Resumen de Valoració dels canvis que pateix la uretra durant l'embaràs objectivats per ecografia 2D i la relació d'aquests amb l'aparició d'incontinència d'orina en la gestació
Introduction Urinary incontinence (UI) is a dysfunction that has a very negative impact on the quality of life of women who suffer from it, and that represents a relevant socioeconomic problem due to its high prevalence. Different factors involved in the development of this dysfunction have been described, childbirth and pregnancy being one of the main ones. The prevalence of UI during pregnancy ranges from 26-55%. Some studies suggest that the onset of UI during pregnancy is a risk factor for the persistence of this dysfunction in the postpartum period. On the other hand, it has been seen that women with a higher degree of UI (moderate / severe / very severe) are more affected by their quality of life.
In order to better understand the pathophysiology of UI, some studies have described different ultrasound variables for the evaluation of the urethra and its supporting structures, looking for a relationship between ultrasound parameters and the appearance of UI. However, there are few studies that analyze these variables throughout pregnancy, and those that do are mostly cross-sectional studies that focus solely on the analysis of one or two ultrasound variables at the end of pregnancy.
Therefore, the main objective of this thesis is to identify those clinical and / or ultrasound variables assessed by 2D ultrasound that help us discriminate, from the first trimester of pregnancy, which pregnant women are at risk to suffer moderate / severe UI in the third trimester, and to develop an application for the prediction of UI moderate / severe in pregnancy.
Methodology A prospective cohort study was performed in nulliparous pregnant women recruited at the visit for the first trimester obstetric ultrasound at the Hospital de Santa Caterina de Salt, between 2018 and 2020.
The estimated sample was 133 nulliparous pregnant women. The pregnant women analyzed were assessed for different clinical and ultrasound variables in both the first and third trimesters. The clinical variables were: ethnicity, age, smoking habit, level of education, BMI and ICIQ-SF questionnaire score. The ultrasound variables evaluated transperineally were: urethral mobility, retrovesical angle at rest and exertion, urethral length at rest and exertion, and urethral sphincter thickness at rest and exertion. The variable urethral mobility was also assessed introitally.
First, a descriptive analysis of the demographic, clinical, and ultrasound variables of the patients included in the study was performed. The predictive model for determining the risk of moderate / severe UI in the 3rd trimester from the clinical and ultrasound data of the 1st trimester was evaluated through a binary logistic regression model. The association has been estimated through the odds ratio (OR) with its corresponding 95% confidence interval. The multivariate model has included those variables that in the bivariate analysis had a statistical significance of less than 0.20 and have been adjusted for those potentially confusing variables. The good fit of the final model was evaluated with the Hosmer-Lemeshow test and the discriminative ability with the area under the ROC curve. In the bivariate and multivariate analysis, the cut-off points that maximize sensitivity and specificity have been determined.
Results The cumulative incidence of UI in the third trimester compared to the first is 38,81%, and that of moderate / severe UI is 21.05%.
In the univariate model, for the ultrasound variables intoital urethral mobility and transperineal urethral mobility measured in the first trimester, we have obtained an odds ratio (OR) of 1.12 (95% CI: 1.03 to 1.21) and of 1.12 (95% CI: 1.04 to 1.21), respectively. Likewise, BMI in the first trimester was also associated with a higher probability of presenting moderate / severe UI in the third, with an OR 1.09 (95% CI: 1.02 to 1.16), and if we categorized the variable BMI, it was observed that for BMI> 30 in the first trimester there was an increase in the probability of suffering moderate / severe UI in the third, with an OR of 4.20 (95% CI: 1.52 - 11.59).
In the multivariate analysis, two models have been designed, one for introital urethral mobility-BMI categories and the other for transperineal urethrral mobility-BMI categories. The ROC curve indicates that introital urethral mobility together with BMI categories have a good discrimination capacity, close to 0.7 (ROC: 0.725). The discriminative power of the multivariate model of transperineal urethral mobility and BMI categories has a lower discrimination capacity with a ROC curve value of 0.687.
Two cut-off points have been identified for each of the multivariate models. The cut-off points for the introital urethral mobility-BMI categories model are 0.14 and 0.27. Pregnant women who have values above 0.27 in the model have a high risk of developing UI; those with values between 0.14 and 0.27 an average risk; and those with values below 0.14 a low risk. The cut-off points for the transperineal urethral mobility-BMI categories model are 0.14 and 0.22.
Conclusions One in five pregnant women who did not have a moderate / severe UI in the first trimester of pregnancy will suffer from it in the third.
The design of two multivariate models (introital urethral mobility-BMI categories and transperineal urethral mobility-BMI categories) will allow us, with good discriminatory power, to inform at the beginning of pregnancy what individual risk each pregnant woman has of developing moderate / severe UI in the third trimester.
An application has been created for each of the models to facilitate their use and to be able to apply it to the usual clinical practice. Based on the individual risk calculated with the application, each pregnant woman may be offered different primary prevention programs according to their risk group (high, medium or low).
