A LONGITUDINAL STUDY OF PROTEIN C ACTIVITY IN PREGNANT NIGERIANS IN SOUTH EASTERN NIGERIA

Abstract

INTRODUCTION; Haemostasis is the process of blood clotting and the subsequent dissolution of the clot, following repair of the injured tissue. It is a dynamic process whereby blood coagulation is initiated and terminated in a rapid and regulated fashion .Pregnancy, on its own is associated with physiological changes with the overall balance of haemostasis tilting towards apparent hyper coagulability as pregnancy progresses and even up to pueperium. These changes in the haemostatic balance, due mainly to increase in the levels of some coagulation factors and high oestrogen levels are a part of the adaptation mechanism of the human female to pregnancy. AIMS AND OBJECTIVES: This study is aimed at evaluating pregnancy induced physiological changes in the activities of protein C (Activated protein C (APC) sensitivity ratio), Prothrombin time ( PT), Activated partial thromboplastin time ( APTT) and platelet count in pregnant women seen in South Eastern Nigeria with the purpose of obtaining the mean value for platelet count, protein C activity (APC sensitivity ratio), Prothrombin time Activated partial thromboplastin time . SUBJECTS AND METHOD: A comparative prospective study involving 145 pregnant subjects recruited from the ante natal clinics of University of Nigeria Teaching hospital ( U.N.T.H.) was carried out. They were recruited during the second trimester and followed up to the third trimester. The study controls included 50 female non pregnant controls. APC sensitivity ratio (Clot based assay) Prothrombin Time (PT), Activated partial thromboplastin Time and platelets were measured for the female non pregnant control subjects and in the second and third trimesters for the pregnant subjects using Kinghawk semi automated coagulometer KH 202 for the coagulation
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assays and Sysmex KX 21 for the platelet count. Data was analyzed using SPSS statistical software version 11 and Graph pad prism statistical software version 5.02 and Graph pad prism Stat mate version 2.00. RESULTS: The mean platelet count for female non pregnant control subjects was 226.34 ± 69.16 x 109/l. The pregnant subjects in the second trimester and third trimester had mean counts of 186.38 ± 42.81 x109/l. and 167.46± 49.63 x109/l respectively. These differences were statistically significant using ANOVA ( P<0.0001). The post hoc multiple comparison showed that this finding was as a result the differences between control subjects versus the pregnant subjects in their 2nd trimester of pregnancy (P<0.0001), the control subjects versus pregnant subjects in their 3rd trimester (P<0.0001), as well as the 2nd trimester versus 3rd trimester (P=0.004). The mean Prothrombin time for female non pregnant control subjects was 13.17 ± 0.77seconds. Pregnant subjects in the second trimester and third trimester had a mean value of 12.19± 0.84 seconds and 13.10± 2.09 seconds respectively. These changes were also statistically significant using ANOVA (P<0. 0001). However, the post hoc multiple comparison showed that this finding was mainly due to the differences between the control subjects versus the pregnant subjects in their 2nd trimester of pregnancy and between the second trimester versus the 3rd trimester (P<0.0001). The differences noted between the control subjects versus pregnant subjects in their 3rd trimester did not contribute to the this. (P=0.960). The mean APTT was 40.09 ±3.44seconds in the non pregnant controls. The pregnant subject had a mean APTT of 36.83 ±3.61seconds in the second trimester and 39.51±4.44 seconds in the third trimester respectively. These changes were also statistically significant using ANOVA
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( P<0.0001).The post hoc multiple comparison showed that this finding was due to differences between the non pregnant control subjects versus the pregnant subjects in their 2nd trimester of pregnancy and also the pregnant subjects in the 2nd trimester versus 3rd trimester (P<0.0001). The differences between control subjects versus pregnant subjects in their 3rd trimester did not contribute to the observed statistical significance (P=0.642). The female non pregnant controls and pregnant subjects in their second and third trimester with APC sensitivity ratio ≥4 were 20% ,52% and 27% respectively while those with APC sensitivity ratio ≤4 were 8% ,38% and 61% respectively. Chi square analysis were statistically significant (p=0.000) .The non pregnant controls had mean APC ratio of 4.34 ± 0.43. The pregnant subjects had a mean APC ratio of 4.27± 0.44 in the second trimester and 3.87± 0.50 in the third trimester respectively. These changes were also statistically significant using ANOVA (P<0.0001). The post hoc multiple comparison showed that these findings were mainly due to differences between the non pregnant control subjects versus pregnant subjects in their 3rd trimester and also differences in the pregnant subjects between the 2nd trimester versus 3rd trimester (P<0.0001). However, the differences between non pregnant control subjects versus the pregnant subjects in their 2nd trimester of pregnancy did not contribute to this. (P=0.671). CONCLUSION: This study has showed overall that there are indeed pregnancy induced changes in APC sensitivity ratio ( protein C activity) of Prothrombin time PT, Activated thromboplastin time (APTT )and platelet count and these changes in these haemostatic parameters are influenced by the gestational age of the pregnancy .