Abstract: Objective     To explore the effect of intravesical prostatic protrusion with different forms on urination by the finite element analysis method.    Methods    The finite element models for male lower urinary tract was reconstructed based on MRI images of a patient with middle lobe and bilateral lateral lobes protrusion into the bladder model 3. Other models with only the bilateral lateral protrusion and only the middle lobe protrusion were created by adjusting the shape of the protruded part. The two-way fluid-structure interaction of the lower urinary tract was simulated by the finite element analysis software. The deformation of prostatic urethra and flow dynamics parameters were compared between models with different IPP shapes. Results     The largest reduction of prostatic urethra angle was found in model 3 during  urination, followed by model 2 and model 1. The liquid pressure loss was most severe in model 3. The velocity in majority part of model 1 was higher than that of other two models. The maximum flow rate of model 3 was lower than that of other two models. Under the same bladder outlet cross-sectional area, the maximum flow rate of model 3 was lower than that of other models, and increasing bladder outlet cross-sectional area would further widen this gap.    Conclusions    This study reveals that patients with middle lobe and bilateral lateral lobes protrusion have greater urethral resistance and smaller maximum flow rate than those having comparable-length IPP with only middle lobe protrusion or only bilateral lateral lobes protrusion. When evaluating IPP, we should measure its length, as well pay attention to its form.

Key words: Benign prostatic hyperplasia,  ,  , Intravesical prostatic protrusion,  ,  , Finite element analysis, Fluid-structure interaction