Pudendal Nerve Block for Postoperative Pain Relief in Women Undergoing Posterior Vaginal Repairs: a Pilot Study

Pelvic Organ Prolapse (POP) can occur in up to 50% of women after childbirth. Common complications include urinary infection, postoperative pain, and wound infection.

The majority of prolapse repair procedures are carried out under general anaesthetic (GA) with regular analgesia required post operatively. The pain is often described as "agonizing" and results in a substantial consumption of analgesia, often leading to extended periods of bladder catheterisation and bowel dysfunction. Despite numerous attempts to modify surgical techniques and anaesthetic regimens, the problems persist.

In an attempt to relieve the problem local clinicians have had promising results from the addition of a standardised preventive Pudendal Nerve Block (PNB) in reducing post- op pain. To widen the clinical utility of this procedure an evidence base will be required.

Preventive analgesia: Preventive analgesia is a broad term used to describe an analgesic regime given during surgery to control post - op pain and its aim is to reduce the impact of the process known as central sensitization. This refers to an increase in synaptic efficacy in the somatosensory neurons following tissue injury (e.g. surgery) or nerve damage. This leads to a reduction in pain threshold, an amplification of pain responses and a spread of pain sensitivity to non-injured areas resulting in increased post -op pain intensity and analgesic requirements. Preventive analgesics (including nerve blocks) have been incorporated into a range of surgical procedures, with a recent review identifying its strong positive impact on post-operative pain and analgesic consumption.

The Pudendal nerve is a mixed nerve (sensory and motor) derived from the somatic component of sacral nerve roots S2-S4. It is located behind the sacrospinous ligament. It supplies anal and urethral sphincters, the pelvic floor muscles, anal and perineal skin. PNB is a routine procedure used during instrumental deliveries in obstetrics and as a low-risk, low-cost anaesthetic technique effectively reducing perineal and vaginal discomfort during repair of obstetric lacerations. PNB is also increasingly being utilised as a preventive analgesia with positive results on pain relief, reduced analgesics, improved spontaneous micturition, less pain on defecation and shorter hospital stay and pain on following haemorrhoidectomy. Improving post- operative pain relief and enhancing patient recovery is of fundamental importance to both the individual and the National Health Service (NHS). This study is a preliminary step in the assessment of a preventive analgesia on women's post- op experience following routine posterior vaginal wall surgery.