In a nutshell:

Endometrial ablation uses heat energy to destroy the inner lining of the uterus. The adenomyosis tissue within the uterine muscle wall remains untreated. More glands are now trapped, making pain worse.

Adenomyosis and Ablation Failure

Endometrial ablation is a procedure that uses an energy source to destroy the inner lining of the uterus, so there will no longer be menstrual bleeding. The energy might be heat (hot water, hot wires), laser, radiofrequency waves, or microwaves. Ablation can be an effective treatment in 90% of women with heavy menstrual bleeding. However, studies have shown the presence of adenomyosis predicts a poor outcome and usually results in persistent or worsening period pain.

This is not difficult to understand. Adenomyosis is a disease caused by migration of the endometrial gland (adeno) into the muscle layer (myosis). When energy is used to destroy the lining of the uterus, more adenomyotic tissue is trapped within the muscle layer, so therefore, worsening pain is not surprising. Premenstrual bloating, a common symptom of adenomyosis, is also likely to be worse, as more glands are now trapped.

Modern ablation uses radiofrequency energy to generate local heat to destroy the lining of the uterine cavity. The device is inserted and then expanded to be in contact with the endometrial lining. However, only up to 4-9mm of tissue is heated and destroyed. We often use a junctional zone thickness of 12mm as an MRI diagnostic criterion for adenomyosis. Therefore, all of the adenomyosis that we can confidently diagnose on MRI, would have adenomyosis involvement deeper than an ablation device can treat. In other words, if the diagnosis of adenomyosis is made on MRI criteria, ablation is likely to fail.

In a 2013 study on women who failed endometrial ablation and had subsequent hysterectomy, adenomyosis was found in 43% of cases.

In 2019, a review study published in “Obstetrics & Gynecology”, a prestigious journal, has identified “period pain” as the strongest predictor of ablation failure. Period pain, in the presence of heavy menstrual bleeding, suggests underlying adenomyosis or the coexistence of endometriosis. The review stated that both conditions are difficult to recognize on an ultrasound and therefore can be easily missed.  The pain associated with both of these conditions should not be treated by ablation. The presence of period pain alone is a significant factor in predicting poor patient outcome from ablation.

Many women who had worsening of pain following ablation were treated with hysterectomy. Studies has shown that UAE is effective in treating adenomyosis related heavy bleeding and pain. UAE treats adenomyosis anywhere the disease is present and therefore potentially useful to treating pain as well as ongoing bleeding, related to ablation failure.

 

References

 

  1. Prognostic Factors for the Failure of Endometrial Ablation: A Systematic Review and Meta-analysis. Beelen, A., Pleun ; Reinders, W., Imke M. ; Scheepers, C., Wessel F. ; Herman, J., Malou ; Geomini, J., Peggy M. A. ; Van Kuijk, Y., Sander M. ; Bongers, Y., Marlies Obstetrics & Gynecology, 2019, Vol.134(6), pp.1269-1281

 

  1. Morphological changes in hysterectomies after endometrial ablation. Tresserra F, Grases P, Ubeda A, Pascual MA, Grases PJ, Labastida R.  Hum Reprod. 1999;14(6):14731477

 

  1. Long-term complications of endometrial ablation: cause, diagnosis, treatment, and prevention. McCausland AM, McCausland VM.  J Minim Invasive Gynecol. 2007;14(4):399406

 

  1. Characteristics of patients undergoing hysterectomy for failed endometrial ablation

Riley, Kristin A ; Davies, Matthew F ; Harkins, Gerald J; Riley, Kristin A (correspondence author) ; Riley, Kristin A (record owner)JSLS : Journal of the Society of Laparoendoscopic Surgeons, 2013 Oct-Dec, Vol.17(4), pp.503-507

https://www.accessdata.fda.gov/cdrh_docs/pdf/P010013b.pdf