Assessment of the Effects of Different Delivery Methods on the Pelvic Floor Muscle Function in Primiparous Women by Total Pelvic Floor Ultrasound and Surface Electromyography

Objective :To investigate the effects of cesarean section(CS) and vaginal delivery(VD) on postpartum pelvic floor muscle function by total pelvic floor ultrasond(TPFUL) and pelvic floor surface electromyography(sEMG). Methods: A retrospective analysis was performed on 210 primiparous women with full-term singleton pregnancies who delivered at Wuhu Hospital of Traditional Chinese Medicine between July 2022 and December 2023. The cohort was divided into the CS group (n=57) and VD group (n=153). All postpartum women underwent TPFUS and sEMG examinations 6～8 weeks after delivery. The primary outcomes included the incidence of PFD, TPFUS-derived parameters [bladder neck mobility (BNM), urethral rotation angle (URA), posterior vesicourethral angle (PVUA), levator ani muscle hiatus area (LAMHA)], and sEMG-related indices [Type I/II fiber strength, dynamic vaginal pressure (DVP)]. Receiver operating characteristic (ROC) curves were plotted to analyze the diagnostic efficacy of TPFUS parameters, and Kappa consistency test was conducted to assess the agreement between positive DVP findings and PFD diagnosis. Results: The overall incidence of PFD in the VD group (69.28%) was significantly higher than that in the CS group (43.86%, P<0.05). The individual incidences of uterine prolapse and cystocele in the VD group were also significantly elevated compared with the CS group (all P<0.05). Cystocele in both groups was predominantly classified as Green Type II, the individual incidences of rectocele and distribution of cystocele subtypes had no statistically significant difference between the two groups (P>0.05). TPFUS measurements revealed that BNM, URA, PVUA, and LAMHA in the VD group were significantly larger than those in the CS group (all P<0.001), among which LAMHA exhibited the highest area under the curve (AUC=0.717). sEMG results showed that the abnormal rates of the Type I and Type II muscle fibers had a significant intergroup difference (P<0.001). The VD group had a higher incidence of abnormal DVP (66.01%) and a lower mean DVP value (78.72±11.51 cmH₂O) compared with the CS group (both P<0.001). Moreover, there was substantial consistency between positive DVP findings and PFD diagnosis (K=0.676, P<0.001). Conclusion: Combined examination with TPFUS and sEMG revealed that the VD group had higher incidence of total PFD, individual incidences of uterine prolapse and cystocele, abnormal rates of type Ⅰ/Ⅱ muscle fibers, and positive DVP findings than the CS group. Nevertheless, no statistically significant differences were observed between the two groups in terms of rectocele rate and cystocele classification.The combined application of TPFUS and sEMG enables comprehensive evaluation of pelvic floor muscle function from both morphological and functional perspectives. Among the indicators, the LAMNA serves as the optimal morphological diagnostic marker for PFD, while DVP is an effective functional screening index. Their combined use can provide precise guidance for postpartum pelvic floor rehabilitation.