Implantation, development of the fetal membranes, and placentation in the captive black mastiff bat, Molossus ater

Uterine events during pregnancy were examined histologically in laboratory-bred black mastiff bats (Molossus ater) as part of an effort to develop this species as a model for studies of the factors controlling trophoblastic growth. Embryos entered the uterus at the morula stage and in most cases shed their zonae pellucidae reasonably intact, apparently as blastocyst expansion occurred. Implantation was superficial and observed to occur only in the right uterine horn. During implantation to the endometrium by both blastocyst expansion and closure of the uterine lumen. A decidual reaction was evident at an early stage of uterine epithelial displacement and spread rapidly through the endometrium. Initial trophoblastic proliferation occurred along the uterine lumen and into the glands, while its invasion of the endometrial stroma was delayed. Although one or several primordial cavities have been observed to develop within the epiblast during implantation, these subsequently opened to a trophoepiblastic cavity, and the definitive amnion was formed by folding. A choriovitelline placenta was present briefly at thesomite stage, but disappeared as the exocoelom enlarged and the yolk sac collapsed. The latter persisted through pregnancy, however, as a glandular-appearing body. As the yolk sac retracted from the chorion, it was replaced by allantoic mesoderm, creating a diffuse labyrinthine endotheliodichorial placenta. This was prominent during mid-gestation, but was supplanted by the discoidal hemochorial placenta as the major site of feto-maternal exchange during late pregnancy.     

Can Intrapartum Cardiotocography Predict Uterine Rupture among Women with Prior Caesarean Delivery?: A Population Based Case-Control Study

Objective

To compare cardiotocographic abnormalities recorded during labour in women with prior caesarean delivery (CD) and complete uterine rupture with those recorded in controls with prior CD without uterine rupture.

Study Design

Women with complete uterine rupture during labour between 1997 and 2008 were identified in the Danish Medical Birth Registry (n = 181). Cases were validated by review of medical records and 53 cases with prior CD, trial of labour, available cardiotocogram (CTG) and complete uterine rupture were included and compared with 43 controls with prior CD, trial of labour and available CTG. The CTG tracings were assessed by 19 independent experts divided into groups of three different experts for each tracing. The assessors were blinded to group, outcome and clinical data. They analyzed occurrence of defined abnormalities and classified the traces as normal, suspicious, pathological or pre-terminal according to international guidelines (FIGO).

Results

A pathological CTG during the first stage of labour was present in 77% of cases and in 53% of the controls (OR 2.58 [CI: 0.96–6.94] P = 0.066). Fetal tachycardia was more frequent in cases with uterine rupture (OR 2.50 [CI: 1.0–6.26] P = 0.053). Significantly more cases showed more than 10 severe variable decelerations compared with controls (OR 22 [CI: 1.54–314.2] P = 0.022). Uterine tachysystole was not correlated with the presence of uterine rupture.

Conclusion

A pathological cardiotocogram should lead to particular attention on threatening uterine rupture but cannot be considered a strong predictor as it is common in all women with trial of labour after caesarean delivery.     

The effect of experimentally induced hypocalcaemia on uterine activity at parturition in the ewe

The effect of hypocalcaemia experimentally induced by the intravenous infusion of ethylene-diamine tetraacetic acid, disodium salt (Na(2)EDTA) upon myometrial activity at parturition was studied in eleven ewes. Infusions of Na(2)EDTA were performed during first stage of labour (three animals), second stage (four animals), third stage (three animals) and postpartum (two animals); one in the latter group had been previously treated during second and third stages. Uterine activity was recorded using balloon-tipped catheters surgically implanted into the uterus and was expressed in Montevideo Units (M.U.). Plasma calcium (nonchelated) concentrations were monitored throughout the infusion. Induced hypocalcaemia resulted in a reduction of the activity of the uterus when Na(2)EDTA was administered during the first stage of labour. In the ewes infused during the second stage of labour, there was difficulty in reducing the activity of the uterus and, consequently, in delaying parturition. Reduction in uterine activity was easier in the ewes infused during the third stage of labour and during postpartum. Uterine activity started decreasing when plasma calcium concentrations were 6.6 and 7.1 mg/100 ml in the ewes infused during third stage of labour and postpartum, respectively, compared with 4.9 mg/100 ml in those infused during first stage of labour; the difference between this last group and the first two was significant (p < 0.05). After the end of the infusion, the plasma calcium started rising and normal uterine activity quickly resumed.     

Creatine phosphokinase and aspartate aminotransverase profiles and its relation to the severity of uterine torsion in Egyptian buffalo

Thirty-five female buffalo suffering from uterine torsion were brought to the veterinary clinic and were clinically examined as well as monitored using trans-rectal and trans-abdominal ultrasonography. Three blood samples were taken from each animal (before re-torsion, 1h and 24h after delivery) to investigate the relationship between the serum concentrations of creatine phosphokinase (CPK), aspartate aminotransverase (AST) and the severity of uterine torsion. The incidence of uterine torsion was greater in multiparous than young buffalo. The concentration of CPK and AST showed a significant (P<0.05) increase with increased duration and severity of uterine torsion. However, the concentration of CPK was less in the cases delivering a live foetus than a dead one. Animals with CPK above 450 IU usually had uterine rupture during labour (85.7%) and CPK level above 500 U/l did not respond to treatment. After labour, the AST concentration reached normal in some cases (1-6 and 24-48h). Animals with AST above 100 U/l may be either not respond to the re-torsion procedures or respond but exposed to uterine rupture during vaginal delivery. Occurrence of the uterine torsion is usually accompanied by an elevation (P<0.05) of AST concentration regardless the degree, position and viability of the foetus (76.47-100.25 U/l vs. 59.43 U/l). Animals with severe torsion or carrying a dead foetus had greater (P<0.05) AST compared to those having a mild degree or carrying live foetus. After labour, the concentration of AST decreased (P<0.05) but never reached normal concentrations up to 24h except in animals having a live foetus. In conclusion, concentration of CPK and AST can be used as a prognostic indicator for the occurrence of uterine torsion in Egyptian buffalo.     

Effect of alpha-adrenergic blocking agents on uterine activity in the ewe at the end of gestation

The electromyographic activity (EMG) of the uterus was recorded in vivo in 8 unanaesthetized ewes from the 140th day of gestation up to parturition. The effects on uterine activity of treatments with an alpha 1-receptor blocker (prazosin) and an alpha 2-receptor blocker (yohimbine) were studied. During the last days of gestation, EMG activity consisted of periodic active phases (1-2/h). During the last 16-17 hours, uterine activity increased sharply; this period was referred to a labour. Intravenous perfusion of prazosin (0.03 mg/kg/mn over 1 h) or intravenous injections (1 mg/kg) did not modify uterine activity either before or during labour. Intravenous perfusion of yohimbine (0.03 mg/kg/mn during 1h) inhibited uterine activity before and during labour. In all cases, lambing occurred between the 142nd and 145th day of gestation, which corresponds to the normal lambing period. These results suggest that, in the ewe, uterine alpha 2-receptors are important for normal uterine activity at the end of gestation and in. parturition.     

Paraoxonase 2 Protein Is Spatially Expressed in the Human Placenta and Selectively Reduced in Labour

Humans parturition involves interaction of hormonal, neurological, mechanical stretch and inflammatory pathways and the placenta plays a crucial role. The paraoxonases (PONs 1–3) protect against oxidative damage and lipid peroxidation, modulation of endoplasmic reticulum stress and regulation of apoptosis. Nothing is known about the role of PON2 in the placenta and labour. Since PON2 plays a role in oxidative stress and inflammation, both features of labour, we hypothesised that placental PON2 expression would alter during labour. PON2 was examined in placentas obtained from women who delivered by cesarean section and were not in labour and compared to the equivalent zone of placentas obtained from women who delivered vaginally following an uncomplicated labour. Samples were obtained from 12 sites within each placenta: 4 equally spaced apart pieces were sampled from the inner, middle and outer placental regions. PON2 expression was investigated by Western blotting and real time PCR. Two PON2 forms, one at 62 kDa and one at 43 kDa were found in all samples. No difference in protein expression of either isoform was found between the three sites in either the labour or non-labour group. At the middle site there was a highly significant decrease in PON2 expression in the labour group when compared to the non-labour group for both the 62 kDa form (p = 0.02) and the 43 kDa form (p = 0.006). No spatial differences were found within placentas at the mRNA level in either labour or non-labour. There was, paradoxically, an increase in PON2 mRNA in the labour group at the middle site only. This is the first report to describe changes in PON2 in the placenta in labour. The physiological and pathological significance of these remains to be elucidated but since PON2 is anti-inflammatory further studies are warranted to understand its role.     

Efficacy of Intrauterine Bakri Balloon Tamponade in Cesarean Section for Placenta Previa Patients

Purpose

The aims of this study were to analyze the predictive factors for the use of intrauterine balloon insertion and to evaluate the efficacy and factors affecting failure of uterine tamponade with a Bakri balloon during cesarean section for abnormal placentation.

Methods

We reviewed the medical records of 137 patients who underwent elective cesarean section for placenta previa between July 2009 and March 2014. Cesarean section and Bakri balloon insertion were performed by a single qualified surgeon. The Bakri balloon was applied when blood loss during cesarean delivery exceeded 1,000 mL.

Results

Sixty-four patients (46.7%) required uterine balloon tamponade during cesarean section due to postpartum bleeding from the lower uterine segment, of whom 50 (78.1%) had placenta previa totalis. The overall success rate was 75% (48/64) for placenta previa patients. Previous cesarean section history, anterior placenta, peripartum platelet count, and disseminated intravascular coagulopathy all significantly differed according to balloon success or failure (all p<0.05). The drainage amount over 1 hour was 500 mL (20–1200 mL) in the balloon failure group and 60 mL (5–500 mL) in the balloon success group (p<0.01).

Conclusion

Intrauterine tamponade with a Bakri balloon is an adequate adjunct management for postpartum hemorrhage following cesarean section for placenta previa to preserve the uterus. This method is simple to apply, non-invasive, and inexpensive. However, possible factors related to failure of Bakri balloon tamponade for placenta previa patients such as prior cesarean section history, anterior placentation, thrombocytopenia, presence of DIC at the time of catheter insertion, and catheter drainage volume more than 500 mL within 1 hour of catheter placement should be recognized, and the next-line management should be prepared in advance.     

Renal prostaglandins for induction of labour — A dual clinical advantage in toxemia of pregnancy

Prostaglandin A₁ is known to be an antihypertensive vasodepressor agent produced by the kidney and has the basic potentialities of a hormone. No information is available at present concerning its effect on the human pregnant uterus and whether it can be used as an oxytocic compound to induce labour. The uterine stimulating and labour inducing ability of PGA₁ was evaluated in 10 cases ; seven patients were suffering from pregnancy toxemia while three were normal pregnancies near full term. Cardiotocographic tracings showed that uterine activity was markedly stimulated to a degree sufficient to induce labour. Continuous i.v. infusions at a rate of 0.25–1.0 μg/Kgm/min given over a fixed period of only 6 hours resulted in delivery in all cases except one following the discontinuation of administration. Beneficial effects on blood pressure were observed in toxemic subjects. Potentially serious FHR patterns and occasional hypertonus during therapy were seen and stress the need for more information to evaluate the safety, optimum dosage and duration of infusion as well as the place of this approach in clinical practice for the management of pregnancy toxemia. The absence of antidiuretic effect, the hypotensive response and uterine stimulating property of PGA₁ indicate a possible advantage in toxemia of pregnancy as compared to oxytocin infusions.     

The effect of labour on uterine blood flow in the pregnant ewe.

The effect of labour on cardiac output and uterine blood flow was measured in pregnant ewes at a mean gestation of 124 days using radioactive microspheres labelled with 169Yb and 85Sr. Labour was induced by a continuous infusion of ACTH into the foetal circulation. Cardiac ouput measured before ACTH infusion in seven ewes was 5234 +/- 175-9 ml./min (mean +/- S.E.) and total uterine blood flow was 732 +/- 57-9 ml./min (mean +/- S.E.). Measurements during labour in six ewes showed a significant increase in cardiac output to 6175 +/- 149-6 ml./min (P less than 0-005) but no significant change in uterine blood flow. However, the partition of blood flow was altered; thus myometrial flow increased by 67% from 114 +/- 15-4 ml./min to 190 +/- 13-2 ml./min (P less than 0-005) while placental blood flow decreased, although not significantly, from 618 +/- 55-9 ml./min to 575 +/- 40-7 ml./min. Similar changes were observed in one ewe in spontaneous labour at term and in another ewe receiving an infusion of 4 mg oestradiol 17beta over a 24 hr period. It is concluded that labour is not associated with any major alternation in total uterine blood flow although myometrial blood flow is increased. It is not known whether this is due to the rise in circulating oestrogens which occurs prior to parturition in the ewe, or to other factors such as the work of uterine muscle during labour.     

Cardiac output during labour.

Serial measurements of cardiac output and mean arterial pressure were performed in 15 women during the first stage of labour and at one and 24 hours after delivery. Cardiac output was measured by Doppler and cross sectional echocardiography at the pulmonary valve. Basal cardiac output (between uterine contractions) increased from a prelabour mean of 6.99 l/min to 7.88 l/min at greater than or equal to 8 cm of cervical dilatation as a result of an increase in stroke volume. Over the same period basal mean arterial pressure also increased. During uterine contractions there was a further increase in cardiac output as a result of increases in both stroke volume and heart rate. The increment in cardiac output during contractions became progressively greater as labour advanced. At greater than or equal to 8 cm of dilatation cardiac output increased from a basal mean of 7.88 l/min to 10.57 l/min during contractions. There were also further increases in mean blood pressure during contractions. One hour after delivery heart rate and cardiac output had returned to prelabour values, though mean arterial pressure and stroke volume remained raised. By 24 hours after delivery all haemodynamic variables had returned to prelabour values. Haemodynamic changes of the magnitude found in this series are of considerable clinical relevance in managing mothers with complicated cardiovascular function.     

Effets immédiats du dimenhydrinate sur la contraction utérine e le rythme cardiaque foetal durant le travail.

The effects of intravenous administration of 100 mg of dimenhydrinate (Gravol) were studied in 20 patients during active spontaneous labour. The uterine activity and the fetal heart rate were monitored by an invasive technique. After administration of the medication the uterine activity increases significantly, and in 20% of the cases decelerations in the fetal heart rate of the hypoxic type occurred. Because of its unpredictable effects, this drug should be used with care during labour.     

The use of synthetic prostaglandin analogue (fluprostenol) to induce foaling.

The synthetic prostaglandin (PG) analogue fluprostenol was used to induce parturition in mares and its mode of action was investigated by measuring endocrine changes before and during the induction period. Progestagens and unconjugated oestrogens showed little change during the induction period, but two different patterns in plasma PGFM levels were observed. The first was seen when foaling occurred within 90 min of injection; PGFM levels rose soon after injection and peaked during the maximum expulsive stage of labour, thus resembling events during natural foaling. The second occurred when foaling took longer than 90 min, and in these mares PGFM levels rose at various times after injection and peaked well before the onset of the expulsive stage of labour. It is suggested that these differences reflect the hormonal readiness of the mares to foal. Other procedures, such as rupture of the allantochorion, and dilatation of the cervix and injection of fluprostenol into the allantois, produced no uterine activity and did not stimulate labour or PGFM release.     

Local and systemic control of myometrial contractile activity during labour in the sheep

The relative contribution of systemic versus local (intrauterine) factors in the activation and stimulation of the sheep myometrium during labour was examined using an in-vivo myometrial explant preparation. Myometrial tissue alone (MYO) or with attached endometrium (ENDO/MYO) was removed from the pregnant uterine horn, sutured to a stainless-steel frame and placed into the omental fat. After 7-10 days the explants developed a pattern of electromyographic activity qualitatively similar to that of the uterine myometrium. Induction of preterm labour by infusion of ACTH (66.6 ng/min for 15 min every 2 h) to the fetus resulted in a reduction in plasma progesterone concentrations and increases in values of oestradiol-17 beta and 13,14-dihydro 15-keto PGF-2 alpha in maternal plasma. The onset of labour, which followed these endocrine changes, was characterized by an increase in EMG burst frequency and reduction in burst duration occurring simultaneously in both the uterine myometrium and in the explants. The response of the uterine and explant myometrium to oxytocin also exhibited a parallel significant increase over the 24-h period leading to delivery. No differences were apparent between the explants containing myometrial tissue alone or those comprising endometrial and myometrial tissue. There was no significant change in uterine or explant EMG activity, or oxytocin responsiveness, after saline administration to the fetus. The pattern of EMG activity changes during spontaneous labour were not distinguishable from those during ACTH-induced labour. As with oxytocin, the responsiveness of the explants to electrical stimulation increased significantly at labour compared to pre-labour. These data suggest that factors within the systemic circulation play a major role in both the onset of labour contractions and the increased response to electrical or hormonal (oxytocin) stimulation during parturition in sheep.     

Progesterone Deficiency and Premature Labour

Plasma oestradiol 17β and progesterone levels in 11 patients admitted to hospital for threatened premature labour of unknown aetiology were compared with those of women at similar stages of gestation whose pregnancy was normal. Oestradiol levels in the study group were slightly higher than in the normal controls but their progesterone levels were significantly lower. This progesterone deficiency increased the oestradiol/progesterone ratio in the study group patients, and it increased still more as the progesterone withdrawal continued during premature labour.Since uterine activity during pregnancy is regulated by a balanced action of several factors a deficiency in progesterone, an opponent of uterine activity, creates a regulatory imbalance which, if uncorrected, provokes premature labour. An increase in uterine volume stimulates uterine activity, and the present study reinforced our previous conclusion that the uterine-volume/plasma-progesterone ratio is a more accurate measure of the state of regulatory balance than the progesterone level alone.The cause of the progesterone deficiency in these cases remains unexplained, but we suggest that placental growth and function are contributory factors. We are investigating ways of correcting the resulting imbalance in the regulatory mechanism.     

Delivery after caesarean section: review of 2176 consecutive cases.

A total of 2176 consecutive patients who had had one previous caesarean section were studied retrospectively. A repeat elective caesarean section was performed in 395 (18.2%). Labour started spontaneously in 1363 patients, 301 of whom were given oxytocin to accelerate inert labour, and was induced by amniotomy and infusion of oxytocin in 418 women; 1618 of these 1781 patients (90.8%) delivered vaginally. Patients who had had a previous vaginal delivery were more likely to deliver vaginally again. Those women in whom the initial caesarean section had been performed during labour before the cervix was 4 cm dilated were less likely to deliver vaginally than those who had progressed further in labour or those who had had an elective caesarean section. Similarly, those who received oxytocin to stimulate inert labour were more likely to require a repeat caesarean section than those who did not. The uterine scar ruptured in only eight (0.45%) of the 1781 patients allowed into labour. The risk of rupture of the scar was not increased by the use of oxytocin alone either to induce or to accelerate labour. The combination of oxytocin to accelerate labour and epidural analgesia to provide pain relief, however, was associated with an increased incidence of scar rupture. Labour may be safely allowed in women who have had a previous caesarean section, most of whom will deliver vaginally. Induction of labour does not increase the risk of either a repeat caesarean section or rupture of a uterine scar.     

Hemorrhage of late pregnancy

Rupture of the uterus, cesarean section and uterine atony were the major causes of maternal death associated with hemorrhage of late pregnancy for the five years 1945 to 1949 in New York County. Shock occurred earliest in rupture of the uterus and cesarean section, while in uterine atony there was some delay before shock was evident. Placenta previa was preceded by an initial small hemorrhage, and the time interval before shock was relatively long. It appeared that in cases of retained placenta, manual removal of the organ and hysterectomy were unduly delayed. Ten per cent of the maternal deaths reviewed were associated with severe transfusion reactions. Early recognition of a serious situation, rapid blood replacement and hysterectomy might have salvaged most of the patients.     

Local regulation of the uterine blood flow by the umbilical circulation.

Observations were made of the responses of the uterine blood flow in the near-term pregnancy to occlusion of the umbilical circulation to a few cotyledons of the near-term sheep placenta and in one placenta of the multiparous rabbit pregnancy. It was found that the uterine blood flow declined to 67% of its predicted value 1 day after umbilical ligation in the sheep placenta and to 61% of its predicted value 1 day after the death of one of the fetuses of the rabbit pregnancy. The change in the uterine blood flow in response to the occlusion of the umbilical blood supply to the adjacent area is a local response and is similar in its time course and magnitude to the response of the whole placenta which has been previously observed by Raye et al. (9). This local response of the uterine blood flow is considered to be evidence that the uterine blood flow is in part determined and controlled by the structural or chemical nature of the adjacent fetal compartment.     

The origin of circulating 13,14-dihydro-15-keto-prostaglandin F2α during delivery

All uterine tissues as well as the fetal membranes and the placenta can form prostaglandins from endogenous precursors but it is not clear which of the tissues is the main site for the increase in PGF_2α production during human parturition. To examine this question, we measured plasma prostaglandin levels before and at intervals after expulsion of the fetus, placenta, and membranes. The concentration of PGFM at the beginning of the second stage of labor was significantly higher than before the onset of labor. Five minutes after the birth of the infant, the concentration had doubled. Thirty minutes after the expulsion of placenta and membranes, plasma PGFM had fallen to the levels at full dilatation; two hours postpartum it was still significantly raised over levels before labor. Since the halflife of PGFM in the circulation is about 7 minutes, these findings indicate that the uterine tissues are important sources of PGFM during labor. In contrast, endogenous oxytocin levels, which were significantly raised over control levels at the second stage of labor, did not change during the third stage, and decline postpartum to control levels. Oxytocin infusion did not influence PGFM levels at 5 and at 30 minutes postpartum, but raised them at 2 hours.     

The Link Between Human Menstruation and Placental Delivery: A Novel Evolutionary Interpretation

A new interpretation of human menstruation is presented, resulting from a cross‐disciplinary investigation of evolution, developmental biology, and physiology. A process evolutionarily associated with childbirth expresses itself as menstruation in women for whom frequent and continual failure to conceive has become the default situation. In humans and Old World primates, contractile uterine spiral arterioles evolved as the complement of the highly invasive hemochorionic placenta and is the selected phenotype. Placental progesterone withdrawal during the last stage of birth leads to arrested blood flow through maternal spiral arterioles, allowing detachment of the deciduous placenta with minimal maternal hemorrhage. In nonpregnant females, progesterone withdrawal from a degenerating corpus luteum initiates menstruation and stops blood flow through uterine spiral arterioles. Both events share similar physiological mechanisms and sequences. This explanation may improve our understanding of a recurrent event experienced by half of the human population and for a quarter of their adult reproductive life.     

子宫动脉栓塞术在穿透性凶险性前置胎盘中的临床应用研究

目的:探讨子宫动脉栓塞术在穿透性凶险性前置胎盘中的临床应用效果。方法:选取2010年1月~2014年12月唐山市妇幼保健院收治的孕晩期穿透性凶险性前置胎盘患者36例,依据是否行子宫动脉栓塞术分为子宫动脉栓塞组20例和非子宫动脉栓塞组16例,比较两组患者的术中情况和临床结局。结果:子宫动脉栓塞组患者失血量、红细胞输血量、冷沉淀输血量均少于非子宫动脉栓塞组(P0.05)。两组患者血浆输血量和术后住院时间比较差异无统计学意义(P0.05)。子宫动脉栓塞组ICU入住率、子宫切除率、产后出血、DIC发生率均低于非子宫动脉栓塞组(P0.05)。两组患者的产褥感染率、失血性休克发生率、早产儿发生率以及新生儿轻度窒息率比较差异均无统计学意义(P0.05)。结论:子宫动脉栓塞术可以减少术中出血及术后并发症的发生率,改善穿透性凶险性前置胎盘的临床结局。