Epidurals are a common pain relief method during labor and delivery. While generally successful in providing comfort, an epidural may not offer complete pain relief, a situation often called “epidural failure.”
Defining Epidural Failure
Epidural failure can manifest as partial or inadequate relief, where pain is lessened but still uncomfortable. A one-sided block provides relief on only one side of the body. A patchy block occurs when areas of numbness are interspersed with areas that still experience pain. Complete absence of pain relief is possible but less common. Epidural failure is estimated to occur in about 2% to 12% of cases, with partial or patchy relief being more frequent than total failure.
Reasons Why Epidurals May Not Work
Anatomical variations in an individual’s spine can make precise catheter placement challenging. Tough ligaments, unusual contours of the epidural space, scoliosis, or previous spinal surgery can impede uniform medication spread or catheter insertion. Scar tissue from prior back surgeries, known as epidural fibrosis, can also interfere with medication diffusion and effectiveness.
Catheter placement issues frequently cause insufficient pain control. The catheter might be inserted too shallowly into subcutaneous tissue, too deeply into the spinal fluid space (intrathecal), or inadvertently into a blood vessel. The catheter can also migrate or move after initial placement, leading to reduced or uneven pain relief.
Medication factors also affect epidural effectiveness. An insufficient dosage or concentration of anesthetic medication for an individual’s pain level or labor progression may result in inadequate relief. While less common, some individuals might metabolize the medication more rapidly, diminishing its effect. The selection of local anesthetic and any added medications, such as opioids, also influences block quality.
Rapid labor progression may outpace the epidural’s onset or effectiveness, leaving insufficient time for the medication to take full effect before delivery. Patient-specific factors, such as obesity, also present challenges during epidural placement. Increased body mass index can make it more difficult to identify anatomical landmarks and insert the needle accurately, potentially leading to a less effective block.
Managing Pain When an Epidural Fails
When an epidural does not provide adequate pain relief, medical professionals take several steps. The initial response involves assessing the patient’s pain level and the catheter’s position to determine the cause. An anesthesiologist may then administer additional medication, known as re-dosing or bolusing, through the existing catheter to enhance the block.
Repositioning the patient is another common strategy, as changing posture may help medication spread more evenly within the epidural space. If these measures are unsuccessful, the medical team might adjust the catheter’s depth or, if necessary, remove the existing catheter and place a new one.
If the epidural still does not provide sufficient pain relief, alternative options are available. These include intravenous pain medication, which offers systemic relief, or nitrous oxide (laughing gas) for a calming effect. In some cases, a spinal block, which provides rapid, strong pain relief but is typically a single injection, might be considered, especially if delivery is near. Clear communication with the anesthesia provider is important to discuss symptoms and explore available solutions.