantly elevated by 20%. Computation of glomerular intracapillary oncotic pressure (pi(GC)) from knowledge of pl asma oncotic pressure and the filtration fraction revealed this quantity to be significantly reduced in postpartum women, 20.6 +/- 1.7 versus 26.1 +/- 2.0 mmHg in control subjects (P < 0.001). A theoretical analysis of glomer ular ultrafiltration suggests that depression of pi(GC) the force opposing the formation of filtrate, is predominantly or uniquely responsible for the observed postpartum hyperfiltration.