Affiliations: Fetal Medicine Unit, Queen Charlotte's and Chelsea Hospital, Goldhawk Rd, London W6 0XG | Department of Physiology and Biophysics, St Mary's Hospital Medical School, Norfolk Place, London, W2 1PG
Note: [] Correspondence to: Dr. C.R. Welch. Fetal Centre, Liverpool Maternity Hospital, Oxford Street, Liverpool, L7 7BN, UK.
Abstract: 202 human fetuses underwent percutaneous fetal blood sampling under ultrasound guidance for investigation of fetal structural abnormalities, red cell alloimmunization, or fetal infection. 75 were subsequently found not to be affected by the condition for which they were being investigated, or to have any other discernable abnormality. The blood samples from these 75 ‘normal fetuses’ were used to derive gestational reference ranges for fetal whole blood viscosity (over a range of shear rates), plasma viscosity, total plasma proteins and fibrinogen. The results show that fetal haematocrit is the major determinant of fetal whole blood viscosity, that fetal plasma proteins and hence plasma viscosity are at very low levels compared to the adult and that all fetal haemorheological parameters rise significantly with gestation.
