Amniocentesis

Has anyone been recommended an amniocentesis at week 24 or around? What's your story? What are my chances of results being ok? The 1st trim double test had a very good result. Now they see some asymmetry in her brain, although some people with medical knowledge tell me it might be normal, that the brain atill develops and it might fix itself. Everythimg was so good until now and now i feel the sky is falling..