tocodometer

A tocodometer, also known as a tocodynometer or tocography device, is a medical instrument used to monitor uterine contractions during pregnancy and labor. It measures the mechanical activity of the uterus to help assess labor progress and timing, often in conjunction with fetal heart rate monitoring.

External tocodometer devices consist of a pressure-sensing transducer embedded in a belt or strap placed around the patient's abdomen. The device detects changes in abdominal wall tension produced by each contraction and records a tracing on a monitor. External tocodometry provides information on the contraction frequency and approximate duration and intensity, but its measurements of strength can be influenced by factors such as body habitus, position, and amniotic fluid.

Internal tocodometers use an intrauterine pressure catheter (IUPC) inserted through the cervix into the uterus. The IUPC provides a direct measurement of intrauterine pressure, yielding a more accurate assessment of contraction amplitude in millimeters of mercury (mmHg). Internal monitoring is typically used when precise assessment is required, such as during labor with certain risk factors or when external monitoring is inconclusive.

Clinical use of a tocodometer is common during labor for continuous monitoring of contractions and, when paired with fetal heart rate monitoring, to evaluate fetal well-being and the progress of labor. Interpretation focuses on contraction frequency, duration, and, when available, intensity or intrauterine pressure, as well as the overall response of the fetus.

Terminology varies; the terms tocodometer, tocodynometer, and tocography device are often used interchangeably.