The study was terminated prematurely following a pre-planned interim analysis demonstrating futility

Post-operative urinary retention (POUR) is a common complication after inguinal hernia repair with a reported incidence up 34%. It can be described as the inability to initiate urination or properly empty one's bladder following surgery. It is usually self-limited, but it requires the use of catheterization to empty the bladder in order to prevent further injury to the bladder or kidneys and to relief the discomfort of a full bladder. Tamsulosin is a medication that is commonly used in men with urinary symptoms related to an enlarged prostate. There is some evidence to suggest that it may also potentially be beneficial for preventing post-operative urinary retention.

The purpose of this study is to determine if tamsulosin ("TAMSULOSIN Mepha Ret Depocaps 0.4 mg") is effective in preventing post-operative urinary retention following endoscopic total extraperitoneal inguinal hernia repair and its impact on hospital length of stay.

In this RCT subjects are randomly and parallel assigned to one of two groups: one (the experimental group) receiving "Tamsulosin 0.4 mg"/ day, 5 days prior to the day of laparoscopic inguinal hernia repair surgery, at the day of surgery and for 1 day following surgery. (5+1+1), and the other (the control group) receiving one placebo capsule matching the active study drug per day from 5 days prior to the day of surgery, at the day of surgery and for 1 day following surgery. (5+1+1). There will be effective (concealed) randomization of the subjects to the intervention/control groups (to eliminate selection bias and minimize confounding variables). Both groups will be treated identically in all respects except for the intervention being tested and to this end patients, investigators, care providers and outcomes assessors will be blinded to which group an individual is assigned. Group assignment will be performed using a covariate-adaptive allocation procedure to provide a balance for selected covariates (Site, IPSS-Score, Age, "uni- or bilateral surgery" and "history of prostate or bladder surgery". To achieve that; Minimization, first described by Taves [and expanded by Pocock and Simon [the most commonly used covariate-adaptive randomization method will be applied. It achieves the balance in treatment assignments across factor levels by choosing the allocation for the new subject that would lead to the smallest degree of imbalance possible across the set of his baseline characteristics. The two groups are then followed up to 3 days after surgery to see if there are any differences between them in primary and secondary outcomes. Patients are analyzed within the group to which they were allocated, irrespective of whether they experienced the intended intervention (intention to treat analysis). This RCT is designed as a superiority trial and aims to demonstrate the superiority of Tamsulosin in prevention of POUR compared to placebo. We anticipate the detection of a 65% relative risk reduction of POUR in the experimental group in comparison with the placebo group. To detect a 65% reduction of POUR in the experimental group (2.9% anticipated) in comparison with the placebo group (8.3% anticipated) and to assure a study power of 80% with a Fisher's Exact Test and a significance level of 5% and adjusting for a drop-out rate of 2% we need 634 patients in total; 317 in each group. Our target population consists of male patients ≥ 60 yrs, scheduled for elective endoscopic inguinal hernia repair. The studied sample is appropriate to the hypothesis being tested so that any results will be appropriately generalizable.](streamdown:incomplete-link)

Inclusion Criteria:

• Males
• ≥60 years old
• Planned uni- or bilateral endoscopic total extraperitoneal inguinal hernia repair
• Surgery scheduled more than 6 days from the time of consent
• Informed Consent as documented by signature (Appendix Informed Consent Form)

Exclusion Criteria:

• Orthostatic hypotension (feeling of dizziness after getting up from a sitting or lying position)
• Severe liver disease (Child Pugh C)
• Taking strong inhibitors of CYP3A4 (ketoconazole, itraconazole, clarithromycin, ritonavir, indinavir/ritonavir, lopinavir, or conivaptan)
• Being on alpha-blockers (alfuzosin, doxazosin, prazosin, terazosin, tamsulosin, phenoxybenzamine, or silodosin) or a combination product containing alpha-blocker (duodart)
• History of allergy or sensitivity to tamsulosin or other alpha-blockers (alfuzosin, doxazosin, prazosin, terazosin, or phenoxybenzamine)
• Long term Indwelling urinary or suprapubic catheter
• Status post cystectomy
• Inability to provide informed consent
• Known or suspected non-compliance, drug or alcohol abuse,
• Inability to follow the procedures of the study, e.g. due to language problems, psychological disorders, dementia, etc. of the participant,
• Participation in another study with investigational drug within the 30 days preceding and during the present study,
• Previous enrolment into the current study

Deidentified participant data are available upon reasonable request from https://orcid.org/0000-0002-7339-1458.