Ultrasound-guided ganglion impar block: A technical report

Chia Shiang Lin, Jen Kun Cheng, Yung Wei Hsu, Chien Chuan Chen, Hsuan Chih Lao, Chun Jen Huang, Peter H. Cheng, Samer Narouze

Research output: Contribution to journalArticlepeer-review

35 Citations (Scopus)


Background and Objectives: Ganglion impar block is an uncommon procedure that has been performed traditional with fluoroscopy. One approach is the trans-sacrococcygeal approach. Sometimes this can be difficult because the sacrococcygeal joint (SCJ) cannot be readily seen on anteroposterior (AP) and lateral fluoroscopy. This technical report describes the feasibility of ultrasound in assisting ganglion impar blocks. Methods: We performed ganglion impar block using ultrasound as the primary imaging tool, with fluoroscopic confirmation in 15 patients. We used a linear array transducer (5-12 MHz) to obtain sonographic transverse and longitudinal views at the sacral cornua; we identified the first cleft below the sacral hiatus as the SCJ. Then we inserted a 23-gauge (7 cm in length) needle into the SCJ under sonographic guidance. Then we confirmed proper needle depth by lateral fluoroscopy and injection of contrast agent. Results: In all 15 procedures, we accurately located and passed the needle into the patients' SCJs under real time sonographic guidance. Conclusions: In cases where the cleft cannot be readily seen on AP and lateral fluoroscopy, we have found ultrasound to be of assistance. Ultrasound does not replace fluoroscopy, because lateral fluoroscopy is still required to establish safe depth, and correct site of injection. However, ultrasound can be helpful when fluoroscopy alone is insufficient.

Original languageEnglish
Pages (from-to)390-394
Number of pages5
JournalPain Medicine
Issue number3
Publication statusPublished - Jan 1 2010
Externally publishedYes


  • Ganglion impar block
  • Sacrococcygeal approach
  • Ultrasound

ASJC Scopus subject areas

  • Clinical Neurology
  • Anesthesiology and Pain Medicine


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