Differential Diagnosis for Vaginal Bleeding at 29 Weeks of Pregnancy
The patient's presentation of vaginal bleeding at 29 weeks of pregnancy, particularly after sexual intercourse and without pain, prompts a thorough evaluation of potential causes. The following differential diagnosis is organized into categories based on likelihood and potential impact:
- Single Most Likely Diagnosis
- Placenta Previa: This condition, where the placenta partially or completely covers the internal cervical os, is a common cause of painless vaginal bleeding in the second and third trimesters. The bleeding often stops spontaneously, as seen in this patient. The history of a prior cesarean section increases the risk for placenta previa.
- Other Likely Diagnoses
- Placental Abruption: Although typically associated with painful vaginal bleeding, placental abruption can occasionally present without pain. It involves the premature separation of the placenta from the uterus and is a significant cause of antepartum hemorrhage.
- Cervical Erosion or Cervicitis: These conditions can cause bleeding, especially after sexual intercourse due to mechanical irritation of the cervix.
- Do Not Miss Diagnoses
- Uterine Rupture: Although rare, uterine rupture is a life-threatening emergency, especially in a patient with a history of a prior cesarean section. It typically presents with severe abdominal pain and possibly vaginal bleeding, but the absence of pain does not rule out this diagnosis.
- Vasa Previa: This condition involves fetal blood vessels running through the membranes over the internal cervical os, unprotected by Wharton's jelly. Rupture of these vessels can lead to severe fetal hemorrhage and is often precipitated by membrane rupture or vaginal bleeding.
- Rare Diagnoses
- Uterine Artery Aneurysm or Pseudoaneurysm: These are rare vascular abnormalities that can cause antepartum hemorrhage. They might be considered in the differential diagnosis, especially if other causes are ruled out.
- Choriocarcinoma: A rare malignant tumor that can cause vaginal bleeding during pregnancy. It is more commonly associated with gestational trophoblastic disease.
Each of these diagnoses requires careful consideration based on the patient's presentation, history, and physical examination findings. Further diagnostic testing, such as ultrasound, may be necessary to determine the cause of the vaginal bleeding and to guide appropriate management.