Objective. To study whether avulsion and ballooning are independent risk factors for symptoms and/or signs of pelvic organ prolapse. Design. Retrospective analysis of data obtained in clinical practice. Setting. Tertiary urogynecology unit. Population. Seven hundred and sixty-one consecutive women with symptoms of pelvic floor dysfunction. Methods. Evaluation included history, vaginal examination and four-dimensional translabial ultrasound. Ultrasound analysis was performed off-line, blinded against clinical data. Hiatal dimensions were measured at the plane of minimal hiatal dimensions. Puborectalis avulsion was identified using tomographic imaging. Main outcome measures. Symptoms and objective signs of prolapse (ICS POP-Q stage 2+). Results. Owing to previous surgery 156 women were excluded, leaving 605, of whom 258 (43%) had prolapse symptoms. Significant prolapse (International Continence Society Prolapse Quantification System grade 2+) was identified as follows: cystocele in 222 (37%) women, rectocele in 159 (27%) and apical in 40 (8%), while 110 (18%) had an avulsion. There was a strong association between avulsion, hiatal ballooning and symptoms/signs of prolapse (p < 0.001). On multivariable backwards stepwise logistic regression, puborectalis avulsion was associated with an increased risk of symptoms and signs of prolapse, even after allowing for the degree of levator ballooning. The presence of avulsion did not modify the relation between hiatal area and symptoms of prolapse. Conclusions. Puborectalis avulsion injury and levator hiatal ballooning are independent risk factors for symptoms and signs of prolapse. The role of avulsion in the pathogenesis of prolapse is not fully explained by its effect on hiatal dimensions. It is likely that avulsion implies not only muscular trauma but also damage to structures impossible to assess clinically or by imaging, i.e. myofascial and connective tissue.