Definitely do not panic. That tends to show that you really can't handle things.
Include the job on your resume.
Depending on questions asked and such you will want to be ready with basically what you have told us. That you did not have urology experience, that the employer knew that but promised training, that the person who was responsible to train you effectively refused to do so not even answering questions from you.
This basically left the employer in a tough position, and the employer threatened to fire the uncooperative employee, but here's the problem. If the employer fired her, she was left with a good employee who still didn't understand urology, so she fired you because that would leave the employer with one who did, and now they can hire another who already does.
If I could, I would try to get a copy of my employee file, particularly the good review. Because that would back up the fact you were a good employee.
Your former employer hired you because they needed another person who understood urology, and while it's not necessarily your fault and certainly not totally yoru fault, they didn't get that, and if they fired the person at fault they were out even that one that understood urology. So they made what looks to me to be a nonpersonal business decision, because they still need another person who understands urology. If they kept you, you couldn't train in a new person. And you and the person already there hadn't been able to work it out, and so off you went. As an employer, there are just some combinations of people which don't work. You could stand there with a stick but that kind of gets old and you have things to do too. So you make a business decision on which to get rid of, and often the next one get along just fine.
Now if you were someone I would kill to hire. I'd hear from you that you were in that tough situation and the person who was supposed to train you didn't so you took it upon yourself to train yourself. Maybe getting books, or taking a course, or something. If I'm interviewing someone and I say do you know Greek? I love to hear, no, but I will before long if you want me to. Because everyone has things they don't know, but the most important thing is both willingness to learn and an unwillingness not to. Other employers would have different things they look for. I remember one fellow (who had a couple of hundred employees) who told me he would find something for anyone who came in and asked for work, but if they asked for a job, he wouldn't hire them even if he needed someone. Those two words might sound the same to you or I but they didn't to him.
In any case, when asked be open with the truth. And assuming it's something that you do know, you would say something like. I didn't know urology and the employer knew it and the person responsible to train me wouldn't. So that's why I'm here because I want to get back to doing something I know how to do. I was a square peg in a round hole and it wasn't comfortable, but my employer still gave me good reviews, just got frustrated that I wasn't trained and wasn't getting trained.
I'm not so sure that I wouldn't still call back the employer and ask them if they actually thought you weren't capable as in just not able to handle it due to personal shortcomings or if they simply meant you didn't have the specific knowledge. Employers can be kind of cautious about saying things because they might think you are gathering information to sue them or something but often if you talk a bit, instead of hearing one thing and getting hurt and just shutting up and walking away, you can get some clarity. It's business, not personal. Don't take it personally.
Marv