Maternal Death Following Cardiopulmonary Collapse After Delivery: Amniotic Fluid Embolism or Septic Shock Due to Intrauterine Infection?

Citation Romero R, Kadar N, Vaisbuch E, Hassan SS. Maternal death following cardiopulmonary collapse after delivery: amniotic fluid embolism or septic shock due to intrauterine infection? Am J Reprod Immunol 2010; 64: 113–125 Problem The amniotic fluid embolism (AFE) syndrome is a catastrophic complication of pregnancy frequently associated with maternal death. The causes and mechanisms of disease responsible for this syndrome remain elusive. Method of study We report two cases of maternal deaths attributed to AFE: (1) one woman presented with spontaneous labor at term, developed intrapartum fever, and after delivery had sudden cardiovascular collapse and disseminated intravascular coagulation (DIC), leading to death; (2) another woman presented with preterm labor and foul‐smelling amniotic fluid, underwent a Cesarean section for fetal distress, and also had postpartum cardiovascular collapse and DIC, leading to death. Results Of major importance is that in both cases, the maternal plasma concentration of tumor necrosis factor‐α at the time of admission to the hospital and when patients had no clinical evidence of infection was in the lethal range (a lethal range is considered to be above 0.1 ng/mL). Conclusion We propose that subclinical intraamniotic infection may be a cause of postpartum cardiovascular collapse and DIC and resemble AFE. Thus, some patients with the clinical diagnosis of AFE may have infection/systemic inflammation as a mechanism of disease. These observations have implications for the understanding of the mechanisms of disease of patients who develop cardiovascular collapse and DIC, frequently attributed to AFE. It may be possible to identify a subset of patients who have biochemical and immunological evidence of systemic inflammation at the time of admission, and before a catastrophic event occurs.     

Amniotic fluid embolism with haemostasis complications: primary fibrinogenolysis or disseminated intravascular coagulation?

Amniotic fluid embolism (AFE) is characterized by the passage of amniotic fluid (AF) into the maternal circulation during or just after childbirth. AFE is a rare disorder occurring in 1/8,000 to 1/80,000 deliveries but with a maternal morbidity ranging from 26% in a recent report to 86% in earlier ones. In patients who survive, AFE may affect coagulation resulting in severe bleeding. While disseminated intravascular coagulation (DIC) is usually seen in such cases, we reported a case of AFE in which the hemostatic abnormalities were compatible with primary fibrinogenolysis rather than with DIC.     

A hypothesis regarding complement activation and amniotic fluid embolism

Amniotic fluid embolism, a rare, sudden and often fatal illness of pregnancy may not be a true embolic event resulting from the physical obstruction of the pulmonary vasculature. The high degree of variability in symptoms, the lack of characteristic findings on radiological exam, the absence of a dose-response effect on symptoms, and the occasional occurrence of coagulopathies are not entirely consistent with a physical block to the circulation as the main mechanism of disease. Alternatively, it might be the result of complement activation initiated by fetal antigen leaking into the maternal circulation. This rare immune response may be initiated by a rare pathological antigen, or by common antigens presented uncommonly--in amount, timing, or frequency of entry into the maternal circulation. Some very early evidence in AFE patients supports this hypothesis but is not conclusive. Complement levels remain well within the normal range during uncomplicated parturition. A prior theory that AFE might be a result of maternal anaphylaxis to fetal antigen has much less evidence to support it. The disseminated intravascular coagulation often seen in this and other serious obstetrical illnesses may be a secondary result of complement activation rather than the direct introduction of pro-coagulants into the maternal circulation although the link between the complement and coagulation pathways, if any, remains poorly defined. Through currently available laboratory testing, both the complement hypothesis and the anaphylaxis mechanism are able to be assessed. Direct measurement of serum complement as well as serum tryptase and urinary histamine are readily obtained tests in community hospitals as well as tertiary care hospitals. If the hypothesis proves true, this investigation may be of profound importance to understanding immune tolerance. Rather, than asking why one pregnant woman in 20,000 develops a violent immune reaction to the fetus, a better question is why do not all pregnant women reject the fetus which is a large collection of foreign antigens?     

羊水栓塞的病理诊断

目的探讨羊水栓塞病人病理诊断的有关问题。方法通过HE染色、胆色素和黏液组织化学染色以及CD34、cytokeratin(H)、HCG-β免疫组化染色，对死于围产期的13例尸检资料及1例抢救成功的外检资料进行回顾性分析。结果尸检中明确诊断为羊水栓塞的5例，在其HE染色的肺组织切片中小血管及毛细血管内都看到了长梭形，三五成团或散在分布的鳞状上皮，其中4例观察到胎粪小体的存在，经胆色素染色证实，3例观察到黏液，2例经黏液染色证实。1例外检诊断为羊水栓塞抢救成功的病例在子宫小血管及毛细血管内也看到了鳞状上皮，并经免疫组化标记证实。其他8例病例，无1例观察到明确羊水成分，其中6例在肺小血管内发现红染、丝状细胞团，但量少且无其他羊水成分证据，cytokeratin(H)全部阴性，CD34染色有3例阳性，3例在肺血管或子宫血管内看到了大细胞，HCG染色均为阴性。结论羊水栓塞的病理诊断应该以HE切片结合病史及临床表现为主，特殊染色及免疫组化染色可以辅助诊断，但不应完全依赖于特殊染色及免疫组化染色。     

孕妇外周血中胎儿有核红细胞在性连锁遗传病产前诊断中的初步应用

目的：探讨利用母血胎儿有核红细胞进行性连锁遗传病产前诊断的可行性;方法：通过密度梯度离心富集母血胎儿有核红细胞,并经流式细胞仪鉴定,对富集后胎儿有核红细胞进行了ＳＲＹ 基因的套式ＰＣＲ检测;结果：５ 例有性连锁遗传病家族史的孕妇外周血中经扩增后３ 例阳性、２ 例阴性,所得结果均得到相应羊水、胎盘ＤＮＡＳＲＹ／ＰＣＲ 检测或出生胎儿生殖器检查结果的证实;结论：母血中胎儿有核红细胞可用于性连锁遗传病的早期产前诊断     

Prenatal HLA typing of uncultured amniocytes prior to the collection of related allogeneic cord blood

DNA samples isolated from corresponding uncultured amniotic fluid, cord blood and maternal blood (n=5) were subjected to low resolution typing of the HLA-A, -B and -DRB loci by the polymerase chain reaction using sequence-specific primers (PCR-SSP). Furthermore, the effect of ethylene diamine tetraacetate disodium salt (EDTA) on the quality of genomic DNA isolated from amniotic fluid samples after long-term storage was evaluated. Unambiguous results of HLA typing could be achieved from all amniotic fluid samples stabilized with EDTA. PCR-SSP typing failed in DNA samples from amniotic fluid without the addition of EDTA. In all cases the fetal HLA type could be confirmed by the result from the corresponding cord blood typing. Contamination with maternal DNA led to additional weak PCR-SSP bands in one case, but data interpretation was still unambiguous. Reliable fetal HLA typing can be achieved directly from amniotic fluid and culturing of amniocytes is not required.     

Comparative evaluation of virological and serological methods in prenatal diagnosis of parvovirus B19 fetal hydrops.

Human parvovirus B19 infection in pregnancy represents a potential hazard to the fetus since fetal loss or fetal hydrops can occur. The risk of fetal loss due to transplacental B19 transmission has been evaluated in several studies using different diagnostic methods on maternal and fetal specimens. We analyzed the diagnostic value of virological and serological techniques on maternal serum, fetal cord blood, and amniotic fluid specimens obtained at the time of clinical diagnosis of fetal hydrops in 18 cases of B19 fetal hydrops. B19 DNA was detected by nested PCR, dot blot hybridization, and in situ hybridization assay. Anti-B19 immunoglobulin M and G antibodies were detected by immunoassays using recombinant B19 antigens. Our data suggest that for maternal sera, virological and serological methods have a complementary role in diagnosis, while for fetal specimens the in situ detection of B19 DNA in fetal cord blood is the most sensitive diagnostic system.     

Complement C3a expression and tryptase degranulation as promising histopathological tests for diagnosing fatal amniotic fluid embolism

To date, the most recent specific diagnostic investigations for amniotic fluid embolism have been unable to conclusively identify any mechanism of disease other than a physical block to the circulation. We selected eight fatal cases in previously healthy women with uneventful singleton term pregnancies who presented to tertiary care centers in Italy for delivery. Pathologic features were assessed immunohistochemically using anti-fibrinogen, anti-tryptase, anti-C_3a, and anti-cytokeratin antibodies. AE1/AE3 cytokeratin stains proved positive, and tryptase-positive material was documented outside pulmonary mast cells. In all studied cases, expression of complement C_3a was twofold lower than in the control group, suggesting a possible complement activation in AFE, initiated by fetal antigen leaking into the maternal circulation.     

Quantification of all fetal nucleated cells in maternal blood between the 18th and 22nd weeks of pregnancy using molecular cytogenetic techniques

Different types of nucleated fetal cells (trophoblasts, erythroblasts, lymphocytes, and granulocytes) have been recovered in maternal peripheral blood. In spite of many attempts to estimate the number of fetal cells in maternal circulation, there is still much controversy concerning this aspect. The numbers obtained vary widely, ranging from 1 nucleated cell per 104 to 1 per 109 nucleated maternal cells. The purpose of our project was to determine the absolute number of all different types of male fetal nucleated cells per unit volume of peripheral maternal blood. Peripheral blood samples were obtained from 12 normal pregnant women known to carry a male fetus between 18 and 22 weeks of pregnancy. Three milliliters (3 ml) of maternal blood has been processed without any enrichment procedures. Fluorescence in situ hybridization (FISH) and primed in situ labeling (PRINS) were performed, and fetal XY cells were identified (among maternal XX cells) and scored by fluorescent microscopy screening. The total number of male fetal nucleated cells per milliliter of maternal blood was consistent in each woman studied and varied from 2 to 6 cells per milliliter within the group of normal pregnancies. The number of fetal cells in maternal blood, at a given period, is reproducible and can therefore be assessed by cytogenetic methods. This confirms the possibility of developing a non-invasive prenatal diagnosis test for aneuploidies. Furthermore, we demonstrate that it is possible to repeatedly identify an extremely small number of fetal cells among millions of maternal cells.     

Fetal DNA in maternal plasma: application to non-invasive blood group genotyping of the fetus.

The non-invasive determination of fetal genetic characteristics, including blood group types, is a long-sought goal of modern genetics. Previous work on the use of fetal cells in maternal blood has been hampered by the rarity of such cells. The recent discovery of cell-tree fetal DNA in maternal blood has opened up new possibilities for non-invasive prenatal diagnosis. It is particularly useful that fetal DNA is present in relatively high concentrations in maternal plasma, making its robust detection possible using modern technology. Large-scale clinical trials and standardization of protocols still need to be carried out. However, there is optimism that the accurate and safe prenatal determination of fetal blood group types may be achieved in routine clinical practice in the near future.     

Recent developments in fetal nucleic acids in maternal plasma: implications to noninvasive prenatal fetal blood group genotyping.

The discovery of circulating cell-free fetal DNA in maternal plasma has opened up new possibilities for noninvasive prenatal diagnosis. Fetal DNA in maternal plasma has been used for the noninvasive prenatal determination of the RhD status of fetuses carried by RhD-negative pregnant women. In such analysis, the possible need of an internal control for the presence of detectable amounts of fetal DNA in a particular maternal plasma sample has been actively discussed. Recently, the development of a robust method for discriminating single nucleotide differences in plasma DNA using single allele base extension reaction (SABER) followed by matrix-assisted laser-desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) has opened up the possibilities of using a panel of single nucleotide polymorphisms as such a positive control. A second approach is the recent successful development of fetal epigenetic markers which can be developed into universal fetal DNA markers. These developments hold promise to allow the eventual widespread utilization of maternal plasma DNA analysis for the noninvasive prenatal diagnosis of blood group mismatches between the mother and fetus.     

Rapid prenatal diagnosis of congenital Toxoplasma infection by using polymerase chain reaction and amniotic fluid.

Infection of pregnant women with Toxoplasma gondii places the developing fetus at risk for congenital infection. We report a prospective study of 43 documented cases of acute maternal Toxoplasma infections acquired during gestation in which the polymerase chain reaction (PCR) was evaluated for diagnosis of fetal infection and compared with the current standard methods. On the basis of direct lysis of pelleted amniotic fluid cells followed by amplification of a gene sequence specific for T. gondii, PCR correctly identified the presence of T. gondii in five of five samples of amniotic fluid from four proven cases of congenital infection. PCR also detected three of five positive cases from a nonprospective group. The two diagnostic methods of comparable speed, detection of specific immunoglobulin M from fetal blood and and inoculation of amniotic fluid into tissue culture, correctly identified only 3 and 4 of the 10 positive samples, respectively. The considerably more time-consuming methods of mouse inoculation of amniotic fluid and fetal blood both detected 7 of 10 positive samples. There were no false-positive diagnoses by any of the methods. Therefore, detection of T. gondii by PCR appears to be the most promising method for prenatal diagnosis of congenital Toxoplasma infection, since it is both extremely rapid and highly sensitive.     

An in-vivo study on placental transfer of naproxen in early human pregnancy

BACKGROUND: Naproxen is one of the most common non-steroidal anti-inflammatory drugs used by women of reproductive age. Naproxen is known to be teratogenic in animals. The aim of this study was to investigate the placental transfer of naproxen in the first trimester of human pregnancy, and to determine the amount of the drug in different embryonic compartments. METHODS: Twenty-eight patients who requested surgical termination of pregnancy in the first trimester were given two oral 500 mg doses of naproxen before the surgical procedure. Four biological samples, maternal venous blood, coelomic fluid, amniotic fluid and fetal tissue, were collected from each patient for drug analyses by high performance liquid chromatography. RESULTS: Naproxen was detected in all samples. The mean (+/- SD) concentrations were 69.5 +/- 12.2 microg/ml, 6.4 +/- 2.4 microg/g, 1.85 +/- 1.03 microg/ml and 0.14 +/- 0.11 microg/ml in maternal serum, fetal tissue, coelomic fluid and amniotic fluid respectively. The mean amniotic fluid/maternal drug ratio and fetal/maternal drug ratio were 0.002 (range 0.0005-0.0064) and 0.092 (range 0.022-0.155) respectively. There was a positive correlation between the fetal drug concentration (r = 0.59, P = 0.001), amniotic fluid drug concentration (r = 0.47, P = 0.013), amniotic fluid/maternal ratio (r = 0.536, P = 0.003) and fetal/maternal ratio (r = 0.72, P < 0.001) with advancing gestational age. CONCLUSIONS: Although naproxen can cross the placenta readily in the first trimester of human pregnancy, only a small amount was present in fetal tissues. Since there is no information on whether this small amount of naproxen would be teratogenic or not, women of reproductive age who are taking naproxen regularly should be warned of the possible fetal side-effects.     

母血浆及血清中胎儿游离DNA的研究进展

1997年胎儿游离DNA的发现为无创性产前诊断开辟了新的途径。母血循环中的胎儿游离DNA含量相对较高,获取方法比较简单,在早孕阶段就可以检测到,这些优点成为极具潜力的无创伤性产前诊断方法。目前,胎儿游离DNA已经应用于某些性连锁疾病、妊娠相关疾病、染色体病、胎儿RhD血型检测等很多疾病的产前诊断中。我们希望此技术的进一步发展和完善可以使这种无创性的产前诊断方法在临床得到更广泛的应用。     

Isolating fetal cells in the maternal circulation

Fetal cells exist in maternal blood and can be utilized forprenatal genetic diagnosis. The use of polymerase chain reaction(PCR) technology on maternal blood has enabled the detectionof fetal sex, Mendelian disorders (e.g. (rß-globinmutations), HLA polymorphisms and fetal Rhesus (D) blood type.Enrichment for erythro-blasts and trophoblasts by various densitygradient and flow sorting techniques followed by fluorescencein-situ hybridization (FISH) with chromosome-specific DNA probeshas allowed detection of trisomy 21, trisomy 18, Klinefeltersyndrome (47,XXY) and 47,XYY. The fetal cell type that has generatedthe most success is the nucleated erythrocyte; however, trophoblasts,lymphocytes and granulocytes are also considered to be presentin maternal blood. Fetal cells circulate in maternal blood duringthe first and second trimesters, with frequency increasing asgestation advances. Emphasis is thus now directed toward determiningthe most practical and efficacious manner for this techniqueto be applied to prenatal genetic diagnosis. A large scale collaborationof clinical evaluations is underway in the USA, upon completionof which assessment can be made of whether this technology canserve as an alternative to conventional invasive and non-invasivemethods of prenatal cytogenetic diagnosis.     

Fetal cells in transcervical samples at an early stage of gestation

Several investigations are in progress with the aim of performing prenatal diagnosis of inherited disorders by noninvasive or minimally invasive techniques. The most important approaches are based on the detection of fetal nucleated cells in maternal blood, the analysis of fetal DNA present in maternal plasma, and the identification and isolation of fetal trophoblastic cellular elements shed into the uterine cavity and the endocervical canal. In this review, we discuss the methods that have been employed for the collection of the transcervical samples at an early stage of gestation and the techniques used for the identification of fetal cells. We also report the results of using endocervical cells for the detection of fetal chromosomal disorders by fluorescent in-situ hybridization and for performing prenatal diagnosis of fetal Rh(D) phenotypes. Recent investigations have also shown that — after the isolation of trophoblastic cells from maternal contaminants by micromanipulation — transcervical samples can be employed for the prenatal diagnosis of single gene defects, such as those causing thalassemia and sickle cell anemia. Although the present results are promising, further investigations are required to demonstrate the feasibility of performing accurate diagnosis of fetal diseases by this minimally invasive approach in all transcervical samples retrieved at an early stage of gestation. Received: November 7, 2000 / Accepted: November 27, 2000     

Distribution of acute-phase alpha 2-macroglobulin in rat fetomaternal compartments

Rat acute-phase alpha 2-macroglobulin (AP alpha 2M) concentration was measured by radioimmunoassay in maternal serum, fetal plasma, maternal liver, fetal liver, and amniotic fluid as a function of gestational and neonatal age. The concentration profiles of AP alpha 2M in maternal serum and fetal plasma displayed two peaks, one in early gestation and another during late gestation. Synthesis of AP alpha 2M was confirmed by the immunoprecipitation of [35S]methionine incorporated into cultures of selected tissues. The following observations were made. 1) Maternal serum concentrations of AP alpha 2M were higher than those observed in fetal plasma in early gestation. This was attributable to a high level of maternal AP alpha 2M synthesis in metrial gland which was absent in liver and moderate in yolk sac. 2) In late gestation fetal plasma concentrations of AP alpha 2M greatly exceeded those observed in maternal serum. This could be explained by the pronounced synthesis of AP alpha 2M in fetal liver that was not apparent in maternal liver or yolk sac. 3) During labor, a transient increase in AP alpha 2M concentration was observed in maternal serum and fetal plasma. 4) During lactation a moderately elevated maternal serum concentration of AP alpha 2M was maintained. 5) Amniotic fluid concentration of AP alpha 2M was very low throughout gestation, which indicated that the fetal glomerulus was relatively impermeable to this large protein. It is concluded that in early gestation a principal maternal source of AP alpha 2M appears to be the metrial gland, whereas in late gestation fetal liver is a major source of AP alpha 2M appearing in fetal plasma from where some of this macroglobulin is speculated to be transported to the maternal circulation.     

Circulating cell-free fetal DNA in maternal serum appears to originate from cyto- and syncytio-trophoblastic cells. Case report

Circulating cell-free fetal DNA in maternal serum offers an early and non-invasive method for prenatal diagnosis, but the origin of this DNA is still unknown. We report the absence of the SRY gene in maternal serum of a pregnant woman despite male genitalia at ultrasound. The karyotype was 45,X after direct trophoblast analysis and 45,X/46,Xidic(Yp) after culture and in all fetal tissues studied. Due to the absence of the SRY sequence in maternal blood and in the cytotrophoblast, we presume that free fetal DNA in this case originates from trophoblastic cells. As the case presented here is exceptional, it only has a minor impact on the accuracy of fetal sex determination by maternal serum analysis, but highlights the importance of and the necessity for the complementary ultrasonographic control.     

Flow cytometric methods for prenatal and neonatal diagnosis

Flow cytometry offers a promising alternative to the current methods of amniocentesis or chorionic villus sampling (CVS) for fetal cell sorting for prenatal diagnosis. While flow cytometric methods have been greatly improved to be more sensitive at detecting fetal cells within the maternal circulation, there are still several challenges that need to be overcome before application in prenatal diagnosis. However, flow cytometry is a powerful tool that can be used to enhance molecular testing and other diagnostic testing modalities in prenatal and neonatal diagnosis. It remains the gold standard to identify cellular immunodeficiencies and, for some immunological disorders with established biomarkers, flow cytometric assays can be used to make a definitive diagnosis. In this review, the advantages and disadvantages of using MACS and FACS analysis for fetal cell sorting are discussed. This review also includes an overview of the current flow cytometric assays and biomarkers that may be used for prenatal and neonatal diagnosis of common immunological and hematological abnormalities and the role of flow cytometry in treatment monitoring after bone marrow and stem cell transplantation.