Epidemiology and Diagnosis

It is important to remember that BPH is a pathological diagnosis, and most of the patients seen in practice have clinically enlarged prostate glands but no histological confirmation of BPH. Hence the term "benign prostatic enlargement" (BPE) is more appropriate in those in whom tissue diagnosis is not confirmed. BPH is one of the most prevalent conditions affecting men aged 40 and above. Histological studies have shown features of BPH to be present in the prostate of approximately 60% of men aged 60, and closer to 100% of men aged 80 and above. The only clear risk factors for the development of BPH are increasing age and the presence of circulating androgens. Clearly there are specific genetic patterns since histological BPH has been shown to be more prevalent in Afro-Caribbean than Caucasian populations. Asians tend to have a lower incidence still, but this is not maintained in migratory populations, also implying environmental factors in the development of BPH. Clinical BPH seems to run in families, although the genes responsible are yet to be identified.

There are three components to the clinical picture of BPH. It has been shown that there is considerable overlap between BPH and LUTS, and again between BPH and BOO, but they are by no means the same entities. LUTS may or may not be due to BPH, and BOO may or may not be present with BPH and/or LUTS (see Fig. 11.1). What can be said with certainty is that patients with BPH, LUTS, and BOO are at greatest risk of disease progression, including episodes of AUR (Weiss et al. 2001; Choong and Emberton 2000; Anderson et al. 2001; Abrams 1997; Kirby and McConnell 2005).

Diagnosis is based on clinical history and examination, including an assessment of LUTS and digital rectal examination (DRE). Although the International Prostate Symptom Score (IPSS) (the American Urology Association [AUA] Symptom Score Index) is advocated for the office assessment of LUTS and it is widely used in clinical trials to assess response to treatments (Weiss et al. 1991), in the emergency situation it is of limited applicability.

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Fig. 11.1. The relationship between prostatic hypertrophy, symptoms and obstruction. Each may exist independently or in combination in each individual patient

Acutely, patients presenting with AUR will typically complain of both an intense desire to void and a degree of suprapubic pain (Fitzpatrick and Kirby 2006). They may give a history of preceding LUTS, with a reduced urine flow rate and a sensation of incomplete bladder emptying correlating best with subsequent progression to AUR. Those with chronic retention will not typically have pain. Some may describe a feeling of fullness, and some may even notice a suprapubic swelling. Usually, however, they present simply with an inability to pass urine, often having not voided for over 24 h. Some of these patients will, however, present in extremis with acute renal failure. These patients are often uremic, and some may have life-threatening electrolyte imbalances including hyperkalemia. Typically, on catheterization, they will have very large residual volumes and subsequently may have a significant diuresis, which needs careful observation and management with appropriate fluid replacement. In the presence of disturbed renal function, investigations into the state of the upper urinary tracts (typically ultrasound) should also be car-riedout (see Sect. 11.2.2.5).

In the history it is important, as well as asking about LUTS, to exclude any other co-morbidities that could be contributing to the presentation. It is important to exclude neurological disorders, including cerebrovas-cular events, multiple sclerosis (MS), spinal cord injury (SCI), pelvic or perineal trauma, Parkinson's disease, multisystem atrophy (MSA), and motor neuron disease (MND), and consider if they are taking any drugs that could contribute to dysfunctional voiding (anticholin-ergics, antidepressants, anesthetic agents, analgesics). Also, it is important to assess the patient's general medical state to ensure that they are not going to come to any harm as a result of any therapy instigated.

Physical examination is performed as a matter of routine. It should include a full cardiorespiratory assessment, neurological examination including cognitive state (specifically examining the low lumbar and sacral dermatomes and myotomes to rule out cauda equina syndrome), and examination of the abdomen, paying special attention to the kidneys and the presence or absence of a palpable urinary bladder. Examination of the external genitalia is important to ensure urethral catheterization is not going to be impossible and to identify phimosis or meatal stenosis, as well as to rule out associated infective complications such as epididymitis. If suprapubic catheterization is to be considered, then inspection of the lower abdomen to look for lower midline scars is essential (see Chap. 19, "Surgical Techniques and Percutaneous Procedures").

DRE is performed to both give an estimation of prostate size and to exclude malignancy and prostatitis as alternative causes of UR (see also Sects. 11.2.3 and 11.2.5.2). As such it is possibly the most important part of the examination in male patients presenting with failure to empty their bladder. The normal male prostate is less than 20 cm3 in volume, so BPE can be diagnosed by the experienced clinician based on DRE alone, although the accuracy of size estimation tends to be very subjective and is certainly reduced in glands bigger than 50 cm3. The gland should be symmetrical. Any nodules or irregularity, or a gland that is diffusely firm or asymmetrical could represent malignancy. It is important to note that inflammatory conditions such as prostatitis can also feel firm and irregular, but the difference is that in the acute phase, these will be tender to palpation.

In the acute setting, especially in cases presenting with UR, testing for prostate-specific antigen (PSA) is deferred. Although PSA correlates well with both gland size in BPH and tumor size in prostate cancer, it is also usually significantly raised in episodes of retention or infection and after instrumentation or examination. (In the nonacute office setting, with patients presenting with LUTS and BPE, it is entirely reasonable to perform PSA testing as long as the implications are understood by the patient. Important information can also be obtained in this setting by assessment of peak urine flow and concurrent assessment of postvoid residual urine volume.)

Urinalysis should be performed on the urine obtained immediately after catheterization (if the patient is completely unable to void) and if anything abnormal is seen, the urine should be sent for formal microscopy and culture, and if sexually transmitted infection is suspected, particularly in younger sexually active patients, urine should also be sent for gonorrhea and chlamydia PCR testing (see also Sect. 11.2.5.2).

In some cases, patients may present with symptoms suggestive of both AUR and UTI, for example, a few days history of dysuria and offensive smelling urine, with an acute history of inability to pass urine. In these patients, to avoid instrumenting the urinary tract unnecessarily and in the presence of infection, a measurement of residual urine volume can be helpful. This is typically carried out using a bedside portable ultrasound bladder scanner (Bladderscan BVI 3000, Verathon Inc., Bothel, WA, USA). If the residual volume is very low (less than 150 ml) then the patient should not be catheterized. A course of antibiotics should be commenced and the patient should only be catheterized if he is unable to void with a more significant urine volume in the bladder.

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