Physiology

To understand how a varicocele impedes male fertility, it is helpful to have a basic understanding of the parts of the male reproductive system and how they work.

The testicles - or testes - are the paired male organs that produce sperm. They are located in an external sac beneath the penis called the scrotum. Each testicle is connected to a small coiled tube called the epididymis, where sperm are stored as they mature. The epididymes, in turn, are connected to the prostate gland by a pair of tubes called the vas deferens. The vas deferens are part of a larger bundle of tissues, blood vessels, nerves and lymphatic channels called the spermatic cord. The veins of the spermatic cord circulate blood throughout these structures, eventually draining into the body's main circulatory system.

What are the causes and risks of the condition?

All veins contain valves that reduce back pressure and keep blood flowing in one direction - toward the heart. If one of these valves becomes weak or fails to function properly, back pressure can build up inside the vein, producing a pool of heavy, stagnant blood. Over time, this pooled blood and back pressure can build up enough to cause swelling in the vein, producing a varicose vein or varicocele.

It is helpful to draw an analogy between the body's circulatory network and the cooling system in an automobile. Most people know that a typical automobile engine is protected from overheating by a system that circulates a cooling fluid through it in a continuous loop. A similar process occurs in the human body: blood pumped to the outer extremities by the heart is cooled to a constant temperature as it returns through the veins.

However, because blood flows sluggishly through a varicose vein, cooling of the blood in a varicocele is incomplete. When a varicocele develops in one of the veins of the spermatic cord (known collectively as the pampiniform plexus), the temperature of the blood within it increases. This, in turn, raises the temperature of the testes. Because sperm are sensitive to heat, this increase in temperature can decrease the production of healthy sperm, leading to male infertility.

Although a varicocele can develop in either or both testicles, in most men the problem occurs on the left testicle. There is a physiological reason for this, too: The spermatic cord on the left side is longer and takes a more circuitous route back toward the heart. It connects to the left kidney vein, which has higher blood pressure within it. The higher blood pressure on this side increases the likelihood of swelling in a weakened vein. By contrast, the right testicular vein is usually shorter. It connects directly to the vena cava - the primary vein leading to the heart - which is characterized by lower blood pressure. For this reason, varicoceles of the right testicle are uncommon.

What are the signs and symptoms of the condition?

The most common symptom of a varicocele is a dull, constant ache or persistent sensation of heaviness in the testicle. This is caused by the unrelieved pressure against the well of the weakened varicose vein. Some men say the problem is most noticeable when they have been standing for a prolonged period. Often, the patient will report that his discomfort is minimal when he first gets up in the morning, but increases toward the end of the day. Some men say their pain diminishes when they lie down.

In some cases, the decrease in circulation to a testicle will cause it to shrink in size (atrophy). In others, particularly those in whom the condition develops gradually over an extended period of time, patients may assume this shrinkage or discomfort is in some way associated with aging. Others may wrongly attribute the onset of pain to muscular strain, such as from heavy lifting.

All men should be aware that any recurrent or constant discomfort or pain in the genital region is abnormal and should see their urologist or primary care physician as soon as possible.

Many men with varicoceles experience no symptoms at all. Most asymptomatic cases of varicocele are diagnosed when a man undergoes a physical examination, either as part of a routine medical check-up or in response to a perceived difficulty in conceiving children (see Male Infertility).

How is this condition diagnosed?

Varicoceles may be large or small. Prominent ones can be seen easily with the naked eye. The trained physician also can detect the presence of a bulging vein the patient's scrotum by palpating (exploring by feeling) the area. As part of this process, a physician usually will have the patient perform the Valsalva maneuver. For this, the patient is asked to stand upright, take a deep breath, then give a forced exhale with a closed nose and mouth. This increases pressure in the area and causes a varicocele to bulge, making it more easily discernible to the doctor's touch. Additional palpitation of the area may be conducted while the patient is lying down (supine).

Small or hidden varicoceles may require the use of more sophisticated diagnostic procedures. These may include:

Doppler ultrasonography, a visual imaging of the internal organs in which the physician uses ultrasound echos to detect the characteristic sound of poor blood flow in a suspected varicocele; a thermogram, a procedure which detects pockets of heat caused by the pooled blood within a varicocele, or a venogram, an outpatient procedure in which the physician makes a small incision, under local anesthetic, in the patient's scrotum, through which a special dye is injected into the spermatic vein. This enables the physician to see the vein more clearly on an X-ray and detect the presence of even a very small varicocele.

If the examination is being done because of suspected male infertility, the physician usually will perform a comparative analysis of several samples of the patient's semen. This is because infertility brought on by a varicocele typically displays a consistent pattern of incompletely developed, damaged, dead or dying sperm.