To investigate whether voiding position affects urine flow measurement (UFM) and post voided residual (PVR) in adult males.

This study was conducted from October 2022 to October 2023 after approval by the Ethics Committee of our hospital using a prospective study design. A total of 98 people, from 22 to 78 years old males, they were from our hospital medical students and urological outpatients. According to age and presence of dysuria symptoms, the participants were divided into young healthy group (group A: 43), young dysuria group (group B: 11), middle-aged and elderly healthy group (group C: 16), and middle-aged and elderly people with dysuria group (group D: 28). Urine flow was measured in standing position, seating with forward-bending and seating position, and PVR was measured by B-ultrasound immediately after each urination. The statistical software SPSS 26.0 was used to compare the differences of voided volume (VV), maximum urine flow rate (Qmax), average urine flow rate (Qave) and PVR among the three voiding positions by repeated measurement ANOVA and non-parametric Friedman Test.

A total of 98 adult males with an average  age of 51.8[22, 78] years were included in this study. The results of the three urination positions of the participants in each group were as follows: standing position, seating with forward-bending position and sitting position:

1. Group A:The Qmax and Qave values of standing and seating with forward-bending urination were significantly higher, and the PVR values were significantly lower than those of sitting urination (P<0.05); There was no significant difference in Qmax, Qave and PVR values between standing position and seating with forward-bending position.

2. Group B:The Qmax and Qave values of seating with forward-bending urination were significantly higher, and the PVR values were significantly lower than those of sitting and standing urination (P<0.05); The PVR value of sitting urination was significantly lower than that of standing urination (P<0.05). There was no significant difference in Qmax and Qave values between standing and sitting urination.

3. Group C:The Qmax and Qave values of seating with forward-bending urination were significantly higher, and the PVR values were significantly lower than those of sitting and standing urination (P<0.05); The Qmax and Qave values of seating urination were significantly higher, and the PVR values were significantly lower than those of standing urination (P<0.05)

4. Group D:The Qmax and Qave values of seating with forward-bending urination were significantly higher, and the PVR values were significantly lower than those of sitting and standing urination (P<0.05); The Qmax and Qave values of seating urination were significantly higher, and the PVR values were significantly lower than those of standing urination (P<0.05).

In this study, seating with forward-bending urination showed better urine flow rate parameters in all groups of adult males, which may be related to the increase of abdominal pressure during seating with forward-bending position. When the body is bent forward, the Angle between the torso and the thigh decreases, and the abdominal pressure increases compared with the sitting position. In middle-aged and elderly people, urine flow rate parameters of sitting on the toilet are better than those of standing, which may be related to the difficulty of standing for a long time and the desire to end urination earlier.

Voiding position shows a significant  effect on uroflowmetry  and PVR in adult males. The seating with forward-bending position is more beneficial to improve the urinary flow rate and empty the bladder, especially  in the middle-aged and elderly population. The results of this study suggest that the seating with forward-bending position may be the best position for adult males to voiding.