US Duplex Doppler Pelvis Although Doppler velocimetry US is an adjunct to any of the other procedures for evaluation of painful vaginal bleeding, it can be invaluable for identification of pathologic entities like placental abruption. An acute clot within the uterus can have an echogenicity similar to that of the placenta; therefore, a placental abruption can be difficult to diagnose, especially prior to organization of the clot [5]. Identification of an area of interest contiguous with the placenta but with no blood flow as documented using color or power Doppler US could suggest the presence of an acute clot as seen with placental abruption. Although color or power Doppler US appears to be helpful with the diagnosis of placental abruption, spectral Doppler US of the fetal arterial vessels appears to be less helpful [27]. US Pregnant Uterus Transabdominal Transabdominal US assessment is the preferred initial procedure for this evaluation and for assessment of the placenta. As in those with painless vaginal bleeding, an evaluation for placenta previa and vasa previa is indicated. The placenta is also comprehensively evaluated to assess its location, the presence of any clot as seen with placental separation in placental abruption, the placental location, and the presence of any vessels overlying the internal cervical os [23,24]. Although US is not sensitive for the diagnosis of placental abruption, the identification of a placental abruption is associated with worse perinatal outcomes [28]. The uterus should be evaluated for signs of uterine rupture, especially among those with a history of prior cesarean delivery. Although uterine rupture is typically a clinical diagnosis, imaging might be helpful in certain cases. Any disruption of the myometrium would suggest a uterine rupture. A threshold of 2.5-mm thickness of the lower uterine segment has been shown to be predictive of uterine dehiscence [29].
Second and Third Trimester Vaginal Bleeding. US Duplex Doppler Pelvis Although Doppler velocimetry US is an adjunct to any of the other procedures for evaluation of painful vaginal bleeding, it can be invaluable for identification of pathologic entities like placental abruption. An acute clot within the uterus can have an echogenicity similar to that of the placenta; therefore, a placental abruption can be difficult to diagnose, especially prior to organization of the clot [5]. Identification of an area of interest contiguous with the placenta but with no blood flow as documented using color or power Doppler US could suggest the presence of an acute clot as seen with placental abruption. Although color or power Doppler US appears to be helpful with the diagnosis of placental abruption, spectral Doppler US of the fetal arterial vessels appears to be less helpful [27]. US Pregnant Uterus Transabdominal Transabdominal US assessment is the preferred initial procedure for this evaluation and for assessment of the placenta. As in those with painless vaginal bleeding, an evaluation for placenta previa and vasa previa is indicated. The placenta is also comprehensively evaluated to assess its location, the presence of any clot as seen with placental separation in placental abruption, the placental location, and the presence of any vessels overlying the internal cervical os [23,24]. Although US is not sensitive for the diagnosis of placental abruption, the identification of a placental abruption is associated with worse perinatal outcomes [28]. The uterus should be evaluated for signs of uterine rupture, especially among those with a history of prior cesarean delivery. Although uterine rupture is typically a clinical diagnosis, imaging might be helpful in certain cases. Any disruption of the myometrium would suggest a uterine rupture. A threshold of 2.5-mm thickness of the lower uterine segment has been shown to be predictive of uterine dehiscence [29].