Hysterectomy and risk of stress-urinary-incontinence surgery: nationwide cohort study

Hysterectomy for benign indications has been associated with an increased risk for lower-urinary-tract sequela, but results have been inconclusive. We aimed to establish the risk for stress-urinary-incontinence surgery after hysterectomy for benign indications.

Hysterectomy is a preferred treatment option in women because of its low perioperative morbidity and effectiveness in bringing a definitive cure to disorders such as menometrorrhagia, leiomyoma, uterine prolapse, adenomyosis, and postmenopausal bleeding. By age 55 years, about one in five British women will have undergone a hysterectomy. In the USA, 600 000 procedures are undertaken every year, of which 90% are done for benign indications.

Large variations exist in rates of hysterectomy between and within countries and between populations with similar characteristics. and Although health-economic factors and differences in morbidity can account for some of the variation, rates of hysterectomy for benign indications are largely affected by differences in medical practice and attitudes and Considering the generally high hysterectomy rates in premenopausal and perimenopausal women, increased knowledge of the long-term outcomes associated with undertaking hysterectomy for benign indications is essential.

For decades, the effects of hysterectomy on lower-urinary-tract function have been controversial. One theory suggests that hysterectomy could initiate stress urinary incontinence by interruption of the local nerve supply to the urethra, and the procedure might cause changes in urethral pressure dynamics by distortion of pelvic-organ anatomy. Results from many previous studies relating hysterectomy to adverse effects of the lower urinary tract have been inconsistent. The conflicting evidence could be attributed to methodological shortcomings including inadequate statistical precision owing to small sample sizes, scarcity of controls who have not had hysterectomy, short durations of follow up, and systematic errors, such as ascertainment, selection, or recall bias.

Female stress urinary incontinence, defined as involuntary leakage of urine on effort or exertion, has a population-based prevalence of nearly 40% in most industrialised countries, usually with severe implications for daily function, social interactions, sexuality, and psychological wellbeing. Stress urinary incontinence also has a major effect on health economy and is increasingly recognised as a global health concern. Identification and possible reduction of risk factors for stress urinary incontinence is, therefore, of importance for women at risk and for society's direct health-care costs. The primary aim of this nationwide, population-based, cohort study was to assess short-term and long-term risk for stress-urinary-incontinence surgery after hysterectomy for benign indications.

Study population

The Swedish Inpatient Registry contains data for individual hospital discharges. The register was established in 1964; in 1973, it covered more than 60% of the population, in 1983 coverage was 85%, and from 1987 complete national coverage was achieved. Every inpatient discharge record contains: (1) dates of hospital admission and discharge; (2) up to eight discharge diagnoses, coded according to the International Classification of Diseases (ICD-7 until 1968, ICD-8 from 1968 to 1986, ICD-9 from 1987 to 1996, and ICD-10 thereafter); and (3) up to 12 operation codes from the Swedish Classification of Operations and Major Procedures. The Swedish Inpatient Registry also includes information about the unique national registration number assigned to all Swedish residents, allowing unambiguous record linkage across all national registers in Sweden. Correct coding for surgical procedures is achieved in 98% of records in the Registry, with a less than 1% yearly loss to registration.