The sonographic appearance and obstetric management of placenta accreta

Abstract

Placenta accreta is a condition of abnormal placental implantation in which the placental tissue invades beyond the decidua basalis. It may invade into or even through the myometrium and adjacent organs, such as the urinary bladder. The incidence has been rising in recent years. It is one of the important obstetric complications nowadays, leading to significant maternal morbidity and mortality. In the past, this condition was often diagnosed at the time of delivery when massive and unexpected hemorrhage occurred. Hysterectomy, associated with significant physical and psychological consequences, was usually the only management option. As more obstetricians have become aware of this condition, early identification with antenatal imaging diagnostic technology has become possible. Ultrasound scan plays an important role in the antenatal diagnosis. Various sonographic features with different specificity and sensitivity have been described in the literature. In equivocal cases, magnetic resonance imaging may be helpful. With such information, more accurate counseling can be offered to the mothers and their families before delivery. The delivery can also be arranged at a favorable time and in an institution where multidisciplinary support is available. Input from a hematologist, interventional radiologist, intensive care physician, urology surgeon, and/or other specialist are desirable. Apart from hysterectomy, various forms of conservative management can also be considered when the diagnosis is made prior to delivery. Fertility can therefore be preserved. After delivery, with or without hysterectomy performed, psychological support to the mothers and their families is essential.

Keywords: hemorrhage; hysterectomy; ultrasonography.

Figure 1

Deficiency of retroplacental sonolucent zone. Note: Image courtesy of the Department of Diagnostic Radiology, Queen Mary Hospital, Hong Kong.

Figure 2

Vascular lacunae. Note: Image courtesy of the Department of Diagnostic Radiology, Queen Mary Hospital, Hong Kong.

Figure 3

Myometrial thinning. Note: Image courtesy of the Department of Diagnostic Radiology, Queen Mary Hospital, Hong Kong.

Figure 4

Interruption of bladder line. Note: Image courtesy of the Department of Diagnostic Radiology, Queen Mary Hospital, Hong Kong.

Figure 5

Ultrasound examination with Doppler study showing a major anterior placenta previa accreta with bladder wall involvement. Notes: (A) and (B) -Transvaginal ultrasound scan images revealed no myometrial tissue between the lower uterine wall and the bladder. An abnormal vessel running within the bladder wall can also been seen (white arrows). (C) and (D) - Coronal and sagittal magnetic resonance images indicated a bulge at the bladder wall (black arrowheads). Image courtesy of the Department of Diagnostic Radiology, Queen Mary Hospital, Hong Kong. Abbreviation: MRI, magnetic resonance imaging.

Figure 6

Thin and very vascular uterine lower segment at the time of cesarean section. Note: The rich vascularity usually correlates with the position of placentation.