Indication
Surgery of the penis (e.g. circumcision, meatoplasty, preputioplasty, hypospadias)
This block is historically performed as a landmark technique, but the ultrasound guided technique is safer, more superficial and requires less volume of local anaesthetic. Furthermore, it has a higher success rate than the blind approach as it confirms the distribution of the local anaesthetic.
Complications
Considerations
Contraindications
See general contraindications
Anatomy
The penis consist of 3 erectile columns: 2 corpora cavernosa and a corpus spongiosum, the latter contains the urethra. These 3 erectile bodies are surrounded by a deep penile fascia (Buck’s fascia) which also envelops the deep dorsal vein and paired dorsal arteries, lying on top of the corpora cavernosa. The penis is innervated by the right and left dorsal penile nerves that arise from the pudendal nerve (S2-S4) and travel below the Buck’s fascia, near the dorsal arteries. Tiny scrotal branches of the pudendal nerve will travel on the ventral side of the penis and need to be blocked as well for complete analgesia.
A penile block aims to deposit local anaesthetic deep to Buck’s fascia, bilaterally, near the dorsal arteries. A small amount of local anaesthetic is also applied to the ventral side of the penis to obtain circumferential spread.
NOTE: The blind technique is generally performed more proximally where you pop through the superficial fascia of the abdomen (scarpa fascia). The ultrasound technique is aimed to put local anaesthetic more distally and closer to the penile nerves. This approach is safer and allows for the use of smaller doses of local anaesthetic.
Patient Position
Supine
Have a colleague hold the penis steady, apply gentle caudal traction
(tip: use a swab to hold the penis as the ultrasound gel is slippery)
Probe can be positioned either at the dorsal base or the ventral aspect of the penis (see next section)
Alternative positioning (probe on ventral side of penis) -> US image will be flipped
Sonoanatomy
Ultrasound probe selection: smaller high frequency linear probe (5-10MHz)
NOTE: due to the superficial nature of the target location, needle insertion might be difficult, and the structures are easily compressed. An alternative approach would be to put the ultrasound probe at the ventral aspect of the penis (the image will be inverted). It compresses the anatomy less and makes needling easier.
Needling
Use a 50-60mm block needle
Target depth: 0.1-3cm
NOTE: the target locations are very superficial and can be easily compressed with probe pressure
NOTE: The dorsal penile nerves are often not clearly seen but run adjacent to the dorsal arteries and therefore LA can be deposited adjacent to these.
Levobupivacaine 0.25% 0.1ml/kg (usually about 1-2mls each side for infants under 3yo – max. 5mls each side)
dorsal image
Ventral image