The bladder and bladder function

The bladder is a distensible and contractile muscular bag lying in the lower part of the pelvic cavity. It acts as a storage receptacle for urine before its intermittent discharge. It receives a continuous inflow of urine from the kidneys via the two ureters (one from each kidney).

Bladder function -:

• The muscle layer around the bladder is called the detrusor muscle – this is the muscle that contracts to empty the bladder.
• In the neonatal period micturition (passing urine) occurs in the region of 20 times a day due to uncontrolled detrusor muscle contractions in a small capacity bladder.
• Bladder capacity increases during childhood from 60-70 ml in the neonatal period to 120-140ml at 4 years of age.
• Bladder awareness or sensation of bladder fullness develops in the first few years of life.
• Approximately 30% of 2 year olds, 70% of 3 year olds and 100% of 4 year olds are able to indicate bladder awareness. This is obviously not the same as having control of bladder function (micturition).
• Urine is stored in the bladder, which stretches like a balloon as it fills up. When it stretches to a certain point the nerves in the bladder will send a message to the brain saying that it needs to be emptied.
• Children acquire the ability to suppress detrusor contractions voluntarily and co-ordinate sphincter control and detrusor function.
• Daytime bladder control is achieved in most children by 4 years of age, while night bladder control is generally achieved by 7 years of age (93%).
• Referral to a nocturnal enuresis clinic is not accepted before the age of 7 years.