Thousand patients of Covid 19 admitted during the study period were taken into study. The patients were classified as mild(stage 1) moderate(stage 2)& severe (stage 3) based on the clinical criteria suggested by WHO. In the 1000 patients 79% belonged to mild category, 16% belonged to moderate and 5% belonged to severe category.
Comparison of Peripheral blood counts and Clinical Stage
The clinical stage of the patient was correlated with total WBC count and differential count. The variation of total WBC count , differential neutrophil count, differential lymphocyte count and differential monocyte count between stages 1&2 and stages 1&3 was found to be significant (p<0.005). Whereas the correlation between other groups were not significant(p>0.005).
The mean blood count values in different clinical stage of the disease is described in Table 1. An increase in mean WBC count, differential neutrophil count and a decrease in differential lymphocyte count was seen in stage 3 disease.
Totally 12% of cases (out of 1000 cases) showed leucocytosis. 8% cases in stage 1(out of 789 cases), 27% of cases in stage 2(out of 163 cases) and 32 % of cases in stage 3(out of 48 cases) showed leucocytosis. Thus emphasizing the fact that an increase in WBC count was seen in the course of disease progression.
35% of cases (out of 1000 cases) showed neutrophilia. 25% cases in stage 1(out of 789 cases), 72% cases in stage 2 (out of 163 cases) & 89% (out of 48 cases) cases in stage 3 showed neutrophilia. Thus an increase in neutrophil count serves as a significant factor in determining disease progression.
14.7% of cases (out of 1000 cases) showed thrombocytopenia. There was no significant difference in platelet count between groups.
Comparison of Peripheral smear morphological changes and Clinical Stage
The morphological changes of the blood cells and their presentations in various disease stages are discussed in Table 2. From the findings it has been observed that presence of neutrophilia with toxic changes were more prevalent in stage 3 disease thus emphasizing the fact that an increase in neutrophil count and occurrence of toxic changes in neutrophils is an important indicator for disease progression[Fig. 1]. Activated lymphocytes and monocytoid lymphocytes were common in all stages signifying the fact that this is a common morphological parameter seen in all covid patients irrespective of the stage of the disease[Fig. 2]. Whereas occurrence of plasmacytoid lymphocytes was more common in stage 3 disease emphasizing the fact this morphological finding can also be a factor indicating disease progression [Fig. 2].
Monocyte cytoplasmic vacuolation and giant platelets were other morphological findings observed in the peripheral smear but there was no significant relationship between these changes and the disease stage [ Fig. 3 &4].
Comparison of peripheral smear blood counts , morphological changes with coagulation parameters (PT, APTT & D dimer)
The mean prothrombin time, activated partial thromoboplastin time and D dimer values in different stages of the disease are discussed in table 3. There was an increased mean PT, APTT and D dimer values in stage 3 disease.
(i) Prolonged PT & peripheral smear findings
3.5% of cases in the study presented with prolonged PT. 60% of these cases belonged to stage 2 and stage 3 and 40% belonged to stage 1. The peripheral smear findings of the patients with prolonged PT are discussed in Table 2
(ii) Prolonged APTT & peripheral smear findings
3.3% of cases in the study presented with prolonged APTT. 55% of these cases belonged to stage 2 and stage 3 and 45% belonged to stage 1. The peripheral smear findings of the patients with prolonged APTT are discussed in Table 2
(ii) Elevated D dimer & peripheral smear findings
19.5% of cases in the study presented with elevated D dimer values. 55% of these cases belonged to stage 2 and stage 3 and 45% belonged to stage 1. The peripheral smear findings of the patients with elevated D dimer values are discussed in Table 4
(iv) Prolonged PT, APTT , elevated D dimer values & peripheral smear findings
1% of covid patients in our study presented with derangement of all coagulation parameters( PT, APTT & D dimer). The peripheral smear findings of these patients are described in table 5
The peripheral smear findings of patients with deranged coagulation parameters ( prolonged PT , APTT & elevated Dimer) showed neutrophilia, toxic changes in neutrophils & activated lymphocytes as the most common presentation. Therefore presence or development of these morphological parameters in covid positive patients may suggest that the patient is progressing into a state of coagulopathy.