Definition According to the 1990 criteria of the International Continence Society (ICS), involuntary leakage of urine that occurs when coughing, sneezing, laughing, exercising, or changing position is considered stress urinary incontinence (SUI). Due to the relaxation of the pelvic floor myofascial tissues for various reasons, the anatomical position of the bladder and urethra changes and urethral resistance decreases, resulting in dysfunction of urinary self-control. It is characterized by the absence of urine loss under normal conditions and the automatic outflow of urine when the abdominal pressure is suddenly increased. Epidemiology The prevalence of stress urinary incontinence is inconsistent across countries. In the United States, the prevalence of urinary incontinence ranges from 2% to 46% among women aged 15 to 64 years, and about 29% of working women experience incontinence at least once a month. A questionnaire survey of 15904 women ≥40 years of age in a community in the United Kingdom showed that the prevalence of urinary incontinence was 34%, and the prevalence and severity of the disease increased with age, with a prevalence of 69% in women over 60 years of age; however, only 30% of them caused social and health problems, and 1/4 of the patients sought medical attention, and only 2% of the patients had very severe symptoms. The Norwegian Epidemiologic Survey, the widest international survey, showed a prevalence of 8% to 48%, with a high prevalence in the elderly; 50%, 10% and 40% for stress, urgency and mixed respectively. In conclusion, stress urinary incontinence is a common urinary dysfunction disease, which seriously affects people’s quality of life. Etiology and risk factors The etiology of stress incontinence can be multifaceted, and one or more causes may coexist. The causes can be: (1) labor and delivery injuries, especially difficult labor and forceps operation; (2) urethra and periurethral tissue changes, such as postmenopausal hypogonadism resulting in pelvic floor tissue atrophy; (3) vaginal and urethral surgery; (4) perineal and urethral injuries; (5) pelvic mass resulting in increased abdominal pressure, bladder neck position is lowered. Risk factors for the development of urinary incontinence are related to age, gender, childbirth, sleep, obesity, living alone, and lack of help. The prevalence of urinary incontinence is significantly higher in older age, more frequent deliveries, newborns weighing >4000 g, mobility disorders, difficulty in sleeping, widowhood, and obesity, high body mass index, and women are more likely to suffer from urinary incontinence than men. Constipation, chronic obstructive airway disease, stroke, Parkinson’s disease, bone fracture and diabetes mellitus were associated with the development of urinary incontinence, suggesting that the above indicators can be used to screen for urinary incontinence in high-risk groups, which is conducive to the detection of new cases and the development of related preventive strategies. Diet and smoking did not appear to be significantly associated with the development of urinary incontinence. The incidence of urinary incontinence increased with age, but SUI decreased slightly after 50 years old. From 45 to 59 years old, the incidence of SUI decreased by 0.55% to 0.43% for every 1-year increase in age, while urge incontinence increased by 0.08% to 0.2% for every 1-year increase in age in the same age group. Urge incontinence is more associated with childbirth. Pathogenesis The normal urethra can resist any increase in abdominal pressure without urinary incontinence.The mechanism of USI is accepted by the majority of scholars as Green’s proposed mechanism of USI, that is:(1) When intra-abdominal pressure increases suddenly in normal women, the pressure can be transmitted uniformly to the bladder and the proximal 2/3 of the urethra, and intra-bladder and intra-urethral pressures increase in proportion to each other, and pressures exerted by the bladder and the proximal 2/3 of the urethra cancel each other out. The pressures on the bladder and the proximal 2/3 of the urethra offset each other, and the intravesical pressure is always lower than the intraurethral pressure, and the bladder neck and urethra are in a closed state. When the pelvic floor relaxes, the bladder base and proximal urethra shift downward, and the increase in abdominal pressure increases the intravesical pressure accordingly, but the intraurethral pressure increases less or not, the intravesical pressure is temporarily higher than the intraurethral pressure, and urinary incontinence occurs. When the abdominal pressure disappears, the incontinence stops, which is typical of SUI or anatomical urinary incontinence. (2) Normal urethro-bladder angle is 90-100 degrees, USI patient’s bladder base is shifted downward and backward, so that the urethro-bladder angle disappears and the urethra is shortened, this change seems to be the initial stage of urination, once the intra-abdominal pressure is increased, involuntary urination can be induced. (3) In patients with severe USI, in addition to the disappearance of the posterior urethrovesical angle, the urethral axis is also rotated, increasing its angle of inclination from the normal 10-30 degrees to ≥90 degrees. (4) Intrinsic urethral dilator defect. Stress urinary incontinence is graded as mild, moderate, or severe. The degree of SUI was determined by Mario et al. based on a clinical score of the state, frequency, and amount of urinary incontinence occurring. The state of incontinence was rated as 1 if it occurred when coughing, sneezing, lifting heavy objects, or running, and 2 if it occurred when walking up stairs, walking, laughing, or having sexual intercourse. In terms of frequency of incontinence, if it occurs weekly, score 1; if it occurs daily, score 2. In terms of the amount of incontinence, if it is less than one sanitary napkin per day, score 1; if it is more than two sanitary napkins per day, score 2. A total cumulative score of 1 to 3 was classified as mild, 4 to 7 as moderate, and ≥8 as severe. Diagnosis of stress urinary incontinence The diagnosis of SUI is based primarily on the patient’s symptoms. The history of labor and delivery is important. Risk factors are often suggestive of SUI.In addition to routine examination and gynecological examination, the following tests and examinations may be performed for the diagnosis of SUI. 1. evoked test 2. bladder neck elevation test 3. cystourethrography 4. swab tilt test 5. urethral manometry 6. ultrasonography Treatment (a) non-surgical treatment Mild and moderate SUI can be considered non-surgical treatment, non-surgical treatment can also be used as an adjunctive treatment before and after surgical treatment. 1. Pelvic floor muscle exercise Pelvic floor muscle exercise is also known as Kegel exercise. The method is to tighten the anus, each time tighten no less than 3s, and then relax. Continuously do 15 ~ 30min, 2 ~ 3 times a day; or 150 ~ 200 times a day, 6 ~ 8 weeks for a course of treatment. Whether the contraction of the levator ani muscle is effective can be evaluated by the feeling of the two fingertips in the vagina during the contraction, and the lateral pressure on the fingertips indicates that the muscle is contracted. PFME was reported to be 46 7% cured, and another 30% to 40% of the patients had different degrees of improvement, and the patients’ quality of life was improved to different degrees. 2. Pelvic floor electromagnetic stimulation 3. Bladder training Bladder training is to instruct the patients to record the daily water intake and urination, fill in the bladder function training form, consciously prolong the interval between urination, and finally achieve the goal of urination once every 25-30h, so that the patients can learn to delay urination by suppressing the urgency of urination. This method requires that the patient has no mental disorder, and it is effective in mixed incontinence with USI and urethral instability. 4. Pharmacological treatment: α-adrenergic agonists; estrogen 5. Wearing a urinary device (b) Surgical treatment Indications: (1) due to the urethral sphincter disorders caused by USI, the patient requires surgery; (2) non-surgical treatment is ineffective. The patients should not have difficulty in urinary emptying or instability of the urethral muscle, be psychologically healthy, and have no serious heart, liver, lung, or kidney diseases. Types of surgery: Traditional surgery Minimally invasive surgery 1 Periurethral padding 2 Laparoscopic bladder neck suspension 3 Tension-free suspension of the female midurethra 4 Cuffed sling fixed by pubic rivets Principles of treatment of stress urinary incontinence The main factors affecting the success of various surgical procedures for stress urinary incontinence are mobility of the urethra, function of the urethral dilator muscle, severity of combined pelvic genital prolapse, and age. Therefore, the above factors should be synthesized when choosing the surgical approach. 1. When combined with urge incontinence, urge incontinence should be treated first. 2. Select the appropriate surgical procedure according to the typology.