Reduction in protein S activity during normal pregnancy

Consensus on the investigation of thrombophilia in women and clinical management

Objective

To standardize the investigation and clinical management of women with laboratory and/or clinical abnormalities suggestive of thrombophilia, in order to optimize antithrombotic approach and indication of laboratory tests.

Methodology

A discussion was carried out among 107 physicians (gynecologists/obstetricians, hematologists and vascular surgeons) present at a forum held at the Hospital Israelita Albert Einstein, in São Paulo (SP), Brazil. As a minimum criterion, 80% agreement was established in the voting to each recommendation of conduct in the final document. The cases in which there was agreement below 80% were discussed again, reaching a consensual agreement of conduct for the document writing.

Conclusion

The standardization of an institutional consensus of suggestions of clinical approach contributes to a better management of the group to be evaluated and minimizes risks of intercurrent events. This was the first national consensus on the investigation of thrombophilia in women.

Clinical utility of thrombophilia, anticoagulant treatment, and maternal variables as predictors of placenta-mediated pregnancy complications: an extensive analysis

Objective: The objective of this study is to analyze the usefulness of thrombophilia and antithrombotic drugs in combination with materno-fetal characteristics to generate a predictive model of placenta-mediated pregnancy complications (PMPC) for counseling treatment.Methods: A retrospective analysis was performed in women with singleton pregnancy that required a thrombophilia study, including 222 patients with unknown cause PMPC and 151 women with no complications at current pregnancy in Hospital Clínico Universitario, Lozano, Blesa, Zaragoza, Spain. Chi-squared and Mann-Whitney test were applied to analyze univariate risk factors. Multivariate analysis was performed using logistic regression model with candidate variables: maternal characteristics, obstetric history, thrombophilia, and treatment with low-molecular-weight heparin (LMWH) and/or with acid acetylsalicylic (ASA). The calibration, discrimination, and best cutoff point for the clinical application of the model was analyzed.Results: Maternal characteristics showed differences in median body mass index (BMI), odds ratio (OR): 0.4, smoking habit, OR: 8.5, and hypertension, OR: 11.4, appearing all of them as risk factors. In our study, a prior pregnancy that ended in a child alive was a protective factor OR: 0.02-0.4, and having a previous preterm child was a strong risk factor OR: 4.2. Thrombophilia was not a risk factor. Patients under LMWH treatment (15%) and/or ASA (6.2%) had better pregnancy outcomes, showing both as protective factors: ASA OR: 0.32 and LMWH OR: 0.16. The model has an AUC value of 0.847, with good calibration. A nomogram and an app is provided for this adjusted model with high discrimination ability in internal validation (AUC = 0.833). Our clinical utility analysis guide us to choose 40% as the best threshold probability.Conclusions: We found risk and protective factors associated with PMPC, but our data were not conclusive to demonstrate its relation with maternal thrombophilia. However, the challenger finding is the clinical utility of antithrombotic drugs as a protective factors in PMPC prevention. It is possible to identify patients with high risk of PMPC through a combined predictive model, for counseling treatment.

Free protein s reference ranges in gravidas without hereditary and acquired thrombophilia

We carried out a retrospective cohort study to construct reference ranges for free protein S (FPS) levels during pregnancy and identify any conditions or factors that may affect FPS levels. Patients that were ordered thrombophilia screening tests during gestational period were identified. Patients demonstrated to have hereditary or acquired thrombophilia were excluded. Reference ranges were constructed using regression analysis. Outcome of the index pregnancy and pregnancy complications was used to identify any confounding factors. A total of 455 pregnant women were included. The quadratic equation for FPS according to gestational age (GA) was [75.497 + (-1.516*GA) + 0.018*GA*GA]. FPS level and GA were negatively correlated (Spearmans rho statistic [rs] = -0.436, p = 0.001). FPS level and fetal growth restriction (FGR) were negatively correlated ([rs] = -0.093, p = 0.049). FPS level and placental abruption were positively correlated ([rs] = 0.098, p = 0.039). Stepwise linear regression model constructed to predict FPS level with gestational age, placental abruption and FGR as the predictor variables. Gestational age was the only variable retaining statistically significant relation with FPS level (χ(2) = 0.216, df = 3, p = 0.001). FPS levels decrease significantly throughout gestation in gravidas without hereditary and/or acquired thrombophilias. In patients without thrombophilia FPS levels are not associated with pregnancy complications. The obtained reference intervals may be useful for the clinicians ordering FPS during pregnancy.

Testing children for inherited thrombophilia: more questions than answers

Thrombotic events in children have become an increasingly common problem, particularly in paediatric tertiary care hospitals. The prevalence of inherited thrombophilia in children who develop thrombosis varies substantially depending on the population. Children who develop thrombosis, as well as those who have not but have a positive family history, are frequently tested for inherited thrombophilia. The clinical utility of performing such tests has been questioned, in both adults and children. This review will examine the practise of testing for inherited thrombophilia in children, focusing on the rationale for testing and highlighting areas in which more evidence is needed prior to making strong recommendations. Future studies, many of which are currently being performed or proposed, are necessary to address many of the unanswered questions.