Endometrial ablation devices: How to make them truly safe
Nonhysteroscopic, minimally invasive ablation devices are not entirely benign. Recognizing that fact is the first step toward a solution.
IN THIS ARTICLE
CASE: Leaking fluid causes intraoperative burns
G.S. is a 45-year-old mother of three who is admitted for surgery for persistent menorrhagia. She has experienced at least two menstrual periods every month for several months, each of them associated with heavy bleeding. She has a history of hypothyroidism and hypertension, but no serious disease or surgery, and considers herself to be in good physical and mental health.
G.S. undergoes endometrial hydrothermablation (HTA) under general inhalation anesthesia. After the HTA mechanism is primed, the heating cycle is started, with a good seal and no fluid leaking from the cervix.
Approximately 8 minutes into the procedure, a 5-mL fluid deficit is noted, and a small amount of hot fluid is observed to be leaking from the cervical os. Examination reveals a thermal injury to the cervix and anterior vaginal wall. The wound is irrigated with cool, sterile saline, and silver sulfadiazine cream is applied. The patient is discharged.
Could this injury have been avoided? Is further treatment warranted?
A minimally invasive operation does not necessarily translate to minimal risk of serious complications. Although few studies of nonhysteroscopic endometrial ablation techniques report any complications,1,2 Baggish and Savells3 found a number of injuries when they searched hospital records and the Food and Drug Administration (FDA) database (TABLE). They identified serious complications associated with the following devices:
- HydroThermablator (Boston Scientific), which utilizes a modified operating hysteroscope to deliver 10 to 12 mL of preheated saline into the uterus under low pressure.4 Complications: 16 adverse events were reported to the FDA, 13 of which involved the retrograde leakage of hot water, causing burns to the cervix, vagina, and vulva. Six additional injuries not reported to the FDA were identified at a single institution.
- Novasure (Cytyc), which employs bipolar electrodes that cover a porous bag.5,6 Complications: 32 injuries, 26 of them uterine perforations.
- Thermachoice (Gynecare), a fluid-distended balloon ablator.7 Complications: 22 injuries included retrograde leakage of hot water after balloon failure and transmural thermal injury, with spread to, and injury of, proximal structures. One death was reported.
- Microsulis (MEA), which uses microwave energy to ablate the endometrium.8-10 Complications: 19 injuries, including 13 thermal injuries to the intestines.
Baggish and Savells3 initiated this study after discovering six adverse events within their own hospital system utilizing a single device (HTA). Because these injuries were not reported to the FDA, the overall number of complications is likely higher than the figures given here.
This article describes the proper use of nonhysteroscopic endometrial ablation devices, the best ways to avert serious injury, and optimal treatment when complication occurs.
Complications associated with 4 endometrial ablation devices
Retrograde leakage burn
Transmural uterine burn
* Includes author’s data; 6 retrograde leaks
† Collateral injury
CASE continued: Patient opts for hysterectomy
In the case just described, G.S. was examined 1 week after surgery and found to have an exophytic burn over the entire right half of the cervix, extending into the vagina. She was readmitted for 3 days of intravenous (IV) antibiotic treatment and wound care. Computed tomography imaging showed gas formation within the damaged cervix.
Six weeks after surgery, the patient was still menstruating heavily, but her cervix and vagina had healed. Six months later, she underwent total abdominal hysterectomy for continued menorrhagia.
When is endometrial ablation an option?
Indications for endometrial ablation using a nonhysteroscopic, minimally invasive technique are no different from those for hysteroscopic ablation.11 Abnormal, or dysfunctional, uterine bleeding is the principal reason for this operation. Dysfunctional bleeding is heavy or prolonged menses over 6 months or longer that fail to respond to conservative measures and occur in the absence of tumor, pregnancy, or inflammation (ie, infection).
A woman who meets these criteria should have a desire to retain her uterus if she is to be a candidate for a nonhysteroscopic, minimally invasive technique. She also should understand that ablation can render pregnancy unlikely and even pathologic. Her understanding of this consequence should be documented in the chart! Last, she should be informed that ablation will not necessarily render her sterile, so contraception or sterilization will be required to avoid pregnancy. This should also be clearly documented in the medical record.
Endometrial ablation may also be an alternative to hysterectomy for a mentally retarded woman who is unable to manage menses. Abnormal uterine bleeding in conjunction with bleeding diathesis, significant obesity, or serious medical disorders can also be treated by endometrial ablation.
Avoid endometrial ablation in certain circumstances
These circumstances include the presence of endometrial hyperplasia, endometrial cancer, endocervical neoplasia, cervical stenosis, an undiagnosed adnexal mass, moderate to severe dysmenorrhea, adenomyosis, or a uterine cavity larger than 10 cm.12-15
Valle and Baggish15 reported eight cases in which women developed endometrial carcinoma following ablation, and identified the following major risk factors for postablation cancer:
- endometrial hyperplasia unresponsive to progesterone or progestin therapy
- complex endometrial hyperplasia
- atypical hyperplasia.
These conditions are contraindications to endometrial ablation.
Avoid a rush to ablation
The growing popularity of office-based, minimally invasive, nonhysteroscopic techniques, coupled with an increasing desire for and acceptance of elective cessation of menses, may stretch the indications listed above and cut short the discovery of contraindications. Clearly, thorough endometrial sampling and precise histopathologic interpretation are required before embarking on any type of endometrial ablation, to minimize the risk of complications.
How to prevent injury
Reduce the risk of perforation
Uterine perforation occurs for a variety of reasons:
- position of the uterus is unknown
- uterus has not been gently and carefully sounded
- cervix is insufficiently dilated to permit passage of the probe
- device is too long (large) to be accommodated in an individual patient’s uterus
- uterine cavity is distorted by pathology, such as adhesions, myomas, etc.
Attention to these details before surgery can prevent perforation.
When uterine injury occurs, the bowel is also at risk
The intestines can be injured following perforation or transmural injury of the uterus. Bowel injury has been reported with hysteroscopic ablation and resection as well as with Nd-YAG laser ablation.16-18
Do not activate hot water or electrosurgical energy unless you are 100% certain that the device is within the uterine cavity.
Ideally, manufacturers’ safety studies should guarantee no risk of transtubal spillage of hot liquid.
Hot fluid adds to risk of burns
Devices that permit retrograde leakage of hot fluid, such as the HTA, should be modified to ensure sealing at the level of the external and internal cervical os. The Enable device (Innerdyne), no longer marketed in the United States, had such a sealing mechanism, which minimized retrograde leakage of hot water.
Balloon failure may be an unavoidable injury, but pretesting of the device and careful attention to pressure readings—particularly in a small uterus—may mitigate the risk.
Be alert for electrical leakage
The microwave device operates at the megahertz range of frequency. At this high frequency, the risk of leakage is much greater than with devices that operate in the kilohertz range. Therefore, it is important to pay close attention to grounding sites, such as cardiovascular-monitoring electrodes.
High-power monopolar devices, prolonged application of energy to tissue, and high generator frequency are all associated with leakage and subsequent burns.
A prescription for mainstreaming endometrial ablation techniques and tools
- Keep the success rate above 90%
- Minimize complications by proper technique and instrument selection
- Press the market to develop a range of device sizes that will individualize the procedure
- Keep the price of a procedure under $1,000
- Establish and adhere to careful patient selection criteria
Early recognition and treatment are vital to ensure the patient’s safety and reduce the risk of medicolegal liability. I recommend the following steps:
- Stop the procedure immediately if perforation is suspected. If you suspect that hot water has been dispersed within the abdominal cavity, switch to laparotomy and consult a general surgeon to inspect the entire intestine for injury. If perforation occurs during the use of electrosurgical energy, the same action is warranted. If uterine perforation occurs in isolation (ie, there is no thermal energy compounding the problem), admit the patient for careful observation, appropriate blood chemistries and hematologic studies, and radiologic examination.
- When hot liquids are spilled, switch to retrograde flow immediately and generously flush the vulva, vagina, and cervix with cold water. Cleanse the entire area with a soapless detergent, and apply clindamycin cream to the vagina and silver sulfadiazine cream to the vulva. Admit the patient for application of cold compresses, ice packs, and burn therapy, and obtain baseline cultures and hematologic studies and a plastic surgery consult. If third-degree (full thickness) burns are suspected, treat any suspected wound infection aggressively after obtaining cultures. Severe and inordinate pain should be investigated as a possible sign of necrotizing fasciitis. After discharge, follow the patient’s progress at weekly intervals.
- Talk to the patient and her family. It is a good idea to explain the complication in very clear terms. I believe it is reasonable to explain how the complication occurred, without speculation or theatrical explanations. Also be sure to document this conversation, including date and time. It may be useful to have a neutral witness present during the conversation. By and large, the patient and her family are likely to appreciate an honest account of how the complication occurred. Hiding data or attempting to cover up the injury may motivate the patient to seek legal representation.
The long-term success of endometrial ablation devices as a whole depends on several conditions. Foremost, the entire class of devices should demonstrate efficacy on par with hysteroscopic ablation. Currently, efficacy ranges from 80% to 95% (short-term follow-up).11 The goal of minimally invasive procedures should be a sustainable 92% rate of amenorrhea, hypomenorrhea, or light, periodic menses. A long-term failure rate of 25% is unacceptable.22-24 If the devices can, by their simplicity, be adapted to more or less universal office application and attain a 5-year success rate of 90% or higher, they will become the standard of care.
One size does not really fit all
Serious complications from endometrial ablation devices occur with regular frequency and must be eliminated or greatly reduced. Perforation is a significant problem and may be related to the “one-size-fits-all” design of the device. Perhaps a range of sizes needs to be produced and fitted to the individual uterine cavity.
If such complications as perforation and burns to the bowel, cervix, vagina, and vulva can be eliminated or relegated to rarity, then a happy future for these procedures lies beyond the horizon.
Price ceiling should be set at $1,000
If an operation can consistently be performed for less than $1,000 total cost—the cost of in-hospital endometrial ablation—it will gain mass appeal. In hospitals and so-called surgicenters, ablations are expensive and, therefore, less attractive to self- or third-party payers. If fees are based on the volume of cases, then a procedure may be price-efficient.
Outcome depends on patient selection
Poorly screened patients who have underlying hyperplasia may develop postablation carcinoma. Women who have dysmenorrhea before the procedure can be predicted to suffer from it afterward. Older women (ie, 40 years or older) will have better long-term success than younger women. And women with a large uterus or myomas will have a higher failure rate than women with smaller cavities (ie, less than 10 cm in length).