Dr Foo Keong Tatt

Source: Society For Continence, Singapore



Man is a wonder of creation. He has a brain, which a super computer cannot compare, and a pair of eyes, which the most sophisticated movie camera cannot supersede. He derives his energy from eating food, which is converted by the stomach and intestines into absorbable sugar (glucose). Glucose enters the blood stream, which transports it to all over the body for use as energy. Combined with oxygen, which is absorbed from the lungs, the glucose is burnt as fuel to give us energy. The residue or waste resulting from the burning of fuel need to be removed from the body, and t hat is where the urinary system come into play. The wastes if not removed will accumulate in the body and become toxic and cause death. The urinary system is designed to remove waste and also regulate the water content of the body.



The urinary system consists of one pair of kidneys and a urinary bladder connected by the upper urinary passages called the ureters. The bladder is drained to the outside world by the lower urinary passage, called urethra.

The kidneys are bean shapes, about 10 cm long and situated in the small of the back below the rib cage. They extract wastes and excess water from the blood stream constantly and discharge these down and the upper urinary passages as urine to t he bladder. The bladder acts as a reservoir to store urine so t ha t we do not discharge urine all the while but do so at appropriate intervals!

The bladder is a muscular balloon, which can accommodate up to 300 mls to 500 mls of urine without a rise in pressure. The sphincters around the bladder neck help to keep us dry. T he prostate gland in the male is situated around the bladder neck, surrounding it like a doughnut with the lower urinary passage passing through it. When the prostate enlarges in patients over the age of 50 years, it encroaches on the passage causing obstruction and difficulty in voiding.



To understand abnormal voiding, we need to know what is normal. We normally consume about 3 litres of fluid a day in our beverages and solid food and produce about one and half litres of urine. The balance of fluid consumed is lost through faeces and perspiration (sweat).



Assuming that our urinary bladder can hold an average of 300 mls of urine, and if we produce 1500 mls of urine in 24 hours, we would need to pass urine about 5 times per 24 hours. Generally about 4 times during waking hours and once at night. IN other words, our normal urinary frequency is about once every 4 hours if we sleep 8 hours per day, getting up about once a night.

Many normal and abnormal situations will increase or decrease frequency of voiding. If we drink more fluid, the kidney will extract more water from the blood and produce more urine. Patients with diabetes, because of sugar in the urine will extract more water with it and therefore increase the frequency of voiding. In patients with prostate obstruction, the increases the frequency of voiding can be due to incomplete emptying of t he bladder because of the obstruction or due to premature contraction of the bladder because of irritation to the bladder neck by the enlarged prostate.

The incomplete emptying decreases the functioning capacity of the bladder. As stated before, our normal capacity of the bladder is 300 mls, we normally empty our bladder completely. In obstruction and other malfunction of the bladder this may not be so and emptying is not complete, leading to a sensation of not emptying t he bladder and resultant residual urine. If the residual urine were 200 mls, the effective capacity would be only 100 mls. Our kidney produce an average 1500 mls of urine per 24 hours which is about 60 mls of urine per hour, therefore, we would need to pass urine every one and half hours instead of t he usual 4 to 5 hours.

A lot of residual urine is harmful because it can lead to infection, stone formation and in severe cases leading to kidney failure because of backpressure effect.


Control of voiding

In normal circumstances when the situation is not appropriate, we can control the urge t o void; otherwise we will be wet and embarrassing. This is done through the nerves of the bladder. When the bladder is reaching its capacity, messages are send to the brain, that the bladder is going to contact and empty soon. However, if conditions are not appropriate the brain send inhibitory orders to dampen the urge and save the situation. In suitable surroundings t he brain relaxes control, the sphincter muscles relaxes and the bladder empties without hesitation. If there is no obstruction, the flow is good and strong, hitting the wall of the standing toilet without any problem and the act is completed in a matter of about 20 seconds.

In nervous disorders, such as stroke, the control is lost, and patient develops urgency, unable to hold his urine and if a toilet or urinal is not nearby, would wet himself, giving rise to incontinence. Local factors such as infection of the urine and an enlarged prostate can also irritate the bladder neck area and give rise to urgency and incontinence.


Normal urine

Normally passing urine is painless and the urine should be clear and colourless. If the urine is slightly yellow it is concentrated due to inadequate intake of fluids. It is important to increase intake especially in patient s who have urinary stones or those who are prone to urinary infections. If your urine is cloudy and you have pain passing urine, it can be due to urinary infection and you need to see your doctor. If your urine is red due to blood you should not ignore it, especially if there is no pain because blood in the urine is often due t o cancer of the urinary system. You need to be investigated thoroughly to find the cause. Cancer of the urinary system as in other cancers, if treated early can be cured.



In conclusion we normally take our voiding habits for granted. Passing urine every 4 to 5 hours interval at appropriate places and time without hesitation with good flow and painlessly. I hope I have given you the basic to understand the wonderful mechanisms in our body regulating the process of voiding and how diseases can affect these mechanisms. If you have problems, we can try our best to find the cause and restore you to as normal as possible.