Total abdominal hysterectomy is a routinely performed major surgery that results in substantial post-operative pain and discomfort.  Poorly controlled acute pain after abdominal hysterectomy is associated with increased incidence of post-operative complications like atelectasis, pneumonia, delirium, myocardial ischemia, prolonged hospital stay and an increased likelihood of chronic pain. For postoperative pain relief, non-opioid drugs, patient controlled intravenous strong opioids or central neuroaxial blockade are introduced in a stepwise fashion in response to reported pain intensity, usually combining two or more agents to provide adequate relief whilst minimizing adverse effects from any individual analgesic. Peripheral nerve blockade is an alternative method of providing pain relief, which offers excellent selective analgesia across a wide range of surgical procedures. Epidural analgesia is the gold standard analgesic technique. It is associated with lower visual analogue pain scores (VAS) and higher patient satisfaction. However   undesirable effects like motor blockade and urinary retention with increasing doses of local anaesthetics have been reported. A failure rate ranging from 17-37% has also been reported with the use of this technique. Opioids delivered using patient controlled analgesia is another modality available. Though patients may be comfortable at rest, some may experience significant pain on movement. Adverse effects like sedation, nausea, vomiting, pruritis and respiratory depression are frequently associated with this technique.  Renal toxicity, general bleeding risks are associated with use of non opioids like non steroidal anti-inflammatory drugs.

Abdominal wall incision contributes to a significant component of pain experienced by patients after abdominal surgery. A promising novel approach to post-operative analgesia is to block the sensory nerve supply to the anterior abdominal wall using transversus abdominis plane block. TAP block involves infiltration of local anaesthetic into a plane between the internal oblique and transverse abdominis muscle, thus blocking the sensory nerves before their infiltration of the muscles of anterior abdominal wall.The analgesic efficacy of TAP block has been demonstrated in different surgical procedures.  However, the analgesic efficacy of sonographically guided TAP block has not been compared with epidural analgesia previously.

We hypothesize that co-administration of sonographically guided TAP block  with continuous epidural infusion of local anesthetics as part of a multimodal analgesic technique would result in superior postoperative analgesia (lower pain scores) and better patient satisfaction following total abdominal hysterectomy.