Statistical analysis
Baseline characteristics are presented as median with inter quartile range (IQR) and number of patients (n, %). Histological features of the endometrial samples of the SCSH-Sampling and the Sampling-SCSH group were compared using a Mann-Whitney U test. Furthermore, histological features of the sufficient and insufficient samples were compared to determine which features are critical for the quality (whether the sample was sufficient or insufficient) of the samples.For statistical analysis, the Statistical Package for the Social Sciences (IBM Corp, Armonk, NY, USA) version 24.0 was used. Statistical significance was set at p < 0.05.