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Overview :
The Preterm Prediction Study used fetal fibronectin
concentrations in cervicovaginal secretions and the cervical length to identify
women at risk for preterm delivery. The study was done at multiple university
hospitals across the United States.
Normally fetal fibronectin is present in cervicovaginal
secretions before 21 weeks of gestation and after 37 weeks, but the
concentration is normally low in the interval. The presence of increased levels
of fetal fibronectin correlates with an increased risk for preterm delivery,
often within 7 days of specimen collection.
Requirements for measuring fetal fibronectin to predict
preterm delivery:
(1) The
pregnancy should be between 24 weeks, 0 days and 34 weeks, 6 days of
gestation.
(2) The
membranes should be intact.
(3) There
should not be significant bleeding.
(4) The
specimen should be collected prior to manipulation of the cervix.
(5)
Cervical dilation is minimal (< 3 cm).
NOTE: Revah
et al emphasize that the test is more sensitive in symptomatic than in
asymptomatic patients.
Parameters:
(1) fetal fibronectin concentration in cervicovaginal
secretions
(2) cervical length
|
Parameter |
Finding |
Points |
|
fetal fibronectin |
< 50 ng/mL |
0 |
|
|
>= 50 ng/mL |
1 |
|
cervical length |
> 25 mm (normal) |
0 |
|
|
<= 25 mm (short) |
1 |
number of risk factors =
= SUM(points for the 2 parameters)
Interpretation:
• minimum number of risk factors: 0
• maximum number of risk factors: 2
|
Number of Risk
Factors |
Risk of Spontaneous Preterm
Delivery |
|
0 |
low |
|
1 |
intermediate |
|
2 |
high |
|