Investigation of the acid-base balance of coelomic and amniotic fluids in early human pregnancy

The placenta: a multifaceted, transient organ

The placenta is arguably the most important organ of the body, but paradoxically the most poorly understood. During its transient existence, it performs actions that are later taken on by diverse separate organs, including the lungs, liver, gut, kidneys and endocrine glands. Its principal function is to supply the fetus, and in particular, the fetal brain, with oxygen and nutrients. The placenta is structurally adapted to achieve this, possessing a large surface area for exchange and a thin interhaemal membrane separating the maternal and fetal circulations. In addition, it adopts other strategies that are key to facilitating transfer, including remodelling of the maternal uterine arteries that supply the placenta to ensure optimal perfusion. Furthermore, placental hormones have profound effects on maternal metabolism, initially building up her energy reserves and then releasing these to support fetal growth in later pregnancy and lactation post-natally. Bipedalism has posed unique haemodynamic challenges to the placental circulation, as pressure applied to the vena cava by the pregnant uterus may compromise venous return to the heart. These challenges, along with the immune interactions involved in maternal arterial remodelling, may explain complications of pregnancy that are almost unique to the human, including pre-eclampsia. Such complications may represent a trade-off against the provision for a large fetal brain.

Guidance on classification for reproductive toxicity under the globally harmonized system of classification and labelling of chemicals (GHS)

The Globally Harmonised System of Classification (GHS) is a framework within which the intrinsic hazards of substances may be determined and communicated. It is not a legislative instrument per se, but is enacted into national legislation with the appropriate legislative instruments. GHS covers many aspects of effects upon health and the environment, including adverse effects upon sexual function and fertility or on development. Classification for these effects is based upon observations in humans or from properly designed experiments in animals, although only the latter is covered herein. The decision to classify a substance based upon experimental data, and the category of classification ascribed, is determined by the level of evidence that is available for an adverse effect on sexual function and fertility or on development that does not arise as a secondary non-specific consequence of other toxic effect. This document offers guidance on the determination of level of concern as a measure of adversity, and the level of evidence to ascribe classification based on data from tests in laboratory animals.

Disposition of glycolic acid into rat and rabbit embryos in vitro

High dose gavage administration of ethylene glycol (EG) induces teratogenicity in rodents, but not in rabbits, resulting from saturation of intermediate EG metabolism and glycolic acid (GA) accumulation. In vivo, rat embryos sequester GA 2-4-fold higher than maternal blood, a phenomenon absent in rabbits and proposed not to occur in humans. This research explored the mechanisms of GA disposition into rat and rabbit conceptuses using whole embryo culture (WEC). Rat and rabbit embryos concentrated GA from the culture medium. In vitro to in vivo discordance in the rabbit plausibly stemmed from anatomical differences between these models. GA sequestration was attenuated at 4°C in both species. Rat embryos further demonstrated pH-dependence of GA sequestration and inhibition by D-lactic acid. These data suggest GA disposition into rat and rabbit embryos is energy- and pH-dependent, and carrier-mediated. Anatomical and maternal-to-conceptal pH gradient differences likely underlie the lack of enhanced GA disposition in non-rodent species.

Mid-Trimester Placentation Assessment in High-Risk Pregnancies Using Maternal Serum Screening and Uterine Artery Doppler

OBJECTIVE

To determine the value of uterine artery velocimetry and mid-trimester maternal serum AFP/hCG measurements in predicting pregnancy complications in a high-risk group of pregnant patients.

METHODS

Eighty-eight patients with chronic hypertension, previous preeclampsia, and thrombophilia were included. Maternal serum AFP/hCG was examined between 15-16 weeks gestation. Levels > 3 multiple of median (MoM) for hCG and > 2 MoM for AFP were considered abnormal. Color Doppler ultrasound was performed at 23-24 weeks gestation. Diastolic notching and pulsatility index (PI) above the 95th percentile were considered abnormal.

RESULTS

Thirty-three patients had abnormal uterine artery waveform: 8 patients had abnormal maternal serum hCG and 5 had abnormal maternal serum AFP. Bilateral abnormal uterine artery waveform was associated with pregnancies complicated by lower gestational age at delivery (p=0.05) and birth weight (p<0.01), higher rates of preeclampsia (p=0.006), SGA (p=0.0001), preterm delivery (p=0.0001), and cesarean section rate (p<0.0001) in comparison to patients with normal uterine artery Doppler. Pregnant women with elevated hCG had higher rates of preeclampsia (p=0.006); preterm delivery (p=0.005) and SGA (P=0.03) and, lower birth weight (p=0.001). No significant differences were noted for clinical outcomes according to AFP data. Conclusions. Abnormal uterine artery waveform is superior to maternal serum hCG for identification of placental pathology leading to preterm delivery, low birth weight, and preeclampsia in high-risk pregnant patients.

Application of proteomics for diagnosis of fetal aneuploidies and pregnancy complications

Proteomic technologies represent new strategies towards high-throughput, simultaneous analysis of thousands of biological molecules leading to the discovery of biomarkers for early diagnosis, prognosis and prediction of pregnancy outcome. Proteomics have additional relevance in understanding pathophysiology and the development of molecularly targeted therapeutics. Comparison of normal human amniotic fluid proteome with that coming from pregnancies carrying fetuses with chromosomal abnormalities facilitated the detection of panels of potential biomarkers for prenatal detection of fetal aneuploidies. Candidate biomarkers for the early prediction of preeclampsis are also available, while four biomarkers (defensins-2 and -1, calgranulin-C, and calgranulin-A), which were called the "MR score", can quickly and accurately detect potentially dangerous infections and predict premature birth. Researchers remain hopeful that proteomic studies will allow for the identification of either one protein marker or of a panel of markers for prenatal detection of fetal aneuploidies and pregnancy complications that could be usefully employed for diagnostic purposes or improvement of the current screening methods. For maximum predictive power however, biomarkers should be selected for further comparative analysis of expression and structural modifications in large numbers of samples from chromosomally normal and abnormal pregnancies obtained from different populations.

Species-specificity of ethylene glycol-induced developmental toxicity: toxicokinetic and whole embryo culture studies in the rabbit

High-dose gavage exposure to ethylene glycol (EG) is teratogenic in rats, but not rabbits. To investigate the reason for this species difference, toxicokinetic and whole embryo culture (WEC) studies were conducted in gestation day 9 New Zealand White rabbits, and the data compared to very similar data previously generated in pregnant rats. In the toxicokinetic study, maximal levels of unchanged EG in rabbits were comparable to those reported for rats. However, maximal levels of EG's teratogenic metabolite, glycolic acid (GA), in rabbit maternal blood and embryo were only 46% and 10% of the respective levels in rats. The toxicokinetic profile suggested that the lower GA levels in rabbits were due to a slower rate of maternal metabolism of EG to GA, slow uptake of GA into the yolk sac cavity fluid which surrounds the embryo, and negligible transfer via the visceral yolk sac (VYS) placenta. In the WEC study, exposure of rabbit conceptuses to high concentrations (< or = 12.5 mM) of GA was without effect, which contrasts with reported effects in rat WEC at > or = 3 mM. Overall, these data implicate toxicokinetics as an important factor underlying the species difference, although intrinsic insensitivity of the rabbit embryo might also be involved. Integration of these findings with published human data suggest that the rabbit is the more relevant model for human EG exposure, based on the negligible role of the rabbit VYS in placental transfer (humans lack a VYS) and similar rates of EG metabolism and extraembryonic fluid turnover.

Mass spectrometry-based proteomics in reproductive medicine

The emergence of powerful mass spectrometry-based proteomic techniques has added a new dimension to the field of biomedical research. Application of these high throughput methodologies in pregnancy-related pathology has contributed to the comprehension of the underlying pathophysiologies and the successful identification of relevant protein biomarkers that can potentially change early diagnosis and treatment of several medical conditions related to human pregnancy. Most of the existing research on human reproduction and gestation has focused on follicular fluid, cervical/vaginal fluid, and amniotic fluid. Although proteome technologies in reproductive medicine research are not as yet widely applied, characterization of the proteome of reproductive fluids can be expected to significantly improve maternal healthcare. This article aims to summarize the applications of mass spectrometry based technology on the most important and specific biological fluids related to reproduction and gestation.

Mode of Action: Oxalate Crystal-Induced Renal Tubule Degeneration and Glycolic Acid-Induced Dysmorphogenesis—Renal and Developmental Effects of Ethylene Glycol

Ethylene glycol can cause both renal and developmental toxicity, with metabolism playing a key role in the mode of action (MOA) for each form of toxicity. Renal toxicity is ascribed to the terminal metabolite oxalic acid, which precipitates in the kidney in the form of calcium oxalate crystals and is believed to cause physical damage to the renal tubules. The human relevance of the renal toxicity of ethylene glycol is indicated by the similarity between animals and humans of metabolic pathways, the observation of renal oxalate crystals in toxicity studies in experimental animals and human poisonings, and cases of human kidney and bladder stones related to dietary oxalates and oxalate precursors. High-dose gavage exposures to ethylene glycol also cause axial skeletal defects in rodents (but not rabbits), with the intermediary metabolite, glycolic acid, identified as the causative agent. However, the mechanism by which glycolic acid perturbs development has not been investigated sufficiently to develop a plausible hypothesis of mode of action, nor have any cases of ethylene glycol-induced developmental effects been reported in humans. Given this, and the variations in sensitivity between animal species in response, the relevance to humans of ethylene glycol-induced developmental toxicity in animals is unknown at this time.

Assessment of the perinatal effects of maternal ingestion of Ipomoea carnea in rats

It is believed that Ipomoea carnea toxicosis induces abnormal embryogenesis in livestock. Studies on rats treated with I. carnea aqueous fraction (AF) during gestation, revealed litters with decreased body weight, but the characteristic vacuolar lesions promoted by swainsonine, its main toxic principle, were observed only in young rats on postnatal day (PND) 7. However, these alterations could have resulted as consequence of swainsonine placental passage and/or damage or even ingestion of the contaminated milk by pups. Thus, this perinatal work was performed to verify the transplacental passage of swainsonine and its excretion into milk employing the cross-fostering (CF) procedure as a tool of study. Females were treated with AF or vehicle during gestation and after birth pups were fostered between treated and untreated dams. Pup body weight gain (BWG) and histopathology to observe vacuolar degeneration were performed on PND 3 and 7. In addition, swainsonine detection was performed in amniotic fluid and milk from rats treated with the AF during gestation or lactation. BWG was significantly lower only in pups from mothers treated with the plant and fostered to other treated mothers (AF-AF group of pups). The histopathology revealed that pups from treated mothers fostered to untreated ones showed the characteristic vacuolar lesions; however, the lesions from the AF-AF pups were more severe in both periods evaluated. Amniotic fluid and milk analysis revealed the presence of swainsonine excretion into these fluid compartments. Thus, the results from CF and the chemical analysis allowed concluding that swainsonine passes the placental barrier and affects fetal development and milk excretion participates in I. carnea perinatal toxicosis.

Solutes in Maternal Circulation and Gestational Sac Compartments during Early Human Development

OBJECTIVES

The aim of this study was to review previous work reporting the concentration of solutes measured in maternal circulation, extra-embryonic celomic fluid, and amniotic fluid, to gain insights into the mechanism that could lead to compartmentalization of fluid and solutes within the gestational sac prior to the 12th week of pregnancy.

METHODS

We conducted a Medline and PubMed literature search from January 1990 through March 2004 using the key words amniotic fluid, celomic fluid, coelomic fluid, celocentesis, coelocentesis, amniocentesis, yolk sac and embryonic cavities. We selected those articles describing solutes that had been measured in the same patient in samples obtained prior to 12 weeks' gestation from maternal circulation, celomic fluid and amniotic fluid. Information extracted from these publications included: gestational age at sampling, number of samples evaluated, mean concentration of the solutes in each of the three fluids and bibliographic citation.

RESULTS

We found 73 publications with the key words and selected 13 that met the inclusion criteria. The concentration of 31 solutes reported in each of the three compartments was documented and gradients among compartmental interfaces calculated.

CONCLUSION

This study describes the concentration of solutes measured in maternal circulation, extracelomic fluid and amniotic fluid early in human development. Analysis of calculated gradients across the compartmental interfaces suggests that the shift of fluid may depend on the biophysical properties of the placenta and yolk sac and on graded changes in hydrostatic pressures across compartments.

Embryo/fetal toxicity assessment of lasofoxifene, a selective estrogen receptor modulator (SERM), in rats and rabbits

BACKGROUND

The purpose of this study was to evaluate the effects of lasofoxifene, a selective estrogen receptor modulator (SERM), on rat and rabbit fetal development.

METHODS

Lasofoxifene was administered orally to rats (1, 10, 100 mg/kg) between gestation days (GD) 6-17, and in rabbits (0.1, 1, 3 mg/kg) between GD 6-18. Maternal body weight and food consumption were monitored throughout pregnancy. Fetuses were delivered by Cesarean section on GD 21 in rats, and GD 28 in rabbits, to evaluate fetal viability, weight, and morphology. Drug concentrations in maternal plasma were measured in a separate cohort of animals at several time points commencing on GD 17 (rats) and 18 (rabbits). On GD 18 (rat) and GD 19 (rabbit) drug concentrations were measured in maternal plasma and in fetal tissue 2 hr post dosing to determine the fetal to maternal drug ratio.

RESULTS

In rats, there were dose-related declines in maternal weight gain and food consumption. Post implantation loss was significantly increased at dosages of 10 and 100 mg/kg, and the number of viable fetuses was decreased at 100 mg/kg. The placental weights increased, whereas fetal weights decreased in a dose-dependent manner. Lasofoxifene-related teratologic findings were noted at 10 and 100 mg/kg and included imperforate anus with hypoplastic tails, dilatation of the ureters and renal pelvis, misaligned sternebrae, hypoflexion of hindpaw, wavy ribs, and absent ossification of sternebrae. In rabbits, neither maternal weight gain nor food consumption were affected during treatment. Between GD 26-28, there was a dose-dependent increased incidence of red discharge beneath the cages. At 1 and 3 mg/kg, resorptions and post-implantation loss increased. There were no significant external or visceral effects, but 3 mg/kg there was an increased incidence of supernumerary ribs. Although the maternal plasma Cmax and AUC(0-24) were dose-dependent, the exposures in the rat were many orders of magnitude greater than in the rabbit even for the same 1 mg/kg dose. The single time point fetal/maternal drug ratio was higher in the rat (1.3-0.78) than in the rabbit (0.21-0.16).

CONCLUSION

In general, both maternal and fetal effects of lasofoxifene were similar to those reported with other SERMs. Although the incidence or severity of these effects was, in some instances, greater in the rat than in the rabbit, the doses and the resultant maternal and fetal exposures were many orders of magnitude higher in the rat, suggesting the rabbit to be more sensitive to the toxicological effects of lasofoxifene.

Evaluation of respiratory gases and acid-base gradients in human fetal fluids and uteroplacental tissue between 7 and 16 weeks' gestation

OBJECTIVE

Our purpose was to evaluate the changes in intrauterine gases and acid-base gradients inside the human fetoplacental unit at 7 to 16 weeks' gestation.

STUDY DESIGN

Respiratory gases and acid-base values were recorded by means of a multiparameter sensor and samples from inside the exocoelomic or amniotic cavity, placental tissue, decidua, and fetal blood of 30 early pregnancies.

RESULTS

Before 11 weeks' gestation, placental PO(2) was 2.5 times lower than decidual PO(2). The PO(2) increased independently at both sites during gestation, but a PO(2) gradient of 13.3 mm Hg persisted during the fourth month. At 13 to 16 weeks, PO(2), oxygen saturation, and oxygen content gradients were observed between the fetal blood and the placenta and between the placenta and underlying decidual tissue. There was no fetoplacental gradient for pH and PCO(2) between 7 and 16 weeks, but fetal blood pH values were much lower and fetal PCO(2) values were much higher than those reported in older fetuses.

CONCLUSIONS

Early human placental tissue develops in a physiologically low-oxygen environment compared with uterine tissue. This may be necessary to allow specific placental metabolic activities and to protect both placental and fetal tissues against toxic oxygen metabolites.

In vivo investigation of placental transfer early in human pregnancy

The use of coelocentesis to study placental drug transfer in the first trimester has required the adaptation of existing pharmacologic models to the changing anatomical structures present before and after 12 weeks of gestation. The biochemical properties of the coelomic and amniotic fluids are important parameters in evaluating the pharmacokinetics of drugs and toxins in early pregnancy. In particular, the protein concentration and pH of these fluids are significantly different and vary widely with gestational age. These biochemical variations are less likely to influence the distribution of inert substances such as inulin inside the first trimester conception cavities than the distribution of drugs such as diazepam or propofol. This can explain why they are not all accumulating inside the exocoelomic cavity. It has been demonstrated that the permeability of the placenta is greater in early pregnancy than at term. Furthermore, because of the slow turn-over of the coelomic fluid, substances such as nicotine to which the mother is chronically exposed accumulate inside the exocoelomic cavity. This prolonged fetal exposure to tobacco carcinogens has important teratogenic implications and should be further explored.

Amniotic gas values and acid-base status during acute maternal hyperoxemia and hypoxemia in the early fetal sheep

OBJECTIVE

This study was undertaken to determine amniotic fluid gas values and acid-base balance during maternal hyperoxemia and hypoxemia in early pregnancy.

STUDY DESIGN

Anesthetized sheep (n = 12) in early and mid pregnancy (0.3 to 0.5 gestation) were subjected to hyperoxemia followed by hypoxemia. Amniotic fluid PO (2), pH, PCO (2), bicarbonate concentration, and base excess were monitored continuously with a multiparameter Paratrend (Diametrics Medical Inc, St Paul, Minn) sensor and compared between 0.3 and 0.5 gestation.

RESULTS

During maternal normoxemia all parameters were constant. At all gestational ages maternal hyperoxemia caused no changes apart from a rapid increase in amniotic fluid PO (2) (P <.001). Maternal hypoxemia led to a reduced amniotic fluid PO (2) (P <.001), whereas the PCO (2) and the bicarbonate concentration increased (P <.001). Changes in amniotic fluid gas values and acid-base balance were more pronounced at 0.3 gestation than at 0.5 gestation. Amniotic fluid Po(2) responded earlier to maternal hyperoxemia than to hypoxemia (9. 5 vs 14.3 minutes; P <.001). During hypoxemia maternal PaCO (2) changed faster than did amniotic fluid PCO (2) (P <.001).

CONCLUSIONS

Acute maternal hypoxemia during early pregnancy was quickly reflected in amniotic fluid gas values and acid-base balance, whereas hyperoxygenation induced the quickest changes in amniotic fluid PO (2). The metabolic effects of maternal hyperoxemia and hypoxemia were also more pronounced during early pregnancy than at mid pregnancy.

Amniotic fluid biochemistry in second-trimester trisomic pregnancies: relationships to fetal organ maturation and dysfunction

Protein and enzyme patterns were investigated in amniotic fluid samples of 12 trisomy 21 and five trisomy 18, between 11 and 16 weeks and of a control group of 50 chromosomally and anatomically normal pregnancies at the same gestational age. Positive correlations were found between gestational age and the concentration of urea (P<0.05), creatinine (P<0.01), beta2-microglobulin (P < 0.0001), hCG (P < 0.01), ALP (P < 0.001), LAP (P < 0.0001) and GGT (P <0.0005) in the amniotic fluid of euploid pregnancies. There were also significant correlations between the concentrations of the different variables measured except for hCG and AFP. Different protein and enzyme patterns were found in the amniotic fluid of aneuploid pregnancies where only beta2-microglobulin concentration was significantly correlated with advancing gestational age. The beta2-microglobulin concentration was significantly (P <0.05) higher in aneuploid fetuses presenting with hydrops compared to those without. These findings suggest that the changes in amniotic composition found during the fourth month of normal pregnancies reflect mainly the maturation of the fetal renal glomerular function and the arrival of enzymes from the digestive and respiratory tract into the amniotic cavity. In trisomy 21, there is evidence of a delay in the maturation of these organs whereas in trisomy 18, there is a reduced production of most proteins and enzymes.

Free amino acid distribution inside the first trimester human gestational sac

The trophoblast functions of nutrient transport and protein synthesis generate high concentrations of amino acids in the placenta and in fetal blood during the second half of pregnancy, but little is known about these metabolic processes in embryonic and early fetal periods. The aim of this study is to compare the distribution of amino acids inside the first trimester gestational sac. Free amino acid concentrations were measured in homogenates of placental villi, in samples of coelomic and amniotic fluid, and in the maternal serum from 17 normal pregnancies between 7 and 11 weeks of gestation. Significant positive relationships between maternal serum and placental tissue were found for 10 amino acids, indicating that active amino acid transport and accumulation by the human syncytiotrophoblast occurs as early as 7 weeks of gestation. The transplacental flux of most amino acid transport from maternal blood to the exocoelomic cavity was against a concentration gradient. The highest placental amino acid concentrations were found for taurine, glutamic acid, glycine and alanine. The amniotic fluid contained lower mean concentration of all amino acids than coelomic fluid and maternal serum. The concentration distribution of individual amino acids in coelomic and amniotic fluid were related indicating a passive transfer through the amniotic membrane. A coelomic-maternal gradient was observed in 19 out of 24 amino acids measured and positive correlations were found between maternal serum and coelomic fluid for concentrations of alpha-aminobutyric acid, tyrosine and histidine, suggesting that these amino acids are only partially retained and/or transferred more rapidly by the early placenta.

Distribution of lactate dehydrogenase isoenzymes in coelomic fluid and fetal adnexae

The objective of this study was to evaluate the distribution of lactate dehydrogenase isoenzymes in the human gestational sac. Total lactate dehydrogenase and its isoenzymes were measured in matched coelomic fluid and samples of villous and decidual tissues collected at the time of pregnancy termination in a group of 16 healthy women who were between 7 and 12 weeks of gestation. In addition intact secondary yolk sacs (n = 2) and fragments of fetal liver (n = 3) were collected. For comparison, samples of placental tissue, amniotic membrane and chorion obtained at term, were also investigated. In early pregnancy, H-type lactate dehydrogenase isoenzymes predominate in placental villous tissue and coelomic fluid, whereas M-type lactate dehydrogenase isoenzymes predominate in extracts of decidua, secondary yolk sac and fetal liver. These results highlight the important contribution of placental bioproducts to the constitution of the coelomic fluid. We observed also that placental patterns of lactate dehydrogenase isoenzymes change between the first and the third trimester of gestation, from the H-type to the M-type lactate dehydrogenase isoenzymes. We suggest that the lactate dehydrogenase pattern might be an indicator of proliferative or differentiative potential of the trophoblastic cells throughout pregnancy.

Biochemical investigation of fetal renal maturation in early pregnancy

The objective of this study was to evaluate the biochemical indices of normal fetal kidney maturation in early pregnancy. Urea, creatinine, gamma-glutamyltransferase, and beta 2-microglobulin levels were measured on paired samples of amniotic and coelomic fluids and maternal serum collected at the time of pregnancy termination in a group of woman with pregnancies between 8 and 11 wk, or on paired samples of amniotic fluid and maternal serum collected from woman undergoing early transabdominal amniocentesis between 11 and 16 wk. Before 11 wk of gestation (n = 12), significantly lower concentrations of creatinine and beta 2-microglobulin, and higher concentration of gamma-glutamyltransferase were found in amniotic fluid compared with both maternal serum and coelomic fluid. Significant positive correlations were found between gestational age (8-16 wk) and amniotic fluid (n = 47) levels of urea (r = 0.45; p < 0.01), creatinine (r = 0.68; p < 0.001), gamma-glutamyltransferase (r = 0.71; p < 0.001), and beta 2-microglobulin (r = 0.69; p < 0.001). The maternal serum levels of the corresponding variables did not varied significantly. The abrupt increase in creatinine, gamma-glutamyltransferase, and beta 2-microglobulin amniotic fluid concentrations after 10 wk of gestation provides biochemical evidence for the maturation of the fetal renal glomerular function at a time when the reabsorption capacity of the proximal tubular cells is not established. We suggest that this important variation in the amniotic fluid composition, unrelated to any comparable changes in the maternal serum, reflects the fetal kidney development from the mesonephros to the metanephros.

Early fetal circulation in pregnancies complicated by retroplacental hematoma

The objective of this study was to investigate the effects in early gestation of retroplacental hematomas on Doppler indices measured in different fetal vascular districts and to relate these changes, if any, to the volume of hematoma and pregnancy outcome. Thirty-eight pregnancies complicated by bleeding and ultrasonographic findings of retroplacental hematomas were considered for this study. Menstrual age ranged between 9 and 14 weeks. Blood flow velocity waveforms were measured in the umbilical artery, descending aorta, middle cerebral artery, and inferior vena cava. The pulsatility index in arterial vessels was calculated as well as the percentage reverse flow in the inferior vena cava. The values obtained were compared to previously constructed reference limits. No significant differences were found for any of the Doppler indices when the values obtained in pregnancies complicated by retroplacental hematomas were compared to the reference limits. Furthermore no significant relationships were found between the Doppler indices and either the size of hematoma or pregnancy outcome. In conclusion, retroplacental hematoma does not induce hemodynamic effects in the fetal circulation before 14 weeks, menstrual age. These data do not support the use of Doppler ultrasonography in early gestation for pregnancies complicated by bleeding and retroplacental hematomas.

Biochemical composition of the coelomic fluid in anembryonic pregnancy

OBJECTIVE

Our purpose was to investigate the biochemical composition of the coelomic fluid in first-trimester anembryonic pregnancies.

STUDY DESIGN

Coelomic and maternal serum were obtained from 17 anembryonic pregnancies and 17 apparently normal pregnancies between 7 and 12 weeks of gestation that were matched for gestational age. Electrolytes, total proteins, urea, creatinine, lactate, and human chorionic gonadotropin concentrations and pH were measured.

RESULTS

Significantly higher pH (p < 0.005) and bicarbonate levels (p < 0.001) and significantly lower total protein (p < 0.05), phosphate (p < 0.005), and human chorionic gonadotropin (p < 0.001) levels were found in coelomic fluid from anembryonic pregnancies compared with normal pregnancies. No difference was found for chloride, sodium, potassium, urea, creatinine, and lactate between the study and control groups.

CONCLUSIONS

The fluid collected in anembryonic pregnancies is of exocoelomic origin and its biochemical characteristics reflect a failure of most placental biological mechanisms such as metabolic function, transport function, and endocrine activity.