Introduction

Urinary retention is a condition in which patients are unable to completely empty their bladders. It is classified into acute and chronic urinary retention. Generally, acute urinary retention is characterized by a painful and palpable bladder. This condition often occurs after prolonged anesthesia in extensive surgery, known as postoperative urinary retention (POUR). The incidence of POUR has been reported to range from 2.1 to 80%, varying based on multiple factors such as age, sex, type of anesthesia, surgical techniques, and underlying diseases1, 2, 3, 4, 5, 6. POUR can cause many problems for patients, including embarrassment due to intermittent catheterization, catheter-induced infections, complications from bladder dilatation such as acute kidney injury and detrusor muscle injury, prolonged hospitalization, and the need for additional care after hospital discharge, thereby imposing extra costs on the patient7, 8, 9, 10, 11.

As noted, the type of surgery performed is one of the factors affecting POUR. POUR has been reported in 1 to 52% of cases undergoing anorectal surgeries; however, the causes of POUR in such surgeries are not completely understood7, 12, 13, 14, 15, 16. Various methods have been employed to reduce the risk of urinary retention following anorectal surgeries, including the administration of parasympathomimetic agents, the use of alpha-adrenergic blockers or anxiolytic agents, restriction of perioperative fluid intake, avoidance of excessive anal packing, taking sitz baths, implementing local anesthesia techniques or short-acting anesthetics, and managing surgeries on an outpatient basis13, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27.

Moreover, the role of tamsulosin in preventing POUR has been highlighted in some studies. The mechanism of action of tamsulosin involves relaxing the detrusor muscles and facilitating bladder emptying1, 2, 7, 28, 29, 30, 31, 32, 33. Given the significance of POUR and the limited number of studies conducted on patients undergoing anorectal surgeries in Iran, this study investigates the effect of various potential risk factors associated with urinary retention after these surgeries and evaluates the efficacy of tamsulosin in preventing this complication.

Methods

This study is a retrospective review of data from patients who underwent anorectal surgery at Shahid Madani Hospital, Karaj, from May 2016 to June 2022. Urinary retention was diagnosed when a patient failed to pass urine after the operation despite having a sensation of needing to urinate, adequate fluid intake, and unsuccessful conservative management, such as suprapubic warming, warm sitz baths, and encouragement to get out of bed and walk, which necessitated urinary catheterization. The patients selected for this study had undergone surgery for elective benign anorectal diseases, including hemorrhoids, fissures, and fistulas, from May 2015 to June 2021. Exclusion criteria included age over 70, presence of an active urinary infection, neurologic disorders, urologic diseases, and patients taking tamsulosin for benign prostatic hyperplasia. Patients were divided into two groups: those receiving tamsulosin and a control group. In the tamsulosin group, 0.4 mg of tamsulosin was prescribed 6 hours before and 6 to 12 hours after the operation. In the comparison group, no specific medication was prescribed for urinary excretion. The incidence of postoperative urinary retention (POUR) in the tamsulosin and control groups was considered the main outcome of this study. Factors such as age, sex, type of anorectal disease, diabetes, benign prostatic hyperplasia, and anesthesia techniques were also considered as independent predictors of POUR risk. Differences in the incidence of POUR between the two groups were assessed using the Chi-square test. Univariate analysis and multiple logistic regressions were used to determine the risk factors for POUR. The ROC curve was used to evaluate the goodness of fit of the model. A significance level of 0.05 was considered, and all data analyses were performed using SPSS v.22 software.

Results

The results of the data analysis are presented in Table 1, Table 2, Table 3, Table 4, Table 5 and Figure 1. The results of the univariate analysis of the patients who underwent anorectal surgery are presented in Table 1. Age above and under 50 years, gender, diabetes, benign prostatic hyperplasia, type of anorectal surgery, anesthesia technique, and tamsulosin administration were considered as potential predictors of POUR. The overall prevalence of POUR in this study was 18.83%. Age over 50 years and male gender were identified as risk factors for POUR (OR = 1.51, P = 0.03). Diabetes (OR = 7.152, P < 0.001) and benign prostatic hyperplasia (OR = 3.171, P < 0.001) were other risk factors for POUR in this study. The prevalence of POUR was 18.5% in patients who underwent surgery for hemorrhoids and anal fissures, and 19.5% in cases who underwent surgery for anal fistulas; however, these differences were not statistically significant (P = 0.973). Also, according to the results, saddle anesthesia (OR = 0.253, P < 0.001) and the administration of tamsulosin (OR = 0.182, P < 0.001) could be considered as preventive factors for POUR.

Table 2 to Table 4 present the results of univariate analysis for patients who underwent surgery for hemorrhoids, anal fistulas, and fissures. According to Table 2, age over 50 years (OR = 1.915, P = 0.1) and male gender (OR = 2.012, P = 0.07) were risk factors for POUR; however, these results were not statistically significant. Additionally, the role of diabetes (OR = 22.906, P < 0.001) and benign prostatic hyperplasia (OR = 4.479, P < 0.001) as risk factors, as well as saddle anesthesia (OR = 0.146, P < 0.001) and the administration of tamsulosin (OR = 0.142, P < 0.001) (Table 1), as effective factors in preventing POUR, was also confirmed in people who underwent surgery to remove hemorrhoids.

The results of Table 3 show that in cases who underwent surgery to treat fistulas, the age over 50 years (OR = 2.351, P = 0.031) and male gender (OR = 1.568, P = 0.284) were risk factors for POUR; however, these results were not statistically significant in terms of gender. Similarly (Table 1), diabetes (OR = 3.517, P < 0.001) and benign prostatic hyperplasia (OR = 3.901, P < 0.001) were risk factors, and saddle anesthesia (OR = 0.327, P = 0.003) and the use of tamsulosin (OR = 0.272, P < 0.001) were effective in preventing POUR in patients who underwent surgery for anal fistulas.

Table 4 indicates the results of patients who underwent anal fissure surgery. The age over 50 years (OR = 0.79, P = 0.587) was a preventive factor, and male gender (OR = 1.122, P = 0.856) and benign prostatic hyperplasia (OR = 1.845, P = 0.141) were risk factors for POUR, which were not statistically significant. However, in general (Table 1 ), diabetes (OR = 4.207, P < 0.001) was a risk factor for POUR and saddle anesthesia (OR = 0.327, P = 0.003) and the use of tamsulosin (OR = 0.142, P < 0.001) were factors associated with preventing POUR.

The results of multiple regression analysis are presented in Table 5. The results showed that age over 50 years (OR = 1.659, P = 0.039), diabetes (OR = 6.592, P < 0.001), benign prostatic hyperplasia (OR = 2.680, P = 0.024), and saddle anesthesia (OR = 1.359, P = 0.511) were risk factors for POUR; however, this result was not statistically significant in terms of saddle anesthesia. On the other hand, based on the results, male gender (OR = 0.931, P = 0.833), type of anorectal disease (P = 0.531), and the use of tamsulosin (OR = 0.176, P < 0.001) are factors that prevent POUR, but this issue was only significant in terms of using tamsulosin. The difference between the results of multiple logistic regression and univariate analysis in terms of male gender and saddle anesthesia indicates that their results were distorted by other variables, which could be fixed after being included in the multiple logistic regression model.

Figure 1 shows the ROC curve for the results of the regression model presented in Table 5. According to the results, the good fit of the model was appropriate and the model can correctly predict the incidence of urinary retention after anorectal surgery in approximately 83% of cases (P < 0.001).

Discussion

POUR is one of the most common complications after surgeries2, 10. Urinary retention after anorectal surgeries is also relatively common, with incidence rates reported between 1% to 52%. The wide variation is due to differences in the definition of POUR, differences in inclusion and exclusion criteria, and its multifactorial nature, including variations in age and gender of the patients, the type of anorectal surgeries, and the type of anesthesia. Although the cause of urinary retention after anorectal surgery is not completely clear, some studies have claimed that it could be related to decreased bladder contraction ability or bladder outlet obstruction13, 23, 34. POUR can lead to several problems for patients, including urinary tract infections due to intermittent catheterization, discomfort and embarrassment due to catheterization, and increased treatment costs due to prolonged hospitalization, treatment of secondary infections, and follow-up2, 10. Therefore, the prevention of this complication is of great importance. Several factors, such as age, sex, diabetes, benign prostatic hyperplasia, the type of anorectal surgery, and the type of anesthesia could be responsible for the incidence of POUR. Numerous studies have also suggested the role of tamsulosin in the prevention of this complication1, 2, 7, 28, 29, 30, 31, 32, 33. In our study, the incidence of POUR was 18.83%, which was higher than that in similar studies13, 35. This observation could be due to the higher prevalence of diabetes and benign prostatic hyperplasia in our study, both risk factors for POUR, and the results were also statistically significant. Typically, the incidence of POUR is higher in men, which may be related to an increased rate of prostatomegaly in men with age; however, some studies have reported a higher prevalence in women10, 13, 30, 35, 36, 37, 38. In our study, univariate analysis showed that POUR is more common in men. However, in multiple logistic regression, although its incidence was higher in men, it was not statistically significant, indicating that in univariate analysis, the role of gender in POUR was distorted; therefore, it is recommended to consider this in future studies. The age of patients is another factor that can affect the incidence of POUR, which has been studied previously in various studies. The risk of POUR increases with age, which may be due to impaired neural pathways involved in micturition. Our results showed that the age of over 50 years was a risk factor for POUR, which is consistent with some studies and contradicts others7, 13, 31, 32, 39, 40, 41. In studies where age was not a risk factor for POUR, the sample size was smaller than in our study, while in another study13, where similar to our study from the perspective of the sample size, the age of over 50 years was a risk factor for POUR. Therefore, it seems that the small sample size is the reason for no significant effect of age on POUR in some studies. In our study, diabetes was an important risk factor for POUR, which is consistent with other studies13, 42. Thus, it is recommended to monitor diabetic patients after surgery for retention of urine. Benign prostatic hyperplasia in men can lead to secondary bladder outlet obstruction. Benign prostatic hyperplasia is one of the first and most common causes of bladder outlet obstruction in men and its prevalence increases with age. Treatment failure in benign prostatic hyperplasia can lead to bladder detrusor muscle damage; thus, this condition has been mentioned as one of the risk factors for POUR in various studies19, 43, 44, 45 and is also in line with our results. Some surgeries, including anorectal surgery, are associated with a higher risk of POUR11, 17, 39. On the other hand, Toyonaga 13 showed that in cases who underwent anorectal surgeries, the risk of POUR was higher in those who underwent hemorrhoid, fissure, and fistula surgeries, but in our study, the results showed no significant difference. In terms of surgical and anesthetic techniques, studies have shown different results, so that in some studies, general anesthesia was associated with a higher risk of POUR than local anesthesia, and vice versa3, 40, 46, 47. In our study, only spinal and saddle anesthesia were implemented for surgery. According to the results of univariate analysis, saddle anesthesia was associated with a lower risk of POUR than local anesthesia, while based on multiple regression analysis, the opposite results were obtained, which were not statistically significant, indicating distortion of the results of univariate analysis. The α-adrenergic receptors (α-ARs) located dominantly in the outlet of the bladder and urethra are responsible for the internal sphincter tone, and antagonists of these receptors, including tamsulosin, can reduce the incidence of POUR after colorectal and urological surgeries in men. Tamsulosin mainly acts by alleviating detrusor-sphincter dyssynergia and facilitates bladder emptying, which was confirmed by our results28, 29, 30, 31, 32, 33, 37, 48, 49, 50, 51.

Conclusions

POUR is common in anorectal surgeries. Being over 50 years old, having diabetes, and suffering from benign prostatic hyperplasia are risk factors for POUR after anorectal surgery. Tamsulosin could be used to prevent POUR in candidates undergoing anorectal surgeries.

Abbreviations

POUR - Postoperative Urinary Retention, OR - Odds Ratio, ROC - Receiver Operating Characteristic, SPSS - Statistical Package for the Social Sciences

Acknowledgments

None.

Author’s contributions

All authors significantly contributed to this work, read and approved the final manuscript.

Funding

The financial resources of this research were provided by Shahid Madani Hospital.

Availability of data and materials

Data and materials used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Ethics approval and consent to participate

This study was conducted using the data of patients' files and there was no specific ethical problem that required informed consent.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.