A lower number of studies results in diminished power and subsequently is prone to misinterpretation. It is not possible to pool our data in such a way that this requirement is met. For this reason, no additional tests to objectify bias of published studies were performed. A possible explanation for heterogeneity in the data is the lack of standardization in the measurements of urodynamics. Influences of ejaculation, defecation, intra-abdominal pressure and the setting in which measurements take place affect urodynamics. Apart from the lack of standardization in measurements, the demography of the investigated population should be adequately described; for example, severity of LUTS was not properly objectified in all studies, allowing the possibility of inappropriate comparison. Another possible influencing factor is the accustomed voiding position or location: it is suggested that the mere change to a new position or urinating in a clinical research setting reflects negatively on urodynamic parameters, although no calculable data to perform a meta-analysis on this subject was presented. As seen in the risk of bias assessment, many studies did not take these influences into account. Methodological bias seems of lesser importance in this study. LUTS progresses relatively slowly, long-term follow-up is not required and a carry-over effect of the intervention seems not likely. Therefore, the use of a cross-over design is an adequate study design, not prone to result in methodological bias. Several explanations for the described trend towards a better urodynamic profile in the sitting position are found in the included literature. The typical patients with LUTS/BPH are elderly males who are more prone to fall. It is suggested that the fear of falling while standing can result in involuntary contractions of the pelvic muscles to stabilize one’s position. Contraction of the pelvic muscles is related to a disturbed urinary flow ; relaxation of these muscles is better achieved by urinating in a sitting position and by supporting the feet in a comfortable position. Also, muscle tension in the medial and anterior compartments of the hip is decreased in the sitting position.