Case Study
A fit and well low-risk nulliparous woman presented at 39 weeks’ gestation to the delivery suite. She was contracting twice in 10 minutes, and at vaginal examination, her cervix was dilated 3 cm. Cardiotocography was unremarkable.
Pain relief was requested, and an epidural was inserted by the anesthetist. Patient-controlled epidural analgesia (PCEA) was started using a low-dose mixture (LDM) of 0.1% bupivacaine with 2 µg/ml fentanyl.
Subsequently, labor progression was slow, requiring augmentation with a syntocinon infusion. Although the labor pain was initially well controlled, as augmentation progressed, the patient became increasingly distressed due to pain and required multiple additional clinician-administered boluses of LDM.
After an extended period of augmentation, it was decided to deliver by cesarean due to a lack of labor progress. The patient was transferred to the OR, and an epidural top-up of 20 ml 2% lidocaine with 1:200,000 epinephrine and sodium bicarbonate was administered. Within 10 minutes, a block had been established bilaterally up to T6 to cold, when a prolonged fetal bradycardia necessitated urgent delivery. However, once the baby was delivered, uterine exteriorization resulted in the patient complaining of pronounced pain requiring conversion to general anesthesia (GA).
After rapid-sequence induction, the patient was successfully intubated, and surgery was continued. The patient went on to make an uncomplicated recovery.
Key Points
This patient experienced intraoperative pain during cesarean delivery under epidural anesthesia.
Her epidural required multiple clinician interventions for breakthrough labor pain, and cesarean delivery was expedited after epidural top-up due to fetal compromise.
General anesthesia was administered after delivery to facilitate completion of surgery.
Discussion
Epidural analgesia (EA) is considered by many to be the “gold standard” for labor pain relief. UK audit data has consistently show that approximately 20% of all cesarean deliveries are performed under epidural anesthesia (Figure 30.1). Not only can it effectively relieve the pain of labor, but it also has the benefit of allowing conversion to anesthesia for urgent operative procedures such as cesarean delivery. Additionally, with the use of EA, the safety of obstetric anesthesia has improved markedly. This has been demonstrated by a reduction in airway and aspiration-related mortality and morbidity in serial obstetric safety audits.1
Figure 30.1 The percentage of cesarean deliveries performed under epidural anesthesia in the United Kingdom.
However, EA also present risks related to the procedure itself, the risk of failure, and the risks of subsequent general anesthesia (GA). The risk of failed epidural conversion for cesarean delivery (defined as the failure to induce and provide adequate anesthesia for the length of the procedure or the need for supplemental analgesia or GA) is variously quoted at between 7.1 and 24 percent.2, 3
Risk Factors
A number of risk factors that might predict an increased risk of EA failure have been identified (Table 30.1). The effectiveness of EA in labor is linked to the effectiveness of the same epidural for anesthesia. Supplementation of labor analgesia with additional clinician-administered epidural boluses may be reflective of a suboptimal epidural catheter placement. As in the Case Study, this may then present during cesarean delivery as inadequate EA. If a patient is unable to obtain adequate relief from labor pain, without the need for supplemental epidural boluses, a low threshold for replacing the epidural catheter may reduce the risk of failed EA during cesarean delivery.
Table 30.1 Factors Associated with an Increased Risk of Epidural Conversion Failure
| • Increased number of supplementary clinician boluses in labor |
| • Non-obstetric anesthetist providing care |
| • Urgency of cesarean delivery |
| • High maternal weight or height |
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