The bore/lumen is the innermost part of the vas that transports the sperm. The vas is 1-2 mm in diameter/across and the lumen is 0.2 mm. The lumen normally would only allow 2-3 human hairs to fit inside it.
In this video there is a blue marker (the size of a small skin suture used for repairing a skin laceration) in the bore. This demonstrates the difference in size of the two ends of the vas due to the many years of sperm production under pressure after vasectomy at the testicular end. In this particular case the time between vasectomy and the reversal was 18 years.
On the left, the vas above the previous vasectomy site (that goes to the prostate) is the normal size 0.2 mm. On the right the vas attached to the testicle has a dilated lumen three times the size, 0.6mm, due to the ongoing sperm production and pressure below the vasectomy site.
Special consideration needs to be given to the suturing technique when there is a great difference between the two bores as seen here.
