COMPARISON OF MEAN NORMAL PROTHROMBIN TIME (MNPT) BETWEEN DIFFERENT TRIMESTER OF PREGNANCY WITH NORMAL NON-PREGNANT REPRODUCTIVE AGE GROUP FEMALE SUBJECTS

Dr. B. Vinodh Kumar*

ABSTRACT

Introduction: Pregnancy is hypercoagulable, most coagulation factors increase in normal pregnancy, hence the prothrombin time (PT) and the activated partial thromboplastin time (APTT) are shortened. Therefore INR will be affected in pregnant patients if Mean normal Prothrombin time established in Non-pregnant patients is utilised for calculating INR in pregnant patients. Objective: This study is done to compare the MNPT between different trimesters of pregnancy with normal non-pregnant reproductive age group female subjects and to identify whether the MNPT established for non-pregnant subjects for reporting INR can be used for pregnant subjects also or there is a need to establish a separate MNPT in pregnant patients for reporting INR. Materials and Methods: A total of 80 apparently healthy subjects were enrolled for the study and sub classified into 4 groups. The first group (Group A) is 20 normal pregnant women in first trimester, second group (Group B) is 20 normal pregnant women in second trimester, third group (Group C) is 20 normal pregnant women in third trimester and the fourth group (Group D) is 20 normal non-pregnant women of Reproductive age (15-45 years) group. The subjects on anticoagulant drugs like heparin, warfarin etc, hypertension, diabetes mellitus, severe liver disease, any other acute or chronic illness were excluded from the study. The Prothrombin test was analysed by semi automated photo optic method by Thromborel S reagent. Results: The mean normal prothrombin time of Group A (20 normal pregnant women in first trimester) was 11.39 seconds with SD of 0.39, Group B (20 normal pregnant women in second trimester) was 10.91 seconds with SD of 0.41, Group C (20 normal pregnant women in third trimester) was 10.05 seconds with SD of 0.41 and Group D (- 20 normal non-pregnant women of Reproductive age (18-45 years) group) was 13.01 seconds with SD of 0.45. Conclusion: It is concluded that prothrombin time is decreased in normal pregnancy when compared with non-pregnant women of reproductive age group. Since the degree of difference of MNPT between different trismester of pregnancy with non-pregnant women of reproductive age group is statistically significant, it is warranted to establish a separate mean normal prothrombin time in pregnant subjects for reporting INR.

Keywords: Prothrombin time, coagulation, pregnancy, International Normalised Ratio (INR).