Ultrasonography for neuraxial blocks: a review of the evidence
Bibliographic record
Abstract
INTRODUCTION: This narrative review summarizes the evidence derived from randomized controlled trials (RCTs) pertaining to the use of adjunctive ultrasonography (US) for neuraxial blocks. EVIDENCE ACQUISITION: The literature search was conducted using the MEDLINE, EMBASE and PUBMED databases. For the MEDLINE and EMBASE searches, the MESH terms "ultrasonography" and key word "ultrasound" were queried; using the operator "and", they were combined with the MESH terms "neuraxial block," "epidural anesthesia," "epidural analgesia," "spinal anesthesia," "spinal analgesia," "intrathecal anesthesia," "intrathecal analgesia," "caudal anesthesia," and "caudal analgesia." For the PUBMED search, the search terms "ultrasound neuraxial," "ultrasound intrathecal," "ultrasound epidural" (limited to clinical trials), "ultrasound spinal" (limited to clinical trials), and "ultrasound caudal" (limited to clinical trials) were queried. Seventeen RCTs were retained for analysis. EVIDENCE SYNTHESIS: Compared to conventional palpation of landmarks, US assistance (i.e., preprocedural scanning) results in fewer needle passes/insertions and skin punctures for neuraxial blocks in obstetrical and surgical patients. These benefits seem most pronounced when expert operators carry out the sonographic exams and for patients displaying difficult spinal anatomy. Preliminary findings also suggest that US provides similar pain relief and functional improvement to fluoroscopy for epidural/caudal steroid injection in patients afflicted with chronic spinal pain. Although one trial demonstrated shorter needling time with US guidance (i.e., real-time scanning of needle advancement) compared to US assistance, these findings require further validation. CONCLUSIONS: Published reports of RCTs provide evidence to formulate limited recommendations regarding the use of adjunctive US for neuraxial blocks. Further well-designed RCTs are warranted.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.007 | 0.025 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.005 | 0.004 |
| Bibliometrics | 0.008 | 0.008 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.003 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.003 | 0.002 |
| Insufficient payload (model declined to judge) | 0.007 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".