OBJECTIVE: To assess the prevalence of pelvic floor and anal sphincter trauma in women after assisted vaginal delivery. METHODS: Retrospective study on 201 primiparous women after assisted vaginal delivery, control group 43 women after normal vaginal delivery. 4D translabial ultrasound examination of the levator ani and the anal sphincter was performed according to standard methodology at least 3 months postpartum. Ultrasound classification of trauma was performed by two independent evaluators blinded to clinical data. A third evaluator was asked to confirm findings in case of discrepancy. RESULTS: The LAM avulsion rate for normal delivery was 20.9%, for forceps 60%, for vacuum extraction 21.7% Odds ratio for forceps vs. NVD was 4.32 (1.69, 11.01), for vacuum vs. NVD 0.98 (0.409, 2.327). Ultrasound OASI rate was 33.3% for Forceps and 30.50% for Vacuum. This equated to an OR of 1.78 (0.85 - 3.10) for Forceps and 1.62 (0.85-3.10) for Vacuum relative to NVD. CONCLUSIONS: Our data confirm forceps as the major risk factor for levator avulsion. Forceps also implies a non-significantly higher risk of OASI compared to NVD.