Perfusion of the intervillous space of the human placenta measured with 99mtechnetium labelled human serum albumin.

The perfusion of the intervillous space of the human placenta was investigated with 99Tc-Human Serum Albumin and external counting in 45 pregnant women between the 34th and 38th week of gestation. The pregnancy was normal in 34 women, while there was placental insufficiency in 11. Two variables were calculated from the placenta curve: the placenta flow index (PFI) and the mean transit time (t) for plasma through the intervillous space. From double determinations, the coefficient of variation for PFI was calculated to 1.6%. For t it was 20%. PFI was significantly higher in the controls than in the patients with placental dysfunction (P less than 0.05). There was a significant correlation between PFI and t (rs = - 0.36, P less than 0.05). The plasma oestriol level and the PFI correlated significantly, whereas the correlation between t and the plasma oestriol level was not significant. The placenta flow index can be used to measure the physiological effect of a pharmacological treatment, bedrest or other treatments.