This has not been released for TestRail as of yet. However, I will add your vote to this additional handling of markdown inside tables to help us prioritize this.
In the meantime, you may be able to achieve this with a UI script and a find/replace function. You can find out more about UI scripts in our documentation here.
You wouldn’t necessarily be able to prevent the pipe character from being interpreted as a table column divider inside a test case, however you could use a UI script to change a placeholder in your table into a pipe character in the user interface.
For example, if you used ‘\pipe’ in your table where you need a pipe escaped, and then use a UI script to search for this ‘\pipe’ and replace it with ‘|’.
I hope this helps you in the meantime.