Association of Ultrasonographic Parameters With FIGO Clinical Grading System for Placenta Accreta Spectrum: A Prospective Cohort Study

Evaluation of the association of ultrasonographic parameters suggestive of placenta accreta with intraoperative clinical diagnosis of placenta accreta according to the the clinical grading system for placenta accreta spectrum (PAS) disorders proposed recently by FIGO and histopathological diagnosis of placenta accreta in hysterectomy specimens The following ultrasound items will be examined: number and viability of fetuses, amniotic fluid assessment, fetal biometries, fetal gender if possible, fetal presentation, Estimated fetal weight using Hadlock formula, Umbilical Artery Pulsatility Index (UA PI) measured from an automated/manual trace of at least three consecutive waveforms of the relevant vessel in the absence of fetal breathing movements or uterine contractions. The UA PI will be recorded from a free-floating section of cord.

Next step the investigators will look for suggestive ultrasound parameters of placenta accreta including:

1. Location of placenta: Placenta previa anterior / posterior / totally covering the internal cervical os.
2. Lacunae staging according to Finberg and Williams as follows: grade 0, none seen; grade 1, 1-3 present and generally small; grade 2, 4-6 present and tending to be larger and more irregular; grade 3, many throughout the placenta and appearing large and bizarre.
3. Loss of the clear zone, defined as loss or irregularity of the hypoechoic plane in the myometrium underneath the placental bed
4. Bladder wall interruption, defined as loss or interruption of the bright bladder wall (hyperechoic band or 'line' between the uterine serosa and bladder lumen)
5. Uterovescical hypervascularity, defined as a striking amount of color Doppler signal seen between the myometrium and the posterior wall of the bladder, including vessels appearing to extend from the placenta, across the myometrium and beyond the serosa, into the bladder or other organs, often running perpendicular to the myometrium.
6. Increased vascularity in the parametrial region, defined as the presence of hypervascularity extending beyond the lateral uterine walls and involving the region of the parametria .