questions 6

Placenta Previa

Topic updated on 10/09/17 9:08pm

Snap Shot
  •  A 33-year-old G4P3 presents at 29 weeks gestation by dates with painless vaginal bleeding. The bleeding began two hours ago and has delivered a substantial amount of blood with clots. She is having no uterine contractions and the fetal heart rate is 150. Her last pregnancy was delivered by emergency cesarean at 37 weeks due to double-footing breech presentation during labor.

  • Placenta Abrupto and Placenta Previa are the two most common causes of third trimester bleeding
  • In Placenta Previa, the placenta is implanted over internal cervical os
  • Classified as
    • total
    • partial
    • marginal
    • low lying
  • Incidence is 1/200
  •  Risk factors include
    • prior cesarean sections
    • grand multiparous
    • advanced maternal age
  • Symptoms
    • painless bright red bleeding at 29-30 weeks 
      • of note abruptio is painful
    • bleeding often stops in 1-2 hours with or without uterine contractions
    • usually no fetal distress (vs. vasa previa which normally presents with fetal heart deccelerations due to compression of umbilical vessels)
  • Transabdominal ultrasound to look for abnormally positioned placenta  
  • Vaginal exam and transvaginal ultrasound are contraindicated due to risk of placental disruption 
  •  Abruptio placentae
  • Stablize patient with premature fetus
    •  treatment
      • pelvic rest
      • tocolytics (magnesium sulfate)
      • amniocentesis to check fetal lung maturity
  • Proceed with delivery (Caesarean section) if
    • persistant labor
    • blood loss > 500 mL
    • coagulation defects
    • documented fetal lung maturity
      • L:S ratio > 2
    • > 36 weeks gestation
Prognosis, Prevention, and Complications
  • Associated with 2-fold increase in congenital malformations
  • Placenta accreta
  • Vasa previa
    • rupture of fetal vessels that cross the membranes covering the cervix
    • treat with C-section 
  • Increases risk of postpartum hemorrhage


Qbank (3 Questions)

(M2.OB.16) A 28 year-old woman G2P1 at 29 weeks gestation presents to the obstetrician after noticing red spots on her undergarments over the past week. Her previous child was born by Cesarean section. She denies any pain associated with this spotting and any contractions. She endorses feeling fetal movements. She has received routine prenatal care up to this point and her pregnancy thus far has been uneventful. What is the diagnosis that must be ruled out prior to the patient being examined? Topic Review Topic

1. Uterine rupture
2. Threatened abortion
3. Placenta previa
4. Placenta abruptio
5. Placenta Accreta

(M2.OB.80) A 39-year-old G1P0 female presents to her obstetrician's office during week 29 of her pregnancy. She notes that she had three episodes of bright, red, vaginal bleeding in the previous week. She denies pain, but feels worried that something may be wrong. A transabdominal ultrasound is performed, which shows no abnormalities in the fetus or the placenta. Which of the following is the next best step? Topic Review Topic

1. Administer IV magnesium
2. Emergency Caesarian section
3. Bimanual exam
4. Transvaginal ultrasound
5. Reassurance and follow-up in 3 weeks

(M2.OB.250) A 30-year-old G3P2 presents at 30 weeks gestation for a routine prenatal visit. Past gynecological history is notable for myomectomy for uterine fibroids. You explain to the patient that she is at increased risk for placenta previa. Which of the following is characteristic of placenta previa? Topic Review Topic

1. Second trimester hemorrhage
2. Firm, tender uterus
3. Vaginal bleeding with painful contractions
4. Painless vaginal bleeding
5. Severe abdominal pain of sudden onset

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