From the Research
The recommended protocol for performing a Pudendal Nerve Block (PFIS) involves proper patient positioning, typically in lithotomy or lateral decubitus position, followed by identification of anatomical landmarks. After sterile preparation, a 22-gauge, 10-12 cm needle is inserted 1-1.5 cm medial and posterior to the ischial spine, guided by either anatomical landmarks, ultrasound, or nerve stimulation. The recommended medication is 10-15 mL of local anesthetic, typically 0.25-0.5% bupivacaine or 1-2% lidocaine, with optional addition of epinephrine (1:200,000) to prolong the effect, as seen in studies such as 1. Aspiration should be performed before injection to avoid intravascular administration. The block typically provides anesthesia to the perineum, distal rectum, vulva, or distal penis for 4-24 hours depending on the anesthetic used. Potential complications include intravascular injection, hematoma, infection, and nerve injury. This technique is effective because the pudendal nerve provides sensory innervation to the perineum as it passes through Alcock's canal near the ischial spine, making this location ideal for anesthetic delivery. Bilateral blocks may be necessary depending on the procedure. It's worth noting that the use of ultrasound guidance, as studied in 1, can improve the accuracy and safety of the block. Additionally, the choice of local anesthetic and concentration can affect the onset and duration of the block, as seen in studies such as 2. However, the specific protocol may vary depending on the individual patient and the procedure being performed. In general, the goal is to provide effective anesthesia while minimizing the risk of complications, as supported by the evidence from studies such as 3, 4, and 5.
Some key points to consider when performing a PFIS block include:
- Proper patient positioning and identification of anatomical landmarks
- Use of sterile technique and aspiration before injection
- Choice of local anesthetic and concentration
- Use of ultrasound guidance to improve accuracy and safety
- Potential complications and their management
- Individualization of the block to the patient and procedure.
Overall, the PFIS block is a useful technique for providing anesthesia to the perineum and surrounding areas, and can be performed safely and effectively with proper training and attention to detail, as supported by the evidence from studies such as 1 and 2.