Vessels overlying the internal cervical os can be subtle and challenging to diagnose without optimal imaging conditions, and the use of color and spectral Doppler velocimetry US can be essential for making accurate diagnoses and distinguishing fetal from maternal vessels especially with the presence of fetal arterial vessels. US Pregnant Uterus Transabdominal The primary goal of transabdominal US in the setting of painless bleeding is to exclude pathologic etiologies for the bleeding. Impending miscarriage or early labor can typically be excluded via history and physical examination. The most common etiologies for painless vaginal bleeding would be placenta previa, and, less commonly, vasa previa [23]. Transabdominal US is the preferred initial imaging procedure as a screening tool for placenta previa [24]. This evaluation should include visualization of the placenta, the inferior placental margin, the placental umbilical cord insertion, and the cervix from the external os to the internal os. Any vessels overlying the internal cervical os should be specifically excluded. Transabdominal visualization of the lower uterine segment and cervix can be suboptimal because of inadequate urine in the bladder of from shadowing from the maternal symphysis pubis. US Cervix Transperineal The literature is sparse in regard to defined indications for the use of transperineal US among those with painful vaginal bleeding. In current US use, if transabdominal US demonstrates an open cervix with bulging membranes or if the history and physical examination suggests ruptured membranes, then transperineal US might be considered. If transabdominal US is inconclusive and transvaginal US is declined by the patient, transperineal US may be useful for making an accurate diagnosis.
Second and Third Trimester Vaginal Bleeding. Vessels overlying the internal cervical os can be subtle and challenging to diagnose without optimal imaging conditions, and the use of color and spectral Doppler velocimetry US can be essential for making accurate diagnoses and distinguishing fetal from maternal vessels especially with the presence of fetal arterial vessels. US Pregnant Uterus Transabdominal The primary goal of transabdominal US in the setting of painless bleeding is to exclude pathologic etiologies for the bleeding. Impending miscarriage or early labor can typically be excluded via history and physical examination. The most common etiologies for painless vaginal bleeding would be placenta previa, and, less commonly, vasa previa [23]. Transabdominal US is the preferred initial imaging procedure as a screening tool for placenta previa [24]. This evaluation should include visualization of the placenta, the inferior placental margin, the placental umbilical cord insertion, and the cervix from the external os to the internal os. Any vessels overlying the internal cervical os should be specifically excluded. Transabdominal visualization of the lower uterine segment and cervix can be suboptimal because of inadequate urine in the bladder of from shadowing from the maternal symphysis pubis. US Cervix Transperineal The literature is sparse in regard to defined indications for the use of transperineal US among those with painful vaginal bleeding. In current US use, if transabdominal US demonstrates an open cervix with bulging membranes or if the history and physical examination suggests ruptured membranes, then transperineal US might be considered. If transabdominal US is inconclusive and transvaginal US is declined by the patient, transperineal US may be useful for making an accurate diagnosis.