Table 1.

Histological score.

Score	Alveolar Septae	Alveolar Hemorrhage	Intra-Alveolar Fibrin	Intra-Alveola Infiltrations per Field
0	All are thin and delicate	No hemorrhage	No intra-alveolar fibrin	Less than 5 intra-alveolar cells
1	Congested alveolar septae in less than 1/3 of the field	Erythrocytes per alveolus in 1 to 5 alveoli	Fibrin strands in less than 1/3 of the field	5 to 10 intra-alveolar cells
2	Congested alveolar septae in 1/3 to 2/3 of the field	At least 5 erythrocytes per alveolus in 5 to 10 alveoli	Fibrin strands in 1/3 to 2/3 of the field	10 to 20 intra-alveolar cells
3	Congested alveolar septae in more than 2/3 of the field	At least 5 erythrocytes per alveolus in more than 10 alveoli	Fibrin strands in more than 2/3 of the field	More than 20 intra-alveolar cells