Prevalence:

• 1 in 400 pregnancies.
• Placenta previa with history of previous cesarean section (CS): 3% for 1 CS, 10% for 2 CS, >50% for ≥3 CS.
• A morbidly adherent placenta includes placenta accreta (chorionic villi attach to myometrium), increta (chorionic villi invade into the myometrium) and percreta (chorionic villi invade through the myometrium).

Ultrasound diagnosis:

• Multiple vascular lacunae (spaces) within the placenta (‘Swiss cheese’ appearance) with turbulent flow (peak systolic velocity >15 cm/s),
• Retroplacental myometrial thickness of <1 mm.
• Loss of normal retroplacental hypoechogenic zone.
• Blood vessels and placental tissue bridging uterine-placental margin, myometrial-bladder interface, or crossing uterine serosa. Exophytic masses invading the urinary bladder.
• Irregular vascularization involving the whole uterine serosa–bladder junction, visualised with 3-dimensional power Doppler.

Investigations:

• MRI is recommended if ultrasound findings are inconclusive.
• Fetal antenatal surveillance should be standard.

Follow up:

• Follow-up should be standard.

Delivery:

• Place: hospital with expertise in the management of this condition and a blood bank that can facilitate transfusion of large amounts of various blood products. There is a high chance of hysterectomy and major hemorrhage.
• Time: 36 to 37 weeks.
• Method: cesarean section.

Prognosis:

• Maternal mortality 5-10%, morbidity 75%.
• Early diagnosis reduces mortality and morbidity by 50%.