Clinical utility of transperineal three-dimensional ultrasound for evaluating the impact of delivery mode on pelvic floor structure in primiparous women.

OBJECTIVES: This study evaluated and compared the impacts of forceps delivery (FD), normal vaginal delivery (ND) and cesarean section (CS) on early postpartum pelvic floor structure and function of primiparous women via transperineal three-dimensional (3D) ultrasound. METHODS: 180 primiparous women receiving transperineal 3D pelvic floor ultrasound 6-8 weeks postpartum were equally divided into FD, ND and CS groups (60 per group). Resting and Valsalva-state ultrasound indicators were measured, including distances from bladder neck, cervix and rectal ampulla to pubic symphysis, posterior bladder angle, urethral rotation angle, pelvic organ descent and levator hiatus area, for intergroup comparison. RESULTS: At rest, FD showed shorter bladder neck and cervix-symphysis distances versus ND and CS (all p < 0.05); FD and ND had larger levator hiatus area than CS (p < 0.001). Under Valsalva maneuver, FD and ND had shorter bladder neck-symphysis distance than CS (p < 0.001), while FD retained shorter cervix-symphysis distance (p < 0.05). Vaginal delivery groups presented larger levator hiatus area than CS (p < 0.001). Urethral rotation angle ranked FD > ND > CS (p < 0.01). Vaginal deliveries caused severer bladder neck descent than CS (p < 0.001), with FD exhibiting more dramatic levator hiatus expansion than CS (p < 0.01). CONCLUSION: Three delivery modes induce distinct pelvic floor damage. FD leads to lower pelvic organ positions and stronger organ mobility relative to ND, while CS partially protects pelvic floor anatomy. Transperineal 3D ultrasound offers objective imaging for early pelvic floor evaluation and facilitates stratified postpartum care based on delivery mode.