This video discussed the role of Transversus Abdominis Plane TAP Block in both Obstetrics and Gynecology.
University of Ottawa, The Ottawa Hospital, KK Women’s and Children’s Hospital
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Video Transcript: The Role of TAP Block in OBGYN
KK Women’s and Children’s Hospital and the Ottawa Hospital Research Institute jointly present The Role of TAP Block in Obstetrics and Gynaecology. The objectives are to demonstrate the technique of transversus abdominis plane block and review its role and clinical utility in obstetrics and gynecology.
TAP block is widely used to provide analgesia to the anterolateral abdominal wall. Recent literature suggests that this block may be used to help decrease postoperative pain in laparotomy for gynaecologic surgery, and may help with earlier discharge. Knowledge of the technique for this block may assist the gynecologist and anaesthesiologist to help provide this option for a greater number of patients.
It is important to understand the anatomical relationship of the musculature and nerves of the abdominal wall. The musculature comprises of the external oblique, internal oblique and the transversus abdominis muscles. A transversus abdominis plane is a special plane that lies between the internal oblique and transversus abdominis.
The sensory supply of the anterolateral abdominal wall arises from the anterior rami of the lower sixth thoracic nerves and first lumbar nerve. The branches traverse the transversus abdominis plane to supply the skin, muscle and parietal peritoneum.
T7 to T9 supplies the skin above the umbilicus, T10 supplies the umbilicus, whereas T11, T12, the iliohypogastric and ilioinguinal nerve supply the skin below the umbilicus.
TAP block is a fascial plane technique where a large amount of local anesthetic agent is injected into the transversus abdominis plane to achieve sensory blockades of mid-lower thoracic and upper lumbar nerves.
The equipment required includes aseptic skin preparation, sterile gloves, a 20 ml syringe, 22 gauge spinal needle and long-acting local anesthetic agents such as ropivacaine and bupivacaine.
In the operating room setting, patient-monitoring equipment and resuscitation equipment would be available. For the ultrasound guided technique, an ultrasound machine with high frequency linear transducer with a sterile probe cover is required.
There are two techniques to perform this block, the surface landmark technique and the ultrasound guided technique. The lumbar triangle of the petit is an important anatomical landmark. It is bound by the external oblique anteriorly, the latissimus dorsi posteriorly, and the iliac crest inferiorly.
After aseptic in preparation, the needle is inserted perpendicularly to the skin. Two pops are felt by the operator as the needle is advanced, the first as the needle pierces the fascial extension of the external oblique, and the second as the needle pierces a fascial extension of the internal oblique. The needle reaches the transversus abdominis plane. And it’s important to aspirate before injecting 20 ml of local anesthetic per side.
TAP block done under ultrasound guidance has the advantage of visualizing the needle during insertion to ensure correct placement. This supports injuries and increases success rates. The operator scans from the midline of the abdominal wall towards the area between the iliac crest and the costal margin in the midaxillary line.
The three muscle layers can be seen running parallel to one another, and the transversus abdominis plane can be identified between the internal oblique and transversus abdominis. The needle is inserted anterior to the transducer to allow an in plane view of the needle as it advances through the transversus abdominis plane. Upon injection, the fascial plane is seen to separate and form a hypoechoic elliptical shape between the internal oblique and transversus abdominis.
The absolute contraindications of TAP block are patient refusal, allergic to local anesthetic, a localised infection over the injection point. Relative contraindications include coagulopathy and surgery performed at the site of injection.
TAP block is generally safe, with few complications. Possible complications include failure of the block, bleeding, infection, local anesthetic toxicity, intraperitoneal injection and visceral injury. There have been case reports of bowel hematoma, liver laceration and intrahepatic injection.
TAP block can be used for enhanced analgesia after surgery. It has been shown to lower postop opioid requirements, which reduces respiratory depression and improves pulmonary mechanics. As visceral pain is not blocked, other modes of analgesia, such as oral analgesia and patient-controlled analgesia will still play an important role in postop pain management.
The role of TAP block has been proven in lower abdominal surgeries as part of a multimodal analgesia regimen. Studies have shown that TAP block provided reliable blockade to levels T10 to L1. There was evidence for a reduction in postop pain and opioid requirement in the immediate postoperative period, although these effects are not sustained beyond that.
These blocks are also superior to wound site infiltration with a local anesthetic. However, there was less evidence for laparoscopy, and more well-designed randomized trials are needed. For cesarean sections, evidence suggests that TAP block reduced pain scores and analgesic requirements in patients who received spinal anesthesia, but these benefits were not present in patients who received intrathecal morphine.
To summarise, TAP block is generally safe, efficacious, and technically simple to perform, with low complication rates. In recent years, numerous publications have shown the potential for TAP block in postop pain management. However, it remains underutilized in obstetrics and gynecology. With more research, education and training in its use, it can be more widely incorporated into postoperative multimodal pain management pathways. Thank you.