Ms K, who is in her first pregnancy, attended the midwifery-led unit in spontaneous labour at term. The midwife assessing her observes that she has a mild tachycardia on admission and encourages her to drink. The tachycardia settles, however, after several hours in labour she is transferred to the labour ward for management of slow progress in the first stage of labour.
On the labour ward discussions take place regarding the need to have an intravenous (IV) oxytocin infusion to augment contractions. An IV cannula is inserted, and the oxytocin infusion and intravenous fluids were started. Some variable decelerations of the fetal heart are noted on the cardiotocograph (CTG), and the flow of intravenous fluids is increased.
Ms K progresses to fully dilatation, and after active pushing for around an hour, the CTG is pathological and she consents to a trial of instrumental birth.
In theatre, her behaviour is noted to be unusual, as she appears confused and agitated, but she is tired and exhausted after a prolonged labour. The baby is delivered by forceps in poor condition, the neonatal team begin resuscitation and transfer the baby to the neonatal intensive care unit for ongoing care including therapeutic cooling for seizures.
In maternity recovery, the mother’s behaviour continued to deteriorate and a referral to the liaison psychiatry team is made. Approximately an hour after giving birth, her partner calls for help as she begins to have a seizure.
An arterial blood gas taken following the seizure reveals a sodium level of 117 mmol/l that is confirmed on a venous sample sent to the laboratory. She is transferred to the intensive care unit for ongoing care.
Her partner is not sure but thinks she may have drunk at least three litres of water while in labour. This is in addition to the two litres of intravenous fluid on the drug chart from labour ward and theatre.
The neonatal team are also informed, and a review of the baby’s cord gas results reveal a low sodium at birth of 116 mmol/l, but this was not seen previously.
Learning Points
- This case story highlights the importance of accurately monitoring fluid intake and output during labour to reduce the chance of a mother experiencing hyponatraemia.
- Hyponatremia should be considered as a potential differential diagnosis if a mother appears confused, agitated or has a significant behaviour change during labour and a sodium level should be checked immediately.
- Updated National Institute for Health and Care Excellence Guidance (NICE) guidance advises not to offer intravenous fluids to treat fetal heat rate abnormalities unless the woman is hypotensive or has signs of sepsis.
- Hyponatraemia should be considered as a potential cause for neonatal seizures, particularly if there is no strong evidence of hypoxia during labour or delivery.
Considerations for you
- Do all birth settings in your trust have up-to-date guidance on fluid intake, monitoring, and fluid balance management in labour?
- Does local guidance cover what is appropriate advice to give to women regarding oral fluid intake? Current evidence suggests a rise in cases of hyponatraemia in labour due to excessive oral intake of hypo or isotonic fluids in addition to the recognised effects of intravenous fluids and oxytocin infusion.
- Do partograms used in all birth settings have a section to record fluid input and output?
- Read the Northern Ireland GAIN guideline on hyponatraemia in labour3 and consider whether it could be implemented in your trust.
Previous
