Authors: Berger AA et al.
Anesthesia & Analgesia, February 10, 2026, 10.1213/ANE.0000000000007982
This 10-year single-center retrospective cohort study evaluated whether the injected volume during epidural blood patch (EBP) affects treatment success in obstetric post-dural-puncture headache (PDPH).
Although EBP is widely accepted as the most effective treatment for PDPH, volume targets remain debated—particularly beyond 20 mL. This institution’s practice was to inject autologous blood until persistent back pressure was reported.
Study Design
• 317 obstetric patients underwent EBP between 2014–2024
• 32 single-shot spinal cases were excluded from the primary analysis
• Primary outcome: need for repeat EBP
• Secondary outcome: complete headache resolution
• Statistical modeling: binomial generalized model
Key Findings
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Repeat EBP rate
65 patients (22.8%) required a second EBP. -
Injected volume
Median injected volume was 28 mL (IQR 22–32 mL).
In multivariable analysis:
• Each additional 1 mL of injected blood was associated with reduced odds of repeat EBP (OR 0.96 per mL, P = .028).
• A dose-response relationship was observed between higher volume and reduced repeat EBP (P = .030).
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Timing
Earlier treatment mattered.
Each day delay from PDPH diagnosis to EBP significantly reduced success odds (OR 0.61 per day, P = .002). -
30 mL threshold
When analyzed dichotomously:
• Injection ≥30 mL was significantly associated with complete headache resolution compared with <30 mL (OR 1.85, P = .049). -
Complete resolution
Among patients with ≥3 days follow-up (n=226):
• 52.2% had complete headache resolution after the first EBP.
Interpretation
This study suggests:
• Larger injected volumes are associated with greater primary EBP success
• A practical threshold appears to be around 30 mL
• Delays between PDPH diagnosis and EBP reduce success odds
From a physiologic standpoint, greater volume may improve clot spread and dural defect tamponade. The dose-response relationship strengthens the plausibility of a true association rather than random variation.
However, caution is warranted:
• Retrospective design
• Single-center experience
• Injection was pressure-limited, not protocolized by exact volume
• Causality cannot be established
Importantly, safety concerns (e.g., neurologic symptoms, back pain) were not highlighted as limiting factors in the abstract, though larger volumes can theoretically increase risk.
Key Points
• Repeat EBP occurred in ~23% of patients.
• Greater injected volume was independently associated with lower repeat rate.
• Each 1 mL increase modestly improved success odds.
• Injecting ≥30 mL was associated with higher complete headache resolution.
• Delayed EBP from PDPH diagnosis decreased success.
What You Should Know
For obstetric anesthesia practice, this study supports a more assertive volume target when clinically tolerated. If the patient is comfortable and no neurologic symptoms emerge, advancing toward 30 mL rather than stopping at 15–20 mL may reduce repeat procedures.
Given how disruptive repeat EBP can be—for both patient recovery and workflow—this may have meaningful clinical implications.
A prospective controlled study would be valuable to define optimal volume thresholds and safety boundaries more definitively.
Thank you to Anesthesia & Analgesia for allowing us to summarize and share this article.