diagnostic procedure

NOUN
20 LETTERS · STARTS WITH D

diagnostic procedure is a valid 20-letter word worth 28 points in Scrabble and 34 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
D2I1A1G2N1O1S1T1I1C3P3R1O1C3E1D2U1R1E1
2 + 1 + 1 + 2 + 1 + 1 + 1 + 1 + 1 + 3 + 0 + 3 + 1 + 1 + 3 + 1 + 2 + 1 + 1 + 1 =28 PTS
DOUBLE WORD → 56TRIPLE WORD → 84
MEANING

What does diagnostic procedure mean?