Breakthrough pain may be experienced during the course of operative delivery under spinal or epidural anaesthesia. Breakthrough pain during caesarean section must be dealt with promptly, as inadequate pain control may interfere with surgery and may cause considerable distress to the woman and her partner, leading to patient dissatisfaction or complaints. Indeed, pain during caesarean section is thought to be the most common source of successful litigation against anaesthetists. Pre-warning the patient of the possibility of intraoperative discomfort or pain and the need for supplementation or general anaesthesia, and the accurate pre-procedural assessment and documentation of the height of neuraxial block using multiple modalities, are therefore of crucial importance.
Problems and special considerations
Despite the benefits offered by epidural anaesthesia in terms of titratability and extendability, the technique may not provide the same density of block as spinal anaesthesia, and the onset of adequate surgical anaesthesia may be variable. Supplementation of the block or conversion to general anaesthesia (reported rates of the latter are ~1-4%) may thus reflect an unreliable or incomplete block, or the limited time available to wait until the block becomes adequate.
Sensations of tugging, stretching or pressure during caesarean section are common, and women - especially very anxious ones - may find these symptoms distressing even though they are not painful. It may therefore be difficult for the anaesthetist to be sure that the patient is actually experiencing pain, although he/she must recognise that if the patient is distressed, her symptoms must be taken seriously and treatment offered.
Visceral pain may be experienced in the course of the procedure despite painless skin incision and superficial dissection, and may be secondary to traction on the peritoneum or the uterine ligaments, exteriorisation of the uterus, swabbing of the paracolic recesses or even rough manipulation of tissues.
Chest pain is experienced by some patients. The cause is unclear, but proposed explanations include small air emboli, oesophageal spasm, and irritation of the diaphragm by amniotic fluid or blood. The latter may also cause shoulder-tip pain.
Management
Parturients who receive epidural analgesia, especially those at high risk of operative delivery, must be assessed periodically during the course of labour. A dysfunctional epidural catheter that has failed to provide satisfactory analgesia or one that has required frequent supplementation is less likely to produce a reliable block for caesarean section. Regular review enables the identification of such issues and the manipulation or re-siting of the epidural catheter if necessary.
If the patient complains of pain intraoperatively, surgery must be paused momentarily while the anaesthetist takes steps to establish the origin of the pain and attempt to resolve it, although this may be challenging once the uterine incision is performed or when bleeding is excessive and immediate intervention is necessary. The management of the pain will depend to a large extent on the stage of the operation. Pain experienced in the initial stages of the procedure (i.e. at or immediately after skin incision) indicates a poor-quality neuraxial block, and in the absence of an in-situ epidural catheter to allow further top-up is likely to require either the re-administration of regional anaesthesia, which should be done carefully to avoid precipitating a high block, or conversion to general anaesthesia.
The presence of an epidural catheter in situ may allow extension of the block using rapid-onset agents such as lidocaine or ropivacaine, and opioids such as fentanyl or diamorphine. Additional options for supplementation of the regional anaesthetic at this stage include inhalational analgesia with nitrous oxide, incremental doses of systemic opioids such as alfentanil, fentanyl or diamorphine, short-acting benzodiazepines such as midazolam, or ketamine in analgesic doses (10-20 mg boluses). The administration of intravenous agents should be done with caution in order to avoid excessive maternal sedation and potential airway compromise. The use of local anaesthetic infiltration of tissues may also be employed as a rescue technique. The anaesthetist must maintain effective communication with the patient and continue to provide explanation and reassurance.
Severe maternal emotional distress or failure of the above measures to control her pain must prompt the anaesthetist to offer the woman general anaesthesia. If women decline, it may be because they are scared by the knowledge (often provided by the same anaesthetist preoperatively) that general anaesthesia is considered more dangerous than regional anaesthesia. The anaesthetist must be mindful of this, reassuring her and being prepared on occasion to recommend strongly that general anaesthesia may be the best option, rather than merely ‘offering’ it meekly. Adequate preparation and skilled assistance is of paramount importance, as the procedure may be problematic when performed intraoperatively.
Because of the distress that intraoperative pain may cause, and the risk of psychological trauma and of complaints or litigation, it is crucial that clear records are kept. These must include evidence of:
1. Explanation preoperatively that discomfort or pain is possible, and that the options of supplementation and conversion to general anaesthesia are available
2. Appropriate and adequate regional anaesthetic technique, e.g. method of insertion of a de novo block or top-up of an existing epidural
3. Adequate and thorough assessment of the block before surgery starts
4. Appropriate action if/when pain is felt, e.g. halting surgery, administration of further drugs, offer of general anaesthesia, reassurance/support etc.
5. Provision of postoperative follow-up and explanation(s) and further counselling if the mother wishes
Key points
• Breakthrough pain under caesarean section is multifactorial and may occur despite a seemingly adequate level of surgical anaesthesia.
• Women experiencing pain during surgery may be very distressed and may develop post- traumatic stress disorder.
• A multimodal assessment of the height of neuraxial block for operative delivery is recommended.
• Intraoperative management may include: halting surgery if possible; intravenous, inhalational or epidural supplementation; and conversion to general anaesthesia.
• Effective communication with the patient during the procedure, postoperative follow-up and accurate recording of events are all essential.
Further reading
Bogod D. Pain during caesarean section. BJOG 2016; 123: 753.
Mankowitz SK, Gonzalez Fiol A, Smiley R. Failure to extend epidural labor analgesia for cesarean delivery anesthesia. Anesth Analg 2016; 123: 1174-80.