Is a urethral diverticulum always present if you have one or does it only form once you urinate?

Here are some...: Urethral diverticulum is a herniating pouch formed at weak point of urethral wall possibly related with infection of urethral gland. It becomes evident ballooning at higher pressure of urine flow. At completing urination, it collapses but still retains some urine as an intractable dead space for bacteria to grow. For more understanding of such urodynamic effect, ask your urlogists timely.