Pediatric Ultrasound-Guided Caudal Block

This video demonstrates how to perform an ultrasound-guided single-shot caudal block for postoperative pain control in a pediatric patient about to undergo bilateral inguinal hernia repair.

The performance of an ultrasound-guided caudal block under general anesthesia in a pediatric patient is demonstrated in this video. Ultrasound-guided caudal block is a method used to provide analgesia for procedures in the low-thoracic and lumbosacral regions. Caudal blocks are a type of neuraxial block commonly used to administer analgesia for surgeries of the lower umbilical region (Ref 1,2). Ultrasound (US) guidance provides practical and real-time visualization of structures and can be used to guide proper needle placement and visualize the spread of the local anesthetic. Compared to the conventional landmark technique, the use of US guidance has been reported to result in higher first puncture success rate and decreased complications (Ref 3,4).

Caudal blocks are the most performed neuraxial block in the pediatric population for intraoperative and postoperative pain control. Traditionally, the anatomical landmark technique has been the mainstay for performance. With the increasing use and improvement of technology, ultrasound-guided caudal blocks provide enhanced visualization and guidance. In skillful hands, ultrasound-imaging can help identify landmarks and increase the success rate of the first puncture, especially in those patients whose anatomical landmarks may not be easily palpable or in whom abnormalities are present. Studies have reported higher first puncture success rates and lower incidence of complications associated with its use (Ref 3,4).


· Personal protective equipment (sterile gloves, face mask, cap) 

· Skin Cleaning Solution (chlorhexidine, alcohol, or iodine) 

· Sterile drapes, towels, gauze

 · 7 to 13 MHz linear transducer and ultrasound machine 

· Sterile ultrasound probe cover 

· Sterile ultrasound gel 

· Needle [examples: Monojet 22Gx1-1/2”(0.711mm x 3.8cm), Epican caudal epidural needle 32* Bevel,  22Ga. X 1-3/8 in. (3.5cm),  Braun Introcan Safety IV catheter 22Gx1 in. (0.9 x 25mm) or 20G x 1” (1.1 x 25mm)]

 · Syringe 

· Local anesthetic for injection into caudal space (0.25% bupivacaine or 0.2 % ropivacaine with epinephrine 1:200,000). 

· Bandage 



1. Review patient history, examine patient (rule out sacral abnormalities or signs of occult spina bifida), and obtain informed consent. 

2. Review general contraindications and indications for caudal epidural nerve block. 

3. During time-out, identify the correct patient, scheduled procedure, and location of the procedure. 

4. Monitor vital signs continuously

5. Induce general anesthesia, obtain peripheral intravenous (PIV) access if not pre-existing. 

6. Ensure all necessary equipment for caudal block is available. 

7. Position the patient in lateral decubitus position. 

8. Follow aseptic procedure and maintain a sterile field. 

9. Use chlorhexidine-alcohol-based solutions to clean the skin at the site of the procedure. 

10. Use sterile draping to cover the patient while leaving the procedural site exposed. 

11. While maintaining a sterile field, open and prepare the necessary equipment. 

12. Verify that the ultrasound probe and screen are in the same orientation. 

13. Apply ultrasound gel to the sterile location. 

14. Place the 7 to 13 MHz linear transducer in the middle of the sacrum.

 15. Use the transverse view on the ultrasound to view the sacrococcygeal ligament. The sacrococcygeal ligament is between the two sacral cornua, and is superficial to the sacral bone. 

16. Turn the probe 90 degrees to obtain a longitudinal view. Visualize and identify the pertinent anatomy: end of the dural sac, filum terminale, sacrococcygeal ligament and epidural fat pad.

17. Insert needle in plane from the caudal end of the probe and, keeping a superficial trajectory, advance it into the sacrococcygeal ligament. 

18. A “pop” of the sacrococcygeal ligament should be felt. 

19. Locate the needle on the ultrasound screen.

20. Decrease the angle of the needle and advance the needle 2-3 millimeters forward into the sacral canal. 

21. Hold the needle in place when appropriate placement has been reached. 

22. Aspirate to rule out blood or CSF return. If nothing is aspirated back, inject a standard test dose of local anesthetic solution with 0.5 mcg/kg epinephrine (up to 15 mcg), or 0.1 ml/kg of local anesthetic solution with 1:200,000 epinephrine (up to 3 ml), and visualize its spread in the epidural space. If reassured, continue with aspirating and injecting the rest in small aliquots while monitoring for signs of inadvertent intravascular or intrathecal injection. If resistance increases, check the needle tip positioning on the US, to rule out needle tip migration. 

23. Remove the needle once all the solution has been administered. Place a sterile bandage on the entry site.

With the use of ultrasound-guidance, the caudal block placement was successful on the first attempt, and no complications were observed. The intraoperative and postoperative course was consistent with successful analgesia from this block.

While the landmark technique has traditionally been used for regional anesthetic procedures in pediatric patients, the increasing use of ultrasound technology has provided an alternative method for performing these procedures. Caudal epidural analgesia is indicated when a pediatric patient requires surgery involving the area supplied by low thoracic and lumbosacral dermatomes (at or below the umbilical level) (Ref 1,2). Common procedures requiring caudal blocks in pediatric patients are inguinal hernia repairs, urological surgeries, and other lower extremity procedures (Ref 1,2,5). In adults, although less commonly used, caudal epidural injections are used as analgesic adjuncts in procedures of the lower extremities, lower abdomen and perineum; it is also used to manage acute and chronic lower back pain or radiculopathy (Ref 5). Commonly used local anesthetic for caudal block includes 0.2% ropivacaine and 0.25% bupivacaine with 1:200,000 epinephrine. The volume of local anesthetic required depends on the targeted dermatome level, calculated using the Armitage formula: 0.5 ml/kg for sacral dermatomes, 1 ml/kg for lumbar dermatomes, and 1.2 ml/kg for mid-thoracic dermatomes. To prolong analgesic duration, clonidine at 1-2 mcg/kg and preservative-free morphine at 10-30 mcg/kg are commonly used adjuvants. Ultrasound guidance provides practical and real-time visualization of structures and can guide proper needle placement. Across individuals, there can be significant variations in size, shape and orientation of the sacrum, sacral hiatus and in the termination of the dural sac (Ref 1,2,). Growing children have bones and ligaments that are not completely ossified, so inserting the needle through structures, such as bone, can inadvertently occur when using the landmark technique; these structures can be visualized with ultrasound to avoid this complication. Trained specialists who are facile in the anatomical landmark technique for caudal anesthesia and who want to integrate US to their technique, must train on the basics of ultrasound technology to appreciate its uses and limitations. There is a learning curve to becoming adept at utilizing US to achieve first attempt success rates higher than with the anatomical technique. Potential complications for caudal blocks are needle misplacement, subcutaneous or intravascular injection, infection, dural puncture, anaphylaxis, nerve damage, sacral osteomyelitis, hematoma, delayed respiratory depression, urinary retention, or local anesthetic toxicity (Ref 1,2,5). Contraindications to this procedure include patient or guardian refusal, skin breakdown or infection at site of procedure, epidural hematoma, increased intracranial pressure, coagulopathy, open neural tube defects, neurological dysfunction, and allergic reactions to the local anesthetic (Ref 5).

1. Kao SC, Lin CS. Caudal Epidural Block: An Updated Review of Anatomy and Techniques. Biomed Res Int. 2017;2017:9217145. doi:10.1155/2017/9217145. https://pubmed.ncbi.nlm.nih.gov/28337460/ 2. Wiegele M, Marhofer P, Lönnqvist PA. Caudal epidural blocks in paediatric patients: a review and practical considerations. Br J Anaesth. 2019;122(4):509-517. https://pubmed.ncbi.nlm.nih.gov/30857607/ 3. Boretsky KR, Camelo C, Waisel DB, Falciola V, Sullivan C, Brusseau E, Eastburn E, Gomez-Moraz A, Luckanavanich W. Confirmation of success rate of landmark-based caudal blockade in children using ultrasound: A prospective analysis. Paediatr Anaesth. 2020 Jun;30(6):671-675. https://pubmed.ncbi.nlm.nih.gov/32267040/ 4. Jain D, Hussain SY, Ayub A. Comparative evaluation of landmark technique and ultrasound-guided caudal epidural injection in pediatric population: A systematic review and meta-analysis. Paediatr Anaesth. 2022 Jan;32(1):35-42. https://pubmed.ncbi.nlm.nih.gov/34752689/ 5. Candido K, Tharian A, Winnie A.“Caudal Anesthesia.” NYSORA, 21 Apr. 2022, www.nysora.com/techniques/neuraxial-and-perineuraxial-techniques/caudal-anesthesia/#toc_INDICATIONS-FOR-CAUDAL-EPIDURAL-ANALGESIA-IN-CHILDREN. https://www.nysora.com/techniques/neuraxial-and-perineuraxial-techniques/caudal-anesthesia/ 6. Greaney D, Everett T. Paediatric regional anaesthesia: updates in central neuraxial techniques and thoracic and abdominal blocks. BJA Educ. 2019;19(4):126-134. https://pubmed.ncbi.nlm.nih.gov/33456881/

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