Which imaging modality is used to diagnose placenta previa?

Which imaging modality is used to diagnose placenta previa?

• A. CT scan of the abdomen
• B. Pelvic ultrasound; do not perform pelvic exam
• C. Pelvic X-ray
• D. MRI

Answer: (B)

Placenta previa is when the placenta implants in the lower uterus near or over the internal cervical os, which can cause painless vaginal bleeding in the latter half of pregnancy. The way to confirm this placement is with ultrasound, because it can precisely show where the placenta lies relative to the internal os without exposing the fetus to radiation. A pelvic exam is avoided in suspected placenta previa because manipulating the cervix or uterus can provoke severe bleeding if the placenta is covering the os. Other imaging methods like CT or pelvic X-ray involve radiation and aren’t used for this diagnosis, and MRI isn’t a first-line tool for placental localization. So, pelvic ultrasound is the best imaging modality to diagnose placenta previa, and pelvic examination should be deferred until the placental location is known.

Placenta previa is when the placenta implants in the lower uterus near or over the internal cervical os, which can cause painless vaginal bleeding in the latter half of pregnancy. The way to confirm this placement is with ultrasound, because it can precisely show where the placenta lies relative to the internal os without exposing the fetus to radiation. A pelvic exam is avoided in suspected placenta previa because manipulating the cervix or uterus can provoke severe bleeding if the placenta is covering the os. Other imaging methods like CT or pelvic X-ray involve radiation and aren’t used for this diagnosis, and MRI isn’t a first-line tool for placental localization. So, pelvic ultrasound is the best imaging modality to diagnose placenta previa, and pelvic examination should be deferred until the placental location is known.