Antepartum Hemorrhage



Antepartum Hemorrhage


Anne Kennedy, MD



DIFFERENTIAL DIAGNOSIS


Common



  • Placental Abruption


  • Placenta Previa


  • Marginal Sinus Previa


Less Common



  • Placenta Accreta Spectrum


Rare but Important



  • Vasa Previa


ESSENTIAL INFORMATION


Key Differential Diagnosis Issues



  • Defined as vaginal bleeding from 28 weeks gestation until term



    • Many cases are idiopathic, though most likely from placental bed


    • Non-placental causes (e.g., cervicitis, severe monilial infection) should be apparent on clinical evaluation



      • Typically lighter bleeding (e.g., smear of blood-stained mucus)


  • Evaluation of placental location is important part of every obstetric scan


  • Scan technique important for correct diagnosis



    • Must see placenta and internal os in same image


    • If fetal parts or maternal habitus preclude visualization abdominally, perform transvaginal (TV) scans



      • Most effective method to visualize cervix


    • In patients with ruptured membranes translabial (transperineal) scanning may be helpful


  • Scan from side to side and anterior to posterior



    • Lateral wrap placentae may have low-lying/marginal insertion, which is not apparent on a true midline image


    • Use color Doppler to evaluate for vasa previa


  • Beware of full bladder, focal myometrial contraction



    • Spurious elongation of “cervix” → incorrect diagnosis of placenta previa


  • If low-lying placenta seen at mid-trimester scan, re-image at 32-34 weeks with TV technique



    • 5% of women have a low-lying placenta at 18 weeks


    • ˜ 1% of them have placenta previa at term


Helpful Clues for Common Diagnoses



  • Placental Abruption



    • Abdominal pain, dark red vaginal bleeding


    • Look for hypoechoic blood clot near or behind placenta


    • Marginal



      • Hemorrhage from edge of placenta


      • Can see raised edge in 50%


      • Curvilinear clot near placenta


      • Hemorrhage dissects under chorionic membrane → clot at a distance from placenta, look in front of cervical os


    • Retroplacental



      • Central hematoma between placenta and uterus


      • Large detachment more likely than with marginal abruption → ↑ risk of fetal morbidity


      • Appears acutely as “placentomegaly”


      • Power Doppler delineates clot from placenta


    • Preplacental



      • Hematoma on fetal surface of placenta


      • Clot may compress cord


  • Placenta Previa



    • Painless, bright red vaginal bleeding


    • Symmetric complete placenta previa



      • Placenta centrally implanted on cervix


      • Will not resolve with advancing pregnancy


    • Asymmetric complete placenta previa



      • Small part of placenta crosses internal os


      • May resolve with advancing pregnancy


      • If > 15 mm crosses internal os then less likely to resolve


    • Marginal: Placental edge within 2 cm of internal os



      • Gestational age > 20 weeks, TVUS done for maximal resolution


    • Low-lying placenta



      • Preferred term if < 20 wks and TVUS not done


      • Asymptomatic, majority resolve by 34 weeks


  • Marginal Sinus Previa



    • Maternal placental veins at edge of solid placenta, near or cross internal os



    • Do not confuse with vasa previa (fetal vessels in membranes anterior to internal os)


Helpful Clues for Less Common Diagnoses



  • Placenta Accreta Spectrum



    • Abnormal penetration of placental tissue beyond endometrial lining of uterus


    • Look for



      • Loss of subplacental hypoechoic zone


      • Placental sonolucencies (“swiss cheese appearance”)


      • Abnormal vascularity of placenta (“tornado vessels”)


      • Breach of bladder mucosa seen as defect in echogenic line


      • Use Doppler to look for large vessels in bladder wall


    • Some series claim better resolution with MR



      • May be helpful to look for spread into broad ligament


      • Also helpful if there’s history of other surgery that increases risk (e.g., posterior myomectomy)


    • MR technique



      • Fast T2 weighted sequences


      • Full bladder


      • Surgilube in vagina


      • Gadolinium not necessary (contraindicated in pregnancy)


    • Risk factors



      • Reported 5% risk with placenta previa, no prior C-section


      • 10% of patients with > 4 cesarean sections and no previa


      • 67% if previa and 4 prior C-sections


      • Prior uterine instrumentation


Helpful Clues for Rare Diagnoses



  • Vasa Previa



    • Fetal vessels running in membranes crossing the internal cervical os


    • Risk factors include



      • Placenta previa or low-lying placenta earlier in pregnancy


      • Multiple gestation


      • Succenturiate lobe


      • Low-lying placenta


    • Use transvaginal sonography and Doppler


    • Fetal arterial pulse confirms diagnosis


    • Indication for C-section prior to onset of labor



      • If spontaneous rupture of membranes tears fetal vessels, fetal exsanguination ensues


Other Essential Information

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Aug 10, 2016 | Posted by in OBSTETRICS | Comments Off on Antepartum Hemorrhage

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