Cord whole blood hyperviscosity: measurement, definition, incidence and clinical features.
Cord whole blood viscosity and haematocrit values (PCV) were determined in 2461 live birth infants. Viscosity measurements were performed on an Australian-designed coaxial narrow-gap viscometer. Normal viscosity values were determined for each week of gestation above 34 weeks. Hyperviscosity was defined as a viscosity value above 2 s.d. from the mean for each week of gestation and it occurred in 164 (6.7%) newborn infants. Although a close relationship existed between cord whole blood viscosity and PCV (r = 0.6597, P less than 0.0001), only 47.4% of polycythaemic infants (PCV greater than 65) were also hyperviscous and only 23.9% of hyperviscous infants were also polycythaemic. Hence, using the haematocrit to select which infants require viscosity studies fails to detect many hyperviscous newborn infants. Hyperviscosity was less common (3.6%, P less than 0.001) in infants who were born by Caesarean section and more common (16.5%, P less than 0.001) in those who were growth retarded. Of the hyperviscous infants, 84.5% were not growth retarded, most (87.8%) were term and most (86.6%) were delivered vaginally. Most hyperviscous newborn infants may thus remain undetected unless routine whole blood viscosity studies are performed.
Drew
J H
JH
Department of Paediatrics, Mercy Maternity Hospital, East Melbourne, Victoria, Australia.
Guaran
R L
RL
Grauer
S
S
Hobbs
J B
JB
D001809:Blood Viscosity; D002585:Cesarean Section; D036861:Delivery, Obstetric / Q000379:methods; D005312:Fetal Blood / Q000502:physiology*; D005317:Fetal Growth Retardation / Q000097:blood; D005865:Gestational Age; D006400:Hematocrit; D006801:Humans; D007231:Infant, Newborn; D011086:Polycythemia / Q000097:blood; D012016:Reference Values