Fetal distress is a loosely defined term used to indicate that the baby is compromised and in need of delivery.
Problems and special considerations
The main problem is that the diagnosis of ‘fetal distress’ can be difficult and must take into account many clinical parameters, together with the woman’s previous obstetric history and her age. Although cardiotocography (CTG) and the presence of meconium are most commonly used to indicate fetal distress, fetal heart rate changes and meconium do not always correlate with acidosis or hypoxia, and the sensitivity and specificity for predicting a poor neonatal outcome are relatively low. In particularly high-risk cases, these signs may be more significant; in such cases antenatal diagnosis of impending fetal distress may be possible, based on ultrasound scans, Doppler blood flow studies and CTG monitoring.
Fetal distress is often used as a label to hasten operative delivery. The difficulty of associating intrapartum signs with outcome means that the allowable time before delivery is uncertain. At one end of the spectrum is the baby that needs to be delivered as soon as possible since there is immediate threat to its life, for example from placental abruption. At the other end of the spectrum, the baby needs to be delivered soon but there is time to plan the delivery. Most units’ guidelines call for a maximum of 15-30 minutes between the decision to deliver by caesarean section and delivery itself, for urgent (category-1) caesarean section. However, these times are derived largely from animal experiments over 30 years ago and their relevance is arguable, especially since most cerebral palsy is now known to be related to factors arising before labour. In addition, most units find it difficult to meet these time limits.
Delivery of babies who are diagnosed as being ‘distressed’ before labour (see Chapter 12, Antenatal care) often needs the support of the neonatal intensive care unit (NICU); thus the time and place of delivery must also take account of neonatal cot availability when the gestation of the baby meets the level of NICU care. For women in labour, transfer to another unit is usually not possible, thereby often necessitating ex- utero transfer of the baby.
For the above reasons, the term ‘fetal distress’ has fallen out of favour. For example, in UK national guidance on CTG monitoring, it is not used at all, and potentially abnormal CTG patterns are described as being ‘non-reassuring’, ‘suspicious’ or ‘pathological’. In practice, however, the term is still often used to indicate a potentially compromised fetus.
Management options
It is crucial that there is good communication between all members of the team, the mother and her partner. In particular, obstetricians should describe the clinical situation to their anaesthetic colleagues in more detail than just saying there is ‘fetal distress’ - and anaesthetists must be aware of the various signs that might indicate fetal compromise, so that they can put such descriptions into context. The choice of anaesthetic technique will depend on maternal factors and the degree of urgency of the case, the onus resting with the obstetrician to indicate the latter.
The ability to improve the fetus’s condition while preparing for delivery is often forgotten. Intrauterine resuscitation includes ensuring that the mother is in the left lateral position, giving her oxygen (although there is little hard evidence that this is beneficial, and some have suggested that it may be potentially harmful), giving intravenous fluids and treating any hypotension, stopping oxytocic drugs and giving tocolytic drugs such as salbutamol or terbutaline 100-250 µg intravenously, or glyceryl trinitrate 50 µg intravenously or 200-400 µg sublingually.
Fetal distress is a descriptive label for a variety of diagnoses and clinical situations, but if the anaesthetist understands that not all fetal distress is a life-threatening emergency, the care of the mother will improve. There are few situations in which there is not time to institute or extend a regional block to provide regional anaesthesia. For extreme cases, general anaesthesia is often used; although not necessarily faster than a spinal anaesthetic, it is generally more reliable, if more hazardous.
Key points
• ‘Fetal distress’ is an ill-defined term, and signs of ‘fetal distress’ are poorly correlated with poor neonatal outcome.
• Degree of urgency of delivery is a useful guide for anaesthetists to plan the anaesthetic technique, although definitions are vague.
• Anaesthetists must communicate with their obstetric and midwifery colleagues.
• Intrauterine resuscitation should always be remembered.
Further reading
Committee on Obstetric Practice, American College of Obstetricians and Gynecologists. ACOG Committee Opinion. Number 326, December 2005. Inappropriate use of the terms fetal distress and birth asphyxia. Obstet Gynecol 2005; 106: 1469-70.
National Institute for Health and Care Excellence. Intrapartum Care for Healthy Women and Babies. Clinical Guideline 190. London: NICE, 2014 (updated 2017). www.nice.org.uk/guidance/cg190 (accessed December 2018).
Yentis SM. Whose distress is it anyway? ‘Fetal distress’ and the 30-minute rule. Anaesthesia 2003; 58: 732-3.