Study Objective: To evaluate hysteroscopic transcervical resection (TCR) for atypical polypoid adenomyoma of the uterus (APA).Design: Retrospective study (Canadian Task Force classification II-2).Setting: Single tertiary hospital.Patients: Women who underwent TCR for APA at Kawasaki Municipal Hospital between 2003 and 2015.Interventions: Clinical records were obtained.Measurements and Main Results: Thirty-five patients with APA were evaluated. The median patient age was 35 years (range, 23-43 years), and the median tumor diameter was 22 mm (range, 9-51 mm). The median duration of observation after the first TCR was 34.0 months (range, 4.2-133.7 months). In 19 patients, the tumor recurred after the first TCR. A second TCR was performed in 13 patients, 11 of whom experienced recurrence. A third TCR was performed in 7 patients, all 7 of whom experienced recurrence. A fourth TCR was performed in 4 patients, 3 of whom experienced recurrence. The recurrence rate after the second TCR was higher than that after the first TCR (71.4%-84.6% vs 54.3%; p < .01, t test). The median disease-free interval was 12.4 months after the first TCR, 15.3 months after the second TCR, 10.5 months after the third TCR, and 10.9 months after the fourth TCR. Seven patients progressed to endometrial cancer; however, there was no mortality. Six of the 35 patients conceived, and 4 had a normal spontaneous delivery.Conclusion: Owing to disease-free intervals that follow treatment, TCR is a promising treatment modality as a fertility-preserving option for patients with APA under careful observation. Twenty percent of patients with APA develop cancer; however, the present study showed no mortality. [ABSTRACT FROM AUTHOR]