Platelet reactivity changes significantly throughout all trimesters of pregnancy compared with the nonpregnant state: a prospective study

Management of pregnant women who have bleeding disorders

Bleeding disorders, including von Willebrand disease (VWD), hemophilia, other coagulation factor deficiencies, platelet disorders, defects of fibrinolysis, and connective tissue disorders, have both maternal and fetal implications. Successful management of bleeding disorders in pregnant women requires not only an understanding of bleeding disorders but also an understanding of when and how bleeding occurs in pregnancy. Bleeding does not occur during a normal pregnancy with a healthy placenta. Bleeding occurs during pregnancy when there is an interruption of the normal utero-placental interface, during miscarriage, during an ectopic pregnancy, or at the time of placental separation at the conclusion of pregnancy. Although mild platelet defects may be more prevalent, the most commonly diagnosed bleeding disorder among women is VWD. Other bleeding disorders are less common, but hemophilia carriers are unique in that they are at risk of bleeding themselves and of giving birth to an affected male infant. General guidance for maternal management of a woman who is moderately or severely affected includes obtaining coagulation factor levels at a minimum in the third trimester; planning for delivery at a center with hemostasis expertise; and anticipating the need for hemostatic agents. General guidance for fetal management includes pre-pregnancy counseling; the option of preimplantation genetic testing for hemophilia; delivery at a tertiary care center with pediatric hematology and newborn intensive care; consideration of cesarean delivery of a potentially severely affected infant; and avoidance of invasive procedures such as scalp electrodes and operative vaginal delivery in any potentially affected infant.

Successful Caesarean Section on Ticagrelor Treatment One Day after Primary Percutaneous Coronary Intervention

Caesarean section is a challenging intervention in patients treated with dual antiplatelet therapy. We present a case of a 32-year-old pregnant woman experiencing large acute myocardial infarction (MI) of the anterolateral wall, complicated by cardiogenic shock in the 38th week of pregnancy, and treated with drug-eluting stent implantation and dual antiplatelet therapy (DAPT) consisting of aspirin and ticagrelor. Less than 24 h after the MI delivery started, an urgent Caesarean section was indicated. As multiplate aggregometry testing showed a relatively insufficient level of ticagrelor platelet inhibition and a moderate level of aspirin platelet inhibition, a Caesarean section was performed without discontinuation of ticagrelor, which was decided due to the need for emergency surgery. Local hemostatic measures including administration of tranexamic acid were applied. The patient did not experience excessive bleeding. A healthy male baby was born. To the best of our knowledge, this is the first reported case of surgery in pregnant women treated with DAPT without ticagrelor discontinuation.

Platelets and endothelial dysfunction in gestational diabetes mellitus

The prevalence of gestational diabetes mellitus (GDM) has increased in recent years, along with the higher prevalence of obesity in women of reproductive age. GDM is a pathology associated with vascular dysfunction in the fetoplacental unit. GDM-associated endothelial dysfunction alters the transfer of nutrients to the foetus affecting newborns and pregnant women. Various mechanisms for this vascular dysfunction have been proposed, of which the most studied are metabolic alterations of the vascular endothelium. However, different cell types are involved in GDM-associated endothelial dysfunction, including platelets. Platelets are small, enucleated cell fragments that actively take part in blood haemostasis and thrombus formation. Thus, they play crucial roles in pathologies coursing with endothelial dysfunction, such as atherosclerosis, cardiovascular diseases, and diabetes mellitus. Nevertheless, platelet function in GDM is understudied. Several reports show a potential relationship between platelet volume and mass with GDM; however, platelet roles and signaling mechanisms in GDM-associated endothelial dysfunction are unclear. This review summarizes the reported findings and proposes a link among altered amount, volume, mass, reactivity, and function of platelets and placenta development, resulting in fetoplacental vascular dysfunction in GDM.

Von Willebrand Disease, Hemophilia, and Other Inherited Bleeding Disorders in Pregnancy

Inherited bleeding disorders, which comprise von Willebrand disease (VWD), hemophilia, other congenital clotting factor deficiencies, inherited platelet disorders, defects of fibrinolysis, and connective tissue disorders, have both maternal and fetal implications. Although mild platelet defects may actually be more prevalent, the most common diagnosed bleeding disorder among women is VWD. Other bleeding disorders, including hemophilia carriership, are much less common, but hemophilia carriers are unique in that they are at risk of giving birth to a severely affected male neonate. General guidance for maternal management of inherited bleeding disorders includes obtaining clotting factor levels in the third trimester, planning for delivery at a center with hemostasis expertise if factor levels do not meet the minimum threshold (eg, less than 0.50 international units/1 mL [50%] for von Willebrand factor, factor VIII, or factor IX), and using hemostatic agents such as factor concentrates, desmopressin, or tranexamic acid. General guidance for fetal management includes prepregnancy counseling, the option of preimplantation genetic testing for hemophilia, and consideration of delivery of potentially affected male neonates with hemophilia by cesarean delivery to reduce the risk of neonatal intracranial hemorrhage. In addition, delivery of possibly affected neonates should occur in a facility where there is newborn intensive care and pediatric hemostasis expertise. For patients with other inherited bleeding disorders, unless a severely affected neonate is anticipated, mode of delivery should be dictated by obstetric indications. Nonetheless, invasive procedures such as fetal scalp clip or operative vaginal delivery should be avoided, if possible, in any fetus potentially affected with a bleeding disorder.

Platelet aggregation in normal pregnancy

It was recently shown that abnormal platelet aggregation (PA) had played a critical role in some adverse pregnancies. Till now reference range for PA in normal pregnancy has not been determined. Furthermore, few study has been conducted to explore the factors related to PA. Our study was performed to assess the reference range of PA in normal pregnancy (150 participants in the second trimester), and to determine whether it differs from that of the controls (38 nonpregnant participants). In addition, this study explored the factors related to PA. The results showed that PA was significantly higher in normal pregnancy than that in the controls (84.40% vs. 80.7%, respectively, P = 0.013). The reference interval for PA in normal pregnancy was 74.75%-94.77%. Hemoglobin (Hb), platelet counts (PLT) and albumin (Alb) were significant lower in normal pregnancy than those in the control group. Moreover, it was found that PA was positively correlated with PLT (r = 0.263, P < 0.001), and negatively correlated with platelet distribution width (PDW) (r = -0.342, P < 0.001) and mean platelet volume (r = -0.296, P < 0.001). Linear correlations between PA and Alb, PDW were proved by linear regression model (LRM). In conclusion, PA was enhanced in normal pregnancy, and Alb and PDW might be the possible contributing factors to PA.

A new decade awaits sticky platelet syndrome: where are we now, how do we manage and what are the complications?

INTRODUCTION

Sticky platelet syndrome is a less known platelet function disorder with a familiar occurrence and likely genetic background. Clinically, it is characterized by an increased risk of venous and arterial thromboembolic events and obstetric placenta-mediated complications. The increased aggregation after low-dose ADP and/or epinephrine is its distinctive laboratory feature. Though described for almost 40 years, several issues regarding its etiology, involved pathomechanisms, genetic background, optimal diagnostic and treatment approach remain controversial.

AREAS COVERED

The work aims to summarize published studies, the actual definition of the syndrome, and point out its drawbacks. A literature search on Medline, Embase, and archives from EHA congresses was performed (terms: 'sticky platelet syndrome' - 'platelet hyperreactivity' - 'platelet hyperaggregability'). The authors added in their unpublished data. The introductory overview of the present understanding is followed by the discussion of the pathophysiologic, diagnostic, and therapeutic problems.

EXPERT OPINION

Despite the growing evidence provided by case reports and series, the lack of robust studies limits the decision-making on diagnostics and management. The diagnostic issues, particularly the standardization of light transmission aggregometry, represent the crucial problem for the broader acceptance of the syndrome.

Neuraxial Techniques for Parturients with Thromboprophylaxis or Thrombocytopenia

Pharmacologic thromboprophylaxis from venous thromboembolism (VTE) and thrombocytopenia in pregnancy results in conditions that may preclude the use of neuraxial anesthesia due to a perceived risk of spinal/epidural hematoma. Spinal epidural hematoma is a recognized complication in patients who are hypocoagulable and may lead patients to undergo general anesthesia for delivery or other procedures, which carries numerous complications in obstetric care. A robust understanding of maternal physiologic changes in coagulation status, review of consensus statements, and safety bundles may help to maximize the use of neuraxial anesthesia in obstetric patients who might otherwise be denied these anesthetic techniques.

Morphometric and Nanomechanical Features of Platelets from Women with Early Pregnancy Loss Provide New Evidence of the Impact of Inherited Thrombophilia

Pregnancy is associated with hypercoagulation states and increased thrombotic risk, especially in women with thrombophilia. We combine atomic force microscopy (AFM) and flow cytometry to examine the morphology and nanomechanics of platelets derived from women with early pregnancy loss (EPL) and control pregnant (CP) and non-pregnant (CNP) women. Both control groups exhibit similar morphometric parameters (height and surface roughness) and membrane stiffness of platelets. EPL patients’ platelets, on the other hand, are more activated than the control groups, with prominent cytoskeletal rearrangement. In particular, reduced membrane roughness (22.9 ± 6 nm vs. 39.1 ± 8 nm) (p < 0.05) and height (692 ± 128 nm vs. 1090 ± 131 nm) (p < 0.05), strong alteration in the membrane Young modulus, increased production of platelets’ microparticles, and higher expression of procoagulant surface markers, as well as increased occurrence of thrombophilia (FVL, FII20210A, PLA1/A2, MTHFR C677T or 4G/5G PAI-1) polymorphisms were found. We suggest that the carriage of thrombophilic mutations triggers structural and nanomechanical abnormalities in platelets, resulting in their increased activation. The activation state of platelets can be well characterized by AFM, and the morphometric and nanomechanical characteristics might serve as a new criterion for evaluation of the cause of miscarriage and offer the prospect of an innovative approach serving for diagnostic purposes.

Arachidonic acid-induced platelet aggregation and acetylsalicylic acid treatment during pregnancy in women with recurrent miscarriage, a post hoc study

In this post hoc study, arachidonic acid (AA)-induced platelet aggregation during pregnancy with and without acetylsalicylic acid (ASA) treatment was studied in 323 women with unexplained recurrent first-trimester miscarriage and in 59 healthy women with normal pregnancies. All women had normal AA-induced platelet aggregation in the non-pregnant state. Women with recurrent miscarriage were treated with 75 mg ASA or placebo daily. AA-induced platelet aggregation was measured with multiple electrode impedance aggregometry and presented in units (U), where 1 U = 10 aggregation units x minutes. There were no significant differences in platelet aggregation between placebo-treated women with recurrent miscarriage and healthy women. The mean differences were-0.7 (95%CI; -7.0; 5.6) U in the non-pregnant state, 3.8 (95%CI; -4.6; 12.2) U during the late first trimester and 1.7 (95%CI; -6.7; 10.3) U and 4.1 (95%CI; -3.9; 12.0) U during the early and late third trimester, respectively. ASA reduced platelet aggregation by median -84.0% (Q1; Q3; -89.8; -76.3), -79.9% (-84.7; -69.2) and -75.7% (-83.5; -49.5), respectively, during pregnancy. The degree of inhibition by ASA decreased during the third trimester (p < .0001). There were two (1.9%) complete non-responders to ASA and 32.1% with a partial response. The rate of subsequent miscarriage was not affected by ASA, which did not seem to influence the rate of early miscarriage if treatment was initiated when a viable pregnancy was detectable by ultrasound.

First-Trimester Platelet Count as a Predictive Biomarker for Neonatal Birth Weight Among Pregnant Women at Advanced Maternal Age

The aim of this study was to investigate the association between first-trimester platelet count and neonatal birth weight in pregnant woman at advanced maternal age. Our study included 148 pregnancy women of advanced maternal age, the clinical and laboratory materials were retrospective obtained from medical record system. The neonatal birth weight was positively correlated with maternal body mass index and fetus gestational age (r = 0.332, P < .001; r = 0.469, P < .001), even more interestingly, the neonatal birth weight was positively correlated with first-trimester platelet count in pregnant women of advanced maternal age (r = 0.203, P = .013). Multiple linear regression analysis revealed that neonatal birth weight had an independently association with first-trimester platelet count in pregnant women of advanced maternal age (multiple-adjusted r values 0.167, P = .013). First-trimester platelet count is positively associated with neonatal birth weight, suggesting that first-trimester platelet count may be a predictive biomarker for neonatal birth weight in pregnant women of advanced maternal age.

L-NAME-induced Preeclampsia: correction of functional disorders of the hemostasis system with Resveratrol and Nicorandil

Introduction. Preeclampsia is a formidable disease of the second half of pregnancy, leading to severe complications, including disability and even death. Many authors have recognized the correlation between the severity of preeclampsia and the degree of disturbances in the hemostasis system. In this regard, the objective of this study was to assess inhibition of platelet aggregation and the possibility of its correction with resverаtrol and nicorandil.

Materials and methods. The study was performed on 250 mature white Wistar female rats weighing 250–300 g. The platelet aggregation induced by ADP, collagen, ristomycin, adrenaline was determined, as well as PTT, TT, aPTT, fibrinogen, and the clotting time.

Results and discussion. Introduction of resverаtrol and nicorandil resulted in a decrease in thrombocyte aggregation capacity from 53.8 ± 2.60% to 22.1 ± 1.25% and 37.1 ± 1.79%, respectively, when using ADP as an inducer. The clotting time was from 841 ± 42 s up to 1135 ± 33 s and 1034 ± 26 s, respectively. In addition, there was an increase in temporal parameters of plasma-coagulation hemostasis and a decrease in plasma fibrinogen content. The use of glibenclamide resulted in partial cancellation of the positive effects of resverаtrol and nicorandil, with an increase in platelet aggregation to 28.9 ± 1.8% and 43.9 ± 1.2% when using ADP as an inducer and a decrease in the thrombosis time to 988 ± 26 s and 950 ± 22 s, respectively.

Conclusion. In animals with experimental preeclampsia, there were disturbances in the hemostasis system, comparable to those in the clinical situation. The use of resverаtrol and nicorandil leads to a pronounced correction of hemostasis parameters. The positive effects of the studied pharmacological agents are mediated by several mechanisms, including K+ATP channels.

The course of acquired von Willebrand syndrome during pregnancy among patients with essential thrombocytosis

To investigate the course of acquired type 2A von Willebrand syndrome (AVWS) in relation to patient management and outcomes among pregnant patients with essential thrombocytosis (ET). A review of pregnant women with ET evaluated for AVWS at the beginning of pregnancy and at the third trimester. Eighteen women with 24 pregnancies were included in this study. A history of bleeding was noted in 8 (44%) patients. In 20 (83%) pregnancies AVWS was evident at the initial testing. Following initial testing, antithrombotic therapy was administered in 22 (92%) pregnancies (aspirin, n = 20 and low-molecular-weight heparin, n = 2). In the remaining two pregnancies, VWF:RCo levels were below 30%; thus, aspirin was given only after repeat testing at 14-16 weeks. At third trimester testing, median VWF:RCo levels were significantly higher than at the initial testing (86 vs. 48%, P < 0.001), with no evidence of AVWS in any of the patients. Significant increases were also observed in the VWF:Ag level (127 vs. 84%, P < 0.001), the VWF:RCo/VWF:Ag ratio (0.75 vs. 0.54, P < 0.001) and the FVIII level (103 vs. 68%, P < 0.001); while platelet count (359 vs. 701 × 10⁹/l, P < 0.001) and hemoglobin level (11.6 vs. 13.4 g/dl, P < 0.001) decreased. Neuraxial anesthesia was safely performed in 17 (71%) pregnancies. No significant bleeding events occurred during pregnancy and delivery. AVWS-related abnormalities in women with ET mostly improved during pregnancy, with favorable maternal and fetal outcomes. VWF parameters should be tested at early pregnancy and repeated at the third trimester, to guide pregnancy and delivery management.

Platelet behaviour on von Willebrand Factor changes in pregnancy: Consequences of haemodilution and intrinsic changes in platelet function

Platelet function in pregnancy is poorly understood. Previous studies of platelet function in pregnancy have used non-physiological assays of platelet function with conflicting results. This study using a physiological assay of platelet function investigated platelet interactions with von Willebrand Factor (VWF) in blood from healthy pregnant women and healthy non-pregnant controls. Blood samples (200 µl) from third-trimester pregnancies (n = 21) and non-pregnant controls (n = 21) were perfused through custom-made parallel-plate flow chambers coated with VWF under arterial shear (1,500 s⁻¹). Multi-parameter measurements of platelet interactions with the immobilized VWF surface were recorded by digital-image microscopy and analysed using custom-designed platelet-tracking software. Platelet interactions with VWF decreased in healthy third-trimester pregnant participants relative to controls. This effect is most likely due to haemodilution which occurs physiologically during pregnancy. Interestingly, platelets in blood from pregnant participants translocated more slowly on VWF under arterial-shear conditions. These decreases in platelet translocation speed were independent of haemodilution, suggesting intrinsic changes in platelet function with pregnancy.

Viable pregnancies beyond 28 weeks gestation in women with a history of unexplained recurrent miscarriage have reduced platelet function

OBJECTIVE

The aim of this study was to characterize platelet function in pregnant patients with a history of unexplained recurrent miscarriage (RM) in the third trimester of a subsequent viable pregnancy, a time at which platelet dysfunction may be associated with an increased obstetric risk.

STUDY DESIGN

A prospective study was performed comparing 30 viable pregnancies that had reached at least 28 weeks' gestation amongst patients who had a background history of unexplained RM, with 30 healthy pregnant controls at a similar gestational age. Platelet function was determined by means of platelet aggregation in response to 5 different agonists at multiple concentrations.

RESULTS

Amongst the 30 RM patients with ongoing viable pregnancies, we demonstrated significantly reduced platelet aggregation compared to the pregnant controls in the third trimester. For three out of five agonists, we demonstrated statistically significantly decreased platelet aggregation and for all five agonists we demonstrated significantly decreased platelet aggregation in the postnatal period. There were no obvious differences in obstetric outcomes.

CONCLUSION

This study shows that women with a history of unexplained RM have reduced platelet function after 28 weeks' gestation in their subsequent pregnancies compared to healthy pregnant controls, but without this difference leading to any obvious increase in adverse obstetric risk.

Platelet reactivity in twin pregnancies

BACKGROUND

Gestational thrombocytopenia is more likely to occur in twin than singleton pregnancies. However, it is unclear whether platelets are more reactive in twin than singleton pregnancies.

METHODS

Changes in spontaneous platelet aggregation and concomitant fall in platelet count were examined over 90min after blood sampling in 171 and 52 citrated whole blood (CWB) samples from 59 and 17 women with singleton and twin pregnancies, respectively. Soluble P-selectin (sP-selectin) levels in the plasma were also determined.

RESULTS

CWB 60min after blood sampling during 2nd trimester exhibited significantly larger numbers of platelet aggregates (1297±1600 vs. 497±432/μl, P=0.040) concomitant with significantly greater net decrease in platelet count (152±55 vs. 115±45×10(9)/μl, P=0.036) in twin than singleton pregnancies, respectively. This was followed by significantly lower 3rd trimester platelet count (181±43 vs. 229±62×10(9)/l, P=0.009) with significantly greater mean platelet volume (8.0±1.2 vs. 7.1±1.1fl, P=0.021) in twin than singleton pregnancies, respectively. The 3rd trimester sP-selectin per platelet was significantly higher in twin than singleton pregnancies.

CONCLUSIONS

Platelets were more reactive in the 2nd trimester of twin than singleton pregnancies. This enhanced platelet reactivity may explain the decreased platelet count in the 3rd trimester of twin pregnancy.

Platelet Adhesion and Thrombus Formation in Whole Blood at Arterial Shear Rate at the End of Pregnancy

PROBLEM

Platelet reactivity has not been evaluated in integrated functional testing during normal pregnancy. Here, we analysed platelet functions under arterial shear rate in comparison with static conditions.

METHOD OF STUDY

Thirty pregnant women with uncomplicated pregnancies and 30 healthy non-pregnant women were enrolled in this study. Platelet adhesion to collagen and fibrinogen and subsequent thrombus formation were measured at arterial shear rate in whole blood using a microfluidic and imaging system. Standard light transmission aggregometry, flow cytometry of activation markers in washed platelets and impedance aggregometry in whole blood were also used to assess platelet responsiveness in static conditions.

RESULTS

Compared to non-pregnant controls, thrombus formation on collagen fibres and firm platelet adhesion on fibrinogen under arterial shear rate were significantly reduced in pregnant women. Platelet aggregometry assays in suspension showed a slight increase in platelet reactivity in pregnant women.

CONCLUSION

While platelet aggregometry and platelet activation markers in static conditions show little changes in platelet reactivity, monitoring of platelet adhesion and thrombus growth on collagen or fibrinogen under flow condition in whole blood indicates a significant decrease in pregnant women compared to controls. This decrease might contribute to counteract a hypercoagulable state and to reduce the risk of arterial thrombosis.

Erythrocyte-platelet interaction in uncomplicated pregnancy

Maternal and fetal requirements during uncomplicated pregnancy are associated with changes in the hematopoietic system. Platelets and erythrocytes [red blood cells (RBCs)], and especially their membranes, are involved in coagulation, and their interactions may provide reasons for the changed hematopoietic system during uncomplicated pregnancy. We review literature regarding RBC and platelet membrane structure and interactions during hypercoagulability and hormonal changes. We then study interactions between RBCs and platelets in uncomplicated pregnancy, as their interactions may be one of the reasons for increased hypercoagulability during uncomplicated pregnancy. Scanning electron microscopy was used to study whole blood smears from 90 pregnant females in different phases of pregnancy. Pregnancy-specific interaction was seen between RBCs and platelets. Typically, one or more platelets interacted through platelet spreading and pseudopodia formation with a single RBC. However, multiple interactions with RBCs were also shown for a single platelet. Specific RBC-platelet interaction seen during uncomplicated pregnancy may be caused by increased estrogen and/or increased fibrinogen concentrations. This interaction may contribute to the hypercoagulable state associated with healthy and uncomplicated pregnancy and may also play a fundamental role in gestational thrombocytopenia.