Perineal ultrasound has not yet been adequately evaluated in relation to the diagnosis of anatomical descensus of pelvic organs. Therefore, the aim of the present study was to assess whether it is possible to carry out a topographical comparison between bladders in normal seat and prolapsed ones and to quantify the extent of descensus.The authors selected 140 women, divided into three groups (two control groups and one case group). All patients underwent urogynaecological examination, according to the Pelvic Organ Prolapse Quantification (POP-Q), and perineal ultrasound to evaluate pubo-bladder distance.Considering the data recorded in the two control groups, the authors established the physiological pubo-bladder distance between 27-33 mm at rest and 25-30 mm under stress. In the group with cystocele, the pubo-bladder distance was significantly lower: 20 mm at rest and three mm under stress (mean value). The authors also performed a classification of ultrasound cystocele in four stages, in accordance with clinical staging.In conclusion, the present data show the excellent potential role of perineal ultrasound in the diagnosis of cystocele, but it is necessary to perform randomized studies to standardize the method.