Changes in human amniotic fluid fibrinolytic inhibitor levels during pregnancy

The amniotic fluid (AF) when incubated with the patient's own plasma diminishes the lytic activity of the plasma. It is suggested that this inhibition is due to the presence of fibrinolytic inhibitors in the AF. The inhibitors rate increases as pregnancy advances. Evaluating these inhibitors in a group of 65 women before and after the 38th week of pregnancy, a higher rate of fibrinolytic inhibitors is found after the 38th week. The said differences are statistically significant. For the moment it does not seem that the increasing of the inhibitors in the last part of pregnancy might be used as a fetal maturity test.     

Erythropoietin and the inhibitor of erythropoiesis in the amniotic fluid during the first trimester of normal human pregnancy

The erythropoietic activity of the amniotic fluid from the 1st trimester of pregnancy and of blood plasma of pregnant women was tested biologically on polycythaemic mice by means of radiolabelled 59Fe. It was found that the amniotic fluid exhibits an erythropoietic activity. Then, using Sephadex G-100 gel filtration several fractions of the fluid were separated chromatographically; they were tested on polycythaemic mice for their erythropoiesis-stimulatory and inhibitory activity. It was found that fraction II proteins (mol. w. about 38 000) acted as an erythropoiesis stimulator, while fractions V and VI (mol. w. 6 900 and 4 000, respectively) showed inhibitory properties.     

Fatal amniotic fluid embolism during induced abortion, 1972-1975

From 1972 to 1975, four women have died in the United States from documented amniotic fluid embolism during legal induced abortion. These women, whose pregnancies ranged from 14 to 35 menstrual weeks, had intra-amniotic saline instillation (three cases) and hystereotomy (one case). Performance of abortion in the first trimester and use of curettage technics could minimize the risks of this catastrophe.     

Changes in the amniotic fluid volume in fetal structural anomalies]

Phathalate esters, which are commonly used as plasticizers for polyvinyl chloride, are also well known to disturb Sertoli cells. This study aims to show the effect of prenatally administered phthalate on testicular descent in pre- and postnatal rats. Pregnant rats were exposed to mono-n-butyl phthalate (MBP) by gavage from the 15th to the 18th gestational days. Rats administered with solvent only were used as controls. In 20-day-old fetuses (n = 15), the degree of transabdominal testicular ascent in relation to the bladder neck was thus found to be significantly higher in MBP-treated rats than that of the controls (n = 19). In addition, in MBP-treated male offspring (n = 26), 22 rats showed either bilateral or unilateral cryptorchidism at the age of 30 to 40 days old, and the occurrence of cryptorchidism was 84.6%. By contrast, the occurrence of cryptorchidism was 0% in the control rats (n = 15, P < .001). It is therefore suggested that prenatal exposure to MBP may disturb the Sertoli cells and elevate the fetal testes relative to the bladder neck while also inducing cryptorchidism postnatally. Sertoli cells may thus play an important role in the transabdominal descent of the testis by secreting Müllerian-inhibiting substance (MIS), which is known to act as a putative mediator of the transabdominal phase.     

Relaxin levels in amniotic fluid, extraembryonic coelomic fluid and maternal serum in early human pregnancy

Separately identified samples of amniotic fluid and extraembryonic coelomic fluid together with maternal serum were collected from 22 women between 8 and 11 weeks of pregnancy and analysed for relaxin by immunoassay. Relaxin levels in maternal serum (median 1085 pg/ml; range 390-1259 pg/ml) were substantially higher than those in extraembryonic coelomic fluid (median 57.5 pg/ml; range 17-145 pg/ml; P < 0.0001; Mann-Whitney U-test). In turn, the levels of relaxin in coelomic fluid were higher than those in amniotic fluid (median 10 pg/ml; range 10-37 pg/ml; P < 0.0001; Mann-Whitney U-test). A linear correlation was found between relaxin levels in maternal serum and coelomic fluid (r = 0.68; P = 0.001) but there was no relation between levels in the other fluid compartments.     

Changes in prostaglandin F and 13,14-dihydro-15-keto-prostaglandin F concentrations in amniotic fluid at the onset of and during labour

Concentrations of prostaglandin F (PGF) and its major circulating metabolite 13,14-dihydro-15-keto-PGF (PGFM) have been measured in amniotic fluid during spontaneous labour at term. Levels of both PGF and PGFM were significantly higher during early spontaneous labour, at a cervical dilatation of less than 4 cm, than before the onset of labour. Patients who started labour spontaneously but later required oxytocin therapy for failure to progress in first stage had lower levels of PGF and PGFM than patients who progressed adequately without oxytocin therapy. During spontaneous labour, concentrations of both PGF and PGFM increased significantly with advancing cervical dilatation. These indicate that the accumulation of prostaglandins in amniotic fluid during labour is not due to decreased metabolism. They furthermore provide the strongest evidence available so far for an increase in intrauterine prostaglandin synthesis during human parturition.     

Expression of N-linked sialyl Le(x) determinants and O-glycans in the carbohydrate moiety of human amniotic fluid transferrin during pregnancy

Transferrin, a glycoprotein involved in iron transport in body fluids, was isolated from amniotic fluid of a hydramniospatient by sequential anion-exchange chromatography and gel filtration. The N-glycans of human amniotic fluid transferrin (hAFT) were enzymatically liberated by PNGase-F digestion, isolated by gel filtration and fractionated by (high-pH) anion-exchange chromatography. After alkaline borohydride treatment of native hAFT, the released O-glycans were isolated by gel filtration and fractionated by anion-exchange chroma-tography. Structure elucidation of 14 N- and 2 O-glycans was performed by 500 or 600 MHz1H-NMR spectroscopy. Besides conventional N-glycans established earlier for human serum transferrin (hST), new (alpha1-3)-fucosylated N-glycans were found, representing sialyl Le(x) elements. Furthermore, as compared to hST, a higher degree of (alpha1-6)-fucosylation and an increase in branching from di- to triantennary compounds has been detected. The presence of O-glycans is demonstrated for the first time in transferrin.     

Normal outcome of a pregnancy with mosaicism for double trisomy in amniotic fluid cells

True chromosomal mosaicism of double trisomy (48,XX, +7, +20) was detected in amniotic fluid cell cultures at 16 and 20 weeks of gestation. No aneuploid cells were found in chorionic villus samples (CVS) by semidirect preparation and long-term culture. High-level ultrasound did not indicate any structural abnormality of the fetus. At 38 weeks of gestation, a phenotypically normal girl was born. She is now 22 months old and normally developed. At birth, various samples were investigated by routine cytogenetic methods or by fluorescence in situ hybridization with the probe p7t1 (umbilical cord blood, placental tissue, umbilical cord fibroblasts, urine sediment) and no abnormal cells could be detected in any of those tissues.     

Prostaglandins and thromboxanes in amniotic fluid during rivanol-induced abortion and labour

Abortion or delivery were induced by extra-amniotic instillation of Rivanol during the second trimester in twelve patients and during the third trimester in two patients with fetal death and one patient with fetal acrania. Serial sampling of amniotic fluid was performed through a transabdominal catheter and the levels of free arachidonic acid (AA), prostaglandin F2 alpha (PGF2 alpha), prostaglandin E2 (PGE2), 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) and thromboxane B2 (TXB2) were determined. The levels of AA, PGF2 alpha, PGE2, 6-keto-PGF1 alpha and TXB2 in amniotic fluid increased significantly during induction with the exception of AA in fetal death which was high and remained constant during induction. Furthermore, PGF2 alpha, 6-keto-PGF1 alpha and TXB2 were all significantly correlated to AA. These observations suggested that free AA is released during Rivanol-induction of abortion and labour giving an increased synthesis of PGF2 alpha, PGE2 prostacyclin and thromboxane A2 in the fetal membranes and the decidua but not in the fetus. This increase might be relevant for the initiation and progress of abortion and labour in these patients.     

Prognostic value of amniotic fluid index estimated during labor during chronic fetal acidosis]

There were performed measurements of AFI in 32 women during labour and they were referred to pH of neonatal umbilical vein. It was proved by significant statistic relation p = 0.034 (r = 0.375) between AFI and pH of umbilical vein blood. In anticipation of fetal acidosis with AFI < or = 5 cm with pH < or = 7.25 it was determined that: sensitivity 66.7%, specificity 58.6%, positive predictive value 14.3%, negative predictive value 94.4%, false positive 85.7%, false negative 5.6%, accuracy 59.4%. Obtained data do not differ from those given in literature. Measurements of AFI < or = 5 cm help in identification of the risk group (fetus in danger, of acidosis during labour) but due to low specificity and low positive predictive value (66.7% and 14.3% respectively). Clinical decisions should be made after consideration the result of the other tests of fetal well-being.     

Pathogenesis of amniotic fluid embolism

The reason for existant of amniotic fluid embolism is the disposition, which will be favoured by the overaction of the sympathic system, by age and the number of pregnancy. It happens especially by premature rupture of membrane, pathologic contents in the amniotic fluid, high pressure in the uterus, bad uterine muscel with laceration and with opened endymyometric veins. Pathophysiologic connection between the stages of amniotic fluid embolism are discussed in detail.     

Collagen degradation products in amniotic fluid

It was found that amniotic fluid (38-42 Hbd) contains hydroxyproline in concentration about 10 micrograms/ml. Gel filtration and dialysis demonstrated that most of hydroxyproline exists in a form of low molecular weight products. Furthermore, it was found that amniotic fluid contains a protein which eluates during gel filtration in void volume of the column. It gives a positive reaction for hydroxyproline but the absorption spectrum of such product is not characteristic for this amino acid. Furthermore, it is not digested by bacterial collagenase. It allows to conclude that amniotic fluid (38-42 Hbd) does not contain collagenous proteins. Only low molecular weight degradation products were found. Only part of them is susceptible on the action of bacterial collagenase.     

Clinical aspects of amniotic fluid embolism

At the Clinic Obstetrics and Gynecology, Allgemeines Krankenhaus Celle, two cases of amniotic fluid embolism were observed. The first case showed the two characteristic phases of the disease (cardiopulmonary shock followed by severe disseminated intravascular coagulopathy). During the onset of the cardiorespiratory symptoms, the patient underwent cesarean section and a healthy infant was born. The mother survived. The other patient died of cardiopulmonary arrest. Cesarean section was carried out immediately. At first, the infant was heavily depressed, but further development was normal. Inspite of great advances in intensive care amniotic fluid embolism still is considered to be a very dangerous event with 86% maternal mortality.     

Evaluation of fetal condition in pregnancy complicated by hypertension--biochemical assessment of amniotic fluid. III. Acid-base balance]

Sixty two samples of amniotic fluid, collected by ultrasound guided amniocentesis, were submitted to biochemical investigation including 31 samples from women with pregnancy complicated by hypertension (studied group) and 31 samples deriving from healthy pregnant women (control group with). The following parameters of acid-base balance were measured in amniotic fluids of both groups: pH, pCO2, base deficiency, standard HCO3 and total CO2. Corning device type 168 was used. Distinct metabolic-respiratory acidosis was present in amniotic fluids of studied group showing the decrease of a pH, pO2, standard HCO3 values and an increase of CO2 values and base deficiency. Authors believe in pregnancy complicated by hypertension biochemical environment of intrauterine fetal development with regard to acid-base balance is highly unfavourable.     

Fibrinolytic components in fetal membranes and amniotic fluid

OBJECTIVE: We evaluated fibrinolytic components in plasma and amniotic fluid of pregnant women and in postpartum fetal membranes. STUDY DESIGN: Fibrinolytic parameters in amniotic fluid and plasma were measured by means of enzyme-linked immunosorbent assays. Fetal membranes collected after spontaneous labor at term were analyzed by immunohistochemical methods with immunospecific antibodies against fibrinolytic components. RESULTS: Amniotic fluid contained high plasminogen activator inhibitor-1 concentrations but had low activity. Strong staining for plasminogen activator inhibitor-1 and vitronectin was observed in chorionic trophoblasts and moderate staining in decidual connective tissue. Strong staining for plasminogen activator inhibitor-2 was seen in decidual cells. Although prominent staining of plasminogen activators and plasminogen were observed in the amniotic epithelium, virtually no plasminogen activator inhibitor-1, plasminogen activator inhibitor-2, or alpha 2-plasmin inhibitor staining was detected. CONCLUSION: The delicate balance of fibrinolytic activators and inhibitors in fetal membranes and amniotic fluid may contribute to the triggering of membrane rupture at term.     

Clinical utility of amniotic fluid volume assessment

Abnormal amniotic fluid volume is associated with increased maternal risk and perinatal morbidity and mortality. Until the advent of ultrasonography, the invasive nature of amniotic fluid volume assessment limited its clinical utility. Refinements in quantifying the noninvasive sonographic assessment of oligohydramnios and hydramnios have improved the ability of clinicians to identify at-risk pregnancies. This article reviews the available methods of amniotic fluid volume assessment and outlines a comprehensive approach to sonographic screening and monitoring.     

Decreased levels of amniotic fluid oxytocinase activity in preeclampsia

Oxytocinase (EC 3.4.11.3) activity was determined in 80 amniotic fluid samples obtained from 40 normotensive primigravidas (median age 27 years) and 40 primigravidas (median age 29 years) with pregnancies complicated by preeclampsia between 32 and 39 weeks of gestation. The enzyme activity was significantly lower in preeclampsia than in normal pregnancy with matched gestations (p < 0.01). Considering the possible involvement of vasopressin and angiotensin II in preeclampsia, it is suggested that the enzyme which degrades these pressor hormones may play a role in the pathogenesis of hypertensive pregnancy.