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Cardiotocography is a type of medical test conducted during pregnancy that records fetal heartbeat and uterine contractions. Utilizing a technological device called a cardiotocograph or electronic fetal monitor (EFM), this obstetrics test is commonly performed during the third trimester of pregnancy. When a cardiotocograph is used during the labor process, it is referred to as a stress test.
Dr. Orvan Hess first started preliminary research into the development of cardiotocography as early as the 1930s. In the late '40s, Hess joined forces with Dr. Edward Hon to further his attempts to develop a form of technology that could record fetal heart signals. In 1957, the two doctors utilized the first cardiotocograph to monitor a baby's heartbeat in utero. The testing processes were refined throughout the 1960s and soon became a standard tool used in delivery rooms around the world.
Cardiotocography consists of two separate medical tests conducted at the same time: one records the heart rate of the fetus — which is called a nonstress test if the mother is not in labor — while the other records the uterine contractions of the mother. The tests may be conducted by either internal or external methods. In internal testing, a catheter is placed in the uterus after a specific amount of dilation has taken place. With external tests, a pair of sensory nodes is affixed to the mother's stomach. Between the two, internal measurement is considered to be the more accurate option.
Advances in technology have allowed cardiotocography data to be stored on computers. In many cases, the data is accessible via computer networks, which permits remote observation of the mother and child. Cardiotocography readouts might also be printed out and stored in the mother's medical files.
Cardiotocography is closely related to other fetal testing procedures. A biophysical profile is performed when a nonstress test indicates possible trouble. The biophysical profile includes testing of fetal breathing, movement, and tone, as well as the amniotic fluid volume. Another diagnostic tool is a fetal stethoscope, which is used to monitor fetal heartbeat and is often utilized as a preliminary tool before cardiotocography processes are prescribed.
Sometimes referred to by the acronym CTG, cardiotocography can alert medical professionals to the possibility of fetal distress. Using this technology, doctors and nurses can better gauge the condition of the fetus and can keep a close eye on any changes in heartbeat that might signal complications. They can also measure the length of time between contractions to better determine the time of delivery.