Introduction

Contemporary management of the urological surgery patient incorporates perioperative appreciation of the possibility for thromboembolic complications. Venous throm-boembolism (VTE) and the sequelae of pulmonary embolism (PE) continue to be one of the most critical nonsurgical morbidities for urological procedures. The magnitude of the issue is staggering, with approximately 10% of hospital deaths attributed to PE [1,2]. The true incidence of such potentially life-threatening complications from VTE and PE is prone to underestimation as these issues frequently manifest following hospital discharge [3].

Vast numbers of randomized clinical trials have provided sound evidence that primary thromboprophylaxis reduces VTE and PE [4]. However, the optimal prophylaxis for urological interventions, whether mechanical or pharmacological, as well as the duration of the treatment remains a largely unanswered question. Indeed, only one randomized controlled trial (RCT) has emerged in the urology literature specifically addressing thromboprophylaxis [5].

The incidence of silent VTE is unknown, as are the long-term repercussions of this seemingly occult condition, but estimates suggest a prevalence of asymptomatic DVT of 15–40% following urological surgery for patients without prophylaxis [4]. For symptomatic VTE, rates are highly dependent on the type of surgical intervention, as will be discussed individually in the following sections. In general, symptomatic VTE in urological surgery patients is estimated to occur at procedure-dependent rates between 1% and 5% [4].

A wide variety of factors are known to influence VTE formation from both the medical and surgical perspective. These VTE risk factors are generally agreed to be cumulative [6]. Thrombosis is usually focused in the deep veins of the leg (deep vein thrombosis, DVT) including the iliac, femoral, and popliteal veins. Pelvic veins are particularly at risk for thrombosis during many urological surgeries. Thrombosis may also occur for the urological surgery patient in the operating room simply from the venous stasis caused by immobilization and paralysis.

With recognition of the heightened risk in the surgical patient, the American College of Chest Physicians (ACCP) has created extensive guidelines detailing pharmacological and mechanical strategies for prevention of VTE [4]. The ACCP performed a comprehensive review of available medical literature to define evidence-based guidelines for VTE prophylaxis with specific recommendations for urological surgery. Recently, the American Urological Association (AUA) guidelines panel has published the AUA best practice policy statement with risk-stratified recommendations presented in Table 8.1 [7]. This practice statement integrates available evidence from the urological and surgical literature into treatment strategies for pharmacological and mechanical prophylaxis for each category of urological surgery, with the predominant focus being patient risk stratification. The AUA recommends that once the patient’s risk profile regarding co-morbidities is identified, the urologist must then determine the specific risk category to which the proposed procedure belongs. In this context, according to the AUA classification, minor surgery is defined as a procedure with a relatively short operating time in which the patient is rapidly ambulatory. This chapter incorporates many of these best practice recommendations to develop strategies for perioperative management to diminish the risk for VTE and PE.

In creating guidelines and recommendations for clinical practice, numerous methods of grading evidence exist with no global consensus regarding method. This multiplicity of grading strategies, despite the best intentions of involved researchers, may actually create confusion for clinicians attempting to make point-of-care decisions. Ideally, quality evidence should be defined by a set of factors that have been described by the Grading of Recommendations Assessment, Development and Evaluation (GRADE) Working Group [8–13]. These definitions of quality evidence incorporate several factors including study limitations, consistency of results, directness of the evidence, precision, publication bias, factors that might increase quality of evidence, large magnitude of effect, plausible confounding factors, and any dose–response gradient. The GRADE system culminates with evidence categorized in a binary fashion as strong or weak (alternatively termed conditional). With regard to utilizing these criteria to create a body of evidence, unfortunately only a single RCT on the critical topic of VTE that meets these standards has been published in the urological literature in the past 20 years [5]. Indeed, even the AUA Best Practice Statement on prevention of DVT remarks that due to the lack of robust data, an evidence table could not be developed [7]. Therefore, much of the data upon which recommendations for urological surgery are based have either been derived from other surgical disciplines, somewhat limiting their usefulness or emanate from less rigorous types of analyses.

Table 8.1 Venous thromboembolism prophylaxis recommendations

The grade of data and recommendations for VTE prophylaxis as outlined in the ACCP review have been extensively defined in several versions [14]. Briefly, evidence was graded for the recommendations on a scale from 1A to 2C. In this mode of evidence stratification, evidence earning a grade of 1A–C demonstrates clear clarity of risk/benefit and is generally regarded as providing a strong recommendation for implementation in practice. For the clinical questions discussed in this chapter, the individual grades of evidence as assigned by the ACCP as well as the GRADE score, along with an explanation as applied to the particular urological surgery, are outlined.

Even with prophylaxis against thrombosis, events will occur. This has become of increasing concern as federal regulatory agencies are now mandating hospital-wide reforms to prevent VTE, placing the individual practitioner at jeopardy. Many physicians will themselves be graded on the incidence of VTE and PE in their patients, with scant regard for the complexity of the population that may be seen at tertiary care centers or the extenuating factors driving an alternative choice to prophylaxis. If there is a generally accepted protocol at the hospital for VTE prophylaxis, documentation should reflect for each individual patient any deviations in protocol. In addition to utility as a quality metric by the hospital, the use or failure in use of VTE prophylaxis has transformed into a medicolegal issue of substantial importance. Risk assessment must be carried out for each individual patient and treatment options tailored. However, in the age of computerized order entry, often integrated with hospital policy and evidence-based guidelines, decision trees must be over-ridden by the physician to obtain alternative prophylaxis regimes. Several newer agents are also changing the landscape of VTE prophylaxis, although with every new therapy costs escalate and must be compared against standard regimens with known efficacy and minimal expense.

Modalities of VTE prophylaxis to be discussed include the most commonly employed mechanical and pharmacological agents with robust studies available. With regard to mechanical methods of thromboprophylaxis, early ambulation, graduated compression stockings (GCS) and intermittent pneumatic compression (IPC) devices are the most frequently utilized modalities to reduce venous stasis in the lower extremities. In addition to ease of use and often decreased cost when compared to select pharmaceutical agents, mechanical devices do not increase the risk of hemorrhage. Despite several studies that demonstrate a decreased risk of DVT with mechanical prophylaxis, no studies have reported that these methods diminish the risk of PE or death [4].

For the urologist, a major concern with pharmacological prophylaxis is the risk of postoperative bleeding complications [15,16]. This delicate risk/benefit ratio must be assessed on a case-by-case basis. The majority of contemporary pharmacological prophylaxis is performed with low-dose unfractionated heparin (LDUH) [17], low molecular weight heparin (LMWH) [18] or the activated coagulation factor X inhibitor fondaparinux [19]. Of parti-cular importance for the urological surgery patient is caution regarding use of LMWH and fondaparinux in the setting of renal impairment as their accumulation may potentiate bleeding [4].

Search strategy and study selection criteria

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