This comprehensive test examines the fetus while it is still in your uterus. It helps determine the baby's health. The test is useful in evaluating an infant with intrauterine-growth retardation, when the mother-to-be is diabetic, with a pregnancy in which the baby doesn't move very much, in high-risk pregnancies and in overdue pregnancies.
This test measures and records
|fetal breathing movements|
|body movements of the fetus|
|fetal tone (tightening or contractibility of muscles)|
|reactive fetal heart rate (increase in heart rate when baby moves)|
|amount of amniotic fluid|
Ultrasound, external monitors and observation are used to perform the test and make the different measurements.
Each area is given a score of 0,1 or 2. A total is obtained by adding all five scores together. The higher the score, the better the baby's condition. A low score may indicate problems.
If a baby receives a low score, the situation will be evaluated—the baby may need to be delivered immediately. If the score is reassuring, the test may be repeated at intervals. It may be necessary to repeat the test the following day. Your doctor will evaluate the scores, your health and the pregnancy before any decisions are made.
Contraction Stress Test
A contraction stress test (CST), also called a stress test, is another test that evaluates the baby's well-being in the womb.
If a woman has had problem pregnancies in the past or experiences medical problems during this pregnancy, her doctor may order the contraction stress test in the last few weeks of pregnancy. This is done when the nonstress test is not reassuring.
A monitor is placed on the woman's abdomen to record the fetal heart rate. Sometimes nipple stimulation is used to make the woman's uterus contract, or an I. V. is started and oxytocin is given in small amounts to make the uterus contract. Results indicate how well a baby will tolerate contractions and labor. If the baby doesn't respond well to the contractions, it can be a sign of fetal distress.
Fetal Blood Sampling
This test is another way of evaluating how well a baby is tolerating the stress of labor. To conduct the test, the membranes must have ruptured, and the cervix must be dilated at least 2cm. An instrument is placed inside the mother to make a small nick in the baby's scalp. The baby's blood is collected in a small tube, and its pH (acidity) is checked.
The pH level helps determine whether the baby is having trouble during labor and is under stress. The test helps the physician decide whether labor can continue or if a C-section is necessary.
Tests for Fetal Lung Maturity
A couple of tests can evaluate the maturity of fetal lungs. When a baby is born prematurely, a common problem is immaturity of the lungs, which can lead to development of respiratory-distress syndrome in the baby. This means the lungs are not completely mature at birth, and the baby cannot breathe on its own without assistance.
The respiratory system is the last fetal system to mature. If your doctor knows the baby's lungs are mature, it helps him or her in making a decision about early delivery, if it must be considered.
Two tests give doctors this information. Both are performed by amniocentesis. The L/S ratio measures the ratio of lecithin to sphingomyelin, two substances found in amniotic fluid. Results give the doctor an index of the maturity of the baby's lungs.
The phosphatidyl glycerol (PG) test gives either a positive or negative result. If the result shows phosphatidyl glycerol is present, there is greater assurance that the baby will not develop respiratory-distress syndrome.
If tests reveal the baby's lungs aren't mature enough, the first consideration is to avoid premature delivery, if possible. If premature delivery cannot be prevented, tests are done immediately after birth to determine if the baby has surfactant in its lungs. Surfactant is a chemical essential for respiration. If it is not present, the baby's doctor may introduce surfactant directly into the lungs of the newborn, preventing respiratory-distress syndrome. The baby will not have to be put on a respirator—it can breathe on its own!