Diagnostic ultrasound ( PDFDrive )

CHAPTER 10 The Prostate and Transrectal Ultrasound 407
TRUS images and records areas where biopsy specimens have
been taken. 91 Increasingly, mpMRI and MRI-TRUS fusion biopsy
are proving helpful in complex cases such as in patients with
multiple negative extensive biopsies but rising PSA.
Elastography
Tumors are about 5 to 28 times stifer than normal prostate.
Elastography of the prostate assumes that stif areas such as tumors
with increased cellularity allow less internal movement. he
amount of movement is presented as a color-coded map from
blue (stif) to red (elastic) (see Fig. 10.17G). In strain elastography,
force is applied by probe motion, a technique that is very operator
dependent and does not allow quantiication. In shear wave
elastography, the probe is held still and strain is provided by
sound waves, which allow better standardization and direct
measurement of Young’s modulus.
Meta-analysis of elastography reports sensitivity of 71% to
82% and speciicity of 60% to 90%. Cancer detection increases
with lesion size and Gleason score. However, elastography does
not evaluate the gland uniformly. Performance is better in the
peripheral zone, which is adjacent to the probe, especially the
apex and midgland, and is less accurate at the base, anterior
gland, and transition zone. he technique remains operator
dependent. Although it can assist in lesion localization, it does
not allow avoidance of systematic biopsy. False-positive results
are seen with chronic inlammation and atrophy. Experience has
shown that elastography is subjective and has a long learning
curve and that images are diicult to reproduce. 4,6,91,141
ULTRASOUND-GUIDED BIOPSY
Biopsy should be ofered to men who would beneit from tissue
diagnosis following informed consent and ater shared decision
making. Most men are initially identiied by PSA over 2.5 to
4 ng/mL and/or palpable nodule. Other factors taken into
consideration with regard to biopsy include comorbidities, risk
calculators, results of imaging and biomarker tests, and patient
preferences. But the inal decision is individual, relying on the
physician’s acumen and patient’s wishes. Indications difer between
initial and subsequent biopsies. 26,142,143
Preparation for Biopsy
Typically, TRUS biopsy is performed in an ambulatory setting.
Appropriate clinical information should be available to know
why the biopsy is needed and to allow for its safe performance.
his includes results of DRE, PSA, and other relevant tests
including imaging, prior biopsy results, relevant medications,
and comorbidities. Risk factors that can alter risks of infection
or bleeding should be identiied so they can be appropriately
managed. Informed consent should be obtained.
Antibiotic Prophylaxis
Transrectal biopsy requires antibiotic prophylaxis to minimize
risk of infection and sepsis. Speciic antibiotic choices can be
found by consulting regional urologic association guidelines and
infectious disease specialists and taking into account local and
regional antibiotic resistance patterns. For low-risk patients most
guidelines recommend luoroquinolone (ciproloxacin) or a
cephalosporin. Minimal coverage should start 1 hour before the
procedure and last for 24 hours; some are more comfortable
with 3-day courses, although this additional coverage is debated
as being unnecessary and possibly contributing to antibiotic
resistance. Patients at increased risk of infection may beneit
from supplemental antibiotics such as aminoglycosides or ceftriaxone.
Risk factors include recent urinary infections, recent
antibiotic use, recent instrumentation or catheter, international
travel especially to southeast Asia, hospital exposure (both patients
and workers), and immunotherapy. Endocarditis prophylaxis
for patients with valvular heart disease is no longer recommended.
144 Use of rectal swab stool culture to individualize
antibiotic choices has been suggested and may decrease infections.
Although there are concerns about the logistics of implementing
this approach for every patient, it may be helpful in high-risk
patients and those with prior complications. For complex cases,
infectious disease consultation may helpful. Most prostate biopsies
are done transrectally (Fig. 10.18), but some suggest that transperineal
biopsy should be reintroduced to decrease infection
risk because of the increasing prevalence of cephalosporinresistant
E. coli. 145
Postbiopsy sepsis can occur acutely ater biopsy, and its
seriousness may not be initially appreciated by the patient or
his physician. I ind it useful to emphasize to the patient the
potential seriousness of infection and the need for prompt medical
attention and provide patients with a letter to their physicians
stating that postbiopsy sepsis should be managed promptly with
blood and urine cultures and intravenous broad-spectrum
antibiotics. 146-148
Bowel Preparation
Laxatives or a cleansing enema is helpful to clean the rectum to
improve visibility. Some believe that an enema decreases infection
risk, but this has not been conirmed. Povidone-iodine enemas
and suppositories have been suggested to decrease infections,
but this has not been conirmed. 26,148
Analgesia
Analgesia is important to decrease discomfort of the procedure.
Periprostatic nerve block with 1% lidocaine is standard. In general,
5 mL is injected into the neurovascular bundle on each side
(10 mL total) at the base in the fatty triangle between the prostate
and SV. Some suggest additional injections at the apex and sides
of the prostate, but we have not found these to provide improved
analgesia. Analgesic gel may be helpful if the anus is tight or
sensitive. Some have found oral medications, including acetaminophen
and combinations, to be helpful. In rare cases
conscious sedation may be needed. 26,149,150
Anticoagulation
Aspirin and NSAIDs do not need to be discontinued and are
associated with clinically insigniicant bleeding. Antiplatelet drugs
such as clopidogrel (Plavix) should be discontinued for 5 to 10
days before the biopsy. More potent anticoagulants should be
discontinued, but only ater consultation with the prescribing
physician to ensure patient safety. Bridging anticoagulation with