Pain management for uterine fibroid embolization

Why we cannot do without pain treatment

Uterine fibroid artery embolization (UFE) has become an established treatment for the management of patients with symptomatic uterine fibroids. More than 25,000 UFE procedures are undertaken worldwide with a growing body of evidence demonstrating the effectiveness and safety of this technique. [1–3] However, one of the main issues around UFE treatment is the significant amount of post-operative pain [1–3] as part of the post embolization syndrome which usually occurs within the first 24h and can be difficult to manage, sometimes leading to delayed discharged and increased use of opioid drugs. Pain is experienced by all patients to some degree with worsening pain in the first 2-3 hours post procedure and plateauing at around 12 hours. In addition to the pain and cramping, women can also experience low grade fever, nausea, vomiting, loss of appetite, malaise, and leucocytosis as a result of tissue ischemia and necrosis leading to inflammation. The severity of pain various hugely between women post procedure and multiple factors may be involved including fibroid volume, race, type of particles used, demographic, and cultural pain threshold. Involving patients in their pain management and understanding the pathophysiological factors underlying the pain offers an opportunity to look at better targeted pain relief. If pain can be adequately controlled, then UFE can become a truly day case procedure with huge benefits to patients and institutions.

Addressing post-procedural pain

Many analgesia protocols have been developed to support women during UFE, using a variety of medications including a range of non steroidal anti-inflammatory (NSAID) drugs such as Ibuprofen and Diclofenac. Often they are used in conjunction with opioids, as they work through different pain-inhibitory pathways providing synergistic pain relief. Another NSAID that is often used is Ketorolac which has strong analgesic properties in addition to a moderate anti-inflammatory effect with a half life of 3-9 hours during peak pain and when given with other analgesics can provide additive effects. Given via coated particles and IV, it offers fast-acting analgesic and anti-inflammatory effects which can facilitate UFE to be undertaken as an outpatient procedure. Acetaminophen is also commonly used as an effective and safe analgesic and is one of the most commonly prescribed drugs for the treatment of postoperative pain either on its own or in combination regimens. Opioids such as morphine and Fentanyl are commonly used, including in patient controlled anaesthesia (PCA) allowing patients to have some control of their analgesia. Other commonly used opiates include hydromorphone, hydrocodone, and oxycodone. Use of controlled-release oxycodone on its own or in addition to intrathecal and IV morphine has been shown to reduce pain scores during the first 24 hours post-procedure with less morphine consumption through PCA. [4-6]

Glucocorticoids have a potent anti-inflammatory effect, as they block both the vascular and cellular phase of inflammation. By decreasing the inflammatory mediators after ischemic injury, pain should be better controlled and this has been confirmed by studies using dexamethasone, with reduced pain post procedure. [4-6] To augment these measures intra-arterial lidocaine at the completion of the procedure into the uterine arteries has also been advocated by some authors and been shown to reduce early pain in the first few hours after the procedure, but no longer term pain relief has been demonstrated out at 7-12 hours.

What else is out there other than the usual suspects?

In addition to using medications to control post procedural pain, some authors have also advocated using superior hypogastric nerve block (SHNB) which is an invasive procedure undertaken at the beginning or completion of the UFE procedure. Under fluoroscopic guidance, bupivacaine is injected into the hypogastric nerve ganglia which along with systemic analgesics provides multimodal pain control. Painful stimuli production is blocked at the level of the uterus through inhibition of prostaglandins, transmission of painful signals is blocked with SHNB, and opioids inhibition of pain recognition at the level of the brain. Individual studies following SHNB patients have reported a less traumatic experience , requiring lower doses of narcotic. As an alternative to nerve blocks, early studies have also demonstrated the benefits of using percutaneous nerve stimulation, which has similarly shown reduction in the use of analgesics.

Finally, access may play a role with at least one study suggesting reduced immediate pain scores. However, this was lost later on with no longer term benefit, but is an area for further study.

In summary, there are a multitude of different protocols in the literature demonstrating the complexity of pain management with no consensus regarding which protocol is the most cost-effective. When we conducted a review and meta-analysis of the literature, although single centre studies showed improvement with different regimes, in a pooled meta-analysis of literature we found no benefit of one regimen over the others. [4] Despite opioids NSAIDs ± acetaminophen and intrauterine artery drug administration showing overall slightly better pain scores in comparison with the other treatment groups, this difference was not statistically significant. In addition, there was no difference in duration of hospital stay between the invasive and non-invasive protocols.