ABSTRACT
The urinary bladder is a hollow muscular organ that consists of three principal layers: lamina propria, smooth muscle and urothelium. The lower urinary tract (LUT) is innervated by sympathetic, parasympathetic and somatic afferent and efferent nerves, under higher control from the cerebral cortex and pontine micturition centre. The two predominant neurotransmitters controlling LUT function are acetylcholine and noradrenaline. Antimuscarinics reduce bladder storage pressures, treat detrusor overactivity and improve overactive bladder symptoms. The storage phase of the micturition cycle requires relaxation of the detrusor to ensure low-pressure filling, and contraction of the smooth and striated muscle of the bladder neck, urethra and external urethral sphincter to ensure continence. The voiding phase of the micturition cycle requires coordinated detrusor contraction and relaxation of the bladder outlet to ensure complete bladder emptying. Most congenital bladder anomalies can be detected on antenatal ultrasound after 10–13 weeks’ gestation, when the bladder should be visualised in the majority of cases.
