Endometrioma is a type of ovarian cyst that develops secondary to the presence of endometriosis. It is, also, called ‘’chocolate cyst’’ due to the characteristic colour of the fluid it contains. 17% to 44% of women with endometriosis have an endometrioma (1), of which, in 19% to 28% of cases, the endometrioma is bilateral (2). The exact cause, as well the mechanism that leads to its development, are not entirely clear at this moment.

  It has been demonstrated that the presence of endometrioma per se leads to a decrease in the ovarian reserve, affecting in a negative way the quality of oocytes as well as the serum levels of anti-mullerian hormone (AMH), compared to women with no endometrioma of the same age (3,4). On the other hand, the surgical removal of endometrioma, albeit the method of choice following a Cochrane review (5), leads to a (at least temporarily) a reduction in the post-operative AMH levels (6).

  What happens, therefore, to those women who require surgery to the ovarian endometrioma and have low ovarian reserve pre-operatively or previous ovarian surgery and , at the same time, wish to maintain their fertility.

  In such cases, one can discuss with the woman, instead of removing the endometrioma, the option of draining the endometrioma, followed by ablation of the endometrioma cyst wall. Since ablation of the cyst wall by the use of bipolar energy leads to significant loss of ovarian reserve due to an undesired, ‘’deeper’’ burning effect (7), we have 2 remaining options: ablation of endometrioma by Laser and ablation of endometrioma by Plasma energy.

   The use of various laser types (KTP, CO2, Diode, Argon) leads to ablation to a smaller depth of 1.0 to 1.5 millimetres (8), being ‘’friendlier’’ to the healthy ovarian tissue while, at the same time, allows for a precise treatment of endometrioma. The use of Plasma energy is based on the same idea, leading to an ablation at a depth of 0.6 millimetres (9). Both types of energy can be used for the removal of other endometriosis lesions (outside the ovary) as well. Of course, since the ovarian cyst is not excised and removed, the main concern is that of recurrence (re-appearance) of the endometrioma post-operatively.

  So, what do the published studies tell us about the use of Laser in endometrioma surgery? In a study by Shimizu et al., the use of this technique was associated with a post-operative pregnancy rate of 75.6% (spontaneous or IVF) in patients with infertility of an average duration of 42 months (10). In a study by Ottolina et al., laser ablation of endometrioma led to an improvement in the ovarian reserve, as measured by the use of ultrasound ( Antral Follicular Count, AFC), particularly in women younger than 35 years of age (11). Compared to endometrioma excision, a comparative study demonstrated that laser ablation is associated with a higher risk of post-operative recurrence in the short term, however, the difference is not statistically significant in the long term (6 years after surgery). The same study did not show a significant difference between the 2 techniques in terms of ovarian reserve (AMH and AFC) and pregnancy rates were, also, comparable (12). In another study that compared the 2 techniques, laser ablation led to an improvement in AFC and smaller reduction in post-operative AMH levels (13). The laser technique in ‘’3-steps’’ ( drainage of the endometrioma, followed by 3-month administration of Gnrh analogues and, then, ablation of the cyst by laser) led to an improvement in AFC levels (14,15).

  As regards the use of Plasma energy for endometrioma, a study by Roman et al. demonstrated post-operative pregnancy rates of 67% while, 3 years post-operatively, the recurrence rate was around 11% (16). As regards the post-operative AMH levels, another study demonstrated a reduction at 3 months post-operatively which, however, was not statistically significant at 6 months after the operation (17). The presence of endometriomas bilaterally appears to be associated with a higher risk of recurrence, whilst the concurrent removal of other endometriosis lesions (eg colorectal endometriosis lesions) does not reduce the ovarian reserve any further (18). A retrospective study demonstrated that ablation of endometriomas by plasma energy also led to a significant improvement in pain symptoms (19).

  In summary, ablation of endometrioma by laser or plasma energy appears to be ‘’friendlier’’ to the ovarian tissue, compared to surgical excision, leading, possibly, to a smaller reduction in AMH levels post-operatively. However, the risk of endometrioma recurrence remains a concern, since the actual cyst is ablated, rather than removed. These techniques are a valid alternative for those patients with low AMH levels pre-operatively, as well as those with previous ovarian surgeries who wish to maintain their fertility.

References:

1. Chapron, C.; Vercellini, P.; Barakat, H.; Vieira, M.; Dubuisson, J.-B. Management of ovarian endometriomas. Hum. Reprod. Update 2002, 8, 591–597.
2. Younis, J.S.; Shapso, N.; Fleming, R.; Ben-Shlomo, I.; Izhaki, I. Impact of unilateral versus bilateral ovarian endometriotic cystectomy on ovarian reserve: A systematic review and meta-analysis. Hum. Reprod. Update 2018, 25, 375–391.
3. Younis, J.S.; Shapso, N.; Fleming, R.; Ben-Shlomo, I.; Izhaki, I. Impact of unilateral versus bilateral ovarian endometriotic cystectomy on ovarian reserve: A systematic review and meta-analysis. Hum. Reprod. Update 2018, 25, 375–391.
4. Yılmaz Hanege B, Güler Çekıç S, Ata B. Endometrioma and ovarian reserve: effects of endometriomata per se and its surgical treatment on the ovarian reserve. Facts Views Vis Obgyn. 2019 Jun;11(2):151-157.
5. Hart RJ, Hickey M, Maouris P, Buckett W. Excisional surgery versus ablative surgery for ovarian endometriomata. Cochrane Database Syst Rev. 2008 Apr 16;(2):CD004992. doi: 10.1002/14651858.CD004992.pub3. 
6. Vignali M, Mabrouk M, Ciocca E, Alabiso G, Barbasetti di Prun A, Gentilini D, Busacca M. Surgical excision of ovarian endometriomas: Does it truly impair ovarian reserve? Long term anti-Müllerian hormone (AMH) changes after surgery. J Obstet Gynaecol Res. 2015 Nov;41(11):1773-8. doi: 10.1111/jog.12830.
7. Song T, Kim WY, Lee KW, Kim KH. Effect on ovarian reserve of hemostasis by bipolar coagulation versus suture during laparoendoscopic single-site cystectomy for ovarian endometriomas. J Minim Invasive Gynecol. 2015 Mar-Apr;22(3):415-20. doi: 10.1016/j.jmig.2014.11.002.
8. Donnez J, Wyns C, Nisolle M. Does ovarian surgery for endometriomas impair the ovarian response to gonadotropin? Fertil Steril 2001;76:662–665.
9. Roman H, Auber M, Bourdel N, Martin C, Marpeau L, Puscasiu L. Postoperative recurrence and fertility after endometrioma ablation using plasma energy: retrospective assessment of a 3-year experience. J Minim Invasive Gynecol. 2013 Sep-Oct;20(5):573-82. doi: 10.1016/j.jmig.2013.02.016.
10. Shimizu Y, Takashima A, Takahashi K, Kita N, Fujiwara M, Murakami T. Long-term outcome, including pregnancy rate, recurrence rate and ovarian reserve, after laparoscopic laser ablation surgery in infertile women with endometrioma. J Obstet Gynaecol Res. 2010 Feb;36(1):115-8. doi: 10.1111/j.1447-0756.2009.01119.x.
11. Ottolina J, Castellano LM, Ferrari S, et al. The Impact on Ovarian Reserve of CO2 Laser Fiber Vaporization in the Treatment of Ovarian Endometrioma: A Prospective Clinical Trial. Journal of Endometriosis and Pelvic Pain Disorders. 2017;9(3):206-210.
12. Carmona F, Martínez-Zamora MA, Rabanal A, Martínez-Román S, Balasch J. Ovarian cystectomy versus laser vaporization in the treatment of ovarian endometriomas: a randomized clinical trial with a five-year follow-up. Fertil Steril. 2011 Jul;96(1):251-4.
13. Candiani M, Ottolina J, Posadzka E, Ferrari S, Castellano LM, Tandoi I, Pagliardini L, Nocun A, Jach R. Assessment of ovarian reserve after cystectomy versus ‘one-step’ laser vaporization in the treatment of ovarian endometrioma: a small randomized clinical trial. Hum Reprod. 2018 Dec 1;33(12):2205-2211.
14. Tsolakidis D, Pados G, Vavilis D, Athanatos D, Tsalikis T, Giannakou A, Tarlatzis BC. The impact on ovarian reserve after laparoscopic ovarian cystectomy versus three-stage management in patients with endometriomas: a prospective randomized study. Fertil Steril. 2010 Jun;94(1):71-7. doi: 10.1016/j.fertnstert.2009.01.138.
15. Pados G, Tsolakidis D, Assimakopoulos E, Athanatos D, Tarlatzis B. Sonographic changes after laparoscopic cystectomy compared with three-stage management in patients with ovarian endometriomas: a prospective randomized study. Hum Reprod. 2010 Mar;25(3):672-7. doi: 10.1093/humrep/dep448.
16. Roman H, Auber M, Bourdel N, Martin C, Marpeau L, Puscasiu L. Postoperative recurrence and fertility after endometrioma ablation using plasma energy: retrospective assessment of a 3-year experience. J Minim Invasive Gynecol. 2013 Sep-Oct;20(5):573-82.
17. Roman H, Bubenheim M, Auber M, Marpeau L, Puscasiu L. Antimullerian hormone level and endometrioma ablation using plasma energy. JSLS. 2014 Jul-Sep;18(3):e2014.00002.
18. Roman H, Quibel S, Auber M, Muszynski H, Huet E, Marpeau L, Tuech JJ. Recurrences and fertility after endometrioma ablation in women with and without colorectal endometriosis: a prospective cohort study. Hum Reprod. 2015 Mar;30(3):558-68. doi: 10.1093/humrep/deu354.