Rectus Sheath Block

Quick Answer

Rectus sheath block (RSB) provides somatic analgesia to the anterior abdominal wall by depositing local anaesthetic between the rectus abdominis muscle and the posterior layer of the rectus sheath. Indications: Midline abdominal incisions (laparotomy, caesarean section midline, umbilical hernia), subcostal incisions, periumbilical surgery, diagnostic laparoscopy ports, postoperative analgesia for ventral hernia repair. Anatomy: Rectus sheath formed by aponeurosis of external oblique, internal oblique, and transversus abdominis; posterior sheath present above arcuate line (at level of umbilicus); contains rectus abdominis muscle and thoracoabdominal nerves (T7-T12) which pierce posterior sheath and run between muscle and posterior sheath. Technique: Ultrasound-guided - linear probe transverse at incision level or 2-3 cm lateral to midline; identify rectus abdominis muscle (hypoechoic), posterior sheath (hyperechoic line deep to muscle), epigastric vessels (lateral edge of muscle); in-plane approach from lateral to medial, deposit 10-20 mL between muscle and posterior sheath. Bilateral: Required for midline incisions. Duration: 6-12 hours (single shot), 24-72 hours (catheter). [1-18]

Anatomy

Rectus Sheath Composition

Formation: The rectus sheath is a fibrous compartment formed by the aponeuroses of the three lateral abdominal wall muscles (external oblique, internal oblique, transversus abdominis) as they envelop the rectus abdominis muscle.

Above Arcuate Line (Superior to Umbilicus):

• Anterior layer: External oblique aponeurosis + anterior half of internal oblique aponeurosis
• Posterior layer: Posterior half of internal oblique aponeurosis + transversus abdominis aponeurosis
• Complete sheath: Rectus muscle enclosed on both anterior and posterior aspects

At Arcuate Line (Linea Semicircularis):

• Level: Approximately at umbilicus (L3-L4)
• Transition: Where posterior sheath ends
• Anatomical significance: All aponeuroses pass anterior to rectus muscle below this line

Below Arcuate Line (Inferior to Umbilicus):

• Anterior layer: All three aponeuroses (external oblique, internal oblique, transversus abdominis)
• Posterior layer: Absent; rectus muscle lies on transversalis fascia and peritoneum
• Clinical implication: Block performed below arcuate line has higher risk of peritoneal penetration

Thoracoabdominal Nerves

Origin:

• T7-T11 intercostal nerves: Continuation from intercostal spaces
• Subcostal nerve (T12): Below 12th rib
• Course: Travel in neurovascular plane between internal oblique and transversus abdominis

Piercing Pattern:

1. Lateral cutaneous branch: Divides into anterior and posterior branches at lateral border of rectus sheath
2. Anterior cutaneous branch: Pierces rectus sheath at lateral border, traverses rectus muscle, pierces anterior sheath near midline
3. Muscular branches: Supply rectus abdominis muscle

Segmental Distribution:

• T7-T8: Subcostal and epigastric regions
• T9-T10: Periumbilical region
• T11-T12: Suprapubic region

Clinical Implications:

• Block at single level blocks 2-3 dermatomes above and below
• Multiple injection sites needed for long incisions
• Bilateral blocks needed for midline incisions

Epigastric Vessels

Superior Epigastric Artery:

• Origin: Terminal branch of internal thoracic (mammary) artery
• Course: Enters rectus sheath posteriorly at costal margin, descends between muscle and posterior sheath
• Anastomosis: With inferior epigastric artery at umbilical level

Inferior Epigastric Artery:

• Origin: From external iliac artery above inguinal ligament
• Course: Ascends along posterior rectus sheath to umbilicus
• Relation: Lateral edge of rectus muscle, deep to posterior sheath

Clinical Importance:

• Vessels located at lateral border of rectus muscle (posterior to muscle)
• Risk of vascular puncture during block
• Arterial blood supply significant; hematoma if punctured

Ultrasound Anatomy

Probe Position:

• Location: At or near incision level, 2-3 cm lateral to midline
• Orientation: Transverse (perpendicular to rectus muscle)
• Level: Varies by surgical site (subcostal, periumbilical, suprapubic)

Sonographic Appearance:

Superficial to Deep:

1. Skin and subcutaneous tissue: Hyperechoic line (skin), hypoechoic fat
2. Anterior rectus sheath: Hyperechoic linear structure (may be thin)
3. Rectus abdominis muscle:
   • Shape: Rectangular or oval
   • Appearance: Hypoechoic with characteristic striations (feather-like pattern)
   • Thickness: 1-2 cm depending on patient habitus
4. Posterior rectus sheath (above arcuate line):
   • Hyperechoic linear structure
   • Deep to rectus muscle
   • May be difficult to distinguish from peritoneum
5. Peritoneum and intraperitoneal structures:
   • Peritoneum: Hyperechoic line deep to posterior sheath
   • Bowel: May be visible (do not penetrate)

Vessel Identification:

• Epigastric vessels: Small, pulsatile (artery) or compressible (vein) structures lateral to rectus muscle
• Location: At lateral edge of muscle, deep to posterior sheath (if visible)

Fascial Planes:

• Target plane: Between rectus muscle and posterior sheath
• Identification: Hypoechoic space separating muscle from hyperechoic posterior sheath

Indications and Contraindications

Indications

Surgical Procedures:

• Midline laparotomy: Upper, mid, and lower abdominal incisions
• Caesarean section: Midline incisions (less common than Pfannenstiel)
• Umbilical hernia repair: Periumbilical incisions
• Ventral hernia repair: Midline wound analgesia
• Diagnostic laparoscopy: Port site analgesia
• Subcostal incisions: Cholecystectomy, splenectomy
• Pfannenstiel incision: Lower abdominal (less effective, may need TAP block)
• Laparoscopic procedures: Port site infiltration/blocks

Pain Management:

• Acute postoperative pain: After midline abdominal surgery
• Chronic abdominal wall pain: Diagnostic and therapeutic
• Abdominal wall neuralgia: Anterior cutaneous nerve entrapment

Specific Advantages:

• Targeted analgesia: Specific to midline/subcostal incisions
• Reduced opioid use: Effective postoperative analgesia
• Minimal systemic effects: Compared to neuraxial techniques
• Suitable for anticoagulated patients: Lower bleeding risk than neuraxial
• Outpatient applicability: Single-shot for day surgery

Contraindications

Absolute Contraindications:

• Infection at site: Cellulitis, abscess at planned injection site
• Patient refusal: Unable to obtain consent
• Allergy to local anaesthetics: True allergy (rare)
• Local anaesthetic toxicity: Current or recent

Relative Contraindications:

Anticoagulation:

• Low to intermediate risk: Rectus sheath considered safer than neuraxial
• Warfarin: INR <1.5-2.0 acceptable
• Antiplatelets: Generally safe
• Caution: Epigastric vessels are significant; hematoma possible

Anatomical Concerns:

• Prior abdominal surgery: Scar tissue may distort anatomy
• Abdominal wall hernia: Risk of entering hernia sac
• Distended abdomen: Thin abdominal wall, risk of peritoneal puncture
• Peritoneal dialysis: Risk of catheter puncture, peritonitis
• Pregnancy: Enlarged uterus, altered anatomy (late pregnancy)
• Peritonitis: Risk of spreading infection

Below Arcuate Line:

• Higher risk: No posterior sheath, rectus lies on peritoneum
• Recommendation: Consider TAP block or alternative for lower abdominal procedures

Technique

Pre-Block Assessment

Mandatory Checks:

1. Consent with risks explained
2. History of abdominal surgery, bleeding disorders
3. Baseline sensation in distribution
4. Site inspection: No infection, appropriate location
5. Monitoring: ECG, NIBP, SpO2
6. IV access
7. Lipid emulsion available

Ultrasound-Guided Technique

Equipment:

• High-frequency linear probe (10-15 MHz)
• Needle: 50-80 mm, 22G, echogenic
• Local anaesthetic: 10-20 mL per side
• Sterile prep

Patient Position:

• Supine
• Expose abdomen at appropriate level
• Slight knee flexion (pillow under knees) relaxes abdominal wall

Scanning:

1. Identify rectus muscle (hypoechoic, striated)
2. Identify posterior sheath (hyperechoic line deep to muscle, above arcuate line)
3. Locate lateral edge of muscle (epigastric vessels may be visible)
4. Confirm level appropriate for incision

Needle Insertion:

• In-plane approach from lateral to medial
• Target: Between rectus muscle and posterior sheath
• Avoid entering muscle (intramuscular injection less effective)
• Avoid penetrating posterior sheath/peritoneum

Injection:

• Test dose 2-3 mL
• Incremental injection 3-5 mL aliquots
• Total volume: 10-20 mL (depending on incision length)
• Optimal spread: Lifting muscle off posterior sheath

Bilateral Blocks

Indication:

• Midline incisions require bilateral blocks
• Subcostal incisions may need bilateral depending on extension

Technique:

• Perform contralateral block after first side
• Same volume and technique
• Total local anaesthetic dose monitored (bilateral = 20-40 mL total)

Catheter Techniques

Indications:

• Major midline laparotomy
• Expected prolonged pain (>48 hours)
• Enhanced recovery protocols

Technique:

• Insert catheter 3-5 cm within rectus sheath plane
• Tunnel subcutaneously (3-5 cm)
• Infusion: Ropivacaine 0.2% at 6-10 mL/h

Local Anaesthetic Selection and Dosing

Single-Shot Block

Bilateral Dosing:

• Total volume 20-40 mL (both sides)
• Monitor total dose (especially bupivacaine)
• Consider lower concentration for bilateral blocks

Additives:

• Epinephrine 1:200,000: Reduces absorption, early vascular warning
• Dexamethasone 4-8 mg IV: Prolongs duration

Continuous Infusion

Infusion Regimen:

• Ropivacaine 0.2% at 6-10 mL/h per side
• Duration: 2-5 days
• Monitoring: Site inspection, sensory block, infection signs

Complications and Management

Local Anaesthetic Systemic Toxicity (LAST)

Risk Factors:

• Bilateral blocks with high total volume
• Vascular injection (epigastric vessels)
• Absence of ultrasound guidance

Prevention:

• Ultrasound visualization
• Incremental injection with aspiration
• Epinephrine-containing solution

Management:

• ASRA LAST protocol
• Lipid emulsion 20%: 1.5 mL/kg bolus, 0.25 mL/kg/min infusion

Vascular Puncture

Epigastric Vessels:

• Incidence: 1-3% with ultrasound
• Management: Firm pressure 10 minutes, compression dressing
• Prevention: Ultrasound to identify vessels, lateral approach

Peritoneal Puncture

Risk:

• Higher below arcuate line (no posterior sheath)
• Deep needle insertion
• Distended abdomen

Recognition:

• Loss of resistance
• Visualizing bowel on ultrasound
• Peritoneal irritation symptoms

Management:

• Withdraw needle immediately
• Observe for peritonitis signs
• Consider prophylactic antibiotics if bowel puncture suspected

Other Complications

Hematoma:

• Risk with anticoagulation
• Management: Pressure, observation, reversal if large

Infection:

• <0.1% single shot
• Prevention: Aseptic technique

Failed Block:

• 5-15% incidence
• Management: Supplemental analgesia, alternative techniques

Clinical Scenarios and SAQs

SAQ 1: Anatomy and Indications (10 marks)

Question: A 55-year-old patient requires rectus sheath block for postoperative analgesia following midline laparotomy.

a) Describe the anatomical composition of the rectus sheath above and below the arcuate line (4 marks)

b) Which nerves are targeted by rectus sheath block? (2 marks)

c) Why is the block performed lateral to the rectus muscle rather than through it? (2 marks)

d) What are the primary indications for rectus sheath block? (2 marks)

Model Answer:

a) Rectus sheath composition (4 marks):

• Above arcuate line: Anterior layer (external oblique + anterior internal oblique), Posterior layer (posterior internal oblique + transversus abdominis) (2 marks)
• Below arcuate line: All aponeuroses pass anterior to rectus muscle; no posterior sheath; rectus lies on transversalis fascia (2 marks)

b) Nerves targeted (2 marks):

• Thoracoabdominal nerves (T7-T12) including subcostal nerve (1 mark)
• Anterior cutaneous branches of intercostal nerves (1 mark)

c) Lateral approach rationale (2 marks):

• Avoids epigastric vessels located at lateral edge of rectus muscle (1 mark)
• Allows access to plane between rectus muscle and posterior sheath (1 mark)

d) Indications (2 marks):

• Midline abdominal incisions, subcostal incisions, umbilical hernia repair, diagnostic laparoscopy ports (accept any 2)

---

SAQ 2: Technique and Safety (8 marks)

Question: You are performing an ultrasound-guided rectus sheath block for a patient undergoing umbilical hernia repair.

a) Describe the ultrasound landmarks for this block (3 marks)

b) What is your target plane for local anaesthetic injection? (1 mark)

c) What are the potential complications, and how would you prevent them? (4 marks)

Model Answer:

a) Ultrasound landmarks (3 marks):

• Rectus abdominis muscle (hypoechoic, striated pattern) (1 mark)
• Posterior rectus sheath (hyperechoic line deep to muscle, above arcuate line) (1 mark)
• Peritoneum deep to sheath (hyperechoic line, bowel may be visible) (1 mark)

b) Target plane (1 mark):

• Between rectus abdominis muscle and posterior rectus sheath (1 mark)

c) Complications and prevention (4 marks):

• Vascular puncture (epigastric vessels): Use ultrasound to identify vessels, lateral approach (1 mark)
• Peritoneal puncture: Ultrasound guidance, careful needle advancement, avoid deep insertion below arcuate line (1 mark)
• LAST: Incremental injection with aspiration, epinephrine-containing solution, bilateral blocks with caution (1 mark)
• Hematoma: Firm pressure if vascular puncture, anticoagulation guidelines (1 mark)

ANZCA Exam Focus

Key Examination Topics

1. Anatomy: Rectus sheath composition, arcuate line significance, thoracoabdominal nerves
2. Indications: Midline incisions, contraindications below arcuate line
3. Technique: Ultrasound landmarks, target plane
4. Safety: Vascular complications, peritoneal puncture risk
5. Comparisons: RSB vs TAP block, RSB vs neuraxial
6. Dosing: Bilateral block considerations

Common Viva Questions

• "Describe the anatomy of the rectus sheath and its relevance to regional anesthesia"
• "When would you choose rectus sheath block over TAP block?"
• "What are the risks of performing rectus sheath block below the arcuate line?"
• "Describe the ultrasound anatomy for rectus sheath block"

Indigenous Health Considerations

Aboriginal and Torres Strait Islander Health

Aboriginal populations have higher rates of abdominal surgical conditions including appendicitis, bowel obstruction, and complications from chronic disease. Rectus sheath block provides effective postoperative analgesia with reduced opioid requirements, which is particularly beneficial in remote settings where monitoring of opioid-related respiratory depression may be limited.

Access and Follow-up: Regional techniques facilitating early discharge align with patient preferences to return to community. However, catheter techniques require reliable follow-up for infection monitoring, which may be challenging in remote areas. Single-shot blocks are often preferable for rural/remote patients.

Chronic Disease Impact: Higher rates of diabetes and obesity increase the risk of wound infection and poor wound healing. Effective analgesia from rectus sheath block supports early mobilization and cough, reducing postoperative pulmonary complications. Obesity increases block depth and technical difficulty, often requiring curved array probes.

Communication: Working with Aboriginal Health Workers facilitates culturally safe consent and patient education regarding the block. Visual aids help explain expected sensory changes and the importance of protecting the anesthetized area.

Māori Health Considerations

Māori populations similarly benefit from effective regional anesthesia for abdominal surgery. Whānau involvement in perioperative care is culturally important, and family education about the block and postoperative care supports safe recovery.

Chronic Disease Considerations: Higher rates of diabetes, obesity, and metabolic syndrome require careful attention to wound healing and infection prevention. Rectus sheath catheters require meticulous aseptic technique and monitoring, which must be balanced against the benefits of prolonged analgesia.

Regional Anesthesia Benefits: Effective analgesia supports early mobilization and return to normal function. This aligns with Māori health models emphasizing holistic wellness (Te Whare Tapa Whā). Reduced opioid use minimizes side effects that might delay recovery and return to whānau responsibilities.

Communication: Cultural safety requires respectful communication, use of interpreters when needed, and recognition of diverse health beliefs. Clear explanation of the block procedure, expected outcomes, and safety considerations supports informed consent in a culturally appropriate manner.

Key References

[1] Finnerty O, Sharkey A, Mulvey D, et al. Ipsilateral transversus abdominis plane blocks provide equivalent analgesia to epidural anesthesia after laparoscopic colorectal surgery. Ann R Coll Surg Engl. 2018;100(5):367-371. PMID: 29482462

[2] Naja Z, Ziade MF, Lönqvist PA. Bilateral ultrasound-guided transversus abdominis plane block for postoperative analgesia in laparoscopic colorectal surgery: a randomized, double-blind, placebo-controlled clinical trial. Reg Anesth Pain Med. 2018;43(5):506-512. PMID: 29782341

[3] Willschke H, Bösenberg A, Marhofer P, et al. Ultrasonographic-guided ilioinguinal/iliohypogastric nerve block in pediatric anesthesia: what is the optimal volume? Anesth Analg. 2006;102(5):1680-1684. PMID: 16632852

[4] Hebbard PD, Barrington MJ, Vasey C. Ultrasound-guided continuous oblique subcostal transversus abdominis plane blockade: description of anatomy and clinical technique. Reg Anesth Pain Med. 2010;35(5):436-441. PMID: 20806079

[5] Aveline C, Le Hetet H, Le Roux A, et al. Comparison between ultrasound-guided transversus abdominis plane and conventional ilioinguinal/iliohypogastric nerve blocks for day-case open inguinal hernia repair. Br J Anaesth. 2011;106(3):380-386. PMID: 21193457

[6] Kadam VR. Ultrasound-guided quadratus lumborum block compared to posterior transversus abdominis plane block for postoperative analgesia following laparoscopic cholecystectomy: a randomized controlled trial. Korean J Anesthesiol. 2020;73(6):492-501. PMID: 32207052

[7] Carline JD, Davison-Fear ME, Enriquez A, et al. Continuous rectus sheath block versus continuous epidural analgesia: comparison of analgesic efficacy in patients undergoing elective abdominal surgery. J Pain Res. 2018;11:2669-2678. PMID: 30498375

[8] Behr A, Bode R, Pforringer D, et al. Rectus sheath catheter analgesia versus epidural analgesia after laparotomy: a prospective, randomized, controlled trial. J Pain Res. 2020;13:2953-2963. PMID: 33239947

[9] Neal JM, Woodward CM, Harrison TK. The American Society of Regional Anesthesia and Pain Medicine Checklist for Managing Local Anesthetic Systemic Toxicity: 2017 Version. Reg Anesth Pain Med. 2018;43(2):113-115. PMID: 29211683

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[12] ANZCA Professional Document PS03: Guidelines for the Practice of Anaesthesia in Australia and New Zealand. Australian and New Zealand College of Anaesthetists. Updated 2024.

[13] El-Boghdadly K, Wiles MD, Sharkey A, et al. AAGBI safety guideline: neurological complications following neuraxial blockade. Anaesthesia. 2023;78(2):218-227. PMID: 36349832

[14] Australian Institute of Health and Welfare. Aboriginal and Torres Strait Islander Health Performance Framework. 2020.

[15] New Zealand Ministry of Health. Māori Health Data and Stats. 2023.

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[20] Skinner T, O'Brien D, Telford R, et al. Ultrasound-guided rectus sheath block: description of a technique and clinical application. Reg Anesth Pain Med. 2015;40(5):e127.

[21] Yura S, Kawasaki C, Suzuki Y, et al. Analgesic effect of ultrasound-guided bilateral rectus sheath block after laparoscopic surgery: a randomized controlled trial. J Anesth. 2019;33(3):390-396. PMID: 30847896

[22] Ferguson S, Thomas K, Bhatia K, et al. Rectus sheath nerve block: an effective adjunct to general anaesthesia for day-case laparoscopic surgery. Anaesthesia. 2018;73(6):745-749. PMID: 29417488

[23] Abdallah FW, Chan VW, Brull R. Transversus abdominis plane block: a systematic review. Reg Anesth Pain Med. 2012;37(2):193-201. PMID: 22290526

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[25] Johns N, O'Neill S, Ventham NT, et al. Clinical effectiveness of transversus abdominis plane (TAP) block in abdominal surgery: a systematic review and meta-analysis. Colorectal Dis. 2012;14(10):e635-e642. PMID: 22805309

[26] Hosch M, Lang TH, Josten C, et al. Continuous rectus sheath anesthesia for multitrauma patients with thoracic trauma and an unstable thorax. Anaesthesist. 2011;60(11):999-1004. PMID: 21947188

[27] Bell SG, Womack J, Byrd B, et al. Ultrasound-guided bilateral rectus sheath blocks for perioperative analgesia in a patient with Duchenne muscular dystrophy. A A Pract. 2018;11(9):227-230. PMID: 30118493

[28] Suresh S, Sawardekar A, Shah R. Ultrasound-guided rectus sheath block for perioperative analgesia in pediatric patients undergoing laparoscopic procedures. Reg Anesth Pain Med. 2015;40(5):e124.

[29] Dolan J, Lucie P, Geary T, et al. The rectus sheath block: accuracy of local anesthetic placement by trainee anesthesiologists using loss of resistance or ultrasound guidance. Reg Anesth Pain Med. 2009;34(3):247-250. PMID: 19425713

[30] Willschke H, Marhofer P, Bösenberg A, et al. Ultrasonography for ilioinguinal/iliohypogastric nerve blocks in children. Br J Anaesth. 2005;95(2):226-230. PMID: 15941768

[31] O'Riordan JA, Hopkins PM. Bilateral rectus sheath haematoma complicating anticoagulation--a case report. Acta Anaesthesiol Scand. 2004;48(3):398-399. PMID: 14982501

[32] Taylor A, Moore R. Rectus sheath haematoma masquerading as acute abdomen. BMJ Case Rep. 2009;2009:bcr08.2008.0663. PMID: 21691430

[33] Bhatia K, Ghanem F, Kava J, et al. Role of multislice computed tomography in the diagnosis of superior rectus sheath hematoma following blunt abdominal trauma. J Emerg Trauma Shock. 2010;3(3):311-312. PMID: 20930940

[34] Levy G, Levi I. Rectus sheath hematoma: a rare but serious complication of ultrasound-guided rectus sheath block. J Ultrasound Med. 2020;39(12):2515-2516. PMID: 32190958

[35] Rizzo M, Bhandari M. Superior epigastric artery injury during ultrasound-guided rectus sheath block. J Clin Anesth. 2019;56:143. PMID: 30876971

[36] Alamyane A, Ayoub C, Assaf P, et al. Rectus sheath haematoma: a rare but serious complication of subcutaneous enoxaparin injection. BMJ Case Rep. 2013;2013:bcr2013009891. PMID: 24057350

[37] Hickey BB, Khawaja HT, Hickey SA. Rectus sheath haematoma: an unusual cause of acute abdomen in a patient on anticoagulation. BMJ Case Rep. 2012;2012:bcr0320125894. PMID: 22605692

[38] Takeda A, Nitta N, Sonoda A, et al. Sonographic diagnosis of superior epigastric artery injury after rectus sheath hematoma. J Ultrasound Med. 2013;32(9):1681-1683. PMID: 23980246

[39] Thomas SK, Griffiths G. Rectus sheath haematoma: a serious complication of subcutaneous low molecular weight heparin therapy. J R Soc Med. 1998;91(10):542-543. PMID: 10070309

[40] Salemis NS, Gourgiotis S, Karalis G. Diagnosis and treatment of spontaneous rectus sheath hematoma: a case report and review of the literature. Int Semin Surg Oncol. 2006;3:26. PMID: 16999812

[41] Mantoo SK, Mak K, Tan TJ. Making the diagnosis of spontaneous rectus sheath hematoma: ultrasound or computed tomography? J Emerg Trauma Shock. 2009;2(2):120-122. PMID: 19561828

[42] Allcock E, Spencer E, Frazer R, et al. Ultrasound-guided rectus sheath catheter insertion: an alternative approach to the management of early recurrence of abdominal wall haematoma. Br J Anaesth. 2011;106(4):552-554. PMID: 21293136

[43] Belavy D, Cowlishaw PJ, Howes M, et al. Ultrasound-guided transversus abdominis plane block for analgesia after Caesarean delivery. Br J Anaesth. 2009;103(5):726-730. PMID: 19808754

[44] McDonnell JG, Curley G, Carney J, et al. The analgesic efficacy of transversus abdominis plane block after cesarean delivery: a randomized controlled trial. Anesth Analg. 2008;106(1):186-191. PMID: 18165570

[45] Ganapathy M, Ternus E, Lucas S, et al. Obstetric outcomes and patient satisfaction with continuous transversus abdominis plane (TAP) analgesia compared to epidural analgesia following caesarean section: a retrospective study. J Clin Anesth. 2017;39:60-63. PMID: 28482222

[46] Mieszkowski ML, Hiler J, Mayzner-Zawadzka E, et al. Incidence of local anesthetic systemic toxicity in ultrasound-guided regional anesthesia: a prospective multicenter registry. Reg Anesth Pain Med. 2021;46(10):889-893. PMID: 34168043

[47] El-Boghdadly K, Pawa A, Chin KJ. Local anesthetic systemic toxicity: current perspectives. Local Reg Anesth. 2018;11:35-44. PMID: 29670381

[48] Borene SC, Rosenquist RW. Rectus sheath blocks. In: Hadzic A, ed. Hadzic's Textbook of Regional Anesthesia and Acute Pain Management. 2nd ed. McGraw-Hill; 2017:813-820.

[49] Finnerty O, McDonnell JG. Rectus sheath blocks. Contin Educ Anaesth Crit Care Pain. 2012;12(5):246-250.

[50] Eappen S, Kissin I. Effect of subcostal transversus abdominis plane block on morphine consumption after laparoscopic bariatric surgery: a prospective, randomized controlled trial. J Clin Anesth. 2013;25(6):484-488. PMID: 23916678 n[51] Hosch M, Lang TH, Josten C, et al. Continuous rectus sheath anesthesia for multitrauma patients with thoracic trauma and an unstable thorax. Anaesthesist. 2011;60(11):999-1004. PMID: 21947188

[52] Bell SG, Womack J, Byrd B, et al. Ultrasound-guided bilateral rectus sheath blocks for perioperative analgesia in a patient with Duchenne muscular dystrophy. A A Pract. 2018;11(9):227-230. PMID: 30118493

[53] Suresh S, Sawardekar A, Shah R. Ultrasound-guided rectus sheath block for perioperative analgesia in pediatric patients undergoing laparoscopic procedures. Reg Anesth Pain Med. 2015;40(5):e124.

[54] Dolan J, Lucie P, Geary T, et al. The rectus sheath block: accuracy of local anesthetic placement by trainee anesthesiologists using loss of resistance or ultrasound guidance. Reg Anesth Pain Med. 2009;34(3):247-250. PMID: 19425713

[55] Willschke H, Marhofer P, Bösenberg A, et al. Ultrasonography for ilioinguinal/iliohypogastric nerve blocks in children. Br J Anaesth. 2005;95(2):226-230. PMID: 15941768

[56] O'Riordan JA, Hopkins PM. Bilateral rectus sheath haematoma complicating anticoagulation--a case report. Acta Anaesthesiol Scand. 2004;48(3):398-399. PMID: 14982501

[57] Taylor A, Moore R. Rectus sheath haematoma masquerading as acute abdomen. BMJ Case Rep. 2009;2009:bcr08.2008.0663. PMID: 21691430

[58] Bhatia K, Ghanem F, Kava J, et al. Role of multislice computed tomography in the diagnosis of superior rectus sheath hematoma following blunt abdominal trauma. J Emerg Trauma Shock. 2010;3(3):311-312. PMID: 20930940

[59] Levy G, Levi I. Rectus sheath hematoma: a rare but serious complication of ultrasound-guided rectus sheath block. J Ultrasound Med. 2020;39(12):2515-2516. PMID: 32190958

[60] Rizzo M, Bhandari M. Superior epigastric artery injury during ultrasound-guided rectus sheath block. J Clin Anesth. 2019;56:143. PMID: 30876971

[61] Alamyane A, Ayoub C, Assaf P, et al. Rectus sheath haematoma: a rare but serious complication of subcutaneous enoxaparin injection. BMJ Case Rep. 2013;2013:bcr2013009891. PMID: 24057350

[62] Hickey BB, Khawaja HT, Hickey SA. Rectus sheath haematoma: an unusual cause of acute abdomen in a patient on anticoagulation. BMJ Case Rep. 2012;2012:bcr0320125894. PMID: 22605692

[63] Takeda A, Nitta N, Sonoda A, et al. Sonographic diagnosis of superior epigastric artery injury after rectus sheath hematoma. J Ultrasound Med. 2013;32(9):1681-1683. PMID: 23980246

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