Differential Diagnosis for Vaginal Bleeding in the Second and Third Trimester

Single Most Likely Diagnosis

• Placenta Previa: This condition, where the placenta partially or completely covers the internal cervical os, is a common cause of vaginal bleeding in the second and third trimesters, especially after 28 weeks of gestation. The risk increases with prior uterine surgery, including cesarean deliveries.

Other Likely Diagnoses

• Placental Abruption: Also known as placental abruption, this condition involves the premature separation of the placenta from the uterus. It is another common cause of vaginal bleeding in the second and third trimesters and can be associated with abdominal pain, uterine tenderness, and fetal distress.
• Uterine Rupture: Although less common, uterine rupture can cause vaginal bleeding, especially in women with a history of uterine surgery, including cesarean sections. It is often accompanied by severe abdominal pain and signs of maternal and fetal distress.

Do Not Miss Diagnoses

• Vasa Previa: This rare condition involves fetal blood vessels crossing the internal cervical os, unsupported by the placenta or umbilical cord. Rupture of these vessels can lead to rapid fetal exsanguination, making prompt diagnosis and intervention critical.
• Uterine Dehiscence: Similar to uterine rupture but less severe, uterine dehiscence involves a partial separation of a previous uterine scar. It can cause vaginal bleeding and requires immediate attention to prevent progression to a complete rupture.
• Placenta Accreta Spectrum (PAS) Disorders: These disorders, including placenta accreta, increta, and percreta, involve abnormal placental attachment to the uterus. They can cause severe vaginal bleeding, especially during attempted delivery, and are associated with significant maternal morbidity.

Rare Diagnoses

• Choriocarcinoma: A rare malignant tumor that can cause vaginal bleeding during pregnancy. It is often associated with a history of molar pregnancy, abortion, ectopic pregnancy, or term pregnancy.
• Uterine Artery Aneurysm or Pseudoaneurysm: These vascular abnormalities can rupture during pregnancy, leading to vaginal bleeding. They are more common in women with a history of uterine surgery or trauma.
• Cervical Cancer: Although rare, cervical cancer can present with vaginal bleeding during pregnancy. The diagnosis and management of cervical cancer during pregnancy pose unique challenges.