TRUS-Guided Biopsy of Prostate
Placement of probe
For transrectal ultrasonography (TRUS), the probe should be placed in a controlled manner, with light but slowly increasing pressure applied against the probe as its tapered end dilates the sphincter during entry. Because the anal canal may be slightly angled in one anatomic direction or another, using this technique to allow the probe to find the path of least resistance should minimize pain. Holding the end of the probe between the thumb and forefinger allows greater range of motion than a tight-fisted grip would and makes biopsy easier on the surgeon.
The physician should remain mindful of the topical anatomy throughout the procedure (see the image below). Just as the laparoscopic surgeon should observe the body during instrument entry and exit, so should the ultrasonographer observe the probe to ensure that it points in the direction of the rectal course during placement.
Prostate gland.
Number and location of biopsy cores
Directed biopsies are obtained from any area considered to be suggestive on the basis of TRUS of the prostate or palpable abnormalities found on digital rectal examination. Because the incidence of nonpalpable isoechoic prostate tumors is high, limiting biopsy sites to either ultrasonographically hypoechoic lesions or to areas of palpable abnormality tends to miss many malignancies.
Obtain separate biopsy samples from each sextant of the prostate; this improves the odds of sampling clinically inapparent tumors. Originally, these biopsy sites included the midlobe parasagittal plane at the apex, the midgland, and the base bilaterally. However, many authors subsequently recommended changes to this protocol, involving alternative locations or greater numbers of biopsy samples. [18]
Currently, the authors recommend 14-core biopsy as an initial biopsy strategy on the basis of their findings that increasing the number of cores beyond that yields no benefit for initial investigation. The 14-core strategy involves the standard 12-core template with 1 core medially and laterally in both the parasagittal and lateral aspects of the gland plus 1 core on each side in the extreme apex (the site that has the highest likelihood of unique cancer detection). [19, 20]
The authors place 6 cores parasagittally in the same sites as originally described by Hodge et al [21] ; 6 additional cores are obtained lateral to those sites, with an emphasis on going as far laterally as will still permit full-length cores. Because the needle tract projects toward the base, it is appropriate to situate the entrance site more toward the apex so as to ensure that most of the tissue is not obtained from the superior portion of the gland (which is the area less likely to harbor malignancy).
For all repeat biopsies, the authors have confirmed that a 20-core transrectal saturation biopsy increases cancer detection by approximately 50% as compared with extended biopsy. [22] Morbidity is no higher with this approach, and patients tolerate it well under periprostatic block.
Complications
TRUS-guided prostate biopsy is one of the most frequently performed urologic procedures. Although it is generally a safe and well-tolerated outpatient procedure, it is associated with a complication rate of up to 63-73% in some series.
Fortunately, the complications encountered after TRUS biopsy are commonly minor and self-limited, including mild hematuria, hematospermia, and transient rectal bleeding. Occasionally, the resultant morbidities may be significant enough to require surgical intervention (eg, urinary retention [0.2-2.6%] and severe rectal bleeding [0.6%]). [23, 24]
After bleeding, urinary tract infection (UTI) is the second most frequently noted complication of prostate biopsy. It may be described as a minor or major complication, depending on its severity. Although simple UTI frequently occurs after biopsy (1.2-11.3% of cases), febrile UTIs also are not uncommon (1.4-4.5%). Sepsis, one of the most serious clinical sequelae, is encountered in 0.1-2.2% of cases after biopsy. [2]
Some reports have debated the benefit of antibiotic prophylaxis before biopsy, whereas other studies have demonstrated a 16-100% incidence of asymptomatic bacteriuria and transient bacteremia after biopsies performed without antibiotic prophylaxis.
Currently, most urologists agree on the importance of antibiotic-based prebiopsy preparation for maintaining acceptably low complication rates. In a survey conducted on 900 practicing urologists in the United States, prebiopsy regimens included prophylactic antibiotics in 98.6% of cases and a cleansing rectal enema in 81%. Additionally, 11 different antibiotics were used, with 20 variable doses and 23 different timing-duration regimens.
Although there are no published guidelines or prospective randomized trials on which urologists can rely when attempting to determine the optimal antibiotic type, dose, duration, and schedule in the prebiopsy setting, several studies have demonstrated the benefit offered by a single prebiopsy dose of oral antibiotics.
On the basis of their broad spectrum of activity, which covers most aerobic organisms residing in the bowel, fluoroquinolones have been considered the antibiotic type of choice for most of these regimens. However, because of emerging resistant bacterial patterns, the authors now recommend gentamicin in addition to fluoroquinolones.
Further extension of the antibiotic course may be specifically reserved for high-risk patients (eg, those with valvular heart disease and mechanical prostheses).
The use of enemas in prebiopsy protocols was initially based on the suspicion that the mechanism by which infection occurs might be seeding of rectal flora by the biopsy needle. Nevertheless, the real value of enemas in these protocols remains debatable. Some urologists consider them nothing more than cumbersome procedures that potentially increase patient cost and discomfort without offering any additional benefit over antibiotic prophylaxis alone. Given the absence of a clear justification for their use, the authors do not recommend enemas.
Murray et al reported that the effects of TRUS-guided prostate biopsy on erectile function have probably been “underestimated”; however, the cause of these effects has yet to be determined. Of the 220 patients who underwent TRUS-guided prostate biopsy, 38.6% reported no erectile dysfunction (ED), 22.3% mild ED, 15.5% mild to moderate ED, 10% moderate ED, and 13.6% severe ED. [25, 26]
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Prostate gland.
