Serial plasma fibronectin levels in pre-eclamptic and normotensive women

Reference intervals for plasma levels of fibronectin, von Willebrand factor, free protein S and antithrombin during third-trimester pregnancy

During pregnancy, significant changes occur in the hemostatic system and in the plasma levels for several plasma proteins, especially towards term. In this study changes occurring during normal pregnancy and immediately postpartum were investigated to establish adequate reference intervals for important hemostatic parameters. Blood samples were collected during pregnancy weeks 33, 36, 39 and 1-3 h after delivery from 153 healthy pregnant women with at least one previous normal pregnancy. The plasma samples were analyzed for antithrombin, von Willebrand factor (vWf), free protein S and fibronectin. Fibronectin and vWf are contact-promoting proteins responsible for adhesion and aggregation during primary hemostasis, but are also released from thrombocytes during activation of the coagulation process. Antithrombin is the most important primary physiological inhibitor of activated serine proteases related to the coagulation cascade. Protein S is a co-factor to protein C and in cooperation is also an important inhibitor of the coagulation cascade. During third-trimester pregnancy, vWf was higher than in non-pregnant women, and continued to increase postpartum. The fibronectin plasma level was mostly unchanged in comparison with non-pregnant values. Within this reference interval it gradually increased during the third trimester, but fell slightly postpartum. Antithrombin decreased slightly during the third trimester and even further, postpartum. Free protein S decreased markedly but to a stable level from week 33 to 39, decreasing even more postpartum. The present results are concordant with clinical knowledge of increased risk of thrombosis during pregnancy and early puerperium, with increased levels of vWf and fibronectin and decreased levels of antithrombin and free protein S. Clearly, current reference values based on healthy non-pregnant subjects are not usable during late pregnancy and immediately postpartum.

Third Trimester Maternal Plasma Total Fibronectin Levels in Pregnancy-Induced Hypertension: Results of a Tertiary Center

The aim of this study was to evaluate maternal plasma total fibronectin values in pregnancy-associated hypertension in women in the third trimester of pregnancy. A total of 125 pregnant women at the 24th week of gestation participated in this study. Nonpregnant normotensive women were included as control group (n = 30). Plasma samples for fibronectin were obtained at the 24th, 28th, and 32nd weeks of gestation from all pregnant patients. From this cohort, 10 patients met the criteria for the diagnosis of gestational hypertension and 15 women met the stringent requirements of preeclampsia, whereas 100 patients were normotensive later in gestation. Plasma total fibronectin levels were determined by radial immunodiffusion technique. Data were analyzed using the SPSS program. The mean plasma fibronectin levels of the pregnant women in whom gestational hypertension and preeclampsia developed were significantly higher at the 24th, 28th, and 32nd weeks in comparison to normotensive pregnant women (p < 0.001). However, throughout the period from the 24th to 32nd weeks of pregnancy, plasma total fibronectin levels did not exhibit a significant change in normotensive pregnant patients or in patients with preeclampsia and gestational hypertension. There was also no correlation between plasma fibronectin levels and gestational age, mean arterial pressure, birth weight, and 5-minute Apgar scores in all groups (p < 0.05). The elevated maternal plasma fibronectin level over 40 mg/dL is capable of predicting preeclampsia with a sensitivity of 73% and a specificity of 92%. These results suggest that serial plasma fibronectin measurements before 24 weeks’ of gestation may be helpful in the early detection of preeclampsia in normotensive gravid women who are destined to become clinically preeclamptic.

Microcirculation in Pregnancy

The microcirculation, like all physiological systems undergoes modifications during the course of pregnancy. These changes aid the adaption to the new anatomical and physiological environment of pregnancy and ensure adequate oxygen supply to the fetus. Even though the microcirculation is believed to be involved in major pregnancy related pathologies, it remains poorly understood. The availability of safe and non-interventional technologies enabling scientists to study the intact microcirculation of the pregnant patient will hopefully expand our understanding. In this article we review the physiological changes occurring in the microcirculation during pregnancy and the role of the microcirculation in gestational related pathologies. We will also describe the available techniques for the measurement and evaluation of the microcirculation. Lastly we will highlight the possible fields in which these techniques could be utilized to help provide a clearer view of the microcirculation in the pregnant woman.

Accuracy of fibronectin tests for the prediction of pre-eclampsia: a systematic review

The purpose of this study was to review systematically all studies that assessed the accuracy of maternal plasma fibronectin as a serum marker for early prediction of pre-eclampsia. We therefore assessed studies that reported on fibronectin as serum marker for pre-eclampsia before the 25th gestational week. For the selected studies, sensitivity and specificity were calculated and plotted in ROC-space. We included 12 studies, of which only 5 studies reported sufficient data to calculate accuracy estimates, such as sensitivity and specificity. These five studies reported on 573 pregnant women of whom 109 developed pre-eclampsia. At a sensitivity of at least 50%, specificities ranged between 72 and 96% for cellular fibronectin. For total fibronectin, these numbers were 42-94%. Fibronectin seems to be a promising marker for the prediction of pre-eclampsia, however, further studies are needed to determine whether the accuracy of this test is sufficient to be clinically relevant.

Prediction and prevention of preeclampsia and IUGR

Preeclampsia, being one of the leading causes of maternal and perinatal morbidity and mortality, has been the subject of extensive research since its description. Preeclampsia has been called the disease of theories due to the enigma surrounding its exact pathophysiology. Despite the absence of treatment that reverses the disease process once started, screening for preeclampsia and intrauterine growth restriction (IUGR) has been a major clinical and research issue since the disease was first reported. This review evaluates the current evidence for prediction and prevention of preeclampsia and IUGR using clinical tests, maternal serum markers, and uterine artery Doppler screening. In addition, we critically evaluate the evidence regarding the different therapeutic strategies for the prevention of preeclampsia and IUGR and the latest clinical recommendations for their use.

Prediction of preeclampsia: can it be achieved?

In this review, the various biochemical tests that have been proposed for the prediction of preeclampsia are described and evaluated. Placenta hormone markers do not predict future disease. They denounce the early placental changes that are part of the evolving disease and only predict the imminent of preeclamptic syndrome. This explains why tests are better predictors when preeclampsia supervenes shortly, and why screening in the first trimester is unlikely to work as well as in the second trimester. The use of multiple markers in the screening should reflect different aspects of the disease process and could increase the specificity and sensitivity of the screening and work on different etiologic factors. The possible use of second-trimester biochemical screening to predict the risk of preeclampsia remains to be investigated in the high-risk population.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians

LEARNING OBJECTIVES

After completion of this article, the reader should be able to list the various theories on the etiology of preeclampsia, to relate the various risk factors for the development of preeclampsia, and to describe the various screening tests for preeclampsia.

Maternal plasma cellular fibronectin concentrations in normal and preeclamptic pregnancies: a longitudinal study for early prediction of preeclampsia

OBJECTIVE

The purpose of this study was to examine cellular fibronectin levels throughout normotensive and preeclamptic pregnancies and to analyze its predictive value for the detection of preeclampsia within the second trimester of pregnancy.

STUDY DESIGN

Blood samples were collected at 4-week intervals from 378 healthy, nulliparous women who were recruited before 16 weeks of gestation. Preeclampsia developed in 26 patients; 52 normotensive control subjects were matched from the same cohort. Plasma samples were assayed for ED-B fibronectin by enzyme-linked immunosorbent assay. Trends were compared between groups. Predictive values were determined with the use of second trimester assessments.

RESULTS

In both groups, fibronectin levels rose as pregnancy advanced, but in women with preeclampsia, this increase was significantly higher (94.5% vs 31.8%; P =.006). Throughout pregnancy, patients with preeclampsia exhibited significantly higher fibronectin levels than did control subjects. As early as 9 to 12 weeks of gestation, a difference was established (preeclampsia, 3.72 +/- 0.21; control, 2.94 +/- 0.22 microg/mL [mean +/- SEM]; P =.008). The best cutoff point and time interval to calculate predictive values were 3.8 microg/mL and 22 to 26 weeks of gestation, respectively. Sensitivity, specificity, and positive and negative predictive values were 73%, 87%, 29%, and 98%, respectively; the odds ratio was 16.1 (95% CI, 8.6-30.2).

CONCLUSION

In women in whom clinical preeclampsia developed, endothelial damage seemed to be present since early gestation. Cellular fibronectin levels of >or=3.8 microg/mL within 22 to 26 weeks of gestation may help in the early detection of preeclampsia in healthy nulliparous women.

Nitric oxide dysfunction in the pathophysiology of preeclampsia

Researchers disagree as to the importance of nitric oxide (NO) in preeclampsia. Many researchers have alluded to NO's possible primary or secondary role in the development of preeclampsia, but few have correlated the dysfunction of nitric oxide production with the other metabolic derangements seen in this condition. This paper will review the evidence that the primary dysfunction in preeclampsia is a relative deficiency of available NO (secondary to oxidative degradation) and an excess of peroxynitrite (ONOO(-)). The combination of a deficiency of NO and an increase in ONOO(-) can directly or indirectly initiate the vast majority of physiological and serological changes associated with preeclampsia, such as blood pressure, increased glomerular filtration rate, proteinuria, platelet dysfunction, increased thromboxane and endothelin, and a decrease in prostacyclin. Understanding the complex role of nitric oxide in this condition may explain why previous interventions have been unsuccessful and suggest possible strategies for prevention and treatment in the future.