Painless Bleeding at 30 Weeks With Three Prior Cesareans
A 35-year-old G4P3 with three prior low transverse cesarean deliveries presents at 30 weeks 4 days with a painless episode of bright red vaginal bleeding that has now stopped. Hemoglobin is 10.8 g/dL and she is hemodynamically stable. Transvaginal sonography with an empty bladder shows placental parenchyma completely covering the internal cervical os. The placenta is 4 cm thick with multiple irregular anechoic intraplacental spaces showing turbulent flow on color Doppler. The retroplacental hypoechoic clear zone is absent over the lower uterine segment, the bladder wall interface appears irregular, and color Doppler demonstrates vessels bridging the myometrium at the serosal surface. The fetus is appropriate for dates with a deepest vertical pocket of 4.5 cm.
1. Is transvaginal scanning appropriate in a patient who has just bled, and how do you confirm and describe placental location?
Read the worked answer
Yes - transvaginal scanning is appropriate and is the reference standard for placental location. A recent bleed is not a contraindication.
Technique
- Scan with an empty bladder. A distended bladder compresses the lower uterine segment and can create or mask the appearance of previa.
- Identify the internal os in sagittal and transverse planes, then measure the distance from the placental edge to the os in millimeters.
- Complete coverage of the os = complete previa. An edge within roughly 20 mm without covering = low-lying placenta; that distance is what drives counseling about mode of delivery.
- Transperineal or transabdominal views are useful adjuncts, but transabdominal imaging alone over-calls previa.
- Also assess the cord insertion and screen for vasa previa, and comment on placental thickness and texture.
What not to do
- No digital vaginal examination and no speculum in a woman with suspected previa and bleeding.
Counseling
- At 30 weeks a low-lying placenta may still resolve, but complete coverage at this gestational age with this placental appearance is unlikely to. Plan follow-up imaging at roughly 32–34 weeks and set expectations for cesarean delivery.
2. Which findings support placenta accreta spectrum, and how do they change this patient's management?
Read the worked answer
Signs of placenta accreta spectrum present here
- Placental lacunae - irregular anechoic intraplacental spaces with turbulent flow; the most sensitive grayscale sign.
- Loss of the retroplacental clear zone.
- Irregular or interrupted bladder wall interface, with bridging vessels crossing the serosa on color Doppler - a highly specific sign.
- Also described: placental bulge, focal exophytic mass, and hypervascularity at the uterovesical interface.
Risk context: with previa, accreta risk climbs steeply with each prior cesarean - on the order of a few percent with previa alone, roughly 11% after one, roughly 40% after two, and well over 60% after three or more. This patient has three.
Management implications
- Refer to a center with maternal–fetal medicine, a blood bank, and interventional radiology; plan delivery at about 34–36 weeks by scheduled cesarean hysterectomy.
- Give antenatal corticosteroids for fetal lung maturity given likely preterm delivery; give anti-D if Rh negative.
- Do not attempt manual placental removal - that single intraoperative decision is the most important one.
- Imaging has imperfect sensitivity, so a multidisciplinary plan is warranted even when signs are equivocal. MRI is an adjunct, not a substitute.
3. If the color Doppler had shown no bridging vessels and the retroplacental clear zone had been intact, would you downgrade the plan? Explain your reasoning.
Read the worked answer
No - you would not downgrade the delivery plan, though you would soften the imaging conclusion.
Reasoning
- Grayscale and Doppler signs of accreta have limited sensitivity; a normal-appearing study does not exclude the diagnosis, particularly in a patient with a complete previa plus three prior cesareans, whose pretest probability is already high.
- Sensitivity improves when multiple signs are present and when the examination is performed by experienced operators at referral centers, but a negative study in a high-risk patient is still a negative study, not a reassurance.
- The consequences of an undiagnosed accreta - catastrophic hemorrhage at the time of placental removal - are severe enough that planning decisions are driven by risk stratification, not by imaging alone.
What you would do differently
- Describe the study honestly: state which signs are present and which are absent, and note the limitations.
- Maintain the referral and the multidisciplinary delivery plan, with a contingency for accreta at surgery.
- Document the number of prior cesareans and the previa in the report so the information follows the patient.