Indications and Contraindications of Spinal Anesthesia
Indications
Spinal anesthesia is indicated for any surgical procedure below the diaphragm where an appropriate sensory level can be achieved, and is particularly preferred when avoiding general anesthesia reduces morbidity and mortality risks. 1
Primary Indications Include:
- Lower extremity and lower abdominal surgeries where adequate sensory blockade can be achieved 2
- Cesarean delivery and obstetric procedures - neuraxial techniques are first-line to avoid pulmonary complications from intubation, especially in high-risk patients 3
- Spine surgery procedures including awake spinal fusion and outpatient spinal operations 4
- Vascular and orthopedic procedures of the lower extremities 3
- Patients at high risk for general anesthesia complications including those with difficult airways, aspiration risk, or respiratory compromise 3
Special Populations:
- COVID-19 positive patients: Neuraxial anesthesia is the first choice whenever possible to avoid aerosol-generating intubation 3
- Pediatric patients: Effective for lower body procedures, though most require sedation with careful airway monitoring 5
Absolute Contraindications
The following conditions represent absolute contraindications where spinal anesthesia must not be performed:
- Patient refusal 1
- Infection at the puncture site 5
- Severe, uncorrected hypovolemia or hemodynamic instability 1
- Increased intracranial pressure 5
- Severe coagulopathy or bleeding disorders (see specific parameters below) 3
Relative Contraindications and Coagulation Parameters
Anticoagulation Timing Requirements:
The following minimum time intervals must be observed between anticoagulant administration and spinal anesthesia to prevent vertebral canal hematoma: 3
Prophylactic Anticoagulation:
- LMWH prophylactic dose: >12 hours before block 3
- UFH subcutaneous: >4 hours, with normal APTT 3
- Rivaroxaban prophylaxis: 18 hours before block 3
- Apixaban prophylaxis: 24-48 hours before block 3
- Dabigatran (varies by renal function): 48-96 hours depending on creatinine clearance 3
Therapeutic Anticoagulation:
- LMWH therapeutic dose: >24 hours before block 3
- Rivaroxaban treatment: 48 hours before block 3
- Warfarin: INR must be ≤1.4 3
- Clopidogrel: 7 days before block 3
Thrombocytopenia Thresholds:
Platelet counts must be assessed before neuraxial procedures in at-risk patients: 3
- Normal risk: Platelet count >100 × 10⁹/L 3
- Acceptable for obstetric patients: >75 × 10⁹/L with normal platelet function and stable count 3
- Pre-eclampsia: Platelets <75 × 10⁹/L represent high risk; coagulation screen required if <100 × 10⁹/L 3
- Idiopathic thrombocytopenia: May consider at >50 × 10⁹/L if stable, with individual risk-benefit assessment 3
Critical caveat: COVID-19 patients may develop thrombocytopenia, particularly in severe disease, requiring platelet count verification before neuraxial procedures 3
Additional Relative Contraindications
- Sepsis or bacteremia (risk of seeding infection into CNS) 1
- Pre-existing neurological disease (controversial; requires careful documentation and discussion) 1
- Severe aortic or mitral stenosis (inability to compensate for sympathetic blockade) 1
- Severe spinal deformity (technical difficulty, not absolute contraindication) 1
Critical Safety Considerations
Catheter Management with Anticoagulation:
Epidural catheter removal carries similar bleeding risk as insertion and requires the same anticoagulation timing precautions. 3 Most guidelines recommend:
- Minimum 6 hours after catheter removal before restarting anticoagulation 3
- Only one dose of LMWH in first 24 hours after neuraxial blockade 3
Monitoring for Vertebral Canal Hematoma:
Maintain high index of suspicion for signs of spinal hematoma, particularly when anticoagulation is given shortly after block placement (common in cardiac/vascular surgery). 3 Warning signs include:
- Progressive motor weakness
- Bowel/bladder dysfunction
- Severe back pain
- Sensory level changes
COVID-19 Specific Considerations:
COVID-19 infection itself is NOT a contraindication to neuraxial anesthesia in the absence of other risk factors (thrombocytopenia, sepsis). 3 However: