Pathology of endometrial ablation failures: a clinicopathologic study of 164 cases.

Endometrial ablation is a minimally invasive alternative to hysterectomy for abnormal uterine bleeding. Although the failure rate is low, continued bleeding or development of pelvic pain after ablation does occur. We analyzed the clinicopathologic features of 164 hysterectomy specimens after endometrial ablation, 19 of which were performed for indications other than failed ablation (control cases). Pathologic findings included: dense fibrosis and hyalinization of the endometrial surface ablative necrosis within the uterine cavity and adherent to the endometrial surface, persistent months after ablation; uterine cavity lined by superficial, large, congested, patent blood vessels with atherosis; ablation changes present only in the lower uterine segment; and residual endometrium present in the cornual regions. Patients with ablative necrosis underwent subsequent hysterectomy sooner than those without such debris (median of 5 vs. 23 mo, respectively). Patients with superficial abnormal vessels were also more likely to have a shorter ablation-hysterectomy interval than those without (median of 2 vs. 18 mo, respectively). Patients with associated adenomyosis or prior tubal ligation were significantly more likely to have continued bleeding. Possible sources of continued abnormal bleeding or pelvic pain include: the presence of ablative necrosis or superficial abnormal blood vessels, although the association did not reach statistical significance in this study; incomplete ablation, affecting only the lower uterine segment or sparing the cornual region; tubal endometriosis after ligation; and endometrial regeneration via adenomyosis.