US Pregnant Uterus Transvaginal Transvaginal US is frequently necessary for evaluation of painful vaginal bleeding especially if transabdominal US is inconclusive or inadequate. As with transabdominal US, the evaluation should include visualization of the placenta if identifiable, the inferior placental margin, the presence of any clot within the uterus, the continuity of the myometrium, the cervix from the external os to the internal os, and the identification of any vessels overlying the internal cervical os. Although a transvaginally identified short cervix is well known to be related to preterm delivery, associated vaginal bleeding significantly increases the risk of preterm delivery [30]. Evaluation of the lower uterine segment, the uterine isthmus [31], during transvaginal US can predict bleeding during pregnancy and delivery among those with placenta previa [32]. Variant 3: Second and third trimester vaginal bleeding. Suspicion of or known placental previa, low-lying placental, or vasa previa. Initial imaging. US Cervix Transperineal To our knowledge, there is currently a paucity of literature to support the use of transperineal US for the initial evaluation of placenta previa, low-lying placenta, or vasa previa [33]. US Duplex Doppler Pelvis Although Doppler velocimetry US is an adjunct to transabdominal US and transvaginal US for evaluation of known or suspected placenta previa, low-lying placenta, or vasa previa, it can be invaluable for identification of pathologic Second and Third Trimester Vaginal Bleeding entities like vasa previa. Vessels overlying the internal cervical os can be subtle and challenging to diagnose without optimal imaging conditions, and the use of Doppler velocimetry US can be essential for making this diagnosis [7,34]. Furthermore, spectral Doppler may play an important role in distinguishing fetal arterial vessels from maternal vessels when overlying the internal cervical os.
Second and Third Trimester Vaginal Bleeding. US Pregnant Uterus Transvaginal Transvaginal US is frequently necessary for evaluation of painful vaginal bleeding especially if transabdominal US is inconclusive or inadequate. As with transabdominal US, the evaluation should include visualization of the placenta if identifiable, the inferior placental margin, the presence of any clot within the uterus, the continuity of the myometrium, the cervix from the external os to the internal os, and the identification of any vessels overlying the internal cervical os. Although a transvaginally identified short cervix is well known to be related to preterm delivery, associated vaginal bleeding significantly increases the risk of preterm delivery [30]. Evaluation of the lower uterine segment, the uterine isthmus [31], during transvaginal US can predict bleeding during pregnancy and delivery among those with placenta previa [32]. Variant 3: Second and third trimester vaginal bleeding. Suspicion of or known placental previa, low-lying placental, or vasa previa. Initial imaging. US Cervix Transperineal To our knowledge, there is currently a paucity of literature to support the use of transperineal US for the initial evaluation of placenta previa, low-lying placenta, or vasa previa [33]. US Duplex Doppler Pelvis Although Doppler velocimetry US is an adjunct to transabdominal US and transvaginal US for evaluation of known or suspected placenta previa, low-lying placenta, or vasa previa, it can be invaluable for identification of pathologic Second and Third Trimester Vaginal Bleeding entities like vasa previa. Vessels overlying the internal cervical os can be subtle and challenging to diagnose without optimal imaging conditions, and the use of Doppler velocimetry US can be essential for making this diagnosis [7,34]. Furthermore, spectral Doppler may play an important role in distinguishing fetal arterial vessels from maternal vessels when overlying the internal cervical os.