During the test, you lie on a bed with your back raised. They are tilted a little to the left. This is so that you do not put pressure on the blood vessels in your abdomen. Two straps with sensors are placed around your abdomen. A belt contains the sensor that records your baby`s heart rate. The other sensor measures your contractions. The gel can be applied to your skin with heart rate sensors. The sensors are connected to a recording device. The heart rate monitor can be moved when your baby changes position. Some women who have complications during pregnancy need a CST, although the test is much less common than before.
Most often, you will get a non-stress test or biophysical profile. If these results indicate a potential problem, your doctor may suggest CST as follow-up. You get the hormone oxytocin in a vein (intravenous or IV). It is started in low doses. The dose is increased until you have three contractions in 10 minutes, each lasting more than 45 seconds. Or you may be asked to massage one of your nipples by hand to begin contractions. If you do not have a second contraction within 2 minutes of the first, you will rub your nipple again. If contractions do not occur within 15 minutes, massage both nipples.
The contraction stress test helps predict how your baby will behave during labor. The test triggers contractions and records how your baby`s heart reacts. A normal heartbeat is a good sign that your baby will be healthy during labor. Hospital staff will monitor you closely during and after the test. If you are at risk of preterm labour or have placenta previa, CST may not be recommended. Before you experienced contractions, you placed two separate fetal monitoring devices on your abdomen with elastic straps. These electronic monitors measure both your contractions and your baby`s heart rate, and display the results through a print. The contraction stress test can take up to one to two hours. Most women say the test is unpleasant, but not painful; Some don`t even feel the contractions. If you smoke, stop for 2 hours before the test.
Smoking can reduce your baby`s activity and heart rate. Clinical assessment of the condition of the fetal airways at the beginning of labour depends largely on the interpretation of changes in continuous recording of fetal heart rate (FHR). The work imposes a variety of endocrine, behavioral, and reflex stimuli on the fetal cardiorespiratory system, making it unlikely that changes in the FHR model are directly related to acid-base state unless it is significantly abnormal. Therefore, there are large rates of false positives (1) and false negatives (8) when FHR is used alone. The contraction stress test (CST), or oxytocin challenge test, has been accepted by many as a way to assess fetal reserve in late pregnancy, especially in a high-risk pregnancy (6). However, this also has significant rates of false positives and false negatives (7.10). The NIH working group (13) recommended research into new methods of fetal monitoring, and our group developed a fetal scalp mass spectrometer converter (9), which was evaluated in the paper with a modified magnetic sector industrial mass spectrometer (11). In an effort to improve the assessment of fetal reserve during preterm birth, we have now used the multi-gas sampling potential of the mass spectrometer to perform continuous measurements of maternal-fetal transfer of oxygen and helium. Animal studies are currently being used to develop a short, reproducible test with argon, hoping to develop a simple placental transfer test suitable for use in early human work. The goal of all advanced pregnancy tests is to assess whether a fetus is at risk of stillbirth. If the results of the CST are not reassuring, doctors can intervene before birth.
During a CST, your doctor will induce slight contractions while monitoring your baby`s heart rate with an external fetal heart monitor. You will lie down and wear two belts with sensors around your stomach. One records your baby`s heart rate, the other measures your contractions. To induce contractions, your doctor will give you low doses of oxytocin (which is the hormone your body releases to start labor) or you can let things help by rubbing your nipples (which triggers a natural flow of oxytocin). The test lasts until you have had three moderately strong contractions on a 10-minute window. A normal or negative reaction to this test – meaning your baby`s heart rate doesn`t slow down in response to contractions – indicates that your baby is likely to be getting enough oxygen and should handle the challenges of labor well. Nevertheless, your practitioner may want to repeat the test every week just to be on the safe side. An abnormal or positive reaction occurs when your baby`s heart rate drops during or immediately after a contraction.
This suggests that additional testing may be needed. What is a contraction resistance test? This procedure measures your baby`s heart rate in response to the uterus when it contracts. Studies have shown that a positive result is a valuable predictor of abnormal fetal heart rate patterns during childbirth. If the results of CST are positive, your doctor may suggest options for induction or caesarean delivery. Your baby is expected to be able to cope with the stress of labor if there is no late slowing of your baby`s heart rate for three contractions over a 10-minute period. Do not worry. This test is very good at showing when everything is going well, but not so accurately predicting if things are not going well. In other words, it has a high rate of false positives. For this reason, follow-up tests are usually performed according to this procedure. Contractions should subside shortly after the test.
You may need to rest until they settle in, which is why a CST can take about two hours. You will be asked to sign a consent form stating that you understand the risks of the test and agree that this is the case. CSE is generally safe, but it sometimes triggers early labor. The test is riskier for women who have placenta previa, a higher risk of uterine rupture, or who have already had a caesarean section. Your doctor will help you weigh the benefits and risks before the test. The contraction resistance test has always been most often used as a follow-up assessment after a non-reactive stress test. Experimental data suggest that the onset of late slowdowns with contractions, the basis of a positive (abnormal) stress test, is a harbinger of uteroplacentic insufficiency.58-60,64 The established clinical and experimental premise of the stress test is that chronic uteroplacentic insufficiency leads to a late slowing of the fetal heart rate, a sign of fetal hypoxia (see discussion below) in response to uterine contractions; These can be stimulated by breast stimulation or oxytocin infusion.58,65-68 In about 10% of women, spontaneous uterine contractions make stimulation of uterine contractions superfluous. A positive (abnormal) result is indicated by persistent late slowdowns over several or more contractions; These positive tests may be subdivided rather than reactive if they are accompanied by accelerations at some point during the test, or non-reactive if they are not accompanied by accelerations. An ambiguous result refers to the appearance of late non-persistent slowdowns. A negative stress test is defined as the absence of late delay with contractions.
Różańska-Walędziak A, Czajkowski K, Walędziak M, Teliga-Czajkowska J. The current advantage of the oxytocin challenge test – a single-center study. .
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