urethra structure disease

what is the urethra structure disease (USD) ? 

what is the symptoms of (USD)? 

what is the causes and effects of (USD)? 

what is the different between urethroplasty and urethrotomy treatment for (USD)?

why urethrapasty good for long-term success  than urethrotomy?  

can you please answer this question as paragraphs? 

 for example sub heading 

1- urethra structure disease 

2- symptoms 

3- couse and effect

4- treatment

  4.1 urethrotomy 

  4.2 urethroplasty