Complications arising from obstetric anaesthesia: when do they constitute medical negligence?

THE STORY of obstetric anaesthesia over the past 20 years has undoubtedly been one of clinical success. The triennial reports on Confidential Enquiries into Maternal Deaths in the UK clearly show that the number of anaesthetic-related maternal deaths has been steadily falling, despite anaesthetists being involved in an increasing proportion of labours (thanks to the rising epidural and Caesarean section rates).

The change has been achieved via a variety of factors, including improved anaesthetic cover for maternity units, but the most important is almost certainly the move from general to regional anaesthesia (epidural, spinal or combined spinal-epidural) for Caesarean section. Only around 10% of Caesarean sections are now carried out under general anaesthesia, compared to 77% only 20 years ago.

While undoubtedly a major factor in improving patient safety, the emphasis on the use of regional anaesthesia, coupled with the increasing popularity of epidural pain relief in labour, has brought problems of its own, with morbidity taking the place of mortality. At the same time, anaesthetists are becoming increasingly involved in the care of sick obstetric patients, resulting in them having clinical input into the care of 60% of all maternity patients. It is, therefore, hardly surprising that, when two of the highest risk medical specialities – obstetrics and anaesthesia – are combined, medicolegal claims are frequent.

This article explores some of the areas where litigation is on the rise as a result of the changes described above.

Consent
The issue of consent is, unsurprisingly, a particular problem in obstetric practice. A woman in the throes of labour, who may already be under the influence of powerful sedative drugs such as pethidine, is not best placed to make an informed decision about the risks and benefits of interventions such as epidural pain relief.

A large majority of obstetric anaesthetists in the UK take verbal, rather than written, consent for epidural analgesia, but most now record the pertinent risks and benefits that they discuss. These will normally include the possibility that the epidural will fail to provide adequate pain relief (around 5-15%), the risk of headache secondary to inadvertent dural puncture (0.5-1%, see below), the likelihood that the mother’s legs will feel rather heavy during the epidural, the possibility that her blood pressure might fall and, nowadays, the evidence that epidural analgesia increases the chance of instrumental delivery (but not of Caesarean section).

The recent House of Lords ruling in Chester v. Afshar has moved the goalposts considerably, and its impact on the practical application of consent in this most difficult area has yet to be assessed.

Pain during Caesarean section
Pain felt during Caesarean section under epidural or spinal anaesthesia probably represents the commonest successful medico-legal claim made against anaesthetists in the UK.

Pain-free Caesarean section cannot be guaranteed, however good the block; consequently, the patient who feels pain during the operation is not necessarily the victim of negligence. However, for the anaesthetist to have a good defence, he must be able to demonstrate that he took reasonable steps to minimise the chance of pain and then to treat it when it occurred. Those steps can be summarised as:

• Warning the patient about the risk of pain and the possibility of conversion to general anaesthesia. It is wise to make a record of the risks explained to the patient in case of later dispute.
• Using a technique that is recognised as acceptable.
• Testing the extent of block and demonstrating it to be effective. Good current practice is exemplified by Russell’s recommendation of a block to T5 (just below the nipple line) using a touch sensation such as cotton wool. A survey carried out in 1996 showed that only 4% of practitioners would regard a T8 block (half-way between lower end of the sternum and the umbilicus) as adequate for Caesarean section.
• Treating pain adequately when it occurs by use of epidural top-ups, intravenous or inhalational analgesia, or induction of general anaesthesia. General anaesthesia should not be withheld without very good reason if the patient is not coping with the procedure.
• Providing follow-up and support to the patient who feels pain.

Neurological damage after regional block Neurological symptoms in the lower limbs actually arise more frequently as a result of the process of childbirth (around one in 3,000) than as a result of epidural or spinal block (around one in 10,000).