Health professionals are being notified by the FDA of the potential for serious thermal injury and related complications associated with the use of microwave energy to treat benign prostatic hyperplasia (BPH). To provide information that can help avoid these complications the following has been issued (health professionals are invited to copy a freely distribute this information):
Although the use of microwave thermotherapy for the
treatment of BPH has been demonstrated to be safe and effective, and more than
25,000 procedures have been performed, there are concerns about some unexpected procedure-related complications that have occurred since the marketing of these
Currently marketed devices include the Prostatron (Edap Technomed, Inc.) and the Targis System (Urologix, Inc.). Dornier Medical Systems, Inc. has received approval to market their UroWave System but is not yet marketing it. The FDA is working with the manufacturers to ensure that labeling and training programs address these complications.
Nature of the Problem
Since 1996, reports have been received of 16 thermal injuries related to
microwave thermotherapy systems. Of these, 10 resulted in fistula formation and 6 resulted in clinically significant tissue damage to the penis or urethra. These injuries may not be apparent at the time of treatment, and may take hours or days to develop. (Note that the original labeling for these devices did not list fistula formation as a procedure-related complication.) The reported injuries have required colostomies, partial amputation of the penis, and/or other therapeutic interventions.
The FDA has identified several factors that may have contributed to the injuries noted:
- Incorrect placement or undetected migration of either the treatment
catheter or the rectal temperature sensors;
- Failure of the physician to remain with the patient throughout the entire treatment duration;
- Failure to pause treatment when the patient is communicating serious pain;
- Oversedation of the patient, which compromises his ability to communicate pain;
- Treatment of patients who have undergone prior radiation therapy to the
- Treatment of patients whose prostate sizes are outside the ranges
specified in the labeling; and
- Leakage from the balloons used to retain either the urethral catheter or
the rectal temperature sensor in the correct anatomical position;
- When considering a patient for microwave thermotherapy for BPH, ensure
that he meets the device’s indications, including the criteria for
eligible prostate size indicated for the specific system being used.
Additionally, it is important to verify that the patient has not had prior
radiation therapy to the pelvic area, as these patients are at increased
risk of rectal fistula formation. Furthermore, the labeling of each device
lists specific patient populations for which safety and effectiveness of
this therapy are unknown (e.g., those with prostate cancer).
- When discussing the procedure with the patient, it is important to ensure
that he understands the risks and benefits listed in the labeling of the
specific device. He should also understand the duration of the procedure,
the level of pain or discomfort that should be considered normal, the
importance of telling the physician of any unusual pain during treatment,
how to operate any emergency stop button, and the need to remain as still as
possible during treatment.
- Carefully follow the instructions for use provided with these microwave
systems. Note that they require the physician to continually supervise the
procedure throughout the entire treatment period. The physician must (1)
verify that the retention balloons of the urethral catheter and rectal
temperature sensor probe are free of leaks, and (2) confirm the placement of
the urethral catheter and rectal temperature sensor using acceptable methods
(e.g., direct visualization, ultrasound imaging) both prior to treatment and
other specified times consistent with the manufacturer’s recommendations.
Either patient movement or component breakage may cause migration of a
properly placed urethral catheter or rectal temperature sensor.
- Be careful not to oversedate the patient. As patient perception of pain is
an important safety mechanism to ensure that the heating of the tissue is
not excessive, general or spinal anesthesia should not be used.
- Closely monitor the patient and the equipment throughout the entire
treatment, and manually pause treatment if the patient complains of
excessive pain or anything unusual occurs.
Microwave thermotherapy systems are intended to heat the prostate, resulting
in the necrosis of periurethral prostatic tissue, to provide relief of urinary
symptoms in patients with obstructive BPH. These devices heat the prostate to
therapeutic levels using microwave energy delivered by an antenna contained
within a specially designed urethral catheter. The catheter is designed so that
when the balloon is seated at the neck of the bladder, the active portion of the
antenna is positioned within the prostate. To prevent overheating, the systems
circulate cooling fluid through the urethral catheter to protect the urethral
tissue from excessive heat and automatically vary microwave energy output during
treatment based on information supplied by temperature sensors placed posterior
to the prostate within the rectum. Treatment may last from 30 to 60 minutes.
Because the catheter and/or the rectal temperature sensors can migrate during
treatment, and because the correct placement of both of these components is
critical for safe and effective treatment, the labeling for all these devices
instructs the treating physician to: (1) verify that the urethral catheter
(and rectal temperature sensor probe, if applicable) has a working retention
balloon prior to placement, and (2) verify the proper position of both the
urethral catheter and the rectal temperature sensors prior to and at specified
time intervals consistent with the manufacturer’s recommendation for
treatment. These requirements are intended to help ensure that catheter or
rectal temperature sensor migration does not occur in a manner which would cause
undetected excessive heating of surrounding tissues or the delivery of
therapeutic heating levels to areas of the body that are not intended to receive
treatment. The labeling for microwave thermotherapy devices also instructs the
treating physician to monitor the equipment and patient during treatment, and
manually reduce or pause the microwave power if the patient experiences
excessive pain or extreme heating is observed.
Reporting Adverse Events to FDA
The Safe Medical Devices Act of 1990 (SMDA) requires hospitals and other user
facilities to report deaths and serious injuries associated with the use of
medical devices. FDA is interested in additional data on adverse events
involving the use of microwave thermotherapy systems. When submitting a report,
please identify the treatment protocol and catheter type, if known. Healthcare
providers that are employed by facilities that are subject to FDA’s user
facility reporting requirements should follow the reporting procedures
established by their facilities. All other providers may submit their reports to
MedWatch, FDA’s voluntary reporting program. The reports can be submitted by
phone at 1-800-FDA-1088; by fax at 1-800-FDA-0178; by mail to MedWatch, Food and
Drug Administration, HF-2, 5600 Fishers Lane, Rockville, Maryland 20857, or
online at www.accessdata.fda.gov/scripts/medwatch.
Getting More Information
If you have questions, please contact Laura Alonge, Office of Surveillance and Biometrics (HFZ-510), 1350 Piccard Drive, Rockville, Maryland 20850, by fax at 301-594-2968, or by e-mail at firstname.lastname@example.org.
Additionally, a voice mail message may be left at 301-594-0650, and your call
will be returned as soon as possible.