Micturition

Micturition is the physiological process of expelling urine from the urinary bladder to the outside of the body, constituting the final stage of the urinary system's function. It is a complex mechanism controlled both at the level of the autonomic and the somatic nervous systems, involving the cooperation of the detrusor muscle of the bladder (detrusor), the urethral sphincters and the pelvic floor structures. Proper micturition requires precise coordination between the urine storage phase and its voiding, and its disorders can lead to a significant reduction in quality of life and may be a symptom of urological, neurological, or gynecological diseases.

Micturition – what is it

Micturition (Latin: mictio) is an active physiological process in which the urinary bladder is emptied through the coordinated action of muscles and the nervous system. Two main phases of bladder function are distinguished:

the urine storage (filling) phase,
the emptying (actual micturition) phase.

During the storage phase the detrusor muscle remains relaxed, and the urethral sphincters are contracted, which allows urine to be retained in the bladder. At the moment of micturition the following occurs:

contraction of the detrusor muscle,
relaxation of the sphincters,
reduction of pelvic floor muscle tone.

This process is controlled by neural centers in the brain (cerebral cortex, pons) and the spinal cord, which allows conscious initiation or inhibition of urination. In children this mechanism matures with the development of the nervous system, which explains the lack of full control of micturition in early life.

Micturition – normal urinary flow

A normal micturition pattern denotes the physiological process of urination that occurs without pain, excessive effort, or residual urine in the bladder. Key elements of normal micturition include:

regularity – micturition every 3–4 hours during the day,
micturition volume – typically 250–500 ml at a time,
absence of urgency,
continuous, uninterrupted urinary stream,
sensation of complete bladder emptying.

Normal micturition takes place with overall body relaxation, particularly of the pelvic floor muscles. Under physiological conditions it should not require active "straining", which often represents a compensation for functional disorders.

Abnormal voiding habits, such as:

preventive urination "just in case",
chronic withholding of urination,
urinating in a hurry,

can lead to secondary disorders of bladder function and pelvic floor dysfunction.

Micturition – disorders of micturition

Disorders of micturition include a wide group of abnormalities related to the bladder's storage and emptying phases. They may be functional, anatomical, or neurological in nature.

The most common micturition disorders include:

frequent urination (pollakiuria) – increased frequency of urination,
urinary urgency – a sudden, difficult-to-control need to urinate,
urinary incontinence (stress, urge, mixed),
difficulty initiating micturition (hesitation),
intermittent urinary stream,
residual urine after micturition,
nocturia – the need to urinate at night.

The etiology of micturition disorders is multifactorial and includes:

urinary tract infections,
neurological disorders (e.g., spinal cord injuries),
hormonal changes (particularly in women during menopause),
weakening or excessive tension of the pelvic floor muscles,
psychogenic factors.

Diagnosis is based on medical history, physical examination, laboratory tests, and specialized investigations such as urodynamic testing.

Micturition and the pelvic floor

The pelvic floor plays a key role in the regulation of micturition, providing stabilization of the pelvic organs and control over the urethra. Proper function of these structures requires the ability both to contract and to relax the muscles.

In the context of micturition:

During the storage phase the pelvic floor muscles are active and tense, supporting continence mechanisms,
In the emptying phase they should undergo complete relaxation, allowing free flow of urine.

Pelvic floor dysfunctions can lead to micturition disorders of various types:

excessive tension → difficult bladder emptying, sensation of residual urine,
muscle weakness → urinary incontinence, lack of control over micturition.

An important role in the treatment of micturition disorders is played by urogynaecological physiotherapy, which includes:

training in correct micturition patterns,
pelvic floor muscle training,
relaxation and breathing techniques,
manual therapy.

In selected cases supportive methods such as electrostimulation or biofeedback are also used, which allow improvement of control over bladder function and pelvic floor structures.