amniocentesis

Hello I live in the UK (apologies for writing in English) . I am 38 years old, week 15 of second pregnancy (first was a miscarriage week 8). I understand that my age related risk is 1:197. Based on the nucahl scan alone (1:500) AND the combined test (1:1150), it appears that my chance of having a Down's syndrome baby is fairly small. I know, however that the recommendation in Israel is to do the test if the woman is >35. As you can imagine, this is a very painful decision, given the risk for miscarriage. Furthermore, there is a LOT of prerssaure here from doctors not to do the amniocentesis (for whatever reason. Perhaps moral, perhaps they don't like being challenged OR possibly the reason is financial). On the other hand, I know that even the combined test only gives us 92% probability of accuracy. However, having looked into this in some detail, I still don't understand how this probability is calculated OR what the implications of 8% margin of error mean in practical terms. Can you please help? Any advice would be very much appreciated

we recommend the test for a 38 yrs old pt regardless of all other test it seems that your risk is not high but our recommendation is to do the procedure