Many cases of placenta previa are diagnosed during a regular prenatal examination, when an obstetrician-gynecologist (ObGyn) conducts a vaginal examination and performs an abdominal ultrasound (a test that uses sound waves to produce images of the body’s organs).

Ultrasounds are commonly performed as a routine part of prenatal care. When women receive routine prenatal care during pregnancy, placenta previa is usually detected before it poses a danger to the mother or child.

It is common for women to be diagnosed with placenta previa in the first 20 weeks of pregnancy. In most cases, the condition will resolve itself when the placenta migrates away from the cervix.

After 20 weeks of pregnancy, placenta previa may be diagnosed when the women experiences vaginal bleeding. When women experience bleeding in the later stages of pregnancy, a vaginal examination is usually not performed because it can trigger heavy bleeding.

Instead, the physician may conduct an abdominal ultrasound or a transvaginal ultrasound (a procedure in which a probe that emits sound waves is inserted into the vagina to produce a picture of body tissue).

To identify the precise location of the placenta, the physician may perform an MRI (magnetic resonance imaging), a test that helps physicians diagnose diseases of numerous organs and vessels.