This can be Bladder neck dysfunction which is defined as an incomplete opening of the bladder neck during voluntary or involuntary voiding. This can be because of;
1) smooth sphincter dyssynergia,
2) proximal urethral obstruction,
3) primary bladder neck obstruction, and
4) dysfunctional bladder neck.
Evidence of outlet obstruction is easily obtainable by urodynamic study. Once obstruction is diagnosed, it can be localized at the level of the bladder neck by
a) video-urodynamic study, (you have got this although it was not a video)
2) cystourethrography during a bladder contraction, or micturitional urethral profilometry (you need to get it done).
The treatment would entail;
1) Alpha adrenergic blocking agent
2) Bladder neck incision (this would be done by cystoscopy).
Please feel free for your follow up questions.