Obgyno Wino Podcast Episode 57 - Endometrial Ablation
"The pendulum of the mind oscillates between sense and nonsense, not between right and wrong.” - Carl Jung
PB#81 - Published May 2007 (Reaffirmed 2018)
1. Both resectoscopic and non-resectoscopic techniques are safe and effective.
2. Size and shape of the uterine cavity and the presence of fibroids may impact efficacy of non-resectoscopic techniques
3. With resectoscopic techniques, careful monitoring of distension medium fluid is important. If too much fluid intravasates, dilutional electrolyte imbalances can have serious consequences.
4. Ablation is not recommended for patients who wish to preserve fertility.
5. Sample the endometrium before performing an ablation to evaluate for hyperplasia or malignancy.
The basics for counseling
- treats heavy menstrual bleeding that is dangerous due to resulting severe anemia or annoying according to a woman's perception
- contraindicated if future fertility is desired
- women who undergo ablation should expect a decrease in their menses (hopefully to their "normal" or acceptable level) but amenorrhea isn't guaranteed
- risks are technique specific (see below)
What to know before you discuss techniques
- bimanual exam to evaluate size and shape of uterus
- TVUS to determine cavity length and evaluate for intrauterine lesions like fibroids (a sound can also be used to determine cavity length if TVUS not available)
- endometrial biopsy (EMB) to evaluate for endometrial hyperplasia or malignancy
- hysteroscopy or saline-infusion sonohysterogram can also help to evaluate the nature of the cavity
Six techniques currently available
Resectoscopic ablation is in a category of it's own: under hysteroscopic (video) guidance, a device that emits radio-frequency-alternating current is used to vaporize tissue (LESS COMMON)
Non-resectoscopic ablation techniques: all require dilation of the cervix and insertion of a device (MORE COMMON); all methods have safety measures to prevent injury
i) cryotherapy: areas around the cornua are frozen (takes 10 minutes or so), this can be repeated lower in the uterine cavity if necessary; ultrasound guidance is optional
ii) heated free fluid: scalding hot water is infused into the cavity and a tight seal is made at the cervix, water does its thing for 10 minutes, then it's cooled, and the water is sucked back out
iii) microwave: probe is guided under direct visualization to the cornua and then microwave frequency is emitted as operator zaps the lining throughout the cavity iv) radiofrequency: a mesh electrode is deployed within the cavity and radio waves are used to vaporize the lining in about 90 seconds, no visual guidance is necessary v) thermal balloon: balloon is inserted through cervix and filled with super hot 5% dextrose solution
How well does resectoscopic ablation work?
- well...compared to what?
- most studies compare efficacy (measured as patient satisfaction and control of bleeding) of ablation to hysterectomy
- patient satisfaction is higher with hysterectomy (although patients are highly satisfied with both)
- likelihood of amenorrhea is higher with hysterectomy (for obvious reasons)
- fewer post-op complications, shorter hospital stay, and quicker resumption of normal activities with ablation, though
- for women who are pre-menopausal, about 36% will require re-operation within 4 years of the initial ablation (24% will pursue hysterectomy)
Note: Very little data to support one resectoscopic method over another. What matters most is probably operator experience
How well does non-resectoscopic ablation work?
- the data mostly compare the different techniques to resectoscopic ablation
- 1 year follow-up data is in Table 1; further comparison data is as follows:
- comparable to resectoscopic ablation at 2 years
- one decent study that followed up with women for 5 years found that of 260 women who underwent thermal balloon ablation, 188 were available for follow-up and 75% had not required surgery, 21 required repeat ablation and 25 had undergone hysterectomy.
- the thermal balloon technique also doesn't carry as high a risk of uterine perforation or excess absorption of distension medium as resectoscopic techniques
- studies confined only to uterine cavities that have sounded to 10 cm in length or less as well as the in the absence of submucosal fibroids
- data is limited due to high attrition rate in follow-up efforts
- in a study of 279 women: 193 randomized to cryotherapy, 86 to resectoscopic ablation; at 1- year follow-up,156 women were still in touch in the cryotherapy group, and 72 from the resectoscopic ablation group; bleeding was controlled in 84% and 89% of those women, respectively
Heated free fluid
- the biggest published clinical trial compared heated fluid w/ resectoscopic ablation; 276 women were enrolled (177 to heated free fluid group, 99 to resectoscopic ablation); none had submucosal fibroids and polyps
- they were followed-up at 1 year and 3 years post-procedure; 167 of the heated fluid group were available for follow-up at 1 year, 135 at 3 years
- at 1-year follow-up, 127 (94%) reported reduced bleeding to "normal" or less; 72 (53%) reported amenorrhea!
- similar results for resectoscopic group (91% and 46%, respectively)
- results were also similar for patient satisfaction at 3 years: 98% and 97%, respectively
- at 3-year follow-up, 9% and 6% of patients underwent hysterectomy in the free fluid and resectoscopic groups, respectively (2% and 4% for repeat ablation)
- retrospective studies have shown similar results even when submucosal fibroids are present (no prospective data, though)
- 1st RCT: 263 women randomized to microwave (129) or resectocopic ablation (134); followed-up at 1, 2, and 5 years; low attrition; excluded patients with submucosal fibroids
- at 1 year, 75% of patients in both groups were satisfied with the outcome
- at 5 years, both groups reported significant reduction in both bleeding and pain; amenorrhea rates were also similar (65% and 70%, respectively)
- the only difference was in overall satisfaction rates at 5-year mark: 86% versus 74%, respectively
- 2nd RCT: 322 participants, similar results, included patients with submucosal fibroids up to 3cm in size
- RCT compared Novasure against resectoscopic abalation; 265 women enrolled (submucosal fibroids <2 cm were included but subanalysis wasn't performed)
- at 1 year: 88% and 81%, respectively, reported improved bleeding; amenorrhea rates also comparable (41% and 35%, respectively); 3 hysterectomies compared to 2, >90% satisfaction in both groups
- follow-up prospective studies have found that the high satisfaction rates and low subsequent surgical rates remain low at 3 and 4 years
How do the non-resectoscopic techniques compare to one another?
- paucity of literature comparing the techniques in head to head, randomized trials
- best to infer from the data comparison each technique to resectoscopic techniques
How well does endometrial ablation work compared to systemic medical therapy?
- one well-done study randomized patients w/ heavy bleeding to combined oral contraception (COC) or resectoscopic ablation: by 5 years, only 10% of patients of the patients on COC were doing well, and 77% had gone on to have more definitive surgery like hysterectomy; of the patients who were randomized to ablation, only 27% had undergone surgery
How does ablation compare to intrauterine medical therapy?
- comparable satisfaction at 1 year when compared with intrauterine levonorgestrel-releasing system (e.g. Mirena)
- no difference of degree of bleeding by 2 or 3 years, though ablation outperforms the IUD in the 1st year
Do I need to pre-treat before ablation?
- data on pre-treatment before resectoscopic ablation: pre-treatment w/ danazol or a GnRH agonist may result in: shorter procedure, easier procedure, less post-op pain, and greater likelihood of achieving amenorrhea in the short-term (insufficient data to speak to long-term amenorrhea)
- data on pre-treatment before non-resectoscopic ablation: insufficient data to compare, as most data was collected after pre-treatment; most of these techniques only achieve ablation to a depth of 4-6 mm, so it would make sense that pre-treatment would be helpful. You can go as deep as you want with a resectoscope!
Note: Danazol is an androgen receptor agonist
Possible complications associated with endometrial ablation
- resectoscopic and non-resectoscopic techniques have been associated with adverse events
- Table 2 shows the percentages for various minor adverse events; other events are elaborated further
- resectoscopic techniques are uniquely associated w/ risk for distension media fluid overload and resulting electrolyte disturbances; both both resectoscopic and non-resectoscopic techniques carry risks of uterine perforation, injury to nearby organs, and injury to the cervix and vagina
Distension media fluid overload
- pretty straightforward: while ablating resectoscopically, you will expose blood vessels, and the high pressure from the distension media fluid may lead to intravasation of the fluid into systemic absorption
- because the resectoscope are generally monopolar, a non-conductive fluid must be used (e.g. electrolyte-free fluids such as 3% sorbitol, 1.5% glycine, and 5% mannitol)
- if this fluid intravasates at sufficient volume, it can cause profound dilutional hyponatremia and hypoosmolality
- what happens to cells in a hypoosmolar environment? they swell!
- so this issue of intravasation can lead to brain edema and permanent brain damage (even more likely in pre-menopausal women as estrogen and progesterone exhibit inhibitory effects on brain cells' sodium pumps)
- for these reasons, management of fluids during resectoscopic procedures is critical (consider fluid on the floor, inside the patient, and inside the device to monitor a running total!)
- new bipolar instruments have been developed that allow use for normal saline, but you must still watch for volume overload
- perforation of the uterine corpus or laceration of the cervix have been documented with both resectoscopic and non-resectoscopic techniques, but more commonly seen in the former
- highly dependent on operator experience
- injecting intracervical vasopressin can minimize the force required for dilation
- to avoid injury to viscera in the event of perforation, electrode should only be activated when visualization is optimal
- laparoscopic exploration may be warranted if there's any doubt
Thermal injury to cervix, vagina, or vulva
- most likely to occur through coupling while using a polar resectoscopic instrument (can't happen with bipolar instruments)
- can also occur if hot fluid is permitted to leak from the uterine cavity into the vagina if using heated free fluid
- all around low risk for either scenario
Post-ablation tubal ligation syndrome
- phenomenon of cyclical pain post-ablation in patients who underwent tubal occlusion for the purpose of contraception prior to the ablation
- thought to be due to endometrial tissue trapped in the tube (tubal ostia obliterated proximally by the ablation and tube itself occluded distally by prior occlusive procedure like fulguration or salpingectomy)
- incidence is thought to be as high as 10% in this scenario; lower likelihood if laparoscopic salpingectomy is performed concurrently at time of ablation procedure
- pain generally won't resolve with full salpingectomy after the fact; hysterectomy may be the only fix
- rare scenario post-ablation
- if it does happen, it carries a higher risk of malpresentation, placenta accreta, prematurity, and perinatal mortality
- the tissue is scarred over and a past concern was that the absence of bleeding may delay the diagnosis of endometrial cancer
- this hasn't panned out
- still...best to get an EMB before the procedure to evaluate for occult disease
- about a 1% chance with both resectoscopic and non-resectoscopic techniques
- responds well to antibiotics
Do these procedures require anesthesia?
- local anesthesia and procedural sedation have both been described in the literature (neither beneficial over the other)
- you can consider paracervical blocks w/ oral non-steroidal anti-inflammatories (similar to office hysteroscopy)
Note: Uterine cervix is innervated by S2-3; the corpus is innervated by T8-10
Can I use non-resectoscopic techniques in the presence of fibroids?
- microwave and thermal balloon techniques have demonstrated efficacy at least in situations in which submucosal fibroids are <3 cm in size (see above)
- there's less quality evidence of radiofrequency and heated free fluid techniques
Contraindications to ablation
- non-resectoscopic techniques are recommended in patients with significantly distorted uterine cavities
- also not recommended if cavity size exceeds manufacturer's recommendation (Table 3)
- resectoscopic techniques may still be indicated even in larger cavities given success is more closely related to operator experience as opposed to anatomical features
- the use of pre-treatment with GnRH analog, for example, hasn't been specifically studied as a means of improving efficacy of abalation in the presence of submucosal fibroids
- likewise, no data to guide counseling in the event of disorder of mullerian fusion or absorption
- contraindications: recent pregnancy, documented hyperplasia or malignancy, or recent infection
- be careful if they previously have endometrial or uterine surgery, as thin areas of myometrium may more likely be perforated (in fact, w/ the Microwave Endometrial Ablation System, pre-procedural ultrasound measurement of myometrial thickness is recommended and use of the device is not recommended if any part of the myometrium is <10 mm)