Are Doppler-detected venous emboli during cesarean section air emboli?

The incidence of venous emboli during cesarean section was studied using simultaneous precordial ultrasonic Doppler monitoring and two-dimensional echocardiography. Forty-nine patients receiving either general or continuous epidural anesthesia in the horizontal position were monitored with both Doppler monitoring and echocardiography. There was excellent correlation between the embolic events detected by Doppler monitoring and by echocardiography (kappa value = 1). The incidence of venous emboli was 29% (14/49). The venous emboli detected by Doppler monitoring were indeed air emboli, not amniotic fluid or thromboemboli, as illustrated by their echocardiographic appearance.