Assessment of
the patient with prostatism
Abdominal examination is usually normal. In
patients with chronic retention, a distended bladder will be found on palpation,
percussion and sometimes on inspection with loss of the transverse suprapubic
skin crease. General physical examination may demonstrate signs of chronic
renal impairment with anaemia and dehydration. The external urinary meatus
should be examined to exclude stenosis, and the epididymes are palpated for
signs of inflammation.
Rectal
examination
In benign enlargement, the posterior surface
of the prostate is smooth, convex and typically elastic, but the fibrous element
may give the prostate a firm consistency. The rectal mucosa can be made to move
over the prostate. Residual urine may be felt as a fluctuating swelling above
the prostate. It should be noted that if there is a considerable amount of
residual urine present, it pushes the prostate downwards, making it appear
larger than it is.
The nervous
system
The nervous system is examined to eliminate a
neurological lesion. Diabetes mellitus, tabes, disseminated sclerosis, cervical
spondylosis, Parkinson’s disease and other neurological states may mimic
prostatic obstruction. If these are suspected then a pressure—flow urodynamic
study should be carried out to diagnose BOO. Examination of perianal sensation
and anal tone is useful in detection of an S2 to S4 cauda equina lesion.
Serum
prostate-specific antigen
The difficulty here is the uncertain benefit
of early detection and radical treatment of prostate cancer — this is dealt
with in the section on prostate cancer. Certainly men should be informed about
the test, the risks of the prostate biopsy that might be required and the risks
of the detection of a cancer that we are not certain how best to treat. After
suitable counselling, measurement of serum PSA may be helpful. Men in whom a
diagnosis of early prostate cancer might influence treatment option such as
those under 60 or those with a
positive family history who might be offered
radical treatment — should be offered a PSA measurement. If this is in
excess of 4 nmol/litre, then transrectal ultrasound scanning (TRUS) plus
multiple transrectal biopsies should be considered.
If
rectal examination is quite normal with no suspicion of cancer and if no change
in treatment policy would result anyway from the diagnosis of early prostate
cancer then there seems little point in the routine measurement of PSA in men
with uncomplicated BOO.
Flow rate
measurement
For this to be meaningful two or three voids
should be recorded and the voided volume should be in excess of 150—200 ml.
This usually means the patient attending a special flow rate clinic. A typical
history and a flow rate <10 mi/second [for a voided volume of >200 ml (Fig.
66.7)] will be sufficient for most urologists to recommend treatment.
Usually a flow rate measurement will be coupled with ultrasound measurement of
postvoid residual urine.
There
are pitfalls in the measurement of flow rates. The machine must be accurately
calibrated. The patient must void volumes in excess of 150 ml and two or three
recordings are needed to obtain a representative measurement. Decreased flow
rates and symptoms of prostatism may be seen in:
•
BOO;
•
low voided volumes (characteristically in men with detrusor instability);
•
men with weak bladder contractions (low pressure—flow voiding).
Pressure—flow urodynamic studies (Fig.
66.8)
Details of these studies are outlined in
Chapter 65. They should be performed on the following patients:
•
men with suspected neuropathy (Parkinson’s disease, dementia,
long-standing diabetes, previous strokes, multiple sclerosis)
•
men with a dominant history of irritative symptoms and men with life-long
urgency and frequency
•
men with a doubtful history and those with flow rates in the near-normal
range (— or >15 mI/second)
•
men with invalid flow rate measurements (because of low voided volumes)
Blood tests
Serum creatinine, electrolytes and haemoglobin
should be measured.
Examination of
urine
The urine is examined for glucose and blood, a
midstream specimen should be sent for bacteriological examination and
cytological examination may be carried out if carcinoma in situ is thought possible.
Upper tract
imaging
Most urologists no longer carry out imaging of
the upper tract in men with straightforward symptoms. Obviously if infection or
haematuria is present then the upper tract should be imaged by means of an IVU
or USS.
Cystourethroscopy
Inspection of the urethra, the prostate and
the urothelium of the bladder should always be done immediately prior to
prostatectomy, whether it is being done transurethrally or by the open route to
exclude a urethral stricture, a bladder carcinoma and the occasional non opaque
vesical calculus. The decision whether to perform prostatectomy must be made
before cystoscopy. This should be based on the patient’s symptoms, signs and
investigations. Direct inspection of the prostate is a poor indicator of BOO and
need for surgery.
Transrectal
ultrasound scanning
This increases the rate of detection of
associated early prostate cancer but, as pointed out above, unless this would
substantially affect treatment there is no need to carry it out routinely.
Accurate estimation of prostatic size is possible by means of transrectal or
transabdominal ultrasound scanning.