Abstract: Objective To investigate the application value of transvaginal three-dimensional ultrasound (3D-TVUS) imaging in assessing the classification of intrauterine adhesions (IUA) and endometrial receptivity (ER). 
Methods Seventy-six patients with IUA were selected as research subjects, and 3D-TVUS imaging was performed after admission to compare the 3D-TVUS parameters ［uterine artery pulsatility index (PI), resistance index (RI), endometrial thickness (ET), endometrial volume (EV), endometrial vascular index (VI), blood flow index (FI), vascular flow index (VFI)］ in patients with different scores of classifications of IUA and ER, and the correlation and assessment value of each ultrasound parameter with scores of classification of IUA and ER. They were followed up for 1 year to record the pregnancy and compare the ultrasound parameters between pregnant and non-pregnant patients. 
Results The PI and RI of the severe and moderate adhesion groups were higher than those of the mild adhesion group, and higher in the severe adhesion group than in the moderate adhesion group; ET, EV, VI, FI, and VFI of the severe and moderate adhesion groups were lower than those of the mild adhesion group, and lower in the severe adhesion group than in the moderate adhesion group (P＜0.05). PI and RI were higher in ER score ≤3 group and ER score 4-6 group than in ER score 7-8 group, and higher in ER score ≤3 group than in ER score 4-6 group; ET, EV, VI, FI, and VFI were lower in ER≤3 group and ER score 4-6 group than in ER score 7-8 group, and lower in ER score ≤3 group than in ER score 4-6 group (P＜0.05). PI and RI were positively correlated with IUA score and negatively correlated with ER score; ET, EV, VI, FI, and VFI were negatively correlated with IUA score and positively correlated with ER score (P＜0.05). The area under the receiver operating characteristic (AUC) curve (AUC) of PI, RI, ET, EV, VI, FI, and VFI for distinguishing mild and moderate IUA was 0.744, 0.730, 0.816, 0.819, 0.805, 0.824, and 0.718, respectively, and the AUC of combined diagnosis was 0.914. The AUC of these indicators for distinguishing moderate and severe IUA was 0.802, 0.783, 0.750, 0.751, 0.742, 0.758, and 0.807, respectively, and the AUC of combined diagnosis was 0.834. The AUC for distiguishing poor and moderate ER was 0.790, 0.778, 0.717, 0.847, 0.777, 0.754, and 0.799, respectively, while the AUC of combined diagnosis was 0.900. The AUC for differential diagnosis of moderate and good ER was 0.809, 0.829, 0.741, 0.712, 0.795, 0.781, and 0.847, respectively, while the AUC of combined diagnosis was 0.934. Pregnant patients had lower PI and RI, but higher ET, EV, VI, FI, and VFI than those in non-pregnant patients (P＜0.05). 
Conclusion 3D-TVUS can be used in the assessment and diagnosis of classsification of IUA and ER in patients with IUA, providing a reference for early clinical assessment of the condition and prediction of pregnancy in order to develop targeted intervention plans and improve prognosis. 

Key words: gynatresia, endometrial receptivity, transvaginal three-dimensional ultrasound