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An overview of endometrial ablation

Howard T Sharp, MD
Section Editor
Tommaso Falcone, MD, FRCSC, FACOG
Deputy Editor
Sandy J Falk, MD, FACOG


Women with abnormal uterine bleeding have a variety of therapeutic options. Endometrial ablation has become an increasingly popular treatment, since it is minimally invasive and successful ablation avoids chronic use of medications. In a national study in England from 2003 to 2006, 60 percent of all surgical procedures performed for menorrhagia were endometrial ablations [1].

Endometrial ablation is the surgical destruction of the uterine lining. This can be accomplished under hysteroscopic visualization, using resectoscopic instruments to ablate or resect the endometrium. It can also be performed with a non-resectoscopic ablation device, which is inserted into the uterine cavity and delivers energy to uniformly destroy the uterine lining. Non-resectoscopic endometrial ablation techniques are more widely practiced than resectoscopic ablation, since they require less specialized training and often have a shorter operative time [2]. Endometrial ablation is not appropriate for women with endometrial hyperplasia or cancer, or those who wish to preserve their fertility.

This topic review will provide an overview of endometrial ablation. Techniques for non-resectoscopic endometrial ablation and resectoscopic endometrial ablation or resection, as well as other management options for abnormal uterine bleeding, are discussed separately. (See "Endometrial ablation: Non-resectoscopic techniques" and "Endometrial ablation or resection: Resectoscopic techniques" and "Management of abnormal uterine bleeding".)


Terminology used to describe endometrial ablation varies. In this topic review, the following terms will be used:

Endometrial ablation – Surgical destruction of the endometrium. The endometrium must be destroyed or resected to the level of the basalis (figure 1), which is approximately 4 to 6 mm deep, depending upon the stage of the menstrual cycle. In this topic review, endometrial ablation will refer to either non-resectoscopic ablation or resectoscopic ablation, or resection of the endometrium.


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  1. Cromwell DA, Mahmood TA, Templeton A, van der Meulen JH. Surgery for menorrhagia within English regions: variation in rates of endometrial ablation and hysterectomy. BJOG 2009; 116:1373.
  2. Deb S, Flora K, Atiomo W. A survey of preferences and practices of endometrial ablation/resection for menorrhagia in the United Kingdom. Fertil Steril 2008; 90:1812.
  3. Sharp HT. Assessment of new technology in the treatment of idiopathic menorrhagia and uterine leiomyomata. Obstet Gynecol 2006; 108:990.
  4. ACOG Committee on Practice Bulletins. ACOG Practice Bulletin. Clinical management guidelines for obstetrician-gynecologists. Number 81, May 2007. Obstet Gynecol 2007; 109:1233.
  5. Lo JS, Pickersgill A. Pregnancy after endometrial ablation: English literature review and case report. J Minim Invasive Gynecol 2006; 13:88.
  6. Xia E, Li TC, Yu D, et al. The occurrence and outcome of 39 pregnancies after 1621 cases of transcervical resection of endometrium. Hum Reprod 2006; 21:3282.
  7. Ammar K, Koukoura O. Management of menorrhagia with hydrothermal endometrial ablation in 2 women with bicornuate uteri. J Minim Invasive Gynecol 2009; 16:795.
  8. Thamban S, Garg S, Al-Habib A, El-Farra KE. Thermal balloon endometrial ablation in bicornuate uteri. J Obstet Gynaecol 2007; 27:324.
  9. Zarek S, Sharp HT. Global endometrial ablation devices. Clin Obstet Gynecol 2008; 51:167.
  10. Gangadharan A, Revel A, Shushan A. Endometrial thermal balloon ablation in women with previous cesarean delivery: pilot study. J Minim Invasive Gynecol 2010; 17:358.
  11. Khan Z, El-Nashar SA, Hopkins MR, Famuyide AO. Efficacy and safety of global endometrial ablation after cesarean delivery: a cohort study. Am J Obstet Gynecol 2011; 205:450.e1.
  12. http://www.accessdata.fda.gov/cdrh_docs/pdf2/P020031b.pdf (Accessed on May 26, 2010).
  13. Lissak A, Lavie O, Dirnfeld M, et al. Endometrial ablation for the postmenopausal woman. J Am Assoc Gynecol Laparosc 2001; 8:601.
  14. Practice Committee of American Society for Reproductive Medicine. Indications and options for endometrial ablation. Fertil Steril 2008; 90:S236.
  15. Neuwirth RS, Loffer FD, Trenhaile T, Levin B. The incidence of endometrial cancer after endometrial ablation in a low-risk population. J Am Assoc Gynecol Laparosc 2004; 11:492.
  16. Krogh RA, Lauszus FF, Guttorm E, Rasmussen K. Surgery and cancer after endometrial resection. Long-term follow-up on menstrual bleeding and hormone treatment by questionnaire and registry. Arch Gynecol Obstet 2009; 280:911.
  17. Gimpelson RJ. Not so benign endometrial hyperplasia: endometrial cancer after endometrial ablation. J Am Assoc Gynecol Laparosc 1997; 4:507.
  18. Horowitz IR, Copas PR, Aaronoff M, et al. Endometrial adenocarcinoma following endometrial ablation for postmenopausal bleeding. Gynecol Oncol 1995; 56:460.
  19. Valle RF, Baggish MS. Endometrial carcinoma after endometrial ablation: high-risk factors predicting its occurrence. Am J Obstet Gynecol 1998; 179:569.
  20. Sagiv R, Ben-Shem E, Condrea A, et al. Endometrial carcinoma after endometrial resection for dysfunctional uterine bleeding. Obstet Gynecol 2005; 106:1174.
  21. Baggish, MS, Ringgenberg, E, Sze, EHM. Adenocarcinoma of corpus uteri following endometrial ablation. J Gynecol Surg 1995; 11:91.
  22. Iqbal PK, Paterson ME. Endometrial carcinoma after endometrial resection for menorrhagia. Br J Obstet Gynaecol 1997; 104:1097.
  23. Brooks-Carter GN, Killackey MA, Neuwirth RS. Adenocarcinoma of the endometrium after endometrial ablation. Obstet Gynecol 2000; 96:836.
  24. Margolis MT, Thoen LD, Boike GM, et al. Asymptomatic endometrial carcinoma after endometrial ablation. Int J Gynaecol Obstet 1995; 51:255.
  25. Klein, Z, Markovitch, O, Altaras, M, et al. Advanced endometrial adenocarcinoma following endometrial ablation: a case report and review of the literature. Int J Gynecol Cancer 1997; 7:163.
  26. Friberg B, Joergensen C, Ahlgren M. Endometrial thermal coagulation--degree of uterine fibrosis predicts treatment outcome. Gynecol Obstet Invest 1998; 45:54.
  27. Leung PL, Tam WH, Yuen PM. Hysteroscopic appearance of the endometrial cavity following thermal balloon endometrial ablation. Fertil Steril 2003; 79:1226.
  28. Taskin O, Onoglu A, Inal M, et al. Long-term histopathologic and morphologic changes after thermal endometrial ablation. J Am Assoc Gynecol Laparosc 2002; 9:186.
  29. Onoglu A, Taskin O, Inal M, et al. Comparison of the long-term histopathologic and morphologic changes after endometrial rollerball ablation and resection: a prospective randomized trial. J Minim Invasive Gynecol 2007; 14:39.
  30. Ahonkallio SJ, Liakka AK, Martikainen HK, Santala MJ. Feasibility of endometrial assessment after thermal ablation. Eur J Obstet Gynecol Reprod Biol 2009; 147:69.
  31. Copperman AB, DeCherney AH, Olive DL. A case of endometrial cancer following endometrial ablation for dysfunctional uterine bleeding. Obstet Gynecol 1993; 82:640.
  32. Kindelberger, D, Harvard University School of Medicine, 2010, personal communication.
  33. AlHilli MM, Hopkins MR, Famuyide AO. Endometrial cancer after endometrial ablation: systematic review of medical literature. J Minim Invasive Gynecol 2011; 18:393.
  34. Capuano I, Caporale A, Vagnetti P, et al. [Endometrial ablation versus hysterectomy in women treated with tamoxifen]. Minerva Ginecol 2007; 59:499.
  35. Goldenberg M, Nezhat C, Seidman DS. A randomized prospective study of the use of endometrial ablation for prevention of recurrent endometrial polyps in breast cancer patients receiving tamoxifen. Prim Care Update Ob Gyns 1998; 5:160.
  36. Römer T. Successful treatment of recurrent uterine bleeding during tamoxifen therapy by endometrial ablation. Int J Gynaecol Obstet 1995; 49:51.
  37. Fadare O, Wang SA, Renshaw IL. Does the radiofrequency impedance-controlled endometrial ablation have any morphologic effects on uterine leiomyomata? Report of 3 cases. Diagn Pathol 2008; 3:28.
  38. http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cftopic/pma/pma.cfm?num=p020031 (Microwave Endometrial Ablation) (Accessed on June 09, 2010).
  39. http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cftopic/pma/pma.cfm?num=p000032 (Her Option) (Accessed on June 09, 2010).
  40. Cooper JM, Anderson TL, Fortin CA, et al. Microwave endometrial ablation vs. rollerball electroablation for menorrhagia: a multicenter randomized trial. J Am Assoc Gynecol Laparosc 2004; 11:394.
  41. Glasser MH, Heinlein PK, Hung YY. Office endometrial ablation with local anesthesia using the HydroThermAblator system: Comparison of outcomes in patients with submucous myomas with those with normal cavities in 246 cases performed over 5(1/2) years. J Minim Invasive Gynecol 2009; 16:700.
  42. Glasser MH, Zimmerman JD. The HydroThermAblator system for management of menorrhagia in women with submucous myomas: 12- to 20-month follow-up. J Am Assoc Gynecol Laparosc 2003; 10:521.
  43. Rosenbaum SP, Fried M, Munro MG. Endometrial hydrothermablation: a comparison of short-term clinical effectiveness in patients with normal endometrial cavities and those with intracavitary pathology. J Minim Invasive Gynecol 2005; 12:144.
  44. Sabbah R, Desaulniers G. Use of the NovaSure Impedance Controlled Endometrial Ablation System in patients with intracavitary disease: 12-month follow-up results of a prospective, single-arm clinical study. J Minim Invasive Gynecol 2006; 13:467.
  45. Soysal ME, Soysal SK, Vicdan K. Thermal balloon ablation in myoma-induced menorrhagia under local anesthesia. Gynecol Obstet Invest 2001; 51:128.
  46. http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cftopic/pma/pma.cfm?num=p010013 (Novasure) (Accessed on June 09, 2010).
  47. www.ethicon360.com/products/gynecare-thermachoice-uterine-balloon-therapy-system (Accessed on June 09, 2010).
  48. McCausland AM, McCausland VM. Partial rollerball endometrial ablation: a modification of total ablation to treat menorrhagia without causing complications from intrauterine adhesions. Am J Obstet Gynecol 1999; 180:1512.
  49. Bae IH, Pagedas AC. Comparison of Partial and Complete Endomyometrial Resection with Rollerball Endometrial Ablation. J Am Assoc Gynecol Laparosc 1996; 3:S2.
  50. El-Nashar SA, Hopkins MR, Creedon DJ, et al. Prediction of treatment outcomes after global endometrial ablation. Obstet Gynecol 2009; 113:97.
  51. El-Nashar SA, Hopkins MR, Feitoza SS, et al. Global endometrial ablation for menorrhagia in women with bleeding disorders. Obstet Gynecol 2007; 109:1381.
  52. (Accessed on June 09, 2010).
  53. Sowter MC, Lethaby A, Singla AA. Pre-operative endometrial thinning agents before endometrial destruction for heavy menstrual bleeding. Cochrane Database Syst Rev 2002; :CD001124.
  54. Shawki O, Peters A, Abraham-Hebert S. Hysteroscopic endometrial destruction, optimum method for preoperative endometrial preparation: a prospective, randomized, multicenter evaluation. JSLS 2002; 6:23.
  55. Bhatia K, Doonan Y, Giannakou A, Bentick B. A randomised controlled trial comparing GnRH antagonist cetrorelix with GnRH agonist leuprorelin for endometrial thinning prior to transcervical resection of endometrium. BJOG 2008; 115:1214.
  56. www.novasure.com/novasure-procedure/novasure-instructions.cfm (Accessed on February 16, 2010).
  57. Lissak A, Fruchter O, Mashiach S, et al. Immediate versus delayed treatment of perimenopausal bleeding due to benign causes by balloon thermal ablation. J Am Assoc Gynecol Laparosc 1999; 6:145.
  58. Huang MC, Chen CP, Su TH, et al. The safety and efficacy of microwave endometrial ablation after endometrial curettage without hormonal pretreatment. Taiwan J Obstet Gynecol 2007; 46:152.
  59. Jack SA, Cooper KG, Seymour J, et al. A randomised controlled trial of microwave endometrial ablation without endometrial preparation in the outpatient setting: patient acceptability, treatment outcome and costs. BJOG 2005; 112:1109.
  60. Sambrook AM, Jack SA, Cooper KG. Outpatient microwave endometrial ablation: 5-year follow-up of a randomised controlled trial without endometrial preparation versus standard day surgery with endometrial preparation. BJOG 2010; 117:493.
  61. Glasser MH, Heinlein PK, Hung YY. Office endometrial ablation with local anesthesia using the HydroThermAblator system: Comparison of outcomes in patients with submucous myomas with those with normal cavities in 246 cases performed over 5(1/2) years. J Minim Invasive Gynecol 2009; 16:700.
  62. Chapa HO. Utility of in-office endometrial ablation: a prospective cohort study of endometrial ablation under local anesthesia. J Reprod Med 2008; 53:827.
  63. (Accessed on February 16, 2010).
  64. http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cftopic/pma/pma.cfm?num=p020031 (Accessed February 16, 2010).
  65. http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cftopic/pma/pma.cfm?num=p000032 (Accessed on February 16, 2010).
  66. www.ethicon360.com/products/gynecare-thermachoice-uterine-balloon-therapy-system (Accessed on February 16, 2010).
  67. Wallage S, Cooper KG, Graham WJ, Parkin DE. A randomised trial comparing local versus general anaesthesia for microwave endometrial ablation. BJOG 2003; 110:799.
  68. Smith PP, Malick S, Clark TJ. Bipolar radiofrequency compared with thermal balloon ablation in the office: a randomized controlled trial. Obstet Gynecol 2014; 124:219.
  69. Glasser MH. Practical tips for office hysteroscopy and second-generation "global" endometrial ablation. J Minim Invasive Gynecol 2009; 16:384.
  70. Erickson TB, Kirkpatrick DH, DeFrancesco MS, Lawrence HC 3rd. Executive summary of the American College of Obstetricians and Gynecologists Presidential Task Force on Patient Safety in the Office Setting: reinvigorating safety in office-based gynecologic surgery. Obstet Gynecol 2010; 115:147.
  71. Polena V, Mergui JL, Perrot N, et al. Long-term results of hysteroscopic myomectomy in 235 patients. Eur J Obstet Gynecol Reprod Biol 2007; 130:232.
  72. Glasser MH. Endometrial ablation and hysteroscopic myomectomy by electrosurgical vaporization. J Am Assoc Gynecol Laparosc 1997; 4:369.
  73. Rovio PH, Helin R, Heinonen PK. Long-term outcome of hysteroscopic endometrial resection with or without myomectomy in patients with menorrhagia. Arch Gynecol Obstet 2009; 279:159.
  74. Loffer FD. Improving results of hysteroscopic submucosal myomectomy for menorrhagia by concomitant endometrial ablation. J Minim Invasive Gynecol 2005; 12:254.
  75. Loffer FD. Endometrial ablation in patients with myomas. Curr Opin Obstet Gynecol 2006; 18:391.
  76. Low S, Smith K. TCRE and Mirena: Is the combination better? Gynecol Surg 2006; 3:146.
  77. Basama FMS, Muppala H, Inglis TCM. Re-audit: Transcervical resection of the endometrium for heavy menstrual bleeding and the treatment of post-resection uterine stenosis and hematometra by cervical dilation and the insertion of a levonorgestrel-releasing intra-uterine system. Gynecol Surg 2007; 4:35.
  78. Maia H Jr, Maltez A, Coelho G, et al. Insertion of mirena after endometrial resection in patients with adenomyosis. J Am Assoc Gynecol Laparosc 2003; 10:512.
  79. Lethaby A, Hickey M, Garry R, Penninx J. Endometrial resection / ablation techniques for heavy menstrual bleeding. Cochrane Database Syst Rev 2009; :CD001501.
  80. Della Badia C, Nyirjesy P, Atogho A. Endometrial ablation devices: review of a manufacturer and user facility device experience database. J Minim Invasive Gynecol 2007; 14:436.
  81. Gurtcheff SE, Sharp HT. Complications associated with global endometrial ablation: the utility of the MAUDE database. Obstet Gynecol 2003; 102:1278.
  82. Brown J, Blank K. Minimally invasive endometrial ablation device complications and use outside of the manufacturers' instructions. Obstet Gynecol 2012; 120:865.
  83. McCausland AM, McCausland VM. Long-term complications of endometrial ablation: cause, diagnosis, treatment, and prevention. J Minim Invasive Gynecol 2007; 14:399.
  84. Carey ET, El-Nashar SA, Hopkins MR, et al. Pathologic characteristics of hysterectomy specimens in women undergoing hysterectomy after global endometrial ablation. J Minim Invasive Gynecol 2011; 18:96.
  85. McCausland AM, McCausland VM. Frequency of symptomatic cornual hematometra and postablation tubal sterilization syndrome after total rollerball endometrial ablation: a 10-year follow-up. Am J Obstet Gynecol 2002; 186:1274.
  86. Townsend DE, McCausland V, McCausland A, et al. Post-ablation-tubal sterilization syndrome. Obstet Gynecol 1993; 82:422.
  87. Sharp HT. Endometrial ablation: postoperative complications. Am J Obstet Gynecol 2012; 207:242.
  88. Webb JC, Bush MR, Wood MD, Park GS. Hematosalpinx with pelvic pain after endometrial ablation confirms the postablation-tubal sterilization syndrome. J Am Assoc Gynecol Laparosc 1996; 3:419.
  89. Hubert SR, Marcus PS, Rothenberg JM, et al. Hematometra after thermal balloon endometrial ablation in a patient with cervical incompetence. J Laparoendosc Adv Surg Tech A 2001; 11:311.
  90. Bansi-Matharu L, Gurol-Urganci I, Mahmood TA, et al. Rates of subsequent surgery following endometrial ablation among English women with menorrhagia: population-based cohort study. BJOG 2013; 120:1500.
  91. Middleton LJ, Champaneria R, Daniels JP, et al. Hysterectomy, endometrial destruction, and levonorgestrel releasing intrauterine system (Mirena) for heavy menstrual bleeding: systematic review and meta-analysis of data from individual patients. BMJ 2010; 341:c3929.
  92. Newton JR, Reading AE. The effects of psychological preparation on pain at intrauterine device insertion. Contraception 1977; 16:523.
  93. Lekander M, von Essen J, Schultzberg M, et al. Cytokines and memory across the mature life span of women. Scand J Psychol 2011; 52:229.
  94. Higham JM, O'Brien PM, Shaw RW. Assessment of menstrual blood loss using a pictorial chart. Br J Obstet Gynaecol 1990; 97:734.
  95. Duleba AJ, Heppard MC, Soderstrom RM, Townsend DE. A randomized study comparing endometrial cryoablation and rollerball electroablation for treatment of dysfunctional uterine bleeding. J Am Assoc Gynecol Laparosc 2003; 10:17.
  96. Longinotti MK, Jacobson GF, Hung YY, Learman LA. Probability of hysterectomy after endometrial ablation. Obstet Gynecol 2008; 112:1214.
  97. Garside R, Stein K, Wyatt K, et al. A cost-utility analysis of microwave and thermal balloon endometrial ablation techniques for the treatment of heavy menstrual bleeding. BJOG 2004; 111:1103.
  98. Clegg JP, Guest JF, Hurskainen R. Cost-utility of levonorgestrel intrauterine system compared with hysterectomy and second generation endometrial ablative techniques in managing patients with menorrhagia in the UK. Curr Med Res Opin 2007; 23:1637.
  99. Cooper KG, Jack SA, Parkin DE, Grant AM. Five-year follow up of women randomised to medical management or transcervical resection of the endometrium for heavy menstrual loss: clinical and quality of life outcomes. BJOG 2001; 108:1222.
  100. McPherson K, Herbert A, Judge A, et al. Psychosexual health 5 years after hysterectomy: population-based comparison with endometrial ablation for dysfunctional uterine bleeding. Health Expect 2005; 8:234.
  101. Shokeir T, Eid M, Abdel-Hady el-S. Does adjuvant long-acting gestagen therapy improve the outcome of hysteroscopic endometrial resection in women of low-resource settings with heavy menstrual bleeding? J Minim Invasive Gynecol 2013; 20:222.
  102. Jacobs SA, Blumenthal NJ. Endometrial resection follow up: late onset of pain and the effect of depot medroxyprogesterone acetate. Br J Obstet Gynaecol 1994; 101:605.
  103. Maia H Jr, Calmon LC, Marques D, Coutinho EM. Administration of medroxyprogesterone acetate after endomyometrial resection. J Am Assoc Gynecol Laparosc 1997; 4:195.
  104. Vaughan D, Byrne P. An evaluation of the simultaneous use of the levonorgestrel-releasing intrauterine device (LNG-IUS, Mirena®) combined with endometrial ablation in the management of menorrhagia. J Obstet Gynaecol 2012; 32:372.
  105. Zheng J, Xia E, Li TC, Sun X. Comparison of combined transcervical resection of the endometrium and levonorgestrel-containing intrauterine system treatment versus levonorgestrel-containing intrauterine system treatment alone in women with adenomyosis: a prospective clinical trial. J Reprod Med 2013; 58:285.
  106. Gadzinski JA, Sheran J, Garbe G, et al. The postendometrial ablation endometrium: reassessment with biopsy and ultrasonography. Obstet Gynecol 2014; 123 Suppl 1:124S.
  107. MacLean-Fraser E, Penava D, Vilos GA. Perioperative complication rates of primary and repeat hysteroscopic endometrial ablations. J Am Assoc Gynecol Laparosc 2002; 9:175.
  108. Fürst SN, Philipsen T, Joergensen JC. Ten-year follow-up of endometrial ablation. Acta Obstet Gynecol Scand 2007; 86:334.
  109. O'Connor H, Magos A. Endometrial resection for the treatment of menorrhagia. N Engl J Med 1996; 335:151.
  110. A randomised trial of endometrial ablation versus hysterectomy for the treatment of dysfunctional uterine bleeding: outcome at four years. Aberdeen Endometrial Ablation Trials Group. Br J Obstet Gynaecol 1999; 106:360.
  111. Loffer FD, Grainger D. Five-year follow-up of patients participating in a randomized trial of uterine balloon therapy versus rollerball ablation for treatment of menorrhagia. J Am Assoc Gynecol Laparosc 2002; 9:429.
  112. Tsaltas J, Taylor N, Healey M. A 6-year review of the outcome of endometrial ablation. Aust N Z J Obstet Gynaecol 1998; 38:69.
  113. Foote M, Rouse A, Gil KM, et al. Successful pregnancy following both endometrial ablation and uterine artery embolization. Fertil Steril 2007; 88:1676.e15.
  114. Laberge PY. Serious and deadly complications from pregnancy after endometrial ablation: two case reports and review of the literature. J Gynecol Obstet Biol Reprod (Paris) 2008; 37:609.
  115. Bowling MR, Ramsey PS. Spontaneous uterine rupture in pregnancy after endometrial ablation. Obstet Gynecol 2010; 115:405.
  116. Kuzel D, Bartosova L, Rezabek K, et al. Successful pregnancy after thermal balloon endometrial ablation followed by in vitro fertilization and embryo transfer. Fertil Steril 2010; 93:1006.e11.
  117. Hare AA, Olah KS. Pregnancy following endometrial ablation: a review article. J Obstet Gynaecol 2005; 25:108.