Ultrasound‐Guided Superior Hypogastric Plexus Block: A Cadaveric Feasibility Study with Fluoroscopic Confirmation
Bibliographic record
Abstract
Plancarte first described a fluoroscopy-guided superior hypogastric plexus block to manage pelvic pain in 1990. Modifications have since been described using different imaging modalities. Ultrasound-guided approach has been described in a clinical outcome study. However, the accuracy of an ultrasound-guided method has never been validated by alternative imaging. We conducted an experiment aiming to develop ultrasound-guided superior hypogastric plexus block using human cadavers in the supine position. Final needle position and spread of a radiopaque contrast was verified by fluoroscopy, a standard imaging tool. The needle approach to the L5 vertebral body was performed in the short axis as has been recommended. Injection of radiopaque contrast revealed unilateral and cephalad spread to the L5/S1 disk. Additional transabdominal long-axis scanning of the lumbosacral segment was and the needle trajectory was modified to aim for the apex of the L5/S1 disk. Bilateral spread was achieved by strict midline placement of the needle tip and real-time observation of injection. The modified ultrasound-guided technique resulted in a similar spread of injectate as the traditional fluoroscopy-guided technique that in a clinical scenario would offer complete block of the superior hypogastric plexus.
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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 | 0.006 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.008 | 0.002 |
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".