Role of dilatation and curettage performed for spontaneous or induced abortion in the etiology of endometrial thinning

AimThe aim of this study was to clarify the role of dilatation and curettage (D&C) performed for spontaneous or induced abortion in the etiology of endometrial thinning. MethodsThis was a retrospective and cross-sectional study of 310 infertile patients from January 2013 through December 2015. Endometrial thickness observed 5-7 days after ovulation in a natural menstrual cycle was correlated with the number of D&C noted in each patient's history. ResultsStudy 1 was an investigation of patients without D&C (group A: n = 232) and patients with D&C performed for spontaneous abortion (group B: n = 46). Study 2 was an investigation of patients in group A and patients with D&C performed for induced abortion (group C: n = 32). A significant negative correlation (P < 0.01) between endometrial thickness and number of D&C was observed in both studies. The mean endometrial thickness of the patients in group A was 10.9 2.1 mm. The mean endometrial thickness of the patients in group B with one and two D&C was 7.9 +/- 2.3 and 6.9 +/- 2.9 mm, respectively. The mean endometrial thickness of the patients in group C with one and two D&C was 9.1 +/- 2.3 and 7.8 +/- 2.0 mm, respectively. There was a tendency toward gradual endometrial thinning following repeated procedures and the number of previous D&C was significantly associated with endometrial thinning (P < 0.001) in both studies. ConclusionD&C performed for spontaneous or induced abortion may play a causal role in endometrial thinning.