Sonoclot signature during normal pregnancy

Objective: The Sonoclot analyser provides global measurement of haemostasis, including plasma coagulation, platelet function and fibrinolysis. Benefits of its use in cardiovascular and hepatic surgery are well-documented and it may be useful in managing obstetric complications. The aim of this study was to determine ranges of the Sonoclot variables for normal pregnancy. Design: Prospective and longitudinal study. Setting: Antenatal outpatient clinic, university hospital. Patients: Forty-seven healthy women were studied: forty-two completed normal pregnancies and gave birth to healthy infants. Interventions: None. Measurements and results: Sonoclot signatures were performed at 10-15, 32-34 and 38-40 weeks of gestation and at 8 weeks postpartum. Haemoglobin concentration, haematocrit, platelet count, fibrinogen and activated partial thromboplastin time (APTT) were analysed with normal results. Sonact time and peak time were significantly decreased and clot rate and secondary rate were significantly increased during pregnancy compared with 8 weeks postpartum, indicating hypercoagulability. There were no significant changes in these variables during pregnancy. There were no changes in peak amplitude and downward rate. A significant correlation was found between sonact time and APTT, and between clot rate and APTT: Conclusions: We found the Sonoclot analyser simple to handle and the signatures easy to interpret. The ranges for the Sonoclot variables apply throughout pregnancy. The ranges for sonact time, clot rate, secondary rate and peak time during pregnancy differed from the ranges at 8 weeks postpartum.