Potential 32% miss-rate for caudal epidurals placed “blind”, says study


Study recommends radiological confirmation and an epidurogram for accurate needle placement and delivery of injectables to area of pathology for consultants and middle-grade surgeons.

Mr Guy Barham, acting consultant, and Mr Andrew Hilton, consultant spine surgeon, Dorset, UK, have found that in an as-yet unpublished study involving “consultant” and “middle-grade surgeons” that placement of epidurals without X-ray guidance can be “pretty unreliable.”

The study, presented at the annual meeting of the British Association of Spine Surgeons in Sheffield, UK, found that in 26% (36/138 patients) of cases, the spinal needle placement was made outside the epidural space after first blind placement. Also, in a further 6% of cases, the radio-opaque dye did not reach the level of documented pathology, taking the potential “miss” ( where patients derive no benefit from the epidural) rate to 32%.

Barham says it all began “with a number of patients the team saw in clinics who had had epidurals, which were not performed in our department that had given no significant benefit, when we suspected that they should have done. This made us think about whether or not the epidural had been given into the epidural space.”

Their study, with the largest number of consecutive patients receiving caudal epidurals (146, of which five did not attend and three were excluded from the data for inadequate records) was designed to quantify the hit/miss ratio of non-radiologically assisted caudal epidurals. It assessed both accuracy of entry into the epidural space and checked for the flow of contrast and therapeutic agents to the areas of predefined pathology.


Historically, placing a caudal epidural is seen as a simple, safe and effective procedure. Indeed, in wider practice it is still performed without X-ray guidance and without the use of a radio-opaque dye. “But we had long suspected that perhaps the miss rate was higher than we thought. For the last four years I have performed caudal epidurals using X-ray guidance for accurate needle placement, and a radio-opaque dye to confirm that the steroid has been delivered to the area of pathology. This study is important because it shows a reliable, reproducible, way to perform an epidural which has significant diagnostic value,” said Hilton.

Everyone needs x-ray guidance:

“However experienced you are, you still need the radiology and an epidurogram, because you could potentially be off the mark by 32%”, said Barham

In the study, the hit rate was not related to surgeon grade, patient age or patient diagnosis. While consultant spinal surgeons carried out 75 procedures, the remaining 63 cases were performed by “middle grade” surgeons. Importantly, Barham says, “The study shows that when it comes to caudal epidurals, you can become quite competent at doing them relatively early on and your chances of getting it in the right place could be similar to someone with much more experience, but you still need X-ray guidance.”

“We absolutely recommend to anyone performing caudal epidurals to use X-ray guidance and an epidurogram. If you do not do so, there is a significant chance that you will perform an epidural that does not deliver,” says Hilton.

Safety issues with misses:

Both researchers said that “misplaced” needles had, on different occasions, entered an epidural vein or penetrated the dura mater. They highlight that in such cases,it would be dangerous to inject local anaesthetic into the dural space leading to spinal anaesthesia or injecting intravenously leading to systemic toxicity.


Financial implications:

The researchers also stressed that the findings of the study had “huge financial implications for the NHS.” Barham said, “When patients do not experience relief after a getting a caudal epidural, the medical team might reconsider diagnosis, because they do not factor in that the epidural might have been misplaced.” Hilton added, “This could mean the diagnosis is (wrongfully) altered, and the patient undergoes other inappropriate procedures, which could unnecessarily cost the NHS.” The researchers also said performing a procedure where 32% of procedures are inappropriate, is a costly waste in itself.