To compare the analgesic efficacy of ultrasound guided quadratus lumborum block to ultrasound guided transversus abdominis plane (TAP) block in patients undergoing operative laparoscopic gynaecological procedures under general anaesthesia

The increasing use of laparoscopic surgery in modern surgery has led to its widespread use for gynaecological procedures as well. Myomectomy, hysterectomy, cystectomy, salpingo-oophorectomy, salpingectomy and sacral colpopexy are some of the procedures being performed by laparoscopy in the present day.

Laparoscopic surgery has resulted in reducing postoperative pain and improving patient mobilization as compared to open surgery1,2. However, moderate to severe peri- operative pain does occur following major laparoscopic surgery which can interfere with patient mobilization and recovery3. This pain is attributed to the port site incisions and also to the intra-operative peritoneal stretching and visceral handling. Shoulder tip pain due to pneumo-peritoneum has also been reported4.

The use of opioids as a part of multimodal analgesia together with acetaminophen and non steroidal anti inflammatory drugs (NSAIDs) is the standard analgesic regimen for these procedures. The use of opioids however is associated with sedation, post operative nausea and vomiting, respiratory depression and urinary retention. This has led to the incorporation of peripheral nerve block techniques for providing peri-operative analgesia in patients undergoing laparoscopic surgery5.

Bilateral transversus abdominis block (TAP) block is one such technique that has been developed in order to provide peri-operative analgesia. The TAP block has been shown to be useful in the treatment of pain after abdominal wall surgery5. Numerous studies have shown that the TAP block, when used as part of a multimodal analgesic regimen, is an effective component in reducing patients’ postoperative pain scores6,7,8.

In TAP block, infiltration of local anaesthetic agents in the plane between the internal oblique and the transversus abdominis muscle results in blockade of the somatic nerves

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innervating the anterior abdominal wall. Recent reviews have reported more prolonged analgesia with the extension of the local anaesthetic into the paravertebral space as seen with the landmark guided or posterior TAP block10.

The Quadratus Lumborum (QL) block is a newer modification of the TAP block concept that includes deposition of injectate adjacent to the antero-lateral aspect of the QL muscle. The spread pattern obtained by QL block is comparable to that of the landmark-based TAP block, in that there is extension into the thoracic paravertebral space10. The transmuscular approach to the QL block with the needle tip positioned anterior to the quadratus lumborum muscle but posterior to the psoas major muscle has shown to be more successful as the spread of local anaesthetic to the thoracic paravertebral space seems to be of crucial importance for the efficacy of posterior TAP blocks11.

The QL muscle and the psoas major muscle have their embryonic origin in the thoracic cage. Their close proximity to the transversalis fascia and the endothoracic fascia may be responsible for the proposed spread of the local anaesthetic to the thoracic paravertebral space. This enables the potential of the QL block to produce somatic as well as visceral analgesia.

This study aims to ascertain whether USG quadratus lumborum block would result in better pain relief as compared to standard multimodal analgesic regimen that includes TAP block for adult patients undergoing operative laparoscopic gynaecological procedures under general anaesthesia.