From the Guidelines
The most common cause of painless vaginal blood clots at 15 weeks of pregnancy is likely placenta previa, which is a condition where the placenta partially or completely covers the internal cervical os. This condition requires immediate medical evaluation by an obstetrician or at an emergency department to rule out more serious conditions like placental abruption or cervical issues. According to the American College of Radiology Appropriateness Criteria 1, imaging, particularly with ultrasound (US), is the mainstay for making accurate diagnoses and for emergent guidance of management.
Key Considerations
- The outcome of pregnancies with vaginal bleeding in the second and third trimesters depends on the precise etiology for the bleeding 1.
- Transabdominal US is the preferred initial imaging procedure as a screening tool for placenta previa, and transvaginal US is frequently necessary for evaluation of painless vaginal bleeding, especially if transabdominal US is inconclusive or inadequate 1.
- Any vaginal bleeding during pregnancy, especially when accompanied by clots, warrants prompt medical attention to ensure both maternal and fetal wellbeing, even if it seems minor or is painless.
Recommendations
- Immediate medical evaluation by an obstetrician or at an emergency department is necessary to rule out more serious conditions.
- Pelvic rest (avoiding sexual intercourse and strenuous activity) may be recommended until the bleeding resolves.
- Ultrasound (US) imaging, including transabdominal and transvaginal US, is essential for making accurate diagnoses and guiding management.
From the Research
Causes of Painless Vaginal Blood Clots in Week 15 of Pregnancy
- Placental abruption is a leading cause of vaginal bleeding in the second half of pregnancy, which may include painless vaginal blood clots 2, 3, 4.
- The exact cause of placental abruption is multifactorial and not well understood, but several risk factors are known, including prior abruption, smoking, trauma, cocaine use, multifetal gestation, hypertension, preeclampsia, thrombophilias, advanced maternal age, preterm premature rupture of the membranes, intrauterine infections, and hydramnios 3, 5.
- Placental abruption occurs in approximately 0.4-1.0% of all pregnancies, and its prevalence may vary depending on the population being studied 2, 4.
- While placental abruption is a significant cause of maternal and fetal morbidity, most cases cannot be predicted or prevented, but maternal and infant outcomes can be optimized through attention to the risks and benefits of conservative management and expeditious delivery where appropriate 3.
Diagnosis and Management of Placental Abruption
- The diagnosis of placental abruption is a clinical one, and ultrasonography may be of limited value in some cases 3, 6.
- Superb microvascular imaging (SMI) may contribute to a more accurate diagnosis of placental abruption and lead to timely administration of obstetric intervention 6.
- Management of placental abruption should be individualized on a case-by-case basis, depending on the severity of the abruption and the gestational age at which it occurs 3, 4.