Most lower urinary tract symptoms in children have a functional origin, and few children have anatomical or neurological malformations. Some children postpone voiding because they do not want or do not have time to go to the toilet, and develop a 'lazy bladder'. They typically urinate less than four times a day, cross their legs or stand/sit still to avoid accidents, 'squirt' urine into their underwear and then discover that it is suddenly 'overflowing'. Some drink little to limit these accidents.
Constipation is a frequently overlooked diagnosis in children and increases the risk of urinary tract infections and leakage. There is an extensive overlap between lower urinary tract symptoms and bowel disorders, typically referred to as bladder–bowel dysfunction. Children who postpone voiding often also suppress the urge to defecate and are, or become, constipated.
Some children have an overactive bladder, as revealed by the fact that they urinate frequently but in small volumes, experience a sudden strong urge to urinate and often have to urinate at night. Some, but not all, have incontinence. An overactive bladder may be the result of a urinary tract infection.
In a few children, incontinence may be caused by other disorders of the bladder and urinary tract. These can include an underactive bladder, voiding dysfunction, stress incontinence, bladder outlet obstruction due to urinary tract malformations or neurogenic bladder, vaginal reflux and so-called giggle incontinence (1). Secondary incontinence usually has a functional basis, but other causes must be considered.