cardiotocograph

A cardiotocograph, commonly called CTG, is a device and method used to monitor fetal heart rate (FHR) and uterine contractions during late pregnancy and labor. It provides a continuous tracing that helps clinicians assess fetal well‑being and the progress of labor.

Externally, CTG uses a fetal heart rate transducer, usually by ultrasound, and a tocodometer to record uterine contractions. Internally, when indicated, an intrauterine pressure catheter can measure contraction strength and timing, and a fetal scalp electrode may provide a more precise FHR signal. The resulting CTG trace typically shows two streams: one for FHR and one for contractions.

Interpreting the CTG involves assessing the FHR baseline, variability, accelerations, and decelerations, in the context of maternal and fetal status. A normal baseline is roughly 110 to 160 beats per minute, with varying degrees of short‑term variability reflecting autonomic nervous system function. Accelerations are brief increases in FHR and are generally reassuring. Decelerations are decreases in FHR and are categorized as early, late, or variable, each pattern suggesting different etiologies such as head compression, uteroplacental insufficiency, or cord compression. The CTG is interpreted together with clinical information rather than as a standalone diagnostic test.

CTG is used for intrapartum monitoring and for high‑risk pregnancies, induction, or augmentation of labor. It guides management decisions, including interventions or escalation of monitoring, but readings can be affected by artifacts from movement, fetal activity, or equipment issues. While guidelines exist from professional bodies to standardize interpretation and action thresholds, there is ongoing variability in interpretation, underscoring that CTG is a tool used within broader clinical assessment.