Hysterectomy is one of the most common surgical procedures in gynecology and has been suggested to increase the risk of subsequent (de novo) urinary incontinence (UI) [1]. However, the evidence in previous literature is contradictory, and a substantial proportion of women already have UI symptoms prior to hysterectomy due to the overlapping of risk factors underlying pelvic floor dysfunctions [2,3]. Thus the association between hysterectomy and the risk of de novo UI has remained unclear. In this study, we aimed to assess the independent effect of hysterectomy on the risk of different subtypes of de novo UI.

This is a population-based cohort study of women from the Northern Finland Birth Cohort 1966 (NFBC1966, n=5889 females). Firstly, we identified hysterectomy cases (n=461) from the register data of the Care Register for Health Care (CRHC) and classified the operations according to surgery approach into vaginal (VH) (n=107), laparoscopic (LH) (n = 247), and abdominal hysterectomies (AH) (n=107). Women without hysterectomy were considered as the reference group (n=3495).
All women with UI diagnoses and operations were identified in the register, and women with preoperative UI diagnosis (n=36, 7.8%) were excluded from the analysis to assess de novo UI. Data on potential confounding factors were collected from registers and the cohort questionnaire. Incidences of different UI subtypes and UI operations were compared between the hysterectomy and the reference groups, and further disaggregated by different hysterectomy approaches. Logistic regression models were used to analyze the association between hysterectomy and de novo UI, with further adjustments for (model 1) parity, BMI, and smoking status, (model 2) preoperative POP diagnosis, and (model 3) vaginal delivery.

The final hysterectomy group size for analyses was 425 (LH n=230, 54.1%; AH n=104, 24.5% and VH n=91, 21.4%). We found no significant difference in the incidence of UI diagnoses or the rate of subsequent UI operations between the hysterectomy and the reference groups (24 [5.6%] vs. 166 [4.7%], p = 0.416 and 14 [3.3%] vs. 87 [2.5%], p = 0.323). Hysterectomy was not significantly associated with the risk of any subtype of UI (overall UI: OR 1.20, 95% CI 0.77-1.86; stress UI (SUI): OR 1.51, 95% CI 0.89-2.55; other UI: OR 0.80, 95% CI 0.36-1.74). After adjusting for preoperative pelvic organ prolapse (POP) diagnoses, the risk was decreased (overall UI: OR 0.54, 95% CI 0.32-0.90; other than SUI: OR 0.40, 95% CI 0.17-0.95). Regarding different hysterectomy approaches, the risks of overall UI and SUI were significantly increased in vaginal, but not in laparoscopic or abdominal hysterectomy. However, adjusting for preoperative POP diagnosis abolished these risks.

This cross-sectional population-based cohort study showed that hysterectomy is not an independent factor for increasing the postoperative incidence of UI or any UI subtype. Surprisingly, after eliminating the effect of preoperative POP, hysterectomy was even associated with a decreased risk of UI. Furthermore, we found that hysterectomy does not increase the risk of subsequent UI operations. Regarding different surgical approaches, only VH was associated with an increased risk of de novo UI. However, also this association was explained by preceding POP, suggesting that the association is explained by pre-existing pelvic floor conditions rather than hysterectomy or the method of surgery itself. In our data, LH and AH were not associated with an increased risk of incontinence.

The main finding of our population-based cohort study is that hysterectomy performed by any surgical approach is not an independent risk factor for any de novo UI subtype. Instead, POP appears to have a more significant effect on the anatomical and physiological changes in pelvic floor function than the surgical trauma caused by the operation itself. Such information is of critical importance in gynecologists' decision-making and when counseling women on the associated risks related to hysterectomy.

Christoffersen NM, Klarskov N, Gradel KO, Husby KR. Increased risk of stress urinary incontinence surgery after hysterectomy for benign indication-a population-based cohort study. Am J Obstet Gynecol 2023;229. https://doi.org/10.1016/J.AJOG.2023.04.029.
Bohlin KS, Ankardal M, Lindkvist H, Milsom I. Factors influencing the incidence and remission of urinary incontinence after hysterectomy. Am J Obstet Gynecol 2017;216:53.e1-53.e9. https://doi.org/10.1016/j.ajog.2016.08.034.
Christiansen UJ, Hansen MJ, Lauszus FF. Hysterectomy is not associated with de-novo urinary incontinence: A ten-year cohort study. Eur J Obstet Gynecol Reprod Biol 2017;215:175–9. https://doi.org/10.1016/J.EJOGRB.2017.06.022.

Continence 12S (2024) 101574
DOI: 10.1016/j.cont.2024.101574