Rac et al developed a score for predicting placenta accreta based on findings seen on ultrasonography. The authors are from the University of Texas Southwestern Medical Center in Dallas.
Patient selection: pregnant woman with >= 1 previous cesarean deliveries (high risk)
Outcome: placental invasion identified at delivery
Parameters:
(1) number of cesarean deliveries
(2) grade of lacunae using scheme of Finberg and Williams
(3) smallest myometrial thickness in sagittal plane
(4) anterior placenta previa
(5) bridging vessels
Parameters
Findings
Points
number of previous cesarean deliveries
0 or 1
0
>= 2
3
lacunae
Grade 3 (many, large, bizarre)
3.5
Grade 2 (4 to 6, moderate, irregular)
1
Grade 1 (1 to 3, small)
Grade 0 (none seen)
smallest myometrial thickness
<= 1 mm
1.01 to 3 mm
0.5
3.01 to 5 mm
0.25
> 5 mm
anterior placenta previa
no
yes
bridging vessels
total score =
= SUM(points for all 5 parameters)
Interpretation:
• minimum score: 0
• maximum score: 9
• The higher the score the greater the risk of placenta accreta.
Total Score
Probability of Invasion
2%
5%
2
10%
19%
4
33%
5
51%
6
69%
7
83%
8
91%
9
96%
Performance:
• The area under the ROC curve was 0.87
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Specialty: Obstetrics & Gynecology
