Measurement of cardiac output in normal pregnancy by a non-invasive two-dimensional independent Doppler device

To compose a normogram regarding cardiac output during pregnancy measured with ultrasonic cardiac output monitor (USCOM), a non-expensive simple continuous wave Doppler device and to investigate if this machine could be useful for haemodynamic monitoring during pregnancy. Cardiac output was measured in 172 pregnant women with a gestational age < 21 weeks (n = 59), 21-32 weeks (n = 48), and > 32 weeks' gestation (n = 48). Interobserver differences were determined by measuring 24 patients and comparing results between three different observers. A good signal could be obtained in 155 (90.2%) pregnant women. Haemodynamic profiles were in line with data published in the literature. In 9.8 % of cases it was difficult to get a good result. Interobserver variations between the research officer (CK) and two clinicians were good (r = 0.9359 and r = 0.9609). USCOM appears to be a reliable and fast method to measure cardiac output compared with existing highly complex ultrasounds machines used in cardiology. It is easy to learn, cheap and quite reproducible between different observers. Further research is required to define its place in the management of hypertensive complications during pregnancy.