The sumary line goes in the first OBR-4.2 segment:
MSH|^~\&|MAeHCQDC|MAeHCQDC||Fenway|20170921033448||ORU|2295|P|2.3
PID|1|123454|345567|^^|Test^Patient ^^||19910101|F||White|1 mouse way ^^city^ST^02364||tel:+1-123-456-7890
OBR|1|3024291|| BLOOD^Summary Line goes here|||2017091816500400|||||||||^^
OBX|1|ST|5047-6^ANA^5047-6||POSITIVE||||||F|||2017091816500400