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Dealing with technical difficulties in obtaining adequate continuous CTG tracings

A further theme was the management of mothers when there was difficulty obtaining adequate continuous CTG tracings. Time can be lost by blaming the equipment for a CTG abnormality and significant events can be missed if maternity providers do not react and investigate a sudden change in the CTG patterns.

 

Situation

A mother with a history of a previous caesarean section was admitted in early labour and had continuous CTG monitoring and an epidural. The CTG became difficult to interpret with a suspected high baseline and variable decelerations. Vaginal examination was performed and the cervix was 9 cm dilated. After 1 hour, it was noted that the tocograph was not recording the uterine contractions and that they were no longer palpable abdominally. After discussion with the consultant, the decision was made to commence an intravenous oxytocin infusion.

When delay in the second stage of labour was diagnosed, a decision was made to increase the oxytocin dose in preparation for a trial of instrumental delivery in theatre. This was discussed and agreed by the consultant obstetrician. The CTG was described as reassuring. However, on retrospective review the maternal heart rate was 120 beats/minute and it seems likely the CTG was recording the maternal rather than the fetal pulse.

The obstetric registrar performed a forceps delivery of a stillborn infant. This was followed by fresh vaginal bleeding, which persisted after the repair of the perineal tear. The consultant attended, and when the mother started to complain of shoulder tip pain, the possibility of a uterine rupture was considered. A second consultant was called and a laparotomy performed confirming uterine rupture.

Commentary

This vignette highlights the need to be alert to the other aspect of the CTG – the tocograph. Had the sudden loss of contractions in a mother with a previous caesarean section been considered more thoroughly, the diagnosis of uterine rupture may have been made earlier preventing the outcome.

 

Situation

A mother attended with a history of pink vaginal discharge and contractions. Continuous CTG demonstrated a prolonged deceleration and the mother was transferred to theatre. The fetal heart rate recovered and she was transferred to a delivery room with the plan to perform artificial rupture of membranes if decelerations persisted.

After a further deceleration, artificial rupture of membranes was performed at 4 cm dilatation revealing thick meconium. The fetal heart became difficult to monitor. An attempt to place a fetal scalp electrode lasted more than 30 minutes. When a second CTG machine was used, it also failed to record the fetal heart. Eventually, the obstetric registrar was asked to perform an ultrasound scan. A fetal bradycardia was noted and a category 1 caesarean section was performed. The baby was stillborn.

Commentary

When a fetal heart rate becomes undetectable, maternity teams need to act quickly to ensure that the fetal heart rate is satisfactory. Although fetal scalp electrodes are a recognised way to monitor the fetal heart when the transabdominal route is unsatisfactory, they can still be unreliable and it can take time to establish a good trace. Good-quality, continuous recordings of both the fetal heart rate and uterine contractions are a critical prerequisite for adequate CTG interpretation. Trying to achieve this in a timely manner can be intrusive, but it is the duty of health providers, when appropriate, to find a way to adequately monitor women and their babies in labour.

 

Things you can do

Ultrasound scanning should be used to exclude severe fetal heart rate abnormalities when a CTG recording cannot be obtained reliably via a transabdominal transducer or a fetal scalp electrode.