Frequently asked questions
Q: How is the sample handled?
A: The sample is taken with the polyester swab that is included in the test package: The Actim PROM sample is taken from the posterior fornix of the vagina or, if no liquid is visible, from the cervix.
After the swab has absorbed the sample, it is transferred and extracted in the sample extraction solution. At this point, the sample is ready for testing.
Q: Can the same sample be used for both Actim PROM and Actim Partus tests?
A: Separate samples need to be taken for the two tests. The sample for Actim Partus test must be taken from the cervix, while a vaginal or cervical sample can be used for the Actim PROM test. The test requires at least 150 µl of sample to perform correctly, and this may also limit the possibility to run two dipstick tests from the same sample tube.
Q: Can the dipstick be left in the sample to develop?
A: The dipstick should be removed from the sample as soon as the liquid front becomes visible in the result window. Appearance of the liquid front in the result window indicates that enough sample has been absorbed by the dipstick. If the dipstick is left in the sample, the dipstick goes on absorbing the sample which in turn may lead into uncontrollable flow.
Q: Do the results need to be read exactly at 5 minutes?
A: A positive result can be interpreted as soon as two blue lines become visible in the result window. However, a negative test must be confirmed at 5 minutes. As the immunochromatography reaction continues to develop over time, the lines may become stronger or lines may appear in the result area. These lines must not be interpreted as positive as they indicate analyte levels below the detection limit of the test.
Q: Should the intensity of the test line be compared to the intensity of the control line?
A: The result is interpreted by counting the number of lines in the result area. No attention should be paid to the relative intensities of the control and test lines.
Q: How to interpret a weak positive Actim PROM result at term or post-term patients with intact membranes?
A: Occasionally, weakly positive Actim PROM test results are observed even though the membranes are intact. This appears to be due to the fact that the cervix may already be ripening, and there may be large quantities of phosphorylated IGFBP-1 in the sample causing a weak positive result. In such cases the patient may be subsequently tested with the Actim Partus test for verification.
Q: Can the Actim Partus test be used on patients with ruptured membranes?
A: Actim Partus test identifies a different phosphorylation form of IGFBP-1 than the Actim PROM test. However, the level of IGFBP-1 in amniotic fluid is so strongly elevated, that in case of leakage of amniotic fluid, Actim Partus test will give a positive result. To correctly interpret the Partus result, it should be first confirmed that the fetal membranes are intact. This can be done e.g. by first performing the PROM test.
Q: How does blood contamination affect the test result?
A: The concentration of IGFBP-1 in amniotic fluid is 100-1000 times higher than in maternal serum, and even a very small amount of amniotic fluid will be detected by the PROM test. The detection limit of the test has been set to 25 µg/l in the extracted sample. The cut off has been optimized to a level where blood contamination is highly unlikely to affect the test result. However, in cases of heavy bleeding from the placental bed, the concentration of IGFBP-1 may be locally higher than normal maternal blood IGFBP-1 concentration, and a positive result should be interpreted with caution.