Placenta accreta (Latin accretio) involves an increased attachment of the placenta to the uterine wall, with a deficient decidua basalis and an infiltrative growth of the chorionic villi into the myometrium. The presence of certain clinical finding can help identify a woman who is at risk for the condition, which may be associated with considerable maternal morbidity. The authors are from the University of Southern California in Los Angeles.
Placenta accreta is an uncommon condition, occurring in about 1 in 2,500 pregnancies.
|
Risk Factor (for women with history of placenta previa) |
Number |
Relative Risk |
95% CI |
|
history of placenta previa |
|
2,065 |
944 - 4516 |
|
maternal age >= 35 years |
|
2.28 |
1.25 – 4.16 |
|
history of previous Caesarean section |
1 |
4.45 |
2.09 – 9.5 |
|
|
> 2 |
11.32 |
5.59 – 22.92 |
|
implantation of placenta over Caesarean scar |
|
4.5 |
1.68 – 12.07 |
The absence of a history of placenta previa makes placenta accreta very unlikely. The additional risk factors apply only to women with a history of placenta previa.
|
Number previous Caesarean sections |
Age |
Location of Placental Implantation |
Risk of Placenta Accreta with History Placenta Previa |
|
0 |
< 35 |
not over scar |
2.1% |
|
0 |
< 35 |
over scar |
NA |
|
0 |
>= 35 |
not over scar |
6.3% |
|
0 |
>= 35 |
over scar |
NA |
|
1 |
< 35 |
not over scar |
3.7% |
|
1 |
< 35 |
over scar |
15.9% |
|
1 |
>= 35 |
not over scar |
9.1% |
|
1 |
>= 35 |
over scar |
30% |
|
>= 2 |
< 35 |
not over scar |
5.2% |
|
>= 2 |
< 35 |
over scar |
38.5% |
|
>= 2 |
>= 35 |
not over scar |
20% |
|
>= 2 |
>= 35 |
over scar |
38.1% |
from Table III. page 212
Specialty: Obstetrics & Gynecology
