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Caudal Anesthesia

Editor: Muriam Afzal Updated: 2/6/2025 1:22:58 AM

Introduction

Caudal anesthesia is a widely used regional anesthetic technique known for its effectiveness in providing both perioperative and postoperative analgesia. This procedure can be used as the primary anesthetic or as an adjunct to general anesthesia. This technique is especially beneficial for pediatric patients undergoing subumbilical surgeries and for adults managing chronic low back pain.

A retrospective study by Dalens and Hasnaoui, analyzing 750 caudal blocks performed in children, reported a success rate of 96%.[1] With advancements in imaging technologies, such as fluoroscopy and ultrasound guidance, the accuracy of caudal epidural needle placement has significantly improved, leading to reduced block failure rates.[2] 

Anatomy and Physiology

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Anatomy and Physiology

Clinicians perform caudal epidural techniques by accessing the epidural space through the sacral hiatus. In adults, the spinal cord terminates at the L1-L2 level, and the dural sac extends to S1-S2. In children, the spinal cord ends at L3-L4, and the dural sac reaches S3-S4, migrating cephalad during the first year of life. In young infants, there is a risk of inadvertently entering the dural sac during a caudal epidural block.[3]

The sacral canal contains the dural sac and its components, including nerves, blood vessels, adipose tissue, and connective tissue, all of which can affect the efficacy of caudal anesthesia.[4] Variations in anatomy or pathological changes within the sacral canal may further impact the success and safety of the procedure.

Caudal anesthesia is a landmark-based technique commonly used method for performing a caudal epidural block due to its simplicity and reliance on external anatomical landmarks. Although this technique is effective, it has limitations, particularly in cases where anatomical variations, obesity, or scarring obscure the sacral hiatus. In such instances, alternative methods, such as ultrasound or fluoroscopy-guided techniques, may be preferred to improve precision and reduce the risk of complications.

In adults, caudal epidural blocks are usually performed as single-shot techniques due to the challenges of threading a catheter at this location. While single-shot techniques are also commonly used in children, catheter placement is generally easier in the pediatric population. Studies have shown that caudal catheters can be safely placed for short-term use (typically less than 3 days) without a significant risk of systemic infections, such as meningitis, epidural abscess, systemic sepsis, or localized infections.[5][6]

Indications

Caudal anesthesia is widely used in the pediatric population for subumbilical procedures, including inguinal hernia repair, urological interventions, anal atresia repair, and lower extremity procedures. Caudal anesthesia can serve as the primary anesthetic technique or as an adjunct to general anesthesia for these procedures.[7] In adults, caudal anesthesia is also utilized as the primary anesthetic method for minor anorectal procedures.[8] Furthermore, in pediatric inguinal surgeries, caudal epidural blocks have been shown to provide postoperative analgesia comparable in duration to ultrasound-guided ilioinguinal and iliohypogastric blocks with dexmedetomidine as an additive without significant adverse effects.[9]

Caudal epidural injections can be effective in managing chronic lower back pain that has not responded to conservative treatment. While nonmalignant low back pain may be treated with caudal epidural steroid injections, these are particularly indicated for patients without isolated facet joint pain or those with both discogenic and facet joint pain.[10] 

Historically, caudal epidural analgesia with catheter placement was used for labor analgesia during the second stage of labor. However, concerns about its efficacy, the risk of limb paralysis due to large volumes of local anesthetic, and significant maternal hypotension from inadequate sympathectomy control led to a shift toward lumbar epidurals as the primary method for labor analgesia.[11]

Caudal blocks may be preferred over lumbar epidural blocks because they provide sensory and motor blockade of the sacral roots while causing limited sympathectomy, as preganglionic sympathetic neurons extend from the T1 to L2 level. Additionally, caudal blocks are associated with a lower risk of dural puncture. 

Contraindications

Absolute contraindications to caudal anesthesia include patient or guardian refusal, localized infection at the insertion site, severe coagulopathy, increased intracranial pressure, and allergy to medications used during the procedure. Increased intracranial pressure may predispose patients to herniation by exacerbating pressure within the cranial cavity after an epidural injection.[12][13]

Relative contraindications to caudal anesthesia are more varied. Spinal stenosis increases the risk of neurological complications following neuraxial techniques. Hypovolemic patients are at heightened risk for hypotensive responses due to the vasodilatory effects of the procedure.

Severe coagulopathy is an absolute contraindication for neuraxial techniques, while less severe coagulopathies require further evaluation. The latest guidelines for performing neuraxial techniques in the context of thromboprophylaxis or anticoagulation are outlined in the recommendations from the American Society of Regional Anesthesia.[14][15]

Systemic infection is considered a relative contraindication to epidural techniques due to the theoretical risk of infecting the epidural space and the potential hemodynamic instability caused by vasodilation. However, neuraxial techniques can be safely performed once the patient has responded to antibiotic therapy.[16] 

Additional contraindications in the pediatric population include pilonidal cysts, sacral anomalies (such as a previous meningomyelocele), and spinal dysraphism (such as tethered cord syndrome).[7][17] These conditions can complicate caudal block placement and increase the risk of injury or procedural failure.

Equipment

Before performing a caudal epidural block, it is essential to gather the necessary equipment to ensure a safe and effective procedure. The required equipment includes:

  • Appropriately sized syringe
  • Needle or intravenous access catheter
  • Medication
  • Skin cleaning solution (commonly alcohol, chlorhexidine, or iodine solution)
  • Personal protective equipment (sterile gloves, masks, and head covering)

Ultrasound guidance can improve the accuracy of caudal epidural placement in both pediatric and adult patients. The technique enhances the success rate of epidural injections by verifying their precise location.[18] A study by Shin et al demonstrated that ultrasound-assisted identification of the sacral hiatus facilitated the successful completion of caudal epidural placement.[19] 

Fluoroscopy-guided caudal epidural block is considered the gold standard for ensuring accurate placement. However, it is seldom used in the operating room due to its impracticality and the associated radiation exposure to both patients and healthcare providers.

Personnel

Caudal anesthesia should be performed by a trained specialist, which may include anesthesiologists, anesthesiology trainees, nurse anesthetists under the supervision of an anesthesiologist, or chronic pain physicians. The procedure may also require an assistant to assist with patient positioning.

Preparation

Before performing a caudal epidural block, the clinician should review the patient’s medical history, conduct a physical examination, and obtain informed consent. Standard American Society of Anesthesiologists (ASA) monitoring should be implemented throughout the procedure.

The patient can be positioned in either the lateral decubitus or prone position. The legs should be flexed at the hip and knee in the lateral position to ensure stability. Induction is typically performed in pediatric patients before the caudal block is placed. A procedure time-out should be conducted, and the insertion site should be cleaned with betadine, alcohol, or chlorhexidine. For single-shot caudal blocks, a 22- to 25-gauge, short-beveled Tuohy or Crawford needle is commonly used, most of which do not have a stylet.[10]

Caudal blocks are typically performed using 0.125% to 0.25% bupivacaine or 0.1% to 0.375% ropivacaine, with doses adjusted based on the dermatome level. The dose is 0.5 mL/kg for sacral dermatome coverage, 1.0 mL/kg for lumbar dermatome coverage, and 1.25 mL/kg for thoracic dermatome coverage. Ropivacaine may be a preferable option over bupivacaine due to its potential to cause less motor block.[20] 

Various additives and adjuvants, including opioids, local anesthetics, ketamine, neostigmine, steroids, clonidine, and dexmedetomidine, are used in the caudal space to extend the duration and effectiveness of the block.[21] Epinephrine and clonidine help prolong the blockade—epinephrine by vasoconstriction, which reduces uptake, and clonidine by stimulating presynaptic and postsynaptic alpha-2 adrenoceptors. Although opioids, such as morphine and fentanyl, are also used, they may cause adverse effects such as pruritus, nausea, and respiratory depression, often requiring 24-hour observation.[22][23] 

In patients with chronic low back pain and radiculopathy, corticosteroids are frequently injected into the caudal epidural space. Commonly used corticosteroids include dexamethasone, betamethasone, methylprednisolone, and triamcinolone.[24]

Technique or Treatment

Caudal blocks can be performed using various techniques, each providing different levels of precision and guidance. Clinicians may choose between the blind technique and ultrasound or fluoroscopic guidance techniques based on the clinical scenario and available resources.[3]

Blind Caudal Epidural Block

The sacral hiatus is identified by locating the sacral cornua on each side, just superior to the gluteal cleft and at the apex of the triangle formed by the posterior superior iliac crests. After skin preparation, the beveled needle or angiocatheter is inserted at a 45° angle. A "pop" or "give" may be felt, indicating the needle has passed through the sacrococcygeal ligament and entered the epidural space. This loss of resistance technique has a 26% miss rate.[25] Many physicians recommend performing the "whoosh test," which has higher specificity to improve accuracy. This process involves auscultating the thoracolumbar region while injecting air into the caudal epidural space.[26]

Ultrasound-Guided Caudal Epidural Block

With the patient positioned in either the prone or lateral decubitus position, a 7- to 13-MHz linear transducer (or a 2- to 5-MHz curved transducer for obese patients) is placed transversely over the middle of the sacrum. The transverse view reveals hyperechoic structures, including the superficial sacrococcygeal ligament between the 2 sacral cornua and the deeper sacral bone. The target area is the hypoechoic structure between the sacrococcygeal ligament and the sacral bone. The probe is then rotated 90º to obtain a longitudinal view, allowing the needle to be inserted "in-plane" into the sacral hiatus. The needle should not be advanced more than 5 mm beyond the apex to avoid a dural puncture, as the needle becomes invisible beyond this point. Unidirectional flow on color Doppler can confirm the successful placement of the caudal block.

Fluoroscopy-Guided Caudal Epidural Block

With the patient in the prone position, the sacral hiatus is identified as an abrupt drop-off at the end of the S4 lamina. The needle is then advanced into the sacral canal, and proper needle tip placement is confirmed by injecting a contrast medium. This ensures accurate placement and helps rule out intravascular or intrathecal injection.

For children already under general anesthesia, the efficacy of the caudal block can be assessed by evaluating the laxity of the anal sphincter. A study conducted by Dave and Garasia involving 223 patients demonstrated that the anal sphincter tone test was the most reliable predictor of a successful caudal block, and it outperformed the whoosh test and heart rate response to the injection.[27]

Complications

Caudal anesthesia, similar to any medical procedure, carries potential risks and complications, although they are generally rare when performed correctly. These complications can range from minor adverse effects to more severe issues, including infections, neurological damage, and cardiovascular events.

Common complications associated with caudal anesthesia include:

  • Subdural, intravascular, or intraosseous injection
  • Infection
  • Hypotension
  • Injury to the nerve roots
  • Antesacral injection with rectal perforation
  • Hematoma formation
  • Local anesthetic toxicity
  • Delayed respiratory depression
  • Urinary retention
  • Sacral osteomyelitis [7]

A severe complication of a caudal block is total spinal anesthesia, which can occur from an inadvertent dural puncture followed by intrathecal injection of local anesthetic.[28] This complication is more common in infants due to the caudal displacement of the dural sac, which ends at the S3-S4 level (compared to S1-S2 in adults). Additionally, caudal epidural blocks have a higher incidence of local anesthetic-related seizures compared to brachial plexus or lumbar or thoracic epidural blocks. Brown et al reported a 0.69% rate of seizures with caudal anesthesia, compared to 0.01% for lumbar or thoracic epidurals.[29] Thus, administering a test dose with epinephrine is essential for detecting intravascular injection.

Clinical Significance

Caudal anesthesia is one of the oldest neuraxial anesthetic techniques still in use today. While its role in obstetric analgesia has decreased, it continues to be widely utilized in the pediatric population for subumbilical procedures and in the management of chronic low back pain and radiculopathy.

Caudal anesthesia is frequently used as the sole anesthetic technique in pediatric surgeries, which reduces the risks associated with general anesthesia. Caudal blocks have a high success rate, are generally safe, and carry a low risk of complications. Moreover, caudal anesthesia is linked to higher patient satisfaction due to enhanced postoperative pain relief.[4]

Enhancing Healthcare Team Outcomes

Effective coordination between a surgeon and the anesthesiology team is critical to ensure the patient receives the appropriate anesthetic. This interprofessional collaboration among healthcare providers enhances patient safety, comfort, and team efficiency.

Nurses are also critical in patient preparation, monitoring vital signs during the procedure, and providing postprocedural care. They are also responsible for promptly alerting the healthcare team to any concerns. Proficiency in caudal anesthesia is closely tied to the frequency of practice. Surgical centers can implement various strategies to improve outcomes based on case volume, with an interprofessional healthcare team approach ensuring the best possible patient outcomes.

References


[1]

Dalens B, Hasnaoui A. Caudal anesthesia in pediatric surgery: success rate and adverse effects in 750 consecutive patients. Anesthesia and analgesia. 1989 Feb:68(2):83-9     [PubMed PMID: 2913854]

Level 2 (mid-level) evidence

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Chen CP, Tang SF, Hsu TC, Tsai WC, Liu HP, Chen MJ, Date E, Lew HL. Ultrasound guidance in caudal epidural needle placement. Anesthesiology. 2004 Jul:101(1):181-4     [PubMed PMID: 15220789]


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Kao SC, Lin CS. Caudal Epidural Block: An Updated Review of Anatomy and Techniques. BioMed research international. 2017:2017():9217145. doi: 10.1155/2017/9217145. Epub 2017 Feb 26     [PubMed PMID: 28337460]


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Zhang P, Chang H, Yang T, Fu Y, He X, Li J, Yang M, Wang R, Li X. Study on MEV90 of 0.5% ropivacaine for US-guided caudal epidural block in anorectal surgery. Frontiers in medicine. 2022:9():1077478. doi: 10.3389/fmed.2022.1077478. Epub 2023 Jan 19     [PubMed PMID: 36743672]


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Wiegele M, Marhofer P, Lönnqvist PA. Caudal epidural blocks in paediatric patients: a review and practical considerations. British journal of anaesthesia. 2019 Apr:122(4):509-517. doi: 10.1016/j.bja.2018.11.030. Epub 2019 Feb 1     [PubMed PMID: 30857607]


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Varsha R, Desai SN, Mudakanagoudar MS, Annigeri VM. Comparison between caudal epidural and ultrasound-guided ilioinguinal-iliohypogastric block with bupivacaine and dexmedetomidine for postoperative analgesia following pediatric inguinal hernia surgeries: A prospective randomized, double-blind study. Journal of anaesthesiology, clinical pharmacology. 2021 Jul-Sep:37(3):389-394. doi: 10.4103/joacp.JOACP_175_19. Epub 2021 Oct 12     [PubMed PMID: 34759549]

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Silva M, Halpern SH. Epidural analgesia for labor: Current techniques. Local and regional anesthesia. 2010:3():143-53. doi: 10.2147/LRA.S10237. Epub 2010 Dec 8     [PubMed PMID: 23144567]


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Hilt H, Gramm HJ, Link J. Changes in intracranial pressure associated with extradural anaesthesia. British journal of anaesthesia. 1986 Jun:58(6):676-80     [PubMed PMID: 3707805]

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Grocott HP, Mutch WA. Epidural anesthesia and acutely increased intracranial pressure. Lumbar epidural space hydrodynamics in a porcine model. Anesthesiology. 1996 Nov:85(5):1086-91     [PubMed PMID: 8916826]

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Horlocker TT, Vandermeuelen E, Kopp SL, Gogarten W, Leffert LR, Benzon HT. Regional Anesthesia in the Patient Receiving Antithrombotic or Thrombolytic Therapy: American Society of Regional Anesthesia and Pain Medicine Evidence-Based Guidelines (Fourth Edition). Regional anesthesia and pain medicine. 2018 Apr:43(3):263-309. doi: 10.1097/AAP.0000000000000763. Epub     [PubMed PMID: 29561531]

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. Regional Anesthesia in the Patient Receiving Antithrombotic or Thrombolytic Therapy: American Society of Regional Anesthesia and Pain Medicine Evidence-Based Guidelines (Fourth Edition): Erratum. Regional anesthesia and pain medicine. 2018 Jul:43(5):566. doi: 10.1097/AAP.0000000000000807. Epub     [PubMed PMID: 29927858]

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[18]

Hüppe T, Pattar G, Maass B. [Caudal Anesthesia: Overview and Practical Recommendations]. Anasthesiologie, Intensivmedizin, Notfallmedizin, Schmerztherapie : AINS. 2022 Nov:57(11-12):724-736. doi: 10.1055/a-1467-8624. Epub 2022 Nov 29     [PubMed PMID: 36446359]

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[19]

Shin S, Kim JY, Kim WO, Kim SH, Kil HK. Ultrasound visibility of spinal structures and local anesthetic spread in children undergoing caudal block. Ultrasound in medicine & biology. 2014 Nov:40(11):2630-6. doi: 10.1016/j.ultrasmedbio.2014.06.020. Epub 2014 Sep 12     [PubMed PMID: 25220270]


[20]

Suresh S, Ecoffey C, Bosenberg A, Lonnqvist PA, de Oliveira GS Jr, de Leon Casasola O, de Andrés J, Ivani G. The European Society of Regional Anaesthesia and Pain Therapy/American Society of Regional Anesthesia and Pain Medicine Recommendations on Local Anesthetics and Adjuvants Dosage in Pediatric Regional Anesthesia. Regional anesthesia and pain medicine. 2018 Feb:43(2):211-216. doi: 10.1097/AAP.0000000000000702. Epub     [PubMed PMID: 29319604]


[21]

Xu W, Wei H, Zhang T. Methods of prolonging the effect of caudal block in children. Frontiers in pediatrics. 2024:12():1406263. doi: 10.3389/fped.2024.1406263. Epub 2024 Jun 3     [PubMed PMID: 38887564]


[22]

Shukla U, Prabhakar T, Malhotra K. Postoperative analgesia in children when using clonidine or fentanyl with ropivacaine given caudally. Journal of anaesthesiology, clinical pharmacology. 2011 Apr:27(2):205-10. doi: 10.4103/0970-9185.81842. Epub     [PubMed PMID: 21772681]


[23]

Swain A, Nag DS, Sahu S, Samaddar DP. Adjuvants to local anesthetics: Current understanding and future trends. World journal of clinical cases. 2017 Aug 16:5(8):307-323. doi: 10.12998/wjcc.v5.i8.307. Epub     [PubMed PMID: 28868303]

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[24]

Datta R, Upadhyay KK. A Randomized Clinical Trial of Three Different Steroid Agents for Treatment of Low Backache through the Caudal Route. Medical journal, Armed Forces India. 2011 Jan:67(1):25-33. doi: 10.1016/S0377-1237(11)80007-9. Epub 2011 Jul 21     [PubMed PMID: 27365757]

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[25]

Barham G, Hilton A. Caudal epidurals: the accuracy of blind needle placement and the value of a confirmatory epidurogram. European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society. 2010 Sep:19(9):1479-83. doi: 10.1007/s00586-010-1469-8. Epub 2010 May 29     [PubMed PMID: 20512512]


[26]

Eastwood D, Williams C, Buchan I. Caudal epidurals: the whoosh test. Anaesthesia. 1998 Mar:53(3):305-7     [PubMed PMID: 9613279]

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[27]

Dave NM, Garasia M. A comparison of the effectiveness of predictors of caudal block in children-swoosh test, anal sphincter tone, and heart rate response. Journal of anaesthesiology, clinical pharmacology. 2012 Jan:28(1):17-20. doi: 10.4103/0970-9185.92428. Epub     [PubMed PMID: 22345939]


[28]

Afshan G, Khan FA. Total spinal anaesthesia following caudal block with bupivacaine and buprenorphine. Paediatric anaesthesia. 1996:6(3):239-42     [PubMed PMID: 8732618]

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[29]

Brown DL, Ransom DM, Hall JA, Leicht CH, Schroeder DR, Offord KP. Regional anesthesia and local anesthetic-induced systemic toxicity: seizure frequency and accompanying cardiovascular changes. Anesthesia and analgesia. 1995 Aug:81(2):321-8     [PubMed PMID: 7618723]

Level 2 (mid-level) evidence