2026-01-28
Urinary incontinence refers to the involuntary leakage of urine that constitutes a social and health problem and can be objectively confirmed. The commonly referred to urinary incontinence mainly includes four types: stress, urge, mixed, and overflow. Among them, stress urinary incontinence is the most common type, accounting for approximately 40% to 50%.
Stress Urinary Incontinence
Stress urinary incontinence refers to involuntary urine leakage caused by increased abdominal pressure during activities such as coughing, sneezing, changing body positions, and engaging in heavy physical activities. This occurs when the sudden increase in abdominal pressure reaches the bladder, causing the internal pressure in the bladder to rise and exceed the resistance produced by the bladder neck and the urethral sphincter, resulting in urine leakage. The common causes are as follows.
1. Intrinsic sphincter deficiency (ISD)
The internal sphincter deficiency can be accompanied by (or not accompanied by) high urethral activity. The internal sphincter deficiency is mainly composed of smooth muscle, and the causes of its dysfunction include the following four points:
1.1：Neurological disorders: The sympathetic nerves of the thoracic and lumbar vertebrae are the main innervating nerves for the internal sphincter. Congenital diseases in this nerve area, spinal cord tumors, peripheral nerve lesions, and diseases that can lead to systemic muscle atrophy can all cause ISD;
1.2：Delivery, urogenital surgery, and trauma can all damage the internal sphincter and the sympathetic nerves that innervate it, thereby causing the occurrence of ISD;
1.3：Advanced age and estrogen deficiency can lead to a reduction in the number of urethral smooth and striated muscles, resulting in atrophy of the urethral mucosa and the loose connective tissue beneath the urethra, leading to the occurrence of ISD;
1.4：Other treatments such as radiotherapy are also causes of the dysfunction of the urethral intrinsic sphincter.
2. Abnormalities in the pelvic floor support structure
The pelvic floor muscles, connective tissues, and nerves form a balanced system that plays a crucial role in maintaining pelvic floor function. The mechanism of urinary incontinence is the damage or defect of the pelvic floor support structure. The pelvic floor support structure is divided into the active support system (composed of pelvic floor muscles), the passive support system (composed of fascial tissues), and the mixed support system (composed of bones and ligaments), which ensures the coordination of body functions whether in a resting state or an active state. The active support system of the pelvic floor (such as the levator ani muscle) contracts, causing the pelvic floor and organs to move upward and forward. When the pubocervical muscles function, they pull the vagina and urethral walls upward, closing the urethra or resisting the downward pressure of the abdominal cavity on the urethra.
The causes of damage or defect in the pelvic floor support structure include:
2.1：With aging, ovarian function declines and estrogen levels decrease, causing the surrounding sphincter muscles and ligaments of the urethra to become lax.
2.2：During pregnancy, the waist protrudes forward and the abdomen protrudes downward, pushing the uterus downward and towards the vagina. The pelvic floor muscles also shift downward or contract due to the pressure, and prolonged stress leads to increased fatigue of the muscle fibers and a gradual decrease in the contraction ability of different types of muscle fibers, resulting in pelvic floor dysfunction symptoms; multiparity, prolonged labor, difficult labor, excessive amniotic fluid, and large babies are all risk factors.
2.3：Delivery and surgical operations can cause damage to the pelvic floor muscles, sphincters, and ligament structures, thereby leading to functional abnormalities. The injury of the pubocervical ligament is the most important factor of stress urinary incontinence.
2.4：Others: Obesity, heavy physical labor, chronic obstructive pulmonary disease, smoking, and constipation, if present for a long time, can also cause dysfunction of the pelvic floor support structure and the occurrence of urinary incontinence.
3. High activity of the urethra
The hammock theory suggests that the urethra is supported by the fascia beneath it, and this fascia also connects the muscle fibers and connective tissues within the vagina, keeping the urethra closed. Together with the internal urethral sphincter, they function to effectively close the urethra and prevent involuntary urine leakage even when the pressure in the bladder increases. Obesity, chronic cough, constipation, childbirth, advanced age, and prolonged excessive physical load can cause damage to the fascia, the fascia, or the tissues around the vagina, thereby reducing the anatomical support of the bladder neck and the urethra. This loss of support leads to the high activity of the urethra, causing the urethra to move downward when intra-abdominal pressure increases, resulting in the intra-urethral pressure being lower than the intra-bladder pressure, and thus causing urine leakage.
The content of this article is sourced from the internet. The author assumes no responsibility for it. Without permission, copying is strictly prohibited. |
浙公网安备33021202001967号
