A pregnancy complication presents with painless, bright red vaginal bleeding after 20 weeks and requires avoidance of vaginal examinations. What is the most likely diagnosis?

• A. Ectopic pregnancy
• B. Placenta previa
• C. Abruptio placentae
• D. Molar pregnancy

Answer: (B)

Painless vaginal bleeding after 20 weeks points to placenta previa. In this condition the placenta implants low in the uterus, covering or near the internal os (the opening of the cervix). Because the placental vessels are close to or crossing the cervical os, bleeding can occur with little or no pain and may be intermittent. A key safety point is to avoid digital vaginal examinations because probing the cervix can aggravate bleeding and risk massive hemorrhage. Diagnosis is typically confirmed with ultrasound.

In contrast, ectopic pregnancy usually presents with pain and occurs earlier in pregnancy, not after 20 weeks. Abruptio placentae causes painful bleeding with abdominal tenderness and a rigid, tender uterus, often with signs of fetal distress. Molar pregnancy often presents earlier as well, with vaginal bleeding and an unusually enlarged uterus, and may include hyperemesis or high hCG levels. These features make placenta previa the most consistent diagnosis for painless bleeding in the late second or third trimester.