Placenta Previa

1. Placenta Previa Hai Ho, MD Department of Family Practice

2. What is placenta previa? Implantation of placenta over cervical os

3. Types of placenta previa

4. Who are at risk for placenta previa? • Endometrial scarring of upper segment of uterus – implantation in lower uterine segment • Prior D&C or C-section • Multiparity • Advance age – independent risk factor vs. multiparity

5. Who are at risk for placenta previa? • Reduction in uteroplacental oxygen or nutrient delivery – compensation by increasing placental surface area • Male • High altitude • Maternal smoking

6. Factors that determine persistence of placenta previa? • Time of diagnosis or onset of symptoms • Location of placenta previa Placental Migration Repeat ultrasound at 24 – 28 weeks’ gestation

7. Clinical presentations? • Painless vaginal bleeding – 70-80% • 1/3 prior to 30 weeks • Mostly during third trimester – shearing force from lower uterine segment growth and cervical dilation • Sexual intercourse • Uterine contraction – 10-20%

8. Fetal complications? • Malpresentation • Preterm premature rupture of membrane

9. Diagnostic test? Ultrasound

10. Placenta Previa: ultrasound Placenta Bladder Cervix

11. Placenta Previa: ultrasound

12. Placenta accreta? • Abnormal attachment of the placenta to the uterine wall (decidua) such that the chorionic villi invade abnormally into the myometrium • Primary deficiency of or secondary loss of decidual elements (decidua basalis) • Associated with placenta previa in 5-10% of the case • Proportional to the number of prior Cesarean sections

13. Variations of placenta accreta

14. Placenta accreta: ultrasound

15. Vasa Previa?

16. Vasa Previa Velamentous insertion

17. Vasa Previa Velamentous insertion

18. Vasa Previa Velamentous insertion

19. Vasa Previa • Rupture • Compression of vessels • Perinatal mortality rate – 50 – 75%

20. Management of placenta previa? Individualized based on (not much evidence): • Gestational age • Amount of bleeding • Fetal condition and presentation

21. Preterm with minimal or resolved bleeding • Expectant management – bed rest with bathroom privilege • Periodic maternal hematocrit • Prophylactic transfusion to maintain hematocrit > 30% only with continuous low-grade bleeding with falling hematocrit unresponsive to iron therapy

22. Preterm with minimal or resolved bleeding • Fetal heart rate monitoring only with active bleeding • Ultrasound every 3 weeks – fetal growth, AFI, placenta location • Rhogam for RhD-negative mother

23. Preterm with minimal or resolved bleeding • Amniocentesis weekly starting at 36 weeks to assess lung maturity – delivered when lungs reach maturity • Betamethasone or dexamethasone between 24 – 34 weeks’ gestation to enhance lung maturity • Tocolysis – magnesium sulfate

24. Active bleeding • Stabilize mother hemodynamically • Deliver by Cesarean section • Rhogam in Rh-negative mother • Betamethasone or dexamethasone between 24 – 34 weeks’ gestation to enhance lung maturity

25. Management of placenta previa • No large clinical trials for the recommendations • Consider hospitalization in third-trimester • Antepartum fetal surveillance • Corticosteroid for lung maturity • Delivery at 36-37 weeks’ gestation

26. Management of placenta accreta • Cesarean hysterectomy • Uterine conservation • Placental removal and oversewing uterine defect • Localized resection and uterine repair • Leaving the placenta in situ and treat with antibiotics and removing it later

27. Placenta Abruption

28. What is placental abruption? Premature separation of placenta from the uterus

29. Epidemiology • Incident 1 in 86 to 1 in 206 births • One-third of all antepartum bleeding

30. Pathogenesis • Maternal vascular disruption in decidua basalis • Acute versus chronic

31. Types of placental abruption 16% 4% 81%

32. Types of placenta hemorrhage

33. Risk factors for placental abruption? • Maternal hypertension • Maternal age and parity – conflicting data • Blunt trauma – motor vehicle accident and maternal battering • Tobacco smoking and cocaine

34. Risk factors for placental abruption • Prior history of placental abruption • 5-15% recurrence • After 2 consecutive abruptions, 25% recurrence • Sudden decompression of uterus in polyhydramnios or multiple gestation (after first twin delivery) – rare • Thrombophilia such as factor V Leiden mutation

35. Clinical presentations? • ± Vaginal bleeding • Uterine contraction or tetany and pain • Abdominal pain • DIC • 10-20% of placental abruption • Associated with fetal demise • Fetal compromise

36. Diagnostic test? • Ultrasound • Sensitivity ~ 50% • Miss in acute phase because blood could be isoechoic compared to placenta • Hematoma resolution – hypoechoic in 1 week and sonolucent in 2 weeks • Blood tests

37. Ultrasound: subchorionic abruption

38. Ultrasound: retroplacental abruption

39. Ultrasound: retroplacental abruption

40. Blood tests? • CBC – hemoglobin and platelets • Fibrinogen • Normal 450 mg/dL • <150 mg/dL – severe DIC • Fibrin degradation products • PT and PTT

41. Management? • Hemodynamic monitoring • Urine output with Foley • BP drop – late stage, 2-3 liter of blood loss • Fetal monitoring

42. Management: delivery • Timing • Severity of placental abruption • Fetal maturity - consider tocolysis with MgSO4 and corticosteroid (24-34 weeks) • Correction of DIC with transfusion of PRBC, FFP, platelets to maintain hematocrit > 25%, fibrinogen >150-200 mg/dL, and platelets > 60,000/m3 • Mode: vaginal vs. Cesarean-section

43. Couvelaire uterus? • Bleeding into myometrium leading to uterine atony and hemorrhage • Treatment • Most respond to oxytocin and methergine • Hysterectomy for uncontrolled bleeding

44. The End