THE URETHRA

The urethra is the tube passing from the bladder to the tip of the penis, through which urine is voided. It is encircled by the prostate gland and runs through the corpus spongiosum on the underside of the penis.

Urethral infections, scarring and congenital abnormalities occur in both sexes, but they are much more common and serious in the male. This is because the male urethra is at least 10 times longer than the female equivalent.

Urethral Stenosis

This uncommon birth defect causes obstructive narrowing of the urethra due to the persistence of a membrane which normally disappears during foetal development. Urine builds up in the bladder and backed-up pressure can cause serious kidney damage.

Mild urethral narrowing is sometimes relieved by passing a slim, rounded metal dilator through the tip of the penis under a local or general anaesthetic. As this usually has to be repeated at regular intervals, many surgeons prefer instead to operate and remove the urethral membrane completely.

In later life, urethral injury or infection, for example with persistent gonorrhoea (see gonorrhoea), can result in urethral scarring. This leads to narrowing and sometimes shortening as the scar tissue shrinks. Urethral stricture can make it difficult or painful to pass water and ejaculate, and may even cause penile deformity, similar to Peyronie's disease, during erection. If urine builds up behind the stricture, the resulting pressure can damage the kidneys. It also encourages urinary tract infection.

Figure 4: The Distal Urethra

Adult urethral strictures are sometimes correctable by passing a metal dilator through the urethra, as described above. Another technique involves inserting a deflated balloon and inflating it with water to dilate the narrowed area.

If dilatation fails, a cutting instrument (urethrotome) can be inserted to trim the scar; occasionally, however, narrowing is so severe that the urethra must be removed and reconstructed using plastic surgery. As any surgery performed on the urethra can in itself result in scar tissue formation, great delicacy and skill are required.

Meatal Stenosis

The hole at the tip of the penis, the meatus, is the narrowest part of the male urethra. Occasionally the meatus is excessively small at birth. This condition is called meatal stenosis and causes back pressure effects on the bladder and kidneys. In later life, infection, surgery or injury may result in scar tissue which contracts to form a meatal stenosis. This is sometimes correctable by dilatation, but usually an operation to widen the meatus is necessary.

Urethral Valves

Some babies are born with folds of mucous membrane within the urethra that form into valves. These valves come together when passing water and cause severe urinary obstruction. They need surgical removal.

Hypospadias

Hypospadias is the commonest congenital defect of the penis, affecting 1 in 300 babies. In this condition the urethral opening is situated on the underside of the penis rather than at the tip and may be anywhere from a few millimetres to several inches from its correct site. Hypospadias is easily missed at birth, as there is often a deceptive pit at the tip of the penis which looks just like the real thing.

There are five degrees of severity. In its mildest form, the meatus opens just on the underside of the glans. In type 2, the urethra opens beneath the glans at the frenulum. In more severe cases, it opens onto the penile shaft (type 3), at the front of the scrotum (type 4), or even at the base of the scrotum near the anus (type 5). The scrotum may be small and the testes undescended, so that the true sex of the child is not immediately apparent.

In all but type 1, hypospadias is associated with a certain amount of abnormal, downward curvature of the penis. This is known as chordee, and results in the foreskin only developing to cover the front of the penis.

Type 1 hypospadias needs no treatment. The more severe forms are corrected surgically in a single operation. The penis is straightened to correct any chordee and a new length of urethra fashioned from a tube of foreskin, or occasionally from a bit of bladder lining. This is implanted within the penile shaft so the new urethral opening extends to the tip of the penis. Surgery is usually performed before the age of two years. The child is then able to pass urine normally and to have a successful sex life in later years.

Epispadias

Epispadias is the opposite deformity to hypospadias, with the urethral meatus opening onto the upper side of the penis between the glans and the abdominal wall. The penis may also curve upwards (chordee). In the most severe type, the bladder may open onto the abdominal wall. Fortunately epispadias is rare. Surgical repair is similar to that for hypospadias, but more than one operation is usually needed.

Urethral Blockage

A common cause of attendance at Accident and Emergency departments is urethral blockage from objects inserted into the urethra for sexual pleasure. Collections of pens, biro tops, paperclips and hair grips disappear into the hole and cannot be retracted, often because of their barbs. This practice is not recommended.

Lost foreign bodies cause infection, discharge and difficulty when passing water. They are sometimes visible on X-ray or ultrasound, and can occasionally be retrieved by a surgeon using a long pair of forceps.

Often, a flexible telescope (uroscope) must be inserted under general anaesthesia to find the offending object. Large foreign bodies such as hair grips and pieces of knotted tubing frequently have to be removed by slicing open the area behind the scrotum (perineum) and pulling them out. Urethral scarring is a common and troublesome side-effect.

Acute Urethral Syndrome

Acute urethral syndrome consists of pain and discomfort in the lower abdomen and a frequent urge to pass water. Symptoms are similar to those of a urinary tract infection, but no signs of infection are found and the kidneys and urinary tract seem normal. Acute urethral syndrome may be caused by muscular spasm, especially if the patient is stressed or under emotional pressure. Prostatitis and prostatodynia (see page 92) may also be present.

Urethritis

Inflammation or infection of the urethra. See NSU.

Cancer of the Urethra

Cancer of the male urethra is rare. Any ulceration around the opening (meatus) at the tip of the penis, and any lump noticed in the body of the penis, should be checked as soon as possible.