Varicocele is a dilatation and tortuosity of testicular veins. The man testicular vein, the spermatic vein, drains the venous blood from the testis. In the foetus, the testis grows near the kidney, and then slowly migrates to find its place in the scrotum. All the nerves, lymphatics, and vessels of the testis have their origin in the kidney area. Since the spermatic vein is a thin, long vein, where the blood flows opposing gravity, and since the venous drainage is a low pressure circulating system, blood can invert the flow and reflux can occur. Varicocele can impair spermatogenesis. The main aetiology hypothesis is an increased blood flow in the testis. In fact, the testis is outside the body, in the scrotal sac, because spermatogenesis requires a lower temperature than the intracorporeal 37 °C.
An excess of heat to the testis might damage the production and maturation of spermatozoa.
Another hypothesis is a decreased oxygen concentration in refluxing venous blood, with subsequent tissue damage. Some authors have shown in patients with varicocele a decreased testosterone concentration, that improves after ligature of the spermatic vein. Usually, in most cases varicocele affects the left side. This is due to an anatomical reason. While the left spermatic vein joins the left renal vein with a 90° angle, the right spermatic vein joins the vena cava with a small angle: the right spermatic vein is protected from reflux by this angle, in a valve-like fashion. Another risk factor for left varicocele is the length of the left spermatic vein, which is 10 cm. longer than the right one.
Usually varicocele becomes evident at puberty. A varicocele can be diagnosed in 10-15% of all healthy men, in 35% of patients with primary infertility and in 75-80% of patients with secondary infertility.
Varicocele is often related to a decreased testis size and to an impaired fertility. In 70% of patients with varicocele there is an alteration of the total number of spermatozoa, or of their motility, or of their shape. Varicocele diagnosis is based upon inspection, that can reveal a varicocele at rest or during Valsalva manoeuvre (to blow with both mouth and nose closed)
Varicocele can be confirmed by scrotal Doppler ultrasound, which shows venous reflux.Varicocele is clinically classified in 3 degrees.

Varicocele: classification

Classification	Definition
Clinic (palpable):
Grade III (large)	Easily Visible
Grade II (medium)	Palpable at rest (without Valsalva), not visible
Grade I (small)	Palpable only with Valsalva manouvre
Subclinic (not palpable)	Vein >3mm at ultrasound; reflux found by  Doppler during Valsalva manouvre

Non all patients with varicocele deserve treatment. The indication to treatment comes from infertility, from altered sperm count, from local discomfort (scrotal weight after prolonged standing). Young men with large varicocele or decreased testis size should be as well treated.
Though the issue has been long debated, recent studies suggest that when there is a large left varicocele and a small right varicocele, both should be treated. The mainstay of varicocele treatment is reflux interruption. The approach can be surgical, laparoscopic, or percutaneous (intravenous). Open surgery can be performedat the level of iliac bone, with a small incision. The vein is identified, ligated and severed. Sometimes multiple spermatic veins can be found. Even if the artery should be damaged at this level, the testis blood supply would not be impaired. Microsurgical inguinal approach is done with magnification of the field, with every small vein identified and ligated. Though success rate is extremely high, a rare but severe complication is a damage of the artery (< 1% of cases), which, at this level, will lead to testis atrophy. The laparoscopic approach is performed with CO2 insufflation in the abdominal cavity, with 3 ports. It is a mini-invasive procedure, especially useful for the treatment of bilateral varicocele. With the percutaneous technique, an intravenous small catheter is guided under x-ray control into the venous system, to reach and create an embolus in the spermatic vein.
Spermatic vein closure is followed by an improved fertility in 60-80% of cases, according to different series, with an average 50% increase of pregnancy rate. Even patients without spermatozoa at all, varicocele correction may induce in some a temporary sperm production, enough for in vitro fertilization.