Drugs for the prevention of postoperative urinary retention in adults

  • Protocol
  • Intervention



This is the protocol for a review and there is no abstract. The objectives are as follows:

To make the following comparisons involving drugs for the prevention of postoperative urinary retention in adults, in terms of their effectiveness and harm:

  • one drug or drug type versus placebo or no treatment;

  • one drug or drug type versus another drug or drug type;

  • different dosages and timings of administration of the drug.


Description of the condition

Postoperative urinary retention (POUR) is the inability to pass urine following surgery despite a full bladder (painful, palpable or percussible). Although POUR is usually transitory, in some cases it can be prolonged, especially if not identified and managed appropriately.

The incidence of POUR appears to vary between surgical populations and prevalence estimates are affected by varying diagnostic standards. What seems clear, however, is that it is not an uncommon postoperative complication, as the following evidence indicates.

  • On discharge from the recovery room, POUR plus an ultrasonically measured bladder content of more than 500 ml was recorded in 23.7% of patients and POUR plus a bladder content of more than 600 ml was recorded in 16% of patients following mixed elective surgeries (Keita 2005; Lamonerie 2004).

  • POUR plus a bladder content of more than 500 ml resulted in the catheterisation of 69% of men and 39% of women amongst older patients, with a median age of 69 years, following primary total hip or knee arthroplasty (Sarasin 2006).

  • Twenty-four hours after surgery, POUR, defined as a palpable or distended bladder and a need for catheterisation following failed attempts to void, was present in 16.7% of patients following surgery for benign anorectal disease under spinal anaesthesia. Incidence was 21.9% for haemorrhoidectomy and 29.2% for rectal prolapse surgery (Toyonaga 2006).

  • POUR was detected ultrasonically in 9.2% of gynaecological surgery patients 24 hours after their operation. Prevalence varied according to type of operation: laparotomy (excluding hysterectomy) 55.6% (5/9); abdominal hysterectomy 13.7% (17/124); laparoscopically assisted vaginal hysterectomy 8.3% (2/24); laparoscopy 1.2% (1/83); genital prolapse 3.4% (1/29) (Bodker 2003).

  • POUR was present in 5.5% of patients four to seven days after open resection for colorectal cancer: prevalence was 9.1% and 1.7% amongst patients with rectal and colon cancer, respectively (Changchien 2007).

The wide range of POUR rates reflects its varied and often multifactorial etiology, with increased risk associated with surgical, anaesthesiological and patient factors.  The increased risk of POUR observed after pelvic surgery may relate to damage to the innervation of the lower urinary tract, and spasm of the pelvic floor muscle and sphincter due to pain. Some of the drugs administered during anaesthesia and surgery, such as anticholinergics, sympathomimetics, and beta-adrenergic blockers, interfere with bladder function. Anticholinergics, such as atropine, and beta-adrenergic blockers inhibit detrusor contractions and cause bladder relaxation; sympathomimetics, such as adrenaline (epinephrine) and clonidine, increase urethral sphincter contraction. Longer surgeries and high volumes of intravenous fluids administered during surgery, which can result in bladder overdistention and inhibited detrusor function, have also been found to influence the development of POUR (Baldini 2009). Patient characteristics such as age and diabetes mellitus have also been associated with increased risk of POUR (Keita 2005; Lamonerie 2004; Sarasin 2006; Toyonaga 2006).

While normal voiding is re-established, the management of POUR has two main aims: (i) emptying the bladder to prevent discomfort and urinary tract infection caused by stasis; (ii) avoiding over-distension of the bladder, which can result in long-term bladder dysfunction, especially in the elderly. Prolonged POUR that is left untreated can result in hydronephrosis and the possibility of kidney damage leading to chronic kidney disease.

Postoperative urinary retention is most commonly managed by catheterisation. However, catheterisation of any kind can cause discomfort and distress to the patient and all forms of catheterisation are associated with some risks. Intermittent catheterisation is an effective management option for POUR but may not be feasible or acceptable for all patients. Indwelling urethral or suprapubic catheters are also effective but can cause discomfort and distress to the patient. Catheterisation of any kind is associated with a risk of urinary tract infections and other complications such as detrusor overactivity (Niel-Weise 2005; Phipps 2006).

Even when managed appropriately, POUR can lead to delayed discharge from hospital, which can result in inconvenience for the patient, increased care costs and reduced hospital bed availability. A separate Cochrane review is available covering drugs for the treatment of postoperative urinary retention (Buckley 2010).

Thus, the prevention of POUR is desirable where possible, yet there is little consensus on what pharmacological options may be effective as prophylaxis.

Description of the intervention

Several drugs have been used in an effort to prevent POUR. These include:

(1)   cholinergic agents such as bethanechol, carbachol, physostigmine and neostigmine;

(2)   alpha-adrenergic blockers such as tamsulosin, alfuzosin, terazosin and doxazosin; and

(3)   prostaglandins such as PGD2, PFGE2, PGF2, PGI2 and thromboxane A2.

How the intervention might work

It is believed that POUR may be prevented by these agents by either enhancing bladder contraction or decreasing bladder outlet resistance when administered during the perioperative period.

Cholinergic agents facilitate detrusor smooth muscle contraction by either mimicking the effect of acetylcholine or by blocking the acetylcholinesterase enzyme allowing the sustained effect of acetylcholine. Acetylcholine is the principal neurotransmitter that stimulates the contraction of the bladder smooth muscles.

Alpha-adrenergic blockers cause relaxation of the smooth muscles of the bladder neck and urethral sphincter. Such relaxation decreases the resistance of the bladder outlet, allowing a stronger flow or stream of urine out of the bladder.

Prostaglandins are believed to have an excitatory effect on urinary bladder function via modulation of the afferent pathways. Several findings also suggest that prostaglandin directly stimulates detrusor contraction (Park 1999).

Why it is important to do this review

The evidence base for the use of these drugs for POUR prevention is questionable. A systematic review of existing evidence and resultant guidance on the effectiveness of pharmacological treatments for the prevention of POUR will help clinicians and patients to best decide whether such management is appropriate and effective.

This review will assess all current eligible trial-based evidence for the effectiveness of all relevant drugs in the prevention of POUR, with the intention of informing best practice.


To make the following comparisons involving drugs for the prevention of postoperative urinary retention in adults, in terms of their effectiveness and harm:

  • one drug or drug type versus placebo or no treatment;

  • one drug or drug type versus another drug or drug type;

  • different dosages and timings of administration of the drug.


Criteria for considering studies for this review

Types of studies

We will include randomized and quasi-randomized controlled trials.

Types of participants

Adults, male or female, who will undergo or have undergone surgery of any type, not previously diagnosed with urinary retention, and who will receive the intervention before developing urinary retention.

Types of interventions

One of the arms of the study must include a drug for the prevention of POUR, including, but not limited to:

  • cholinergic agents;

  • alpha-adrenergic blockers;

  • prostaglandins.

Comparators may include any of the following:

  • no treatment or placebo;

  • catheterisation (of any type);

  • another drug or drug type;

  • another dosage or route of administration of the same drug or drug type.

We will include comparisons between drugs classes, as well as comparisons between different drug doses and routes of administration. We will not include trials looking at different classes, doses and routes of drugs used primarily for the induction of anaesthesia and analgesia, which may have an impact on the risk of developing POUR. This will be addressed in a separate Cochrane review.

Types of outcome measures

Each study must include any one of the following as an outcome measure:

Primary outcomes

- number of patients who failed to spontaneously void postoperatively;

- number of patients who failed to successfully void upon removal of the catheter postoperatively;

- number of patients requiring catheterisation postoperatively.

Secondary outcomes

- number of patients reporting adverse events, such as urinary tract infection, bacteriuria, prolonged urinary retention, haemodynamic instability (for alpha-adrenergic blockers);

- length of hospital stay;

- patient-centred outcomes such as discomfort or quality of life;

- cost-effectiveness.

Search methods for identification of studies

We will not impose any restrictions, for example language or publication status, on the searches described below.

Electronic searches

This review will draw on the search strategy developed for the Cochrane Incontinence Group. We will identify relevant trials from the Cochrane Incontinence Group Specialised Trials Register. For more details of the search methods used to build the Specialised Register please see the Group's module in The Cochrane Library. The register contains trials identified from the Cochrane Central Register of Controlled Trials (CENTRAL) (1999 onwards), MEDLINE (1966 onwards) and MEDLINE in process (2001 onwards), and handsearching of journals and conference proceedings. Most of the trials in the Cochrane Incontinence Group Specialised Register are also contained in CENTRAL.

The terms to be used to search the Incontinence Group Specialised Register are given below:


(All searches will be of the keyword field of Reference Manager 12 (Reference Manager 2012).

Additionally we plan to search CENTRAL (most recent issue), MEDLINE (1966 onwards), MEDLINE in process (most recent version) and EMBASE and EMBASE Classic (1974 onwards).

Searching other resources

We will check the reference lists of included studies and previous reviews to search for additional studies.

Data collection and analysis

Selection of studies

The titles of reports generated by the searches will be screened by two reviewers, independently, for consideration for this review. Published reports of pre-screened titles of all potentially eligible studies will be evaluated by two reviewers, independently and without prior consideration of the results, for final inclusion into the review. Where disagreement occurs, an arbitrator from the Cochrane Incontinence Group will decide whether or not a trial is to be included. Papers in languages other than English will be assessed by native speakers for eligibility and subsequently for data extraction. Excluded studies and reasons for exclusion will be detailed in a 'Characteristics of Excluded Studies' tables. We will generate a PRISMA flow diagram to describe the search and selection statistics.

Data extraction and management

Standardised data extraction forms will used by two reviewers, independently, and cross-checked. The data from the two forms will be consolidated when all elements are found to be identical and then will be entered into the appropriate sections of the Review Manager (RevMan) 5.2 software application. When any discrepancy in data extraction is found between the two reviewers, this will be resolved by discussion. In cases where insufficient data are reported, authors will be contacted where possible for further information.

Assessment of risk of bias in included studies

The quality of eligible trials will be assessed by two reviewers, independently, using the Cochrane Risk of Bias tool. We will consider quality of sequence generation and allocation concealment (where appropriate), description of drop-outs, withdrawals and missing data, blinding during intervention and at outcome assessment (where appropriate), description of and protection against possible contamination (where appropriate).

Measures of treatment effect

Risk ratios will be determined and reported for dichotomous data (e.g. number of patients with successful spontaneous voiding postoperatively or upon catheter removal, number of patients reporting adverse events) and mean differences with 95% confidence intervals for continuous data (e.g. length of hospital stay, quality of life measurements, cost-effectiveness). We will use a fixed-effect model for data analysis unless there is evidence of marked heterogeneity, in which case we will use a random-effects model.

Unit of analysis issues

The primary analysis will be per person randomised. In case of multi-arm trials, data from the treatment groups will be split in the meta-analyses to avoid double counting.

Dealing with missing data

If insufficient data are included in trial reports, where possible, we will contact authors to request missing data. Otherwise, we will carry out an intention-to-treat analysis and a per protocol analysis.

Assessment of heterogeneity

We will assess heterogeneity through visual inspection of forest plots. The test for heterogeneity and I2 test will be used to consider the influence on meta-analysis of heterogeneity between studies. Where appropriate, heterogeneity between studies will be considered and described.

Assessment of reporting biases

We will assess reporting bias through the generation of funnel plots.

Data synthesis

We will process data as described in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). Where quantitative data synthesis and meta-analysis will not be appropriate because of the nature of reported data or because of evident heterogeneity, we will provide a narrative review of the evidence instead.

Subgroup analysis and investigation of heterogeneity

Where data allow, we will carry out subgroup analysis based on type of operation, patient characteristics such as age and gender, and type and duration of anaesthesia.

Sensitivity analysis

Where possible, we will carry out sensitivity analysis to assess the effect of possible bias associated with individual trials on the outcome of meta-analysis.


The review authors would like to acknowledge the support of Cochrane Incontinence Review Group.

Contributions of authors

MCML and BSB wrote the protocol.

RL and MJA will perform the study selection, study assessment and data abstraction. MCML will supervise these activities and will act as the arbiter in case of disagreement.

MCML, BSB, RL and MJA will perform data analysis and interpretation.

MCML, BSB, RL and MJA will write the completed review.

Declarations of interest

MCML has received a travel grant to attend an educational conference and honorarium as conference speaker from Astellas, Philippines, who manufacture tamsulosin HCl, a drug which may be included in this review.

Sources of support

Internal sources

  • National Institutes of Health - University of the Philippines Manila, Philippines.

    NIH-UPM employs MCML as a research associate professor

  • Philippine General Hospital - University of the Philippines Manila, Philippines.

    PGH-UPM employs RL and MJA

External sources

  • No sources of support supplied