A Unique Form of Endometrial Ablation Utilizing Direct Visualization;
Hydro ThermAblator® (HTA®) FDA 12-Month Registration Trial
Clinical Professor Obstetrics and Gynecology, UCLA School of Medicine, Los Angeles, CA, U.S.A.
There are four basic criteria that should be applied when considering any new Endometrial Ablation
Technology. These criteria are, safety, effectiveness, ease of use and low cost.
The Hydro ThermAblator® (HTA®) offers a revolutionary and simple alternative treatment for
menorrhagia – dysfunctional uterine bleeding. Unlike traditional hysteroscopic ablation technologies
that rely on the precise direct application of laser or electrosurgical energy to the entire lining of the
uterus, the HTA utilizes circulation of heated saline that fully conforms to the entire endometrial lining –
including the cornual areas. As a result, the outcome of Hydro ThermAblator treatment is far less
technical skill dependant than laser or electrosurgical techniques, and eliminates the risk of fluid
overload. Additionally, as a result, anatomical variations such as partial septate uterus do not prevent
effective HTA treatment.
The HTA consists of a microprocessor based control unit that connects to a single-patient disposable
fluid handling set with an integrated hysteroscope. The HTA’s continuous flow hysteroscopic sheath is
7.8mm diameter, constructed of insulated polycarbonate material. This hysteroscopic capability allows
an initial diagnostic hysteroscopy to confirm that no perforation or false passage has been created. With
this assurance the user can then initiate the for ten (10) minutes delivery of heated saline into the uterus
at low pressure at 90C to fully ablate the endometrium.
Since treatment with the HTA is performed under direct visualization, the physician has visual
confirmation of the sheath position before initiating the ablation treatment. The physician can observe
the heated saline circulating throughout the entire uterine cavity during the treatment cycle and confirm
the effect of the treatment. Patients treated utilizing local anesthesia can also observe the effect of the
treatment, which can have an analgesic effect.
The net operating pressure of the HTA is well below the minimum pressure required for fluid to traverse
the Fallopian tubes. The height of the fluid reservoir above the patient’s uterus, set nominally at 115 cm,
results in a net pressure within the uterine cavity of only 50-55 mmHg while fluid is circulating.. This
operating pressure is well below the known minimum tubal opening pressure of 70 mmHg. Over 2000
endometrial ablations have been completed worldwide with no incidence of collateral tissue injury due
to tubal leakage. In addition, the HTA’s safety system continuously monitors the amount of fluid being
circulated and will automatically interrupt the procedure if a loss of 10cc of fluid is detected. FDA Phase
III Clinical Study
The primary objective of the multi-center randomized controlled clinical study was to evaluate the safety
and effectiveness of thermal endometrial ablation using the Hydro ThermAblator (HTA) when
compared with existing ablation therapy (using Roller Ball treatment) to reduce excessive menstrual
bleeding or menorrhagia from benign causes. The study was a prospective and randomized 2:1
controlled clinical trial with patient follow-up conducted at 2 weeks, 3 months, 6 months, and 12 months
post treatment. 276 patients were enrolled into the clinical study. 181 patients received treatment with
the HTA® and 88 patients received treatment with Roller Ball. The primary endpoints of this study were
at six (6) at twelve (12) months. Success was defined as patients having a Janssen1 diary score of 75 or
less. Although statistical success is defined by a reduction in bleeding score, clinical experience has
demonstrated that even a 50% reduction in bleeding has improved patient symptoms. Therefore,
additional patient information, such as quality of life data, was gathered from a subjective menorrhagia
questionnaire, designed by Ruta2.
Inclusion criteria for the study included:
Documented excessive uterine bleeding as presented in the menstrual diary and calculation
worksheets as defined by Janssen. Excessive uterine bleeding or menorrhagia is defined as a score
on the calculation worksheet totaling > 150.
An endometrial cavity measuring < 10.5cm.
Intramural fibroids < 4 cm.
A patient > 30 and < 50 years of age, who had no previous endometrial ablation.
Previously failed, not tolerated, or refused medical therapy.
A normal endometrial biopsy & Pap smear.
The randomization scheme was in two parts: a. 2:1 (HTA® treatments to Roller Ball treatments by site;
b. 30-39 years old: 40-50 years old (specific age groups by site).
The mean age of the patients was 40.6 years. Table 1 depicts the baseline Janssen diary score for both
Pre-Treatment Evaluation and Preparation
Pretreatment evaluations were conducted to determine the size and shape of the uterus and the patients’
overall health was assessed. A pregnancy test was also administered pretreatment and on the day of
surgery to confirm a negative result. Approximately three (3) weeks prior to the endometrial ablation
procedure, pre-operative hormonal treatment was administered to produce endometrial atrophy. One (1)
dose of Lupron Depot® 7.5mg was administered to the patient intramuscularly on cycle day 21 (+ 2
days). The randomized treatment was scheduled 19 to 27 days later.
The study protocol did not dictate what type of anesthesia was to be used. The decision was left up to
the investigator, anesthesiologist and patient, and was often driven by the choice of location chosen to
perform the procedures (hospital, outpatient surgery center, or physician’s office). The choice of
anesthesia ranged from local anesthesia alone, local anesthesia with sedation or general anesthesia.
Fewer of the HTA procedures 55% (101/184) were completed with general anesthesia compared with
76% (65/85) of the Roller Ball cases. Paracervical block alone was used in 15% (28/184) of the HTA
cases and 9% (8/85) of Roller Ball cases. Paracervical block with intravenous sedation was used in 30%
(55/184) of the HTA cases as compared with 13% (11/85) of the Roller Ball cases.
HTA procedures were more frequently performed in an outpatient surgery center (OPSC) or office
compared to Roller Ball, as shown in Table 2.
The time elapsed for each ablation procedure was calculated as the number of minutes between the time
of completion of the surgical preparation to the time that the ablation device was removed from the
uterus. Recorded times included a pre-ablation one-minute uterine cavity flush in all cases. Recorded
times also included the time necessary for trouble shooting device performance incidents. In the clinical
study, the mean HTA time of procedure was 26.4 minutes as compared with 32.2 minutes for Roller
Ball. The percentage of HTA cases that were completed in 30 minutes or less, 71.0% (93/131), was
significantly higher than the 28.6% (36/126) of Roller Ball cases which were completed in 30 minutes or
Procedure and device related adverse events were statistically the same in both groups. The adverse
events that the patients experienced were similar to those events following any other endometrial
Recruitment of patients for the Phase III trial was completed in June 1999, with all patient treatments
completed by August 1999. Collection and analysis of the 12-month follow-up of the patients was
completed in September 2000 and final FDA approval was received on April 20, 2001. The final “per
protocol” analysis of patient diary scores equaling zero for 12 month follow up visits, when calculated
for those patients returning for their 12 month follow-up visit, provides the amenorrhea rates indicated in
The secondary endpoint analysis for this study was the Ruta Quality of Life questionnaire. As expected,
there was significant improvement in both groups of the study at 12 months follow-up. The analysis of
this data is shown in Table 5.
The Hydro ThermAblator® treatment has been shown to be clinically safe and statistically equivalent to
Roller Ball, both with respect to safety and effectiveness in treating menorrhagia via endometrial
ablation. Approximately three-quarters of the patients in both HTA and Roller Ball groups experienced a
clinically significant reduction in their menstrual bleeding as a result of the treatment received. The
primary endpoint in this study, decrease in bleeding as determined by a Janssen score of less than or
equal to 75 was at 12 months was met by 77% of HTA patients and 82% of Roller Ball patients in the
Per Protocol analysis. The between group difference is neither clinically nor statistically significant. The
second efficacy parameter was percent change in the Janssen score from the average pretreatment score
to the post treatment score at 12 months. There was an average 84.8% decrease in Janssen score for
HTA and 87.6% for Roller Ball patients at 12 months post treatment. This substantial decrease in
Janssen scores demonstrates the clinical utility of the HTA device.
In addition to the reduction in bleeding, the HTA treatment affords an additional benefit to the patient as
reflected in the greatly improved Quality of Life Scores at 12 months. The baseline QOL scores were
54.2 in the HTA group versus 53.3 in the Roller Ball group. The mean QOL scores at 12 months were
12.8 for the HTA group and 11.6 for the Roller Ball group.
The safety profile of the new HTA device was shown to be quite similar to that of experienced
practitioners utilizing the Roller Ball. The overall incidence of adverse events was similar in the two
groups. There were no reports of unanticipated adverse effects during this study. The HTA permits
constant visualization of the uterus before and during the treatment phase of the procedure. This affords
the clinician positive visual confirmation of proper placement of the device within the uterine cavity
prior to initiation of the therapeutic cycle. This eliminates the risk of treatment in the presence of a
uterine perforation or placement of the device in a false passage. There were no significant safety
concerns in the HTA group and the ability to monitor fluid in a closed loop system prevents the potential
for intravasation and hyponatremia or hypervolemia.
In conclusion, there is substantial evidence to conclude that the HTA therapy has equivalent efficacy and
safety as compared to Roller Ball in the treatment of premenopausal women with menorrhagia due to
JANSSEN CAH, Scholten PC, et al. “A Simple Visual Assessment Technique to Discriminate
Between Menorrhagia and Normal Blood Loss”, Obstetrics & Gynecology, Vol. 85, No. 6, June 1995.
RUTA, DA et al. “Assessment of Patients with Menorrhagia: How Valid is a Structured Clinical
History as a Measure of Health Status?” Quality of Life Research, Vol. 4, p. 33-40.
Table 1: Pre-Ablation Janssen Diary Scores
Table 2: Comparison of Procedures
Table 3: Phase III Adverse Events (3, 6, and 12 month Follow-up)
Table 4: Amenorrhea Rates (Diary score=0)
Table 5: Ruta Quality of Life Scores