What exactly do we need to submit for the second screening? The clinic…

What exactly do we need to submit for the second screening? The clinic said only urine and that's all, on the first screening I just had blood tests and many other analyses, but for the second screening I don't understand, then ultrasound is mandatory at 20 weeks, should it be taken at 19 weeks or can it be done at 19 weeks? Please tell me, I don't understand much more, there is different information online, I haven't found any specific answer.