To explore the value of three-dimensional pelvic floor ultrasound results in predicting the occurrence of pelvic organ prolapse (POP) in parturients and its influencing factors.

By random number table method, a total of 40 patients with postpartum POP admitted to the First Affiliated Hospital of Hebei North University from April 2019 to February 2022 were randomly selected for the study and included into study group. And 40 cases of parturients with normal pelvic floor function who underwent postpartum reexamination in the same hospital during the same period were selected as controls by random number table method and were included into control group. Subjects in two groups all received three-dimensional pelvic floor ultrasound 6 months after delivery. Relevant clinical data and three-dimensional pelvic floor ultrasound results of two groups were compared by independent-samples t test and chi-square test. The receiver operating characteristic (ROC) curve and its area under the curve (AUC) were used to evaluate the predictive value of three-dimensional pelvic floor ultrasound results alone and in combination for the occurrence of POP in parturients. Multivariate logistic regression analysis was used to analyze the influencing factors of POP in parturients, and the ROC curve, C-index and calibration curve were used to evaluate the predictive accuracy and discriminating ability of this multivariate logistic regression model for the occurrence of POP in parturients. There was no significant difference in general clinical data between two groups, such as age (P>0.05). The study met the requirements of Helsinki Declaration of World Medical Association newly revised 2013.

①The proportions of patients with spontaneous labor, history of lateral episiotomy/laceration and without Kegel training in study group were significantly higher than those in control group, and the differences were statistically significant (χ²=10.03, 8.57, 6.47; P=0.002, 0.003, 0.039). ②The bladder neck rotation angle (BNRA), posterior urethrovesical angle (PUA), bladder neck inclination angle (BNIA), bladder neck distance (BND), anal constriction-levator hiatus area (AC-LHA), rest-levator hiatus area (R-LHA), Valsalva-levator hiatus area (V-LHA) in study group were significantly higher than those in control group, and the differences were statistically significant (t=13.82, 15.36, 10.35, 6.86, 5.41, 3.38, 6.98; all P<0.001). ③The ROC curve analysis results of 7 parameters of three-dimensional pelvic floor ultrasound (BNRA, PUA, BNIA, BND, AC-LHA, R-LHA, V-LHA) for predicting the occurrence of POP in parturients showed that the AUC of these 7 parameters alone and the combination of these 7 parameters for predicting the occurrence of POP in parturients were 0.745 (95%CI: 0.611-0.879, P<0.001), 0.796 (95%CI: 0.692-0.906, P<0.001), 0.720 (95%CI: 0.593-0.847, P=0.001), 0.701 (95%CI: 0.561-0.840, P=0.002), 0.679 (95%CI: 0.545-0.813, P=0.005), 0.653 (95%CI: 0.520-0.786, P=0.008), 0.712 (95%CI: 0.577-0.845, P=0.001) and 0.851 (95%CI: 0.743-0.959, P<0.001), respectively. ④Multivariate unconditional logistic regression analysis with whether the subjects were postpartum POP as dependent variable, and mode of delivery, lateral episiotomy/laceration, Kegel training, the above 7 ultrasound parameters as the independent variables showed that spontaneous labor, history of lateral episiotomy/laceration, BNRA>30°, PUA>135°, BNIA>54°, BND>18 mm, AC-LHA≥13 cm², R-LHA≥17 cm², and V-LHA≥18 cm² all were independent risk factors for the occurrence of POP in parturients (OR=3.800, 2.238, 5.689, 5.992, 5.199, 4.288, 3.301, 2.723, 4.732; 95%CI: 2.814-6.596, 2.110-4.176, 3.556-9.631, 3.707-10.087, 3.362-8.846, 3.009-7.376, 2.592-5.819, 2.291-4.964, 3.179-8.095; all P<0.05); Kegel training had a protective effect on postpartum pelvic floor (OR=0.596, 95%CI: 0.518-0.674, P=0.008). AUC of the multivariate unconditional logistic regression model for predicting the occurrence of POP in parturients was 0.822 (95%CI: 0.759-0.885), with a sensitivity of 94.2% and specificity of 60.1%. The C-index of this model was 0.809 (95%CI: 0.744-0.874), indicating that the model was well differentiated, and P-value of Hosmer-Lemeshow test for this model was 0.870, indicating that the model was well calibrated. Internal data validation of the model showed that the corrected C-index was 0.814 (95%CI: 0.750-0.878) and P-value of the Hosmer-Lemeshow test was 0.894; meanwhile, the validation of calibration of the prediction model showed that the ideal curve in calibration plot for predicting postpartum POP matched good with the actual curve, and the bias calibration curve had a small bias, indicating good agreement between its prediction and actual of POP occurrence in parturients.

The accuracy of combined application of all three-dimensional pelvic floor ultrasound parameters to predict the occurrence of POP in parturients is high. Spontaneous delivery, history of lateral episiotomy/laceration and BNRA>30°, PUA>135°, BNIA>54°, BND>18 mm, AC-LHA≥13 cm², R-LHA≥17 cm², and V-LHA≥18 cm² are independent risk factors for the occurrence of POP in parturients, while Kegel training has a protective effect on the postpartum pelvic floor.