Haemostatic profile of full-term, healthy, small for gestational age neonates

Assessment of Hemostatic Profile in Neonates with Intrauterine Growth Restriction: A Systematic Review of Literature

Intrauterine growth restriction (IUGR) affects nearly 10 to 15% of pregnancies and is responsible for many short- and long-term adverse consequences, including hemostatic derangement. Both thrombotic and hemorrhagic events are described in the perinatal period in these neonates. The aim of this study was to systematically review the literature on the laboratory studies used to evaluate the hemostatic system of the IUGR small for gestational age neonate. We reviewed the current literature via PubMed and Scopus until September 2022. Following our inclusion/exclusion criteria, we finally included 60 studies in our review. Thrombocytopenia, characterized as hyporegenerative and a kinetic upshot of reduced platelet production due to in utero chronic hypoxia, was the main finding of most studies focusing on growth-restricted neonates, in most cases is mild and usually resolves spontaneously with the first 2 weeks of life. In regard to coagulation, growth-restricted newborns present with prolonged standard coagulation tests. Data regarding coagulation factors, fibrinolytic system, and anticoagulant proteins are scarce and conflicting, mainly due to confounding factors. As thromboelastography/rotational thromboelastometry (TEG/ROTEM) provides a more precise evaluation of the in vivo coagulation process compared with standard coagulation tests, its use in transfusion guidance is fundamental. Only one study regarding TEG/ROTEM was retrieved from this population, where no difference in ROTEM parameters compared with appropriate for gestational age neonates was found. Despite the laboratory aberrations, no correlation could be achieved with clinical manifestations of bleeding or thrombosis in the studies included. More studies are needed to assess hemostasis in IUGR neonates and guide targeted therapeutic interventions.

Hemostatic Profile of Intrauterine Growth-Restricted Neonates: Assessment with the Use of NATEM Assay in Cord Blood Samples

BACKGROUND

Intrauterine growth restriction (IUGR) is associated with hemorrhagic and thrombotic complications during the perinatal period. Thrombocytopenia, platelet dysfunction, and prolonged standard coagulation tests are observed in this population. The aim of this study is to examine the hemostatic profile of IUGR neonates with the use of a non-activated assay (NATEM) in cord blood samples.

METHODS

During an 18 month period, a NATEM ROTEM assay was performed on cord blood samples of 101 IUGR neonates. A total of 189 appropriate for gestational age (AGA) neonates were used as a control group. The NATEM variables recorded include the following: clotting time (CT); clot formation time (CFT); clot amplitude at 5, 10, and 20 min (A5, A10, A20); α-angle (a°); maximum clot firmness (MCF); lysis index at 30 and 60 min (LI30, LI60); and maximum clot elasticity (MCE).

RESULTS

IUGR neonates demonstrate a hypocoagulable state, with lower A5, A10, A2, MCF, and MCE values when compared to AGA. Using multiple linear regression, we determined IUGR as an independent factor influencing all NATEM parameters (except CT and LI30) exhibiting a hypocoagulable and hypofibrinolytic profile. Platelet count was positively correlated with A5, A10, A20, MCF, alpha angle, and MCE, and negatively correlated with CFT.

CONCLUSION

IUGR neonates appear with lower clot strength and elasticity and prolonged clot kinetics, as illustrated by ROTEM variables.

Thrombin, protein C, and protein S values in mother-infant dyads in the postpartum period

INTRODUCTION

The objective of the study was to establish the normal range for the levels of antithrombin (AT), protein C (PC), and protein S (PS) in the first week post birth in mother-infant pairings, adjusting for obstetric and perinatal factors, based on 2 different laboratory methods.

METHODS

Determinations were carried out in 83 healthy term neonates and their mothers, establishing 3 postpartum age groups: 1-2 days, 3 days, and 4-7 days.

RESULTS

There were no differences in the levels of any of the proteins between the different age groups in neonates or mothers in the first week post birth. The adjusted analysis found no association with obstetric or perinatal factors. The AT and PC levels were higher in mothers compared to infants (P < .001), while the PS levels were similar in both. Overall, the correlation of maternal and infant protein values was poor, except for the levels of free PS in the first 2 days after delivery. Although we found no differences based on which of the 2 laboratory methods was applied, the absolute values did differ.

The Vascular Endothelium and Coagulation: Homeostasis, Disease, and Treatment, with a Focus on the Von Willebrand Factor and Factors VIII and V

The vascular endothelium has several important functions, including hemostasis. The homeostasis of hemostasis is based on a fine balance between procoagulant and anticoagulant proteins and between fibrinolytic and antifibrinolytic ones. Coagulopathies are characterized by a mutation-induced alteration of the function of certain coagulation factors or by a disturbed balance between the mechanisms responsible for regulating coagulation. Homeostatic therapies consist in replacement and nonreplacement treatments or in the administration of antifibrinolytic agents. Rebalancing products reestablish hemostasis by inhibiting natural anticoagulant pathways. These agents include monoclonal antibodies, such as concizumab and marstacimab, which target the tissue factor pathway inhibitor; interfering RNA therapies, such as fitusiran, which targets antithrombin III; and protease inhibitors, such as serpinPC, which targets active protein C. In cases of thrombophilia (deficiency of protein C, protein S, or factor V Leiden), treatment may consist in direct oral anticoagulants, replacement therapy (plasma or recombinant ADAMTS13) in cases of a congenital deficiency of ADAMTS13, or immunomodulators (prednisone) if the thrombophilia is autoimmune. Monoclonal-antibody-based anti-vWF immunotherapy (caplacizumab) is used in the context of severe thrombophilia, regardless of the cause of the disorder. In cases of disseminated intravascular coagulation, the treatment of choice consists in administration of antifibrinolytics, all-trans-retinoic acid, and recombinant soluble human thrombomodulin.

Neonatal haemostatic parameters in correlation to gestational age and birth weight

INTRODUCTION

The aim of our study was to establish reference ranges for neonatal coagulation and fibrinolysis parameters and to investigate their relationship with gestational age (GA) and birth weight (BW).

METHODS

A single-centre prospective study was conducted in all healthy neonates born in our hospital during the study period, excluding those with maternal or neonatal disorders and diseases that affect haemostasis. The following parameters were measured: fibrinogen, prothrombin time (PT), international normalized ratio (INR), activated partial thromboplastin time (aPTT) as well as factors II, V, VII, VIII, IX, X, XI and XII, von Willebrand (vWF), protein C, free protein S, antithrombin (AT), activated protein C resistance (APCr), tissue plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAI-1).

RESULTS

Study population consisted of 327 neonates. Fibrinogen, AT III, proteins C and S, PAI-1, vWF and factors II, V, VIII, IX, XI and XII were positively correlated, while PT, aPPT, INR, APCr and tPA were negatively correlated with GA and BW. Proteins C and S, factors II, VIII, IX, XI and vWF, as well AT III and PAI-1 had a significant positive linear correlation with GA, while aPTT had a significant negative one. Fibrinogen, and factors V, VII and XII had a significant positive linear correlation with BW, while factor VIII, tPA, as well PT and INR had a significant negative one.

CONCLUSION

Fibrinogen, AT III, proteins C and S, PAI-1, vWF and factors II, V, VIII, IX, XI and XII increase with GA and BW.

Developmental hemostasis in the neonatal period

BACKGROUND

The hemostatic system is complex and evolves continuously since gestation and well into the adult years, in a process known as "developmental hemostasis."

DATA SOURCES

A comprehensive review was performed after an extensive literature search on PubMed/MEDLINE concerning developmental hemostasis during the neonatal period. Relevant cross references were also included.

RESULTS

Although part of a system, each component of the hemostatic system evolves differently, with many displaying both quantitative and qualitative age-related differences. This leads to drastic disparities between the coagulation system of neonates and both other children's and adults', while still maintaining a generally balanced and physiological hemostasis. The motives behind this process remain to be fully elucidated but may be, at least in part, related to non-hemostatic factors.

CONCLUSIONS

Knowledge regarding "developmental hemostasis" is essential for everyone caring for newborns or even children in general and in this review, we describe each hemostatic system component's neonatal characteristics and age-related progression as well as explore some of the possible physiological motives behind the process.

Thromboelastographic profiles of healthy very low birthweight infants serially during their first month

OBJECTIVE

We determined thromboelastographic (TEG) profiles of healthy very low birthweight infants (VLBWIs) of the day of birth and at set intervals during their first month.

DESIGN

Prospective observational study with blinded clinical and laboratory follow-up.

SETTING

Level III neonatal intensive care unit (June 2015 to June 2018).

PATIENTS

Consecutive qualifying VLBWIs were enrolled at birth and followed up for 30 days.

INTERVENTIONS AND MAIN OUTCOMES MEASURES

Laboratory (citrated-native TEG, prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen, blood count) and clinical variables were retrieved at birth, 3rd-5th, 10th and 30th day of life. Blood samples temporally related to events with a potential hemostatic impact (sepsis, bleeding, platelets/plasma transfusions, ibuprofen/indomethacin administration) were excluded from analysis.

RESULTS

We enrolled 201 VLBWIs and 72 full-term neonates. Sixty-seven of the healthy VLBWIs completed the 30-day follow-up. 541 TEG traces were analysed.On day 1, the median (minimum-maximum) TEG values were as follows: reaction time (R), 8.2 min (1-21.8); kinetics (K), 2.8 min (0.8-16); α angle, 51° (14.2-80.6); maximum amplitude (MA), 54.9 mm (23.9-76.8). PT and APTT were 15.9 s (11.7-51.2) and 59 s (37.8-97.5), respectively. The above parameters suggest minor hypocoagulability compared with term infants. On day 30, the median (minimum-maximum) R was 5 (1-16.9), K 1 (0.8-4.1), α 74.7 (41.1-86.7) and MA 70.2 (35.8-79.7). PT and APTT were 12.1 (10.4-16.6) and 38.8 (29.6-51.4), respectively. Those parameters are consistent with a relatively hypercoagulable phenotype, compared with term infants.

CONCLUSIONS

Healthy VLBWIs have a prolonged PT and APTT, but their TEG profiles suggest a relatively balanced hemostatic system, with slight hypocoagulability initially (compared with term neonates), gradually evolving to a somewhat more procoagulant phenotype over the first month.

Effectiveness and Safety of 4-factor Prothrombin Complex Concentrate (4PCC) in Neonates With Intractable Bleeding or Severe Coagulation Disturbances: A Retrospective Study of 37 Cases

BACKGROUND

To date, clinical experience with prothrombin complex concentrate (PCC) in the neonatal population has been limited.

AIM

The objective of this study was to describe our experience regarding the effectiveness and safety of PCC administration in newborns with severe bleeding or coagulopathy resistant to conventional therapy.

METHODOLOGY

We retrospectively analyzed data from 37 neonates with intractable bleeding or severe coagulation disturbances. All patients received intravenous bolus administration of 20 or 30 u/kg of PCC per dose, as a rescue procedure.

RESULTS

Hemostasis was achieved in the majority of neonates and we observed statistically significant improvement in prothrombin time, international normalized ratio, and activated partial thromboplastin time (P<0.001, P=0.044, P<0.001, respectively). Thirteen neonates survived, whereas 24 did not survive. In those who survived, PCC had been administered earlier (<24 h) in the disease process compared with those who died (P=0.043). Neither acute adverse events nor thromboembolic complications were observed in all neonates.

CONCLUSIONS

In our study, PCC seemed to be a safe and effective intervention for hemostasis and early intervention was more effective as a rescue therapy, without any adverse event. Further prospective controlled trials are required to determine optimal dose and timing of PCC administration in neonates.

Thromboelastometry: studying hemostatic profile in small for gestational age neonates-a pilot observational study

Scarce data exists about the hemostatic status of small for gestational age (SGA) neonates. We aimed at evaluating the hemostatic profile of SGA neonates, using thromboelastometry (TEM). This is an observational study performed in a Greek tertiary General Hospital during an 18-month period. Ninety-three neonates were included in the study: 48 appropriate for gestational age weight (AGA) neonates and 45 SGA neonates Extrinsically activated TEM (ex-TEM) parameters, such as clotting time, clot formation time, amplitude recorded at 5 and 10 min, a angle, maximum clot firmness, lysis index at 60 min, and also platelet count, were used for the evaluation of the hemostatic profile in all neonates. No statistically significant differences were noticed regarding all ex-TEM parameters between AGA and SGA neonates, while no event of hemorrhage or thrombosis was noticed in the study population.Conclusions: The coagulation system of SGA neonates seems to be fully functional, with no evident tendency toward coagulopathy or thrombosis, when compared with AGA neonates. TEM seems to provide a promising and valid assessment of coagulation and fibrinolysis systems and may be used as a valuable biomarker, in the future. Further studies, with large samples, are necessary to confirm our results. What is Known: • SGA neonates may present coagulation disorders mainly due to hepatic dysfunction, polycythemia, and thrombocytopenia owing to long-term intrauterine hypoxia. • In the literature, despite the statistically significant differences in laboratory results between SGA and AGA neonates, no clinical manifestations of significantly altered hemostasis were recorded. Data of TEM interpretation of hemostasis in SGA neonates are not available. What is New: • TEM seems to interpret coagulation mechanism of preterm and full-term SGA neonates and confirm previous relevant literature findings regarding hemostasis in these neonates.

von Willebrand factor/ADAMTS-13 interactions at birth: implications for thrombosis in the neonatal period

von Willebrand factor (VWF) and its cleaving protease ADAMTS-13 (A Disintegrin and Metalloproteinase with Thrombospondin type 1 motif, member 13) are essential components to hemostasis. These plasma proteins have also been implicated in a number of disease states, including those affecting children. The best described abnormality is the congenital form of thrombotic thrombocytopenic purpura (TTP) resulting from germline mutations in the ADAMTS-13 gene. The VWF/ADAMTS-13 interaction has more recently emerged as a causative risk factor in the pathogenesis of pediatric stroke and secondary microangiopathies. There is now increasing interest and need to measure these coagulation factors during the neonatal period and throughout childhood. Methods adopted from a multitude of technically diverging studies have been used to understand their role during this period. To date, studies of VWF/ADAMTS-13 in this group of patients have reported conflicting results, which makes interpreting values in the clinical setting especially challenging. In this review we describe the historical evolution of the methodology used to measure VWF/ADAMTS-13 and how it may influence the results obtained during the first days of life. We review the individual assays used to analyze VWF/ADAMTS-13 as well as published reference values. Finally, we bring attention to the potential pathophysiologic role of VWF/ADAMTS-13 in neonatal thrombosis. This has significant implications because the pathologic processes that explain thrombosis in neonates remain poorly characterized and thromboembolism remains a significant source of morbidity and mortality, particularly in sick children.

Differential Contributions of Intrinsic and Extrinsic Pathways to Thrombin Generation in Adult, Maternal and Cord Plasma Samples

Background

Thrombin generation (TG) is a pivotal process in achieving hemostasis. Coagulation profiles during pregnancy and early neonatal period are different from that of normal (non-pregnant) adults. In this ex vivo study, the differences in TG in maternal and cord plasma relative to normal adult plasma were studied.

Methods

Twenty consented pregnant women and ten consented healthy adults were included in the study. Maternal and cord blood samples were collected at the time of delivery. Platelet-poor plasma was isolated for the measurement of TG. In some samples, anti-FIXa aptamer, RB006, or a TFPI inhibitor, BAX499 were added to elucidate the contribution of intrinsic and extrinsic pathway to TG. Additionally, procoagulant and inhibitor levels were measured in maternal and cord plasma, and these values were used to mathematically simulate TG.

Results

Peak TG was increased in maternal plasma (393.6±57.9 nM) compared to adult and cord samples (323.2±38.9 nM and 209.9±29.5 nM, respectively). Inhibitory effects of RB006 on TG were less robust in maternal or cord plasma (52% vs. 12% respectively) than in adult plasma (81%). Likewise the effectiveness of BAX499 as represented by the increase in peak TG was much greater in adult (21%) than in maternal (10%) or cord plasma (12%). Further, BAX499 was more effective in reversing RB006 in adult plasma than in maternal or cord plasma. Ex vivo data were reproducible with the results of the mathematical simulation of TG.

Conclusion

Normal parturient plasma shows a large intrinsic pathway reserve for TG compared to adult and cord plasma, while TG in cord plasma is sustained by extrinsic pathway, and low levels of TFPI and AT.

Early-Onset Thrombocytopenia in Small-For-Gestational-Age Neonates: A Retrospective Cohort Study

Thrombocytopenia is a common finding in small for gestational age (SGA) neonates and is thought to result from a unique pathophysiologic mechanism related to chronic intrauterine hypoxia. Our objective was to estimate the incidence and severity of early-onset thrombocytopenia in SGA neonates, and to identify risk factors for thrombocytopenia. We performed a retrospective cohort study of all consecutive SGA neonates admitted to our ward and a control group of appropriate for gestational age (AGA) neonates matched for gestational age at birth. Main outcome measures were incidence and severity of thrombocytopenia, hematological and clinical risk factors for thrombocytopenia, and bleeding. A total of 330 SGA and 330 AGA neonates were included, with a mean gestational age at birth of 32.9 ± 4 weeks. Thrombocytopenia (<150x10⁹/L) was found in 53% (176/329) of SGA neonates and 20% (66/330) of AGA neonates (relative risk (RR) 2.7, 95% confidence interval (CI) [2.1, 3.4]). Severe thrombocytopenia (21-50x10⁹/L) occurred in 25 neonates (8%) in the SGA and 2 neonates (1%) in the AGA group (RR 12.5, 95% CI [3.0, 52.5]). Platelet counts <20x10⁹/L were not recorded. Within the SGA group, lower gestational age at birth (p = <0.01) and erythroblastosis (p<0.01) were independently associated with a decrease in platelet count. Platelet count was positively correlated with birth weight centiles. In conclusion, early-onset thrombocytopenia is present in over 50% of SGA neonates and occurs 2.7 times as often as in AGA neonates. Thrombocytopenia is seldom severe and is independently associated with lower gestational age at birth and erythroblastosis.

Hemostatic profile in healthy premature neonates; does birth weight affect the coagulation profile?

Context:

There are limited studies assessing the neonatal hemostatic factors in relation to birth weight.

Aims:

This study aims to compare the coagulation factors between three groups of neonates with different birth weight for gestational age (GA).

Settings and Design:

In a cross-sectional study, 74 healthy premature neonates were involved.

Subjects and Methods:

Serum prothrombin time (PT), activated partial thromboplastin time (APTT), international normalized ratio (INR), thrombin clotting time (TT), and levels of fibrinogen, anti-thrombin III, protein S and protein C were measured. Neonates were classified into three groups according to birth weight, including small, appropriate and large for gestational age (SGA, AGA, and LGA).

Statistical Analysis Used:

Statistical analysis was performed using SPSS software.

Results:

There was a significant difference in the levels of protein S (P < 0.001), protein C (P = 0.004), and values of APTT (P = 0.01) between three groups. Other coagulation factors however, did not represent a significant pattern (P > 0.05). Protein S concentration, directly (B = 0.78, P < 0.001), and APTT, inversely (B = −0.29, P = 0.03), associated with birth weight after adjustment for GA and sex.

Conclusions:

Despite the decrease in APTT from SGA to AGA, and LGA neonates, levels of protein S increases directly with birth weight. However, no other coagulation factors revealed an explainable pattern in relation to the state of SGA, AGA, or LGA.

The conundrum of neonatal coagulopathy

The maturation and postnatal development of the human coagulation system was first studied and described more than 20 years ago. These older studies, supported by more recent data, confirm the significant and important differences in the physiology of coagulation and fibrinolysis in neonates and young children compared with older children and adults. Subsequently, significant differences were also described in the physiology of primary hemostasis and in global in vitro tests for hemostasis. These differences, which mostly reflect the immaturity of the neonatal hemostasis system, are functionally balanced. Healthy neonates show no signs of easy bruising or other bleeding diathesis and no increased tendency to thrombosis for any given stimulus compared with adults. Systemic diseases may affect hemostasis, predisposing ill neonates to increased hemorrhagic or thrombotic complications. The immaturity of the hemostasis system in preterm and very-low-birth-weight neonates may contribute to a higher risk for intraventricular hemorrhage. Therapies targeting the hemostasis system can be effective for preventing and treating these events. The concept of “neonatal coagulopathy” has an important impact on both the diagnosis and management of hemorrhagic or thrombotic events in neonates. For diagnosis of hemostasis disorders, diagnostic laboratories processing pediatric samples should use age-, analyzer-, and reagent-appropriate reference ranges. Age-specific guidelines should be followed for the management of neonates with hemostatic disorders.

Age dependency of coagulation parameters during childhood and puberty

BACKGROUND

Use of age-adjusted reference values is crucial for correct diagnosis and management of thrombotic and hemorrhagic disease in children. They vary with utilized reagents and analyzers.

OBJECTIVES

We established reference values with the Sysmex CA-1500 System and in parallel with the Behring BCS System using reagents from Siemens Healthcare Diagnostics Products GmbH.

METHODS

After informed consent, blood samples were obtained from 218 healthy children and 52 healthy adults, grouped as 1-6 months (n = 29), 7-12 months (n = 25), 1-5 years (n = 57), 6-10 years (n = 57), 11-18 years (n = 50) and > 19 years (n = 52).

RESULTS

Most coagulation parameters demonstrate good comparability between analyzers with the exception of PT and APTT. Single coagulation factors fibrinogen, factor (F) II, FIX, FXI and XII were significantly decreased in the youngest children; the strongest age dependency was found for coagulation inhibitors Protein C and S, both significantly decreased in infancy and young childhood. We confirmed that high levels of von Willebrand factor are found in the youngest children without increased levels of FVIII followed by decreased von Willebrand levels in the subsequent age group. In children with blood group O a less distinct increase in time was found, compared with individuals with one of the other blood groups.

CONCLUSIONS

The correlation between the CA-1500 and the BCS system was remarkable. Differences were most pronounced between children < 12 months and older children and adults, confirming the phenomenon of developmental hemostasis. The rationale for age-related changes in the hemostatic system remains unraveled. Our results underline the need for age-specific reference ranges.

Developmental haemostasis: secondary haemostasis

The haemostatic system is a complex interaction between the vasculature, cellular components and plasma proteins that interact to maintain haemostasis in the healthy body. The haemostatic system can be further defined as primary, secondary and tertiary haemostasis to better define the interdependent mechanisms that combine to maintain haemostasis. The term 'developmental haemostasis' was first introduced by Maureen Andrews in the 1980s to describe the age-related physiological changes of the coagulation system as it develops progressively over time from fetal, neonatal, paediatric to adult and geriatric systems. This paper will focus on developmental changes in secondary haemostasis, that is, the plasma protein changes that occur with age, particularly during the fetal and neonatal period, when the changes are most marked compared to the adult system.

Plasminogen activator inhibitor type-1 is an independent marker of metabolic disorders in young adults born small for gestational age

BACKGROUND

Metabolic syndrome (MS) has been associated with being born small for gestational age (SGA). In epidemiological studies plasminogen activator inhibitor type-1 (PAI-1) levels have been associated with MS. Few studies have examined this association in subjects born SGA.

PATIENTS AND METHODS

Five hundred and fifty-seven SGA adults (birth weight < 10th percentile) were compared with 671 subjects with a birth weight between the 25th and 75th percentiles (control group). MS was defined using the World Health Organization (WHO) definition. Active PAI-1 was measured on citrated plasma with bio-immunoassay.

RESULTS

MS was more prevalent in the SGA group (8.7%) than in the control group (5.5%; P = 0.03). In both groups, PAI-1 concentrations were significantly correlated with waist circumference, plasma triglycerides, homeostatic model assessment-insulin resistance (HOMA-IR) and associated with male sex and MS. PAI-1 concentrations were significantly increased in the SGA group (12.2 ± 21.2 vs. 10.0 ± 13.5 IU mL⁻¹, P = 0.03) and this remained after adjustment of metabolic variables (P = 0.009). PAI-1 concentrations above 4.9 IU mL⁻¹ (= median of PAI-1 concentration in the control group) were present in 94% of the subjects with MS. Moreover, the adjusted odds ratio (OR) for having elevated PAI-1 was 1.48 (1.08; 1.95) in the SGA group in comparison with the control group (P = 0.005).

CONCLUSIONS

 PAI-1 plasma concentrations were significantly increased in SGA subjects independently of MS. These data suggest that elevation of PAI-1 concentrations might be an indication of an abnormal secretion at the level of the adipose tissue, endothelial cells or liver and implicated in metabolic disorders reported in SGA subjects.