Placenta accreta is a serious pregnancy complication where the placenta attaches abnormally deep into the uterine wall. Unlike a typical pregnancy, the placenta does not detach easily after childbirth. This can lead to severe complications, including significant blood loss during delivery. Early detection is important for planning a safe delivery and ensuring the well-being of both mother and child.
Understanding Placenta Accreta
Placenta accreta is a medical condition where the placenta attaches too deeply to the myometrium, the muscular layer of the uterine wall. This deep attachment prevents the placenta from detaching naturally after delivery.
Attempting to remove the placenta can lead to massive hemorrhage. Such bleeding may require blood transfusions and, in some cases, a hysterectomy, the surgical removal of the uterus. The incidence of placenta accreta is increasing, largely due to the rising rate of cesarean deliveries, as a previous C-section is a major risk factor.
How Ultrasound Detects Placenta Accreta
Ultrasound serves as the primary diagnostic tool for identifying placenta accreta during pregnancy. This imaging technique allows healthcare providers to visualize the placenta’s position and its relationship to the uterine wall. Screenings are performed during routine prenatal appointments, often in the second and third trimesters, though early indicators can sometimes be seen in the first trimester.
For high-risk pregnancies, such as those with a history of previous cesarean sections or placenta previa, targeted ultrasound scans are recommended. These scans allow clinicians to examine the placental implantation site for signs of abnormal attachment. Identifying concerns before delivery enables the healthcare team to prepare a safe and effective birth plan.
Key Ultrasound Indicators
Doctors look for several visual signs on an ultrasound scan to suspect placenta accreta. One indicator is the loss of the retroplacental clear zone, the normal hypoechoic (darker) plane between the placenta and the uterine muscle. When this clear space is absent or irregular, it suggests the placenta has invaded the uterine wall. Another sign is the presence of placental lacunae, irregular, hypoechoic (darker) spaces within the placenta that show increased blood flow. More than three lacunae or their large size can indicate a higher risk.
Increased blood flow where the placenta meets the bladder wall is also a strong indicator. This can be seen with color Doppler ultrasound, revealing chaotic or bridging vessels extending from the placenta across the myometrium. An irregular bladder wall contour or a placental bulge, where the placenta appears to protrude from the uterus, can suggest deeper invasion. Myometrial thinning, where the uterine wall beneath the placenta measures less than 1 mm, can also be a feature.
Complementary Diagnostics and Post-Diagnosis Steps
When ultrasound findings are inconclusive or to assess the extent of the condition, Magnetic Resonance Imaging (MRI) may be used as a supplementary diagnostic tool. MRI can provide additional detail for surgical planning. While MRI offers valuable insights, ultrasound remains the primary screening method due to its accessibility and effectiveness.
Following a suspected or confirmed diagnosis, a multidisciplinary team approach is adopted for patient care. This involves obstetricians, gynecologists, surgeons, and an anesthesia team. Delivery is planned as a cesarean section, often between 34 and 35 weeks of gestation, to minimize the risk of spontaneous labor and associated hemorrhage. This planned approach in a specialized center with resources for potential massive transfusions helps optimize maternal and fetal outcomes.