Prophylactic Alpha-blockers in the Prevention of Urinary Retention Post Inguinal Hernia Repair
Prophylactic Alpha-blockers in the Prevention of Urinary Retention Post Inguinal Hernia Repair
Post operative urinary retention ( POUR) is caused by sympathetic activation of the internal
 urethral sphincter after surgery. The smooth muscles of the around the internal urethral
 sphincter have been demonstrated to be rich in alpha-1 adrenergic receptors. Our research
 idea is novel because there has been no prior prospective study conducted using
 alpha-blockers to reduce post-operative urinary retention in patients undergoing inguinal
 hernia repair. The proposed research is important as existing studies that sought to
 understand POUR have merely established the risks factors involved. Despite so, the incidence
 of POUR remains high and no studies to date have investigated the use of specific
 interventions to reduce the risk of POUR.

 This is essential as patients who develop POUR have also been successfully shown to have
 significantly longer length of hospitalisation. Besides, the development of POUR can also
 cause significant pain/discomfort, increase risks of long-term urethral catheterisation and
 predispose patients to urinary tract infections
The study will be conducted as a randomised, double blind, placebo-controlled trial. This is
 a single center trial. The experimental design and procedure will be performed in accordance
 to the CONSORT guidelines. Patients will be assessed for eligibility, and selected based on
 the inclusion and exclusion criteria. Once eligible, informed consent will be obtained for
 every patient, and those in agreement to the participation of the trial will be randomly
 provided with pre-assigned sealed envelopes containing either tamsulosin or placebo, for
 which patient and investigators will be blinded to. Patients will then consume either oral
 tamsulosin 0.4mg or placebo daily for 5 days prior to elective surgery. A baseline postural
 blood pressure measurement will be taken before and after the 1st dose, and patients will be
 informed to look out for symptoms of hypersensitivity reactions and orthostatic hypotension,
 and to cease consumption should they develop. Prior to surgery, the patients will require to
 report to the study team if they had finished all 5 drug doses. Patients who develop
 intercurrent illnesses or have urgent matters at hand that would require their surgery to be
 postponed will receive another 5 drug doses that is to be consumed prior the their next
 scheduled surgical date. During the surgery, a maximum dose of 0.1mg/kg of morphine can be
 given to patients. No ilioinguinal block will be performed for patients, but local anesthesia
 10mls 0.5% Bupivacaine will be infiltrated into the wound sites. The patients will then be
 monitored in the 23 hour short stay ward, during which the patient's wound site, scrotum,
 pain levels and ability to pass urine will be assessed prior to being discharged. All
 patients will be provided with a maintenance drip post operatively. Patients will also be
 placed on paracetamol 1g 6 hourly strictly and tramadol 50mg 8 hourly as per required.
 Alternative analgesia will be provided should patients have existing allergies to these drug
 classes.

 Patients will be assessed for presence of voiding difficulty 6 hours post operatively, and
 patients who complain of voiding difficulty or inability to pass urine within 6 hours post
 operatively will be defined to have POUR, while a bladder scan will be performed will be
 performed . Patients with existing bladder volume of more than 400mls will be catheterised,
 while those with less than 400mls will be followed up with subsequent 2 hourly bladder scans,
 and catheterised should their bladder volume be beyond 400mls. Once discharged, patients will
 receive a phone call at 24 hours post discharge and scheduled to return for a follow up
 appointment 1 weeks later in the clinic where urinary symptoms will once again be assessed in
 both settings. The end points of incidence of POUR/catheterisation, length and cost of
 hospitalisation, rates of same day discharge, and patient satisfaction in both arms will be
 recorded and analysed. Patients will be analysed via an intention to treat basis, and
 patients who defaulted treatment (did not receive full 5 doses of medicine), did not turn up
 for surgery or lost to subsequent follow up post operatively will be taken into account, and
 reported and analysed accordingly.
Inclusion Criteria:

 -  Males of 41 to 80 years old who are going for elective inguinal hernia repair
 (laparoscopic or open) under general anesthesia.

 Exclusion Criteria:

 Patient whom has any of the following will be excluded:

 -  Contraindication to tamsulosin : known allergy, known orthostatic hypotension,
 significant cardiac co-morbidities ( New york heart association functional
 classification >2) or heart failure

 -  End stage renal failure

 -  More than two anti-hypertensive use/long term alpha blockers/beta
 blockers/anticholinergic (eg : buscopan)

 -  Previous urological or pelvic surgery

 -  Known benign prostatic hyperplasia on medications

 -  Long term indwelling catheters

 -  Concurrent neurologic disease such as stroke, poliomyelitis, cerebral palsy, multiple
 sclerosis, spinal lesions, diabetic and alcoholic neuropathy