1Department of Clinical Pathology, Faculty of Medicine, Assiut University, Egypt
2Department of Obstetrics & Gynecology, Faculty of Medicine, Assiut University, Egypt
Received Date: 16 Jan, 2020 ; Accepted Date: 23 Jan, 2020 ; Published Date: 29 Jan, 2020
Objectives: To evaluate the significance of Platelet (PLT) count and platelet indices in the diagnosis of patients with Preeclampsia(PE) and eclampsia.
Patients and methods: A cross-sectional study conducted in a tertiary University hospital between May 2017 and October 2018.Twenty women were enrolled in three groups: group (I) women diagnosed as PE, group (II) women diagnosed as eclampsia, and group (III) age-matched normal pregnant women as a control group. Two ml of venous blood were collected for complete blood count and blood film. The following indices were measured PLT count, Mean Platelet Volume (MPV), Platelet Distribution Width (PDW), Mean Platelet Component (MPC), Platelet Distribution Width (PDW), Mean Platelet Mass (MPM) and Plateletcrit (PCT).
Results: PLT count was significantly lower in the PE group (207±42) than the control group (214± 56) (P=0.03), and significantly lower in the eclampsia group (142±77) than the control group (214±56) (P=0.04). Additionally, PLT count was significantly lower in the eclampsia group than PE group (P=0.01). MPV was significantly higher in the PE group (8.60±0.95) than the control group (7.85±0.76) (P=0.02). PCT was significantly lower in PE group compared to eclampsia and control groups (p<0.001). PDW and MPM showed no significant differences between the study groups (P= 0.30 and 0.39, respectively). MPC was significantly lower in PE group than the control group (P= 0.01) and in the eclampsia group than the control group (P= 0.03).
Conclusion: Increased MPV with decreased PCT and MPC are useful markers in the diagnosis of PE and eclampsia in hypertensive pregnant women.
Eclampsia; Platelet count; Platelet indices; Preeclampsia
Preeclampsia and eclampsia are major obstetric problems in developing countries. They remain a significant cause of maternal mortality throughout the world . Preeclampsia (PE) is a pregnancy-specific, multi-system disorder which is characterized by the development of hypertension (blood pressure ≧140/90 mmHg) and proteinuria (≧0.3 g/d), after 20 weeks of gestation . If preeclampsia is associated with convulsions, the condition is called eclampsia . In developing countries, most PE cases remain unrecognized until severe complications such as eclampsia develop. Platelets (PLTs) play an essential role in the pathogenesis of PE . Platelets are normally present in the bloodstream in an inactive state, but they can activate instantly when they come in contact with the damaged or activated endothelial wall . PLT activation begins in the first month of pregnancy in women with risk for PE . PLT count decreases by an average of 10% during the third trimester of uncomplicated pregnancy due to hemodilution .
Increased consumption of PLTs causes thrombocytopenia, which is an essential sign of severe PE. Thrombocytopenia occurs in up to 50% of women with PE . PLT size correlates with platelet activity . Larger PLTs are enzymatically and metabolically more active and have a higher potential thrombotic ability as compared with smaller ones .
When PLT function throughout a normal pregnancy is evaluated, the sensitivity of PLT volume was found to be significantly higher than that of PLT count . When PLTs become larger in size, this may cause changes in some PLT indices such as Mean Platelet Volume (MPV) which reflects the average size of PLTs , Platelet Distribution Width (PDW) as an indicator of volume variability of PLT size , Mean Platelet Component (MPC) measures mean refractive index of platelets by two angle light scatter , Platelet Component Distribution Width (PCDW) which measures the variation of PLT shape , Platelet Large Cell Ratio (PLCR)which is the percentage of PLTs that exceed the normal value of PLT volume in the total PLT count , and Plateletcrit (PCT) which is the volume occupied by PLTs in blood . In PE, increased PLT indices may occur earlier than the development of other recognized manifestations like hypertension and proteinuria. On the other hand, lowered PLT count increased PLT indices in pregnant women during antenatal checks may be considered as a risk factor for the development of PE and eclampsia .
The value of PLT indices in the diagnosis of PE is not fully understood yet. Therefore, the current study aims to evaluate the significance of measurement of PLT count and platelet indices in the diagnosis of patients with PE and eclampsia.
The current study was a cross-sectional study carried out in a tertiary University hospital between May 2017 and October 2018. The Institutional ethical review board approved the study protocol, and informed written consent was obtained from all participants after discussing the nature of the study.
All pregnant patients diagnosed as PE attended the reception unit of the hospital were invited to participate in the study if they met our inclusion criteria. We included women aged 18-40 years, with newly developed hypertension after 20 weeks of gestation. We excluded women who had chronic renal or liver diseases, diabetes mellitus, bleeding disorders, those who use drugs have an antiplatelet effect, women with major fetal anomalies, intrauterine fetal death, and those diagnosed with HELLP syndrome (hemolysis, elevated liver enzymes, and low platelet count). We carried out a pilot study, so no formal sample size calculation was performed. Women diagnosed to have PE according to ACOG guidelines (American College of Obstetricians and Gynecologists), as the presence of (1) Systolic Blood Pressure (SBP) greater than or equal to 140 mmHg or diastolic blood pressure (DBP) greater than or equal to 90 mmHg, on two occasions at least 4 hours apart in a previously normotensive patient, OR (2) an SBP greater than or equal to 160 mmHg or a DBP greater than or equal to 110 mmHg (in this case hypertension can be confirmed within minutes to facilities timely antihypertensive therapy). In addition to the blood pressure criteria, proteinuria greater than or equal to 300 mg/day in a 24-hr urine collection or a urine dipstick protein of 1+ or more is required to diagnose PE .
A detailed history was taken from all women, and Body mass index (BMI) was calculated for each participant. The study was carried out on sixty women divided into three groups: group (I) women diagnosed as PE, group (II) women diagnosed as eclampsia, and group (III) age-matched normal pregnant women as a control group. Each group included 20 women. Two ml of venous blood were collected under complete aseptic conditions into EDT Atubes for complete blood count and blood film. Complete blood count(for patients and control subjects) was done using (ADVIA 2120 i analyzer, Bayern –Germany).
The blood sample was analyzed within four hours after collection, and included by the following:
- Mean platelet volume MPV (fL): Analyser calculated measure of thrombocyte volume= [(plateletcrit /platelet count (×109/l)] ×105.
- Plateletcrit PCT (%): Volume occupied by platelet in blood = platelet count × MPV / 10,000
- Mean platelet component MPC (g/dL): Measure of mean refractive index of platelet component=(mean refractive index -1.333)/(0.0018) where 1.333= refractive index of water and 0.0018 (g/dL)= average refractive index increment.
- Mean platelet mass MPM(pg): is calculated from the platelet dry mass histogram=MPC concentration x MPV x 100
- Platelet distribution width PDW (%): Indicator of volume variability in platelet size =SD of platelet volume /MPV x100
Laminar flow is induced by injecting a slow-moving sample dilution into a stream of fast-moving sheath fluid, which prevents mixing. The sheath fluid surrounds the diluted sample and narrows it so that cells flow through the sensing zone in a single file. This is hydrodynamic focusing.
Data was collected and analyzed using SPSS (Statistical Package for the Social Science, version 20, IBM, and Armonk, New York). Continuous data were expressed in the form of mean ± SD and range, while nominal data were expressed in the form of frequency and percentage. Fisher’s exact test was used to compare the nominal data of different groups in the study, while Mann- Whitney was used to compare mean of different two groups and Kruskal Wallis test for more than two groups supplemented with the post hoc LSD test. The Receiver Operating Characteristic (ROC) curve was plotted for MPC, MPV, and PCT. Based on calculations of sensitivity and specificity for cut off value of the three parameters, the Area Under the Curve (AUC) for each of them was determined. The largest AUC is associated with the best parameter (marker) for PE development. Pearson’s correlation was used to determine the correlation between PLT indices and different continuous parameters in the study. P-value was significant if < 0.05.
The mean age of women with PE was 27.4±6.67 years, and the mean gestational age was 33.6±3.9 weeks while in case of women with eclampsia, the mean age was 26.85±5.25 years, and the mean gestational age was 32.1±3.21 weeks (p=0.16). No statistically significant differences between the study groups regarding age, parity, gestational age, history of hypertension, or PE and BMI (Table 1). Table 2 shows the platelet count and the results of platelet indices in the study groups. PLT count was significantly lower in the PEgroup (mean±SD= 207±42 103/ uL) than the control group (mean±SD=214± 56103/ uL) (P=0.03), and significantly lower in the eclampsia group (mean±SD= 142±77 103/ uL) than the control group (mean±SD= 214± 56 103/ uL) (P=0.04). Additionally, PLT count was significantly lower in eclampsia group (mean±SD=142±77 103/ uL) than PE group (mean±SD= 207±42 103/ uL) (P=0.01).
Regarding the MPV, there was a statistically significant difference between the study groups (P=0.02). MPV was significantly higher only in the PE group (mean±SD=8.60±0.95fL) than the control group (mean±SD=7.85±0.76fL) (P=0.02). PCT showed a statistically significant difference between the study groups (P<0.001). PCT was significantly lower in the PE group compared to eclampsia and control groups (p<0.001). PDW and MPM showed no significant differences between the study groups (P=0.30 and 0.39, respectively). Finally, the MPC showed a statistically significant difference between the study groups (P=0.01). Additionally, it was significantly lower in the PE group than the control group (P= 0.01) and in the eclampsia group than the control group (P= 0.03).
ROC curve analysis of different platelet indices for diagnosis of PE and eclampsia showed that the best cut-off value of MPV for diagnosis of PE was >7.6 with 95% sensitivity and 28% specificity (AUC=0.60, P=0.02) (Figure 1A), while the best cut-off value for the diagnosis of eclampsia was >8.6 with 50% sensitivity and 72.5% specificity (AUC=0.61, P=0.01) (Figure 1B). Regarding the MPC, the best cut-off value for diagnosis of PE and eclampsia was <24.3 with 95% sensitivity and 25% specificity (AUC=0.67, P=0.02) for PE(Figure 2A), and 70% sensitivity and 67.5% specificity (AUC=0.67, P<0.001) for eclampsia (Figure 2B). Regarding PCT, the best cut-off value for diagnosis of PE was <0.17 with 75% sensitivity and 55% specificity (AUC=0.67, P=0.04) (Figure 3A), while the best cut-off value for diagnosis of eclampsia was <0.15 with 70% sensitivity and 75% specificity (AUC=0.76, P=0.02) (Figure 3B). There was no significant correlation between patients’ age and PLT indices except PCT that showed a moderately significant positive correlation with age in patients with PE (r= 0.45, P= 0.03) (Figure 4). Additionally, PCT showed strong significant positive correlation with PLT count (r= 0.9, P= 0.01) (Figure 5). No correlation was found between systolic, diastolic blood pressure, and BMI with all platelet indices in patients with PE and eclampsia.
Pregnancy is associated with complex and incompletely understood changes involving the blood coagulation. Information regarding the behavior of platelets in normal pregnancy has shown varying results . PLT indices are a group of indices that are used to measure the PLT count and PLT morphology . The PLTs count in the blood can be maintained in an equilibrium state by regeneration and elimination in physiological conditions . Thus, either the PLT or their morphology remains relatively constant. Under pathophysiological conditions, any factor which could inhibit PLT regeneration, increase their activation, or accelerate their death will cause changes in both PLT count and morphology and thus results in a change in PLT indices.
In the present study, an attempt has been made to assess the role of PLT count and PLT indices in normotensive pregnant women and also in the diagnosis of PE and eclampsia. PLT count showed a significant decrease in patients with PE and eclampsia compared to the control group. This was consistent with Gupta et al., 2018 study  that found a significant decrease in PLT count in PE patients (168±74.29103/uL) compared to the control group (229.61±73.27103/uL) (P=0.02). Additionally, Sameer et al., 2014  observed that the PLT count was significantly lower in PE (P<0.01) and eclampsia (P<0.01) than the control group. Moreover, our finding of a trend of lowering of PLT count with increasing severity of pregnancy-induced hypertension is consistent with Devi, 2012 and Bhavana et al., 2016 [22,23].
The mean PLT count decreases during pregnancy due to endothelial stress or hemodilution. Young PLTs become bigger and more active than older ones, and MPV level increases, especially around the 28th - 31st weeks . The reduced PLT count and increased MPV values continue throughout pregnancy . Previous studies reported that the high MPV levels in patients with PE are greater than those in healthy pregnant women without any blood pressure issues . MPV has been emphasized as an inflammation marker in some diseases such as PEwhen platelet activation begins in the first month of pregnancy in women with risk for PE; they become larger in size, which causes increased PLT indices such as MPV . Several studies on PLT count and MPV in PE reported different results. Similar to our findings, Abdel Razik, et al.,2018 reported that patients who developed PE showed a significant increase in MPV than normotensive women (p < 0.001) . Additionally, Unlu, et al., 2014 reported that MPV values increase in PE in contrast to normal pregnancies . Dundar, et al., 2008 showed a significant relationship between MPV and PE . Doğan, et al., 2015 documented significantly higher MPV in preeclamptic women than the control group .
On the other hand, in a study by Ceyhan, et al., 2006, there was no difference in MPV levels or PLT count between PE and control groups probably because of the differences in the methods and/or equipment used to obtain hemogram and the number of the studied cases . Additionally, Yavuzcan, et al., 2014 observed no significant difference in the MPV between women with severe PE, healthy pregnant women, and healthy nonpregnant women . Moreover, Al Sheeha et al., 2016 showed no difference in the MPV between the preeclamptic cases and the controls . In the current study, PCT was lower in women with PE than those with eclampsia and the control group with P <0.001 for both. The sensitivity and specificity of PCT value after the 20th week of gestation with a cut off value < 0.17% for the diagnosis of PE development were 75% and 55%, respectively. According to the diagnosis of eclampsia development, the sensitivity and specificity of PCT with a cut off value <0.15 % were 70% and 75%, respectively.
In agreement with our results, Freitas, et al., 2013 observed lower PCT in patients with PE compared to normal pregnant women . Also, Pughikumo, et al., 2015 reported that PCT decreased predictably from the first to the second trimester; this is presumably due to increased PLT consumption and hemodilution . On the other hand, Kurtogluet, al., 2016 showed no significant difference in PCT, and they reported that PCT is the least investigated parameter of PLT indices between normal and preeclamptic pregnancies . The current study showed lower MPC in patients with PE and eclampsia in comparison to the control group. Previous studies on diseased hypertensive patients showed lower MPC in hypertensive patients than the normal group . This was explained by the presence of P-selectin (CD62P), which is a PLT granule component of platelets that is redistributed to the plasma membrane during platelet activation and degranulation . Its expression has been shown to be inversely correlated with the MPC .
Although our study showed an increase in MPV with a decrease in PCT and MPC in preeclamptic women than normal pregnant women, other markers such as PDWshowed no significant differences between preeclamptic, eclamptic women and the control group. Our results were similar to Al Sheeha, et al., 2016 who reported no significant difference in PDW in their study , and Doğan, et al., 2015 who found no significant difference in PDW among women with severe PE, mild PE, and healthy controls . Nonetheless, a significantly higher level of PDW has been observed among women with PE in the study of Freitas et al., 2013  and Karateke, et al., 2015 . Also, Abdel Razik et al., 2018 reported that patients who developed PE showed a significant increase of PDW than normotensive women (p <0.001) . The discrepancy between different studies may be related to different numbers of cases and types of hematology analyzers. The relatively small sample size can be a limitation of the present study. Large scale prospective studies are needed from early pregnancy to evaluate the role of platelet indices in the prediction of PE. The clinical implication of the study is recommending platelet indices estimation as a routine examination during the antenatal screening of high-risk pregnant women for PE.
In conclusion, Increased MPV with decreased PCT and MPC are useful markers in the diagnosis of PE and eclampsia in hypertensive pregnant women. They can be used as good predictors in those patients. On the other hand, MPM and PDW showed no role in the diagnosis of PE and eclampsia.
No funding received for this research.
The authors declare that they have no conflict of interest.
Figure 1: ROC curve shows the diagnostic accuracy of Mean Platelet Volume (MPV) in diagnosis of preeclampsia (A) and eclampsia (B).
Figure 2: ROC curve shows the diagnostic accuracy of Mean Platelet Component (MPC) in diagnosis of preeclampsia (A) and eclampsia (B).
Figure 3: ROC curve shows the diagnostic accuracy of Plateletcrit (PCT) in diagnosis of preeclampsia (A) and eclampsia (B).
Figure 4: Correlation between age and Plateletcrit (PCT) in patients with preeclampsia.
Figure 5: Correlation between platelets count and Plateletcrit (PCT) in patients with preeclampsia.
Data was expressed in form of mean ± SD, frequency (percentage); BMI, body mass index
Table 1: Demographic Data of the study groups.
MPV: mean platelet volume, PCT: plateletcrit, PDW: platelet distribution width, MPC: mean platelet component, MPM: mean platelet mass; P: for difference between the study groups by Kruskal Wallis test; P1: for difference between the preeclampsia and eclampsia groups by Mann-Whitney test; P2: for difference between the preeclampsia and control groups by Mann-Whitney test; P3: for difference between the eclampsia and control groups by Mann-Whitney test
Table 2: Platelet count and platelet indices in the study groups.
Citation: Abd El-Rahman S, Sonosy DAE, Abbas AM, Abdou MAA (2020) Evaluation of Platelet Count and Platelet Indices in The Diagnosis of Preeclampsia and Eclampsia: A Cross-Sectional Study. J Women’s Health Res 1: 101.