The display of a<unk>  The fetal heartbeat is shown in orange, uterine contractions are shown in green, and the small green numbers (lower right) show the mother's heartbeat.<unk>  sound Schematic explanation of<unk> : heart rate (A) is calculated from fetal heart motion determined by ultrasound, and uterine contractions are measured by a tocodynamometer (B). These numbers are represented on a time scale with the help of a running piece of paper, producing a graphical representation. External<unk>  can be used for continuous or intermittent monitoring. The fetal heart rate and the activity of the uterine muscle are detected by two transducers placed on the mother's abdomen, with one above the fetal heart to monitor heart rate, and the other at the fundus of the uterus to measure frequency of contractions. Doppler ultrasound provides the information, which is recorded on a paper strip known as a<unk> <unk> . External to cometry is useful for showing the beginning and end of contractions as well as their frequency, but not the strength of the contractions. The absolute values of pressure readings on an external to cometer are dependent on position and are not sensitive in people who are obese. In cases where information on the strength or precise timing of contractions is needed, an internal to cometer is more appropriate. Internal<unk>  uses an electronic transducer connected directly to the fetus. A wire electrode, sometimes called a spiral or scalp electrode, is attached to the fetal scalp through the cervical opening and is connected to the monitor. Internal monitoring provides a more accurate and consistent transmission of the fetal heart rate, as unlike external monitoring, it is not affected by factors such as movement. Internal monitoring may be used when external monitoring is inadequate, or if closer surveillance is needed. Internal to cometry can only be used if the amniotic sac is ruptured (either spontaneously or artificially) and the cervix is open. To gauge the strength of contractions, a small catheter (called an intrauterine pressure catheter or IUPC) is passed into the uterus past the fetus. Combined with an internal fetal monitor, an IUPC may give a more precise reading of the baby's heart rate and the strength of contractions. A typical<unk>  reading is printed on paper and may be stored on a computer for later reference. A variety of systems for centralized viewing of<unk>  have been installed in maternity hospitals in industrialised countries, allowing simultaneous monitoring of multiple tracings in one or more locations. Display of maternal vital signs, ST signals and an electronic partogram are available in the majority of these systems. A few of them have incorporated computer analysis of<unk> c signals or combined<unk> c and ST data analysis.
Cardiotocography
Vectorcardiography
Electrical cardiometry
Holter monitor
Electrocardiography
Sphygmograph
Magnetocardiography
Electrocochleography