This study is being done to answer the question: What is the impact of a medication called tamsulosin (also called Flomax) on the rate of postoperative urinary retention (POUR) and catheter-associated urinary tract infection (UTI)? One of the most common complications following surgery and associated with Foley catheters is post-operative urinary retention (POUR) after the catheter is removed. This is defined as being unable to urinate spontaneously within 8 hours following the removal of the indwelling Foley catheter (the catheter that sits in your bladder to drain urine after surgery). When this happens, it requires intermittent straight catheterization of the bladder (placing a temporary catheter in the bladder to drain the buildup of urine), which can cause a lot of discomfort and anxiety, as well as increase the risk of catheter-associated urinary tract infection (CAUTI).

All participants in this study will be males who are undergoing a planned surgery on their liver, gallbladder/biliary tract, pancreas, colon, or rectum for any reason. If able to obtain appropriate consent from a legal representative, cognitively impaired patients may be included. After having surgery where a catheter is placed in the bladder to drain urine (this is called a Foley indwelling catheter), the catheter eventually gets removed, and some of the most frequent problems that can happen after that are post-operative urinary retention (POUR) and catheter-associated urinary tract infection (CAUTI).

The goal of this study is to see if a medicine called tamsulosin (also called Flomax) can decrease the rate of POUR, which means not being able to urinate spontaneously like normal, and CAUTI, which means an infection in the urinary tract. This study is important because POUR and CAUTI can cause harm to patients, including discomfort if a temporary catheter has to be placed back in the bladder to get the urine out, infection, anxiety, and stress, and it's known that these complications can also increase hospital charges.

Inclusion Criteria:

• Planned for elective surgery for any reason (benign, malignant, or indeterminate lesion) with either an open or minimally invasive approach (hepatobiliary, pancreatic, and colorectal operations)
• Male and age ≥50 years
• Deemed physically fit for surgery

Exclusion Criteria:

• Inability to obtain informed consent
• Age <50 years
• Female
• Baseline creatinine >1.5x upper limit of normal
• Tamsulosin therapy as a home-medication
• Procedure involving the prostate, bladder, ureters, or kidneys
• Planned Foley catheter removal on the same day of surgery
• Planned nasogastric tube retention on postoperative day 1
• Individuals taking daily phosphodiesterase 5 (PDE5) inhibitors (due to the risk of symptomatic hypotension if given with tamsulosin)

The investigational product (IP)Tamsulosin is used in men to treat the symptoms of an enlarged prostate (benign prostatic hyperplasia or BPH)

The Research Team will share the National Surgical Quality Improvement Program (NSQIP) de-identified data upon request.

The Investigator will share the NSQIP de-identified data for a secondary analysis of the data upon request.