Expansion
The left testicular vein drains at a right angle into the left renal vein
Expansion
About 90 per cent of varicoceles are left-sided, for three anatomical reasons:
- The left testicular vein drains into the left renal vein at a right angle, against gravity, whereas the right drains obliquely into the inferior vena cava
- The left vein is longer, giving a higher hydrostatic column
- The left renal vein may be compressed between the aorta and the superior mesenteric artery (the nutcracker effect)
The left testicular vein is also relatively poorly valved.
Two clinical warnings follow. A varicocele that does not decompress on lying down, or a new right-sided varicocele, suggests obstruction of the testicular vein by a retroperitoneal mass, classically a renal cell carcinoma invading the renal vein.
A varicocele feels like a “bag of worms” and is associated with impaired fertility, thought to result from raised scrotal temperature.