Thrombogenesis-related characteristics of platelets and platelet indices in pregnant COVID-19 women
Authors: Spiridonova N. V. , Gritsenko T. A. , Khurtova E. F. 
Published: November 2023

Introduction. Thrombosis emerging in COVID-19 represents one of its most common complications. The period of pregnancy is accompanied by elevated susceptibility to infectious diseases and increased risk of thrombosis.

Aim: to assess time-dependent change in platelet count and platelet indices in general clinical blood test in pregnant COVID-19 women related to illness onset and developed thrombosis.

Materials and Methods. A retrospective analysis of 230 case histories from pregnant COVID-19 women at the third trimester was carried out. Of these, 99 women were selected who met the inclusion criteria: COVID-19 infection laboratory-verified by polymerase chain reaction (PCR); third trimester of pregnancy; presence/absence of thrombotic complications. All patients were divided into 2 groups: the control group consisted of 94 pregnant women aged 31.5 [28.0; 35.0] years without thrombotic complications and the average gestational age at illness onset was 34.1 [30.2; 37.6] weeks; the main group included 5 patients aged 33.0 [28.5; 37.5] years and the average gestational age at illness onset was 33.2 [30.2; 37.8] weeks, with thrombotic complications emerged during the disease course: thrombosis of upper and lower extremity veins; massive pulmonary embolism; thrombosis of the splenic vein at the spleen hilum; left atrial thrombus. The following parameters were evaluated dynamically (on day 6–8, 9–11, 12–15, 16–23 and 24–72 of the disease): total platelet count, thrombocrit, mean platelet volume, platelet distribution width (PDW), large platelet count. A comparative analysis of the study data and a correlation analysis with the time from disease onset and detected thrombosis were carried out.

Results. Over the entire observation period, there were noted increased RDW (16.30 [15.80; 16.50]%), average platelet volume (10.70 [9.70; 11.80] fl), and large platelet count (73.00 [59.00; 96.00]×109/L) along with platelet count (182.50 [155.00; 184.50]×109/L) tended to elevate in main vs. control group. A correlation was established between the above parameters and illness onset as well as thrombogenesis time point (p < 0.05). The beginning of developing thrombosis in main group was mainly recorded on day 12–15 after the onset. РDW increased in both groups by day 16–23 of illness, but more pronounced changes were found in main group reaching 16.50 [16.40; 16.60]% compared to control group (16.10 [15.80; 16.40]%). By day 16–23, thrombocrit in both groups positively correlated with illness onset. In addition, large platelet count tended to rise in main group remaining, however, below the normal limit: 0.13 [0.11; 0.20]% compared to control group (0.26 [0.21; 0.31]%). Large platelet count was quite high and increased daily in both groups; the average large platelet count throughout entire observation period was lower in the main (73.00 [59.00; 96.00]×109/L) vs. control group (81.00 [66.00; 102.00]×109/L), so that in the former it sharply decreased down to 55.00 [42.00; 78.00]×109/L on day 16–23.

Conclusion. These data mirror the course of thrombotic process and may serve as the basis for assessing the prognosis of thrombotic complications and identification of high-risk groups among pregnant COVID-19 women.