Prostate Biopsy Periprocedural Care

Biopsy devices

Biopsies are best performed with a spring-driven needle core biopsy device (or biopsy gun), which can be passed through the needle guide attached to the ultrasound probe. Most instrumentation provides optimal visualization of the biopsy needle path in the sagittal plane.

In most cases, 18-gauge needles are used, and the tips of the needles are etched with small ridges or pits to render them more echogenic. A ruled puncture trajectory corresponding to the probe’s needle guide should be superimposed on the ultrasound images; this allows anticipation of the needle path.

Ultrasound probes

Two types of prostate ultrasound probes exist: side-fire and end-fire. ^[13] Understanding their differences is important for mastery of transrectal ultrasonography (TRUS) because they provide entirely different views, which can lead to confusion if one type is used in the manner that is appropriate for the other. The direction of imaging should be obvious from the names of the probe types, but the implications of their differences may not be.

Side-fire probes project laterally. For this reason, twisting the probe while keeping its axis neutral with respect to the sagittal plane laterally enables lateral visualization. End-fire probes project an imaging plane either directly or at a slight angle from the end of the probe. Thus, the probe handle must be angled away from the side of interest in order to visualize the lateral areas, with the anus used as a fulcrum.

The above geometric requirements mean that when a patient undergoes TRUS of the prostate with a side-fire probe, the probe should remain essentially in the midline and should be twisted to reach the lateral aspects. Consequently, patient positioning is relatively unimportant, provided that the anus is accessible.

Conversely, when a patient undergoes TRUS of the prostate with an end-fire probe, the probe must be positioned so that its handle can be dropped far enough to reach beneath the plane of the examination table when the right lateral border of the prostate is visualized. To facilitate this, the patient’s buttocks should be directly over the corner of the table, with the legs flexed toward the chest and held by the table extension.

With either type of probe, limited visualization of the lateral aspects can result in 2 problems. First, periprostatic block is performed laterally at the junction of the seminal vesicles and prostate. Second, and equally important, the lateral aspects of the peripheral zone are the areas most likely to harbor cancer; limiting lateral access increases the risk of inadequate and false-negative biopsies.

The authors find that lateral visualization is most readily achieved with an end-fire probe, though they routinely perform biopsies successfully with either type. Another advantage of the end-fire probe is that the trajectory of the biopsy needle as it exits its guide is aimed more directly toward the prostate rather than tangentially. This allows easier biopsy of the apex and anterior horn of the peripheral zone, further minimizing the possibility of a false-negative biopsy.

Rectal swab

Some authors have found that they can identify the presence of resistant bacteria, which might change antibiotic prophylaxis prior to biopsy, by performing a rectal swab culture on a previous visit. This practice has not been widely accepted, probably because of the complexity of adding a visit for many patients to perform the swab. Nevertheless, it is intriguing and might be especially applicable for patients who are likely to have bacterial resistance, such as those who have taken multiple doses of antibiotics in the past or those who have traveled extensively internationally where antibiotic resistance may be higher than in the United States. ^[14]

Anesthesia

Periprostatic block is performed by placing a needle into the notch between the prostate and the seminal vesicle laterally. This is identified ultrasonographically as a white (hyperechoic) pyramidal area that the authors call the Mount Everest sign (because of its resemblance to a snowy mountain peak). Fat in this location makes the area easy to visualize on TRUS.

The authors find that trainees often fail to advance the probe far enough into the rectum to reach the Mount Everest sign. Difficulty in finding this notch immediately upon probe placement is usually due either to inadequate depth of probe placement (which is easily remediable) or to inadequate visualization laterally, often because the novice is twisting the end-fire probe or angling the side-fire probe, either of which can lead to loss of visual orientation and perspective.

Injection of 5 mL of a local anesthetic agent (either lidocaine or bupivacaine) creates a hypoechoic fluid area in the same site as the Mount Everest sign. The “ultrasonic wheal” describes visualization of the anesthetic agent reaching the periprostatic nerves.

Although some authors advocate multiple injections along either side, anesthesia is assured if the hypoechoic agent can be visualized dissecting along the nerve bundles between the prostate and rectum. This confirms that the anesthetic has reached the entire neurovascular bundle coursing along each side of the prostate. If the agent dissects caudally along the neurovascular bundles, prostatic anesthesia is assured regardless of whether a single injection or multiple injections were administered.

Ensuring that the anesthetic reaches the proper plane is facilitated by injecting as the needle enters the space in order to expand its distance, then pulling back slightly in order to open up the potential space until anesthetic is seen dissecting caudally. Note that the space between the rectal wall and the prostate widens when the fluid dissects into this plane.

Because apical sampling is more painful than biopsy of the remainder of the gland, the authors recently introduced rectal wall injection as the lidocaine needle traverses the tissue, which further reduces pain during apical biopsy. Furthermore, a rectal sensation test can be done by touching the biopsy needle against the rectal wall, for proper positioning of the needle in order to not traverse the sensitive anus as the first step of apical biopsy. ^[15]

Other methods of providing pain control are intrarectal application of local anesthetic gel ^[16] and intraprostatic injection of local anesthetic ^[17] ; however, periprostatic block is the most critical.

Positioning

Although some physicians recommend the lithotomy position, the authors find that prostate biopsy can typically be performed more readily with the patient in the left lateral decubitus position. The patient’s buttocks should be at the corner of the bed, especially if the physician is using an end-fire probe, which must be angled to permit visualization of the lateral aspect of the right side of the prostate. The knees should be pulled toward the chest as much as possible to facilitate probe placement.

No specific recommendations exist for care after prostate biopsy. Most patients wish at least to return home for a shower, but it is acceptable for them to resume their previous activity level if they wish. It is important for patients to notify a physician if they experience any fevers or chills. Urine and blood cultures should be obtained on the basis of the potential for resistant bacteria.

It should be kept in mind that after a single negative biopsy result, at least 25% of patients may still harbor histologic prostate cancer; thus, careful monitoring is mandatory. In view of the slow development of prostate cancer and its slow progression in the overwhelming majority of patients, the authors recommend annual prostate-specific antigen (PSA) testing. Some authors recommend more frequent surveillance, and this is a reasonable option.