Perineal ultrasound is facing the development of a standardization process. One important aspect in this process is the choice of an appropriate reference line for the evaluation of the urogenital anatomy. For this purpose, two major reference lines have been proposed in international literature: a horizontal line by Dietz and a central pubic line by Schaer. Inspired by the advantages and being aware of the disadvantages of these two lines, we created a new reference line, which can be drawn between the hyperechoic contours of os pubis and ligamentum arcuatum. The image orientation is set as usual in Germany. As a first step towards the implementation of the new method, we chose to compare the reliability of the three reference lines. Before this could be done, however, the central pubic line had to be excluded from the analysis because of a very low rate of possible assessment. This problem is already known in literature. Especially inexperienced examiners should therefore avoid the use of this reference line. Concerning the resulting values, there is a marked difference between the two remaining reference lines: The new line produces much greater values, which is why the two lines should not be in parallel use. In literature, there is evidence that the new line produced more realistic values than the horizontal line. This, however, has to be verified by validation studies. The reliability analysis revealed – despite of some major outliers – a trend towards a better reproducibility with the horizontal line by Dietz. Nevertheless, both reference lines definitely showed very good repeatability. Probably, minor differences may be neglected, which depends on the result of validation studies. Furthermore, it was observed that for the measurement of parameters during rest, any rest can be chosen, no matter if right at the beginning or after Valsalva, pelvic floor contraction or coughing. This does not influence the result. It could also be shown that there is no significant difference between resulting values during coughing and Valsalva. Concerning this issue, literature presents diverging opinions. To sum up, the newly generated reference line attains similar reliability parameters compared to the horizontal reference line by Dietz, which is already established. The new line is compatible with the standard image orientation of Germany. Particularly for inexperienced examiners, both reference lines are more suitable than the central pubic line by Schaer. Before using the new reference line in routine, validation studies should be performed. As mentioned earlier, a parallel use cannot be recommended
