counting rows before processing with a cursor tsql

If you are able to declare your cursor as STATIC then you can use the built in function @@Cursor_Rows

Cursor Options (Static/ReadOnly/Dynamic)

@@Cursor_Rows

if exists(
    SELECT
        tblHSOutcomes.strOutcomeName, 
        tblHSData.fkHSTest
    FROM
        tblHSData 
        INNER JOIN tblHSOutcomes ON tblHSData.fkOutcome = tblHSOutcomes.uidOutcome 
        INNER JOIN tblHSTests ON tblHSData.fkHSTest = tblHSTests.uidTest
    WHERE
        tblHSData.fkEpisode = @uidHSEpisodes
)
...

Here is a example of how to use @@Cursor_Rows

DECLARE TestCursor CURSOR STATIC FOR
  SELECT <snip>

OPEN TestCursor

IF @@Cursor_Rows > 0 BEGIN

  FETCH NEXT FROM TestCursor INTO @compid, @logid, @category
  WHILE @@FETCH_STATUS = 0 BEGIN   

  <snip>
END

CLOSE TestCursor
DEALLOCATE TestCursor

Please note that you need to declare the cursor STATIC (or KEYSET)