Sonographic and clinical findings during the third stage of labor

Objective: We analyzed the duration and phases of the third stage of labor with gray-scale and color Doppler sonography. We also compared ultrasound f indings with the clinical signs of placental separation and the mode of pla cental delivery. Methods: The third stage of labor was recorded by color Doppler sonography in 57 patients after vaginal delivery. Results: The third stage of labor can be broken down into three distinct ph ases. The latent phase consists of the interval between delivery of the new born and beginning placental separation (median duration 141 sec, range 5-7 90 sec). The beginning of this phase was marked by cessation of blood flow between the myometrium and the placenta. The detachment phase is characteri zed by shearing off of the placenta from the myometrium (median duration 50 sec, range 15-100 sec). The expulsion phase begins with completed separati on and ends with the vaginal delivery of the placenta (median 80.5 sec, ran ge 2-385 sec). Kustner's sign (absent umbilical cord retraction on suprapub ic pressure) was positive and Schroder's sign (fundal elevation) in 98% of women with sonographically separated placentae. Clinically, placental separ ation by the Schultze mechanism was present in 45 cases (79%). In contrast, sonography showed that placental separation began from the inferior pole o f the placenta without retroplacental hematoma in all cases. Conclusion: The third stage of labor consists of three distinct phases. The duration of the third stage is determined mainly by the latent phase, in w hich blood flow between the myometrium and the placenta ceases. Clinical an d sonographic signs of placental separation correlate closely. The lower pa rt of the placenta usually separates first, so that the mechanism described by Schultze is only of theoretical interest.