Cardiotocography

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A cardiotocograph recording fetal heart rate and contractions

In medicine (obstetrics), cardiotocography (CTG) is a technical means of recording (-graphy) the fetal heartbeat (cardio-) and the uterine contractions (-toco-) during childbirth. CTG can be used to identify signs of fetal distress.

1 Method
2 Interpretation
3 Effect on management
4 References
5 See also
6 External links

[edit] Method

Recordings are done by two separate transducers, one for the measurement of the fetal pulse and a second one for the contractions.

External measurement means taping or strapping the two sensors to the abdominal wall, with the heart ultrasonic sensor overlying the fetal heart and the contraction sensor measuring the tension of the maternal abdominal wall, an indirect measure of the intrauterine pressure.

Internal measurement requires a certain degree of cervical dilatation, as it involves inserting a pressure catheter into the uterine cavity, as well as attaching a scalp electrode to the child's head to adequately measure the pulse. Internal measurement is more precise, and might be preferable when a complicated childbirth is expected.

A typical CTG reading is printed on paper and/or stored on a computer for later reference. Use of CTG and a computer network allows continual remote surveillance: a single nurse, midwife, or physician can watch the CTG traces of multiple patients simultaneously, via a computer station.

[edit] Interpretation

CTG times the contractions and the variability in the fetal heart rate. Baseline abnormalities in the heart rate (brady- or tachycardia) may be interpreted in the context of the presentation, as may absence of variability in the FHR.

Decelerations (slowing of the fetal heart rate) during a uterine contraction is normal (type 1 deceleration, or type I dips), but further slowing after resolution of the contraction (type II dips) is generally regarded as pathological and may be taken as a sign of fetal distress.

[edit] Effect on management

A Cochrane Collaboration review has shown that use of cardiotocography reduces the rate of seizures in the newborn, but there is no clear benefit in the prevention of cerebral palsy, death and other complications of labour. In contrast, labour monitored by CTG is slightly more likely to result in instrumental delivery (forceps or vacuum extraction) or caesarian section.^[1]

[edit] References

^ Alfirevic Z, Devane D, Gyte GM (2006). "Continuous cardiotocography (CTG) as a form of electronic fetal monitoring (EFM) for fetal assessment during labour". Cochrane Database Syst Rev 3: CD006066. doi:10.1002/14651858.CD006066. PMID 16856111.