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PubMed1977

Second trimester placenta previa. An apparently normal placentation.

Placental positions in 214 patients scheduled for genetic amniocentesis were reviewed. Forty-five percent were found to have ultrasound findings of a low-lying placenta or partial or total placenta previa. At term, none of these patients required intervention for bleeding or placenta previa. Parity of 4 or more, but not age, correlated with an increased incidence of partial or total placenta previa, but not with a low-lying placenta. Low-lying placenta or placenta previa may be a normal variant in early pregnancy, suggesting that failure of the placenta to relinquish this position can result in an abnormally implanted placenta at term.

Adult↗

PubMed1982

[Prostaglandin Production by the human placenta using a superfusion technique (author's transl)].

In order to clarify the onset mechanism of labor, we studied the prostaglandin production in human placenta tissues of different stage using a superfusion technique. 1) The placenta obtained at Cesarean section before the onset of labor (A): (1) In the control, the production of prostaglandins was not distinctly changed. (2) Administration of arachidonic acid increased gradually the production of PGs. PGs production showed the maximum values at 50-60 minutes fraction of the superfusion. Throughout the experiment, PG production became vigorously active. (3) Administration of oxytocin increased the production of PGs, too, in particular PGE2 and PGF2 alpha. 2) The placenta obtained at Cesarean section during delivery (B): (1) In the control, the production of PGs was not distinctly changed. (2) Administration of arachidonic acid increased the production of PGE2 and PGF2 alpha, but the production of PGs was lower as compared with (A). PGE1 did not change. (3) Oxytocin had no effect on the production of PGE1 and PGE2, but the production of PGF2 alpha showed the maximum values at 50-60 minutes fraction. 3) The delivered placenta (C): (1) In the control, the production of PGs was not distinctly changed. (2) Administration of arachidonic acid increased the production of PGs. (3) Oxytocin had no effect on the production of PGs. On the basis of these data, it may be appropriate to conclude as follows: The enzyme which has a high ability to produce PGs exists in the placenta before the onset of labor. But the enzyme keeps the resting condition by the some inhibiting factor of PG production. During delivery, the PG production by the placenta fell. This result means that the strong ability of the production of PGs by the placenta at this stage is not necessary. After the delivery, the production of PGs by the delivered placenta is unnecessary. It is substantiated Kato's theory which PGE is primarily involved in the onset of labor that the production ability of PGE was recognized only in the placenta of before the onset of labor. It is interesting that administration of oxytocin increased the production of PGF2 alpha and they are similar for the contraction-substance of uterus.

Alprostadil↗

PubMed1993

[Pathological Doppler uterine readings when the placenta is laterally situated].

We carried out a retrospective study on 96 patients whose uterine waveforms were abnormal, in order to determine if a laterally located placenta further increased this risk. Our population was separated into 2 groups (75 women with a laterally located placenta, 21 with a centrally located placenta). We have found a significant difference between ipsi placental uterine blood flow velocity and contralateral placental blood flow velocity when the placenta is located laterally, where as the 2 arteries are similar when the placenta has a central location. The following factors were used to compare the two groups: the patient's previous obstetric record and the incidence of hypertensive disorders and fetal distress. In the group with laterally located placentas, the incidence of complications in previous pregnancies was higher, hypertension was more frequently serious or presented complications, fetal distress and cesarean sections were more frequent as was IUGR. All cases of intrauterine death were found in the group with laterally located placentas. In determining the predictive value of the "laterally located placenta" test, we found in the centrally located placenta group that hypertensive disorders were often less serious and less frequently complicated by albuminuria, that the outcome of pregnancy disorders was less serious for the fetus, and that the neonate was less hypotrophic. No incidence of intrauterine death was recorded for the centrally located group. Placental laterality significantly increases both the frequency and the seriousness of fetomaternal hypertensive disorders.

Adult↗

PubMedDate not supplied

Regulation of creatine kinase isoenzymes in human placenta during early, mid-, and late gestation.

OBJECTIVE: Creatine kinase (CK) isoenzymes play an important role in cellular energy transduction. Two isoenzymes of creatine kinase, ubiquitous mitochondrial creatine kinase (uMtCK) and cytosolic brain creatine kinase (BCK), are postulated to form the creatine phosphate (CP) shuttle, in which creatine serves to transport high-energy phosphate from the mitochondria to its site of utilization. Coordinate regulation of these genes is essential for efficient energy transduction. We examined human CK isoenzyme regulation in placentas during all three trimesters of gestation to define the mRNA and protein expression patterns of uMtCK and BCK and to test the CP shuttle hypothesis. METHODS: Placental samples were collected from a total of 26 patients from the first, second, and third trimesters. Total RNA and protein were prepared from each sample and quantified. Quantitative RNA analysis was performed by gel electrophoresis and dot blot techniques using isoenzyme-specific human cDNA probes for uMtCK and BCK. Protein expression of uMtCK and BCK was examined by Western blot analysis using isoenzyme-specific antibodies to uMtCK and BCK. RESULTS: Analysis of RNA demonstrated the coordinate expression of uMtCK and BCK mRNAs in human placenta, with peak expression of both in the term placentas. Western blot analysis demonstrated coordinate expression of uMtCK and BCK proteins in the first and second trimesters, but not in the term placenta. Expression levels of uMtCK and BCK proteins were not consistent with their respective mRNA levels in the term placenta. CONCLUSION: Expression of uMtCK and BCK in human placenta is highly regulated, and post-transcriptional regulation of uMtCK and BCK expression occurs in the term placenta. The coordinate regulation of uMtCK and BCK in human placenta supports the CP shuttle hypothesis. This analysis demonstrates that human placenta has high energy needs that can change rapidly; thus, a functioning CP shuttle may be important in the maintenance and termination of pregnancy.

Blotting, Northern↗

PubMed1978

Placenta accreta. A clinicopathologic review of 67 cases.

During a 20-year period 67 uteri removed from placenta accreta, among a population of 645,000 live births and stillbirths in Northern Ireland, were examined. Of the 37 involving the cavity, only 31 were placenta accreta vera; 14 of these were total and 17 partial. Three others showed invasion into the wall (placenta increta), and three penetration through the wall (placenta percreta). When any part of the placental adhesion involved the previa site the case was taken to be a placenta previa accreta; here adhesion was extensive in 10 and limited in 7. A further 11 were examples of placenta previa increta, and 2 more of placenta previa percreta. There were only two maternal deaths. These variants are described and illustrated, and the association with high parity and, especially in the previa cases, with previous cesarean section is emphasized. The histologic deficiency of maternal decidua at the implantation site and the recognition and behavior of cells of the nonvillous trophoblast are briefly described. Hysterectomy, which in placenta previa variants must be adequate to excise the area of cervical involvement, appears to be the rational treatment.

Adult↗

PubMed1989

Clearance of calcium across in situ perfused placentas of intrauterine growth-retarded rat fetuses.

Maternofetal clearance of 45Ca and 51Cr-EDTA (diffusional marker) were simultaneously measured across in situ perfused placentas of intrauterine growth-retarded (IUGR) and control rat fetuses on d 20 of gestation. IUGR was induced by uterine artery and vein ligation on d 17 of gestation. Control fetuses and their placentas were taken from sham-operated dams. We hypothesized that calcium transfer would be impaired across placentas of IUGR fetuses. The mean body wt of IUGR fetuses was 42% lower, and the mean nose-anus length was 16% lower than those of control fetuses. The mean total calcium content of IUGR fetuses was significantly lower than that of control fetuses, but not when it was normalized to body wt. The mean maternal whole blood ionized calcium concentration was not significantly different in the two groups. The materno-fetal clearance of 45Ca across IUGR placentas was significantly lower than that across control placentas (IUGR = 35.2 +/- 1.9 micro L/min/g placenta, mean +/- SEM; control = 93.1 +/- 12 microliters/min/g placenta, p less than 0.002). In contrast, the maternofetal clearance of 51Cr-EDTA, the reference diffusional marker, was not significantly different across IUGR and control placentas. We conclude that maternofetal transfer of calcium is reduced across placentas of IUGR rat fetuses.

Animals↗

PubMed2006

Analysis of placental growth factor in placentas of normal pregnant women and women with hypertensive disorders of pregnancy.

To investigate the expressions of placental growth factor (PLGF) in placenta with hypertensive disorders of pregnancy (HDP), 45 women with HDP and 20 normally pregnant women were studied. Among 45 women with HDP, there were 23 cases of severe preeclampsia and one case of eclampsia. The location and level of PLGF proteins was determined by immunohistochemistry and Western blot. The expression of PLGF mRNA in placenta was assessed by reverse transcriptional-polymerase chain reaction (RT-PCR). The results showed that: (1) The distribution of PLGF in placenta with HDP was similar to normal one, which was mainly in the cytoplasm of villous syncytiotrophoblast and villous stroma; (2) The expression of PLGF protein was significantly decreased in placentas with mild and severe preeclampsia compared to the normal ones (0.3 +/- 0.4 vs 0.6 +/- 0.4, 0.2 +/- 0.5 vs 0.6 +/- 0.4, P < 0.01). There were no differences between the gestational hypertension placenta and normal one (0.5 +/- 0.6 vs 0.6 +/- 0.4, P > 0.05); (3) The transcription levels of the PLGF mRNA in placentas with preeclampsia were significantly lower than in normal groups (3.33 +/- 0.39 vs 4.87 +/- 0.60, 1.97 +/- 0.29 vs 4.87 +/- 0.60, P < 0.01), and no differences were found between the gestational hypertension placenta and normal groups. These findings suggest that the abnormal expression of PLGF in placentas is related to the pathogenesis of HDP.

Adult↗

PubMed1995

Placenta accreta encountered during dilation and evacuation in the second trimester.

OBJECTIVE: To assess the frequency of placenta accreta encountered during dilation and evacuation (D&E) in the second trimester. METHODS: Among 16,827 second-trimester D&E procedures performed at our hospitals and clinics, seven cases of placenta accreta, either suspected clinically or proven histologically, were encountered. These cases were analyzed for history of prior cesarean delivery, placenta localization, and histology of hysterectomy specimens. RESULTS: Six of the seven cases suspected clinically were confirmed histologically. All placenta accreta patients had at least one cesarean delivery (mean 1.7), and five had a preoperative sonogram demonstrating some form of placenta previa. The prevalence of clinical placenta accreta encountered during D&Es in the second trimester was 0.04%, the same as that reported for placenta accreta diagnosed clinically in the third trimester. CONCLUSION: Placenta accreta can be a potential complicating factor in the patient undergoing D&E in the second trimester.

Abortion, Induced↗

PubMed2002

Increased expression of vascular endothelial growth factor in placentas of p57(Kip2) null embryos.

Placentas of mice lacking p57(Kip2) expression have trophoblastic hyperplasia. To elucidate the mechanism underlying this phenomenon, we studied expression of two angiogenic factors, vascular endothelial growth factor (VEGF) and placenta growth factor (PlGF). Immunohistochemical analysis with anti-VEGF antibodies indicated that VEGF expression was stronger and more clearly detectable in placentas of p57(Kip2) null embryos compared to wild-type placentas. PlGF showed no significant differences between placentas of p57(Kip2) null and wild-type embryos. In quantitative analysis, placentas of p57(Kip2) null embryos showed higher VEGF messenger (m)RNA and protein levels than did wild-type placentas. PlGF mRNA and protein levels were not significantly different. These findings suggest that VEGF is involved in the hyperplasia that occurs in placentas of p57(Kip2) null embryos.

Animals↗

PubMed2002

Reduced phagocytotic activity of macrophages in the bovine retained placenta.

This study was carried out to investigate the distribution of immune cells in the bovine placenta during the postpartum period and to compare these cells between normal and retained placenta. Within 1 h after normal calving, biopsy samples of placentomes were collected from 10 cows. The occurrence of retention of fetal membranes was monitored for more than 8 h post-calving, and the samples obtained were divided into two groups: normally discharged and retained placenta (n = 5 each). Immunohistochemical procedures were utilized to detect macrophages and T lymphocytes. Numerous CD14-positive macrophages were found in the stroma of both normal placenta and retained placenta whereas only a few CD3-positive T lymphocytes were found in both cases. However, histochemical staining for acid phosphatase, a predominant lysozomal enzyme, revealed that almost all macrophages showed strong enzyme activity in the normally discharged placentas, whereas in retained placenta the activity of acid phosphatase was conspicuously decreased in intensity. These results indicate that there are functional differences in placental macrophages between normal and retained placenta.

Acid Phosphatase↗

PubMed2001

The relevance of placental location at 20-23 gestational weeks for prediction of placenta previa at delivery: evaluation of 8650 cases.

OBJECTIVE: To determine the correlation between placental position at 20-23 weeks and incidence of birth complications caused by placental position. SUBJECTS AND METHODS: In an ongoing prospective study, placental position was determined by transabdominal sonography as part of anomaly scanning at 20-23 gestational weeks, followed by transvaginal sonography in uncertain or suspicious situations. Examination was performed in 9532 cases; feedback was obtained from 8650 patients (90.7%). RESULTS: Transabdominal sonography was followed by transvaginal scan in 363 of 8650 cases (4.2%). In 8551 cases (98.9%), we found normal placental position, with the placenta not reaching the internal os and a Cesarean section rate of 17.1% (1458/8551). The incidence of 'low placental position', with the placenta reaching the internal os was 0.66% (57/8650), with a Cesarean section rate of 21% (12/57). In 0.49% (42/8650) of cases, the placenta overlapped the internal os at 20-23 weeks; Cesarean section because of placenta previa or bleeding was performed in 28 of 8650 cases (0.32%). Vaginal delivery was possible in 43% of cases (13/30), when the overlap did not exceed 25 mm. If the overlap exceeded 25 mm (12 cases), no vaginal delivery was reported. There was no reported case of placenta previa missed at the 20-23-week scan. CONCLUSION: At 20-23 weeks, a combination of routine transabdominal and indication-based transvaginal location of placental position is a powerful tool in predicting placenta previa at delivery. The advantage of determining placental position at this stage of pregnancy is a low false-positive rate compared to at earlier stages of pregnancy. We conclude that an overlapping placenta at 20-23 weeks has the consequence of a high probability of placenta previa at delivery. An overlap of 25 mm or more at 20-23 weeks seems to be incompatible with later vaginal delivery.

Adult↗

PubMed2001

Antioxidative defence mechanisms against reactive oxygen species in bovine retained and not-retained placenta: activity of glutathione peroxidase, glutathione transferase, catalase and superoxide dismutase.

Glutathione peroxidase (GSH-Px), glutathione transferase (GSH-Tr), catalase (CAT) and superoxide dismutase (SOD)-the members of enzymatic antioxidative defence mechanisms against reactive oxygen species-may play an important role in proper or improper release of bovine fetal membranes. The aim of the following study was the determination of GSH-Px, GSH-Tr, CAT and SOD activity in order to define antioxidative status of bovine placenta during retention of fetal membranes (RFM) in cows. Placental samples were collected immediately after spontaneous parturition or during caesarean section before term and at term and divided into six groups as follows: A: caesarean section before term without RFM; B: caesarean section before term with RFM; C: caesarean section at term without RFM; D: caesarean section at term with RFM; E: spontaneous delivery at term without RFM; F: spontaneous delivery at term with RFM. The enzyme activities in placental homogenates were measured spectrophotometrically. GSH-Px activity was statistically significantly higher in fetal than in maternal placenta in all examined groups, increased towards parturition and was higher in caesarean section groups than spontaneous delivery groups. Statistically significantly higher activities were noticed in retained than not-retained placentae. GSH-Tr activity was significantly lower in fetal than in maternal placenta. In preterm groups, the activity was statistically significantly higher in retained than not retained placenta. In term groups, the opposite relationship was observed, higher values in caesarean section groups than spontaneous delivery were noticed. CAT activity was statistically significantly higher in fetal than in maternal part of placenta in all groups examined. The highest values in C and D groups and the differences between retained and not-retained placenta were observed. SOD exhibited the highest values in preterm placenta and alterations between retained and not-retained fetal membranes. In conclusion, the activities of GSH-Px, GSH-Tr, CAT and SOD are altered in cases of retained fetal membranes which may suggest the activation of antioxidative mechanisms caused by the imbalance between production and neutralization of reactive oxygen species.

Animals↗

PubMed1995

Chorangiosis and chorangioma in three cohorts of placentas from Nepal, Tibet, and Japan.

It has been reported that both chorangiosis and chorangioma are increased in placentas at high altitudes. In this study, 1.14% of 2448 Japanese placentas obtained at 30-300 m had chorangiosis or chorangioma, compared with 3.24% of the Nepalese placentas (1300-3000 m) and 9.09% of the Tibetan samples (3800-4200 m). The incidence of both pathologies was significantly higher in the Himalayan groups than those of the Japanese group (P < 0.05). Obstetric complications of the 28 Japanese placentas with chorangiosis and chorangioma included Caesarean section 16 (57.1%), abruptio placentae 2 (7.14%), intrauterine growth retardation 3 (10.7%), intrauterine fetal death 4 (14.2%) and placenta praevia 4 (14.2%). Four infants (14.2%) had Apgar scores ranging from 0 to 3. Among 48 Himalayan placentas with chorangiosis and chorangioma, incidence of marked subchorionic fibrin was significantly higher (25%) than in the Japanese group (3.57%) (P < 0.05). The incidence of abnormal insertion of the cord was significantly higher (14.2%) in the Japanese group than in the Himalayan group (5%) (P < 0.05). There was no significant difference in the frequencies of intervillous thrombosis and infarction between the two groups. These findings suggest that the incidence of pathological change such as chorangiosis and chorangioma may be increased in placentas at Himalayan altitudes.

Altitude↗

PubMed1996

Placenta accreta: mild cases diagnosed by placental examination.

We describe 36 placentas in which microscopic foci of myometrial tissue were adherent to the basal plate with deficient intervening decidua, consistent with a mild or focal form of placenta accreta. In only four cases was a diagnosis of placenta accreta considered clinically, and none of the cases resulted in hysterectomy. Twenty-one of the mothers underwent cesarean section for the current pregnancy, with 10 of the mothers having a history of previous cesarean section. The placenta failed to separate spontaneously in eight of the 15 vaginal deliveries necessitating manual removal of the placenta. Additional maternal factors included multiparity in 33, placenta previa in two, leiomyomas in two, and previous spontaneous abortion or voluntary interruption of pregnancy in 23. Four cases were complicated by retained placental fragments and three by postpartum hemorrhage. We conclude that these milder cases of placenta accreta are frequently associated with previous uterine operations and multiparity, and although not uncommon, are frequently not clinically suspected. Placental examination is useful in making the diagnosis of placenta accreta in cases not requiring hysterectomy, particularly if the basal plate is well sampled.

Adolescent↗

PubMed2000

Changes in the serum levels of human chorionic gonadotropin and the pulsatility index of uterine arteries during conservative management of retained adherent placenta.

OBJECTIVE: Our purpose was to assess the natural course of retained adherent placenta at term. METHODS: Five cases of retained adherent placenta, clinically diagnosed as placenta accreta, were managed conservatively without methotrexate. To assess the biochemical and circulatory changes in the placentas, the serum levels of human chorionic gonadotropin (hCG) and the pulsatility index (PI) of the uterine arteries were examined. RESULTS: Serum hCG levels decreased spontaneously; the half-life of serum hCG was calculated to be 5.2 +/- 0.26 days (mean +/- SEM). The PI of the uterine arteries remained at the level of pregnant women at term, but became elevated within a few days after the removal of the placentas. All the placentas were successfully removed transvaginally within 6 weeks postpartum. CONCLUSIONS: The changes in serum hCG observed in this study indicated the spontaneous degeneration of the placenta. Such changes might be similar to those reported to occur during treatment with methotrexate. In contrast, the PI of the uterine arteries did not reflect degeneration of the placenta.

Adult↗

PubMed2004

Is placenta accreta catching up with us?

BACKGROUND: Concomitant with the increase in Caesarean birth over the past three decades there has been an apparent rise in the incidence of placenta accreta and its variants. The sequelae of an increase in the occurrence of abnormal placentation is the enhanced potential for severe maternal morbidity. AIM: To determine the contempory demographics of placenta accreta over a 5-year period in a tertiary level teaching hospital. METHODS: A retrospective review of all cases of placenta accreta and variants during the period of 1998-2002. Individual charts review followed case ascertainment via the hospital obstetric database. RESULTS: Thirty-two women with placenta accreta (or variant) were identified. Median maternal age was 34 years, with a median parity of 2.5. Seventy-eight percent of cases had had at least one prior Caesarean birth, and 88% of cases were associated with placenta praevia. Pre-delivery ultrasonography was performed in all cases, providing diagnostic sensitivity of 63% and specificity of 43% with a predictive value of 76%. Hysterectomy was performed in 91% of cases with median intraoperative blood loss of 3000 mL. There were no maternal deaths in the current series. CONCLUSION: A strong association between placenta accreta, placenta praevia and prior Caesarean birth has been demonstrated. As there is the potential for significant maternal morbidity the risk of placenta accreta needs to be recognised and women at risk should be considered for delivery at an institution with appropriate expertise and resources in managing this condition.

Adult↗

PubMed2003

[Placenta previa--from the past to the present].

The author present contemporary methods for diagnosis of placenta praevia. He compare old methods as X-ray placentography, radioisotope placentography with using ultrasound to determine the location of placenta. Placenta praevia can be diagnosed prenatally using ultrasound through transabdominal, afterwards with transvaginal ultrasound. This decrease prolonged hospitalization and needless Cesarian section. The author made parallel between frequency in beginning of pregnancy with frequency at term. With advance of gestational age the frequency of placenta praevia decrease. This decreasing incidence with increasing gestational age is attributable to the concept of placental migration. When the placental edge was inicially > 2 cm from cervical os, migration occurred in all cases and no Cesarean sections were necessary for placenta praevia. When the placenta overlapped the cervical os by > 20 mm at 26 weeks, all the women required Cesarian delivery. The author present basic strategies to reduce maternal and fetal mortality and morbidity from placenta praevia. All pregnant women should have a routine sonogram at 20 weeks gestation. When the area over the internal os cannot be identified, a transvaginal sonogram should be performed. Women who have a lower placental edge which is < 1 cm from internal os should have a sonogram at about 34-35 weeks gestation. When placenta praevia is present should be perform prior Cesarian delivery.

Cesarean Section↗

PubMed2004

[Placenta accreta: epidemiology, molecular mechanism (hypothesis) and some clinical remarks].

OBJECTIVE: To develop the hypothesis on biochemical mechanism of the placenta accreta and to review the epidemiological information on that complication. STUDY DESIGN: Data collected in 1995-2002 in the Medline System were the main source of analyzed literature. RESULTS: Placenta accreta occurs in approximately 1 of 2500 deliveries, however among women with placenta praevia, the incidence is nearly 10%. Independent risk factors for placenta accreta are previous cesarean delivery and maternal age > or =35 years. Postpartum hemorrhage is the main cause of maternal mortality. Hysterectomy is often performed to save the life of the mother. Ligation of internal pelvic arteries is considered to be ineffective procedure in about 50%. An another option in management of hemorrhage is embolisation of pelvic arteries. Recombinant factor VIIa is recommended is a new agent in pharmacological therapy. Our hypothesis is as follows: The complex of uPA/uPAR (urokinase plasminogen activator/receptor of urokinase plasminogen activator complex) plays crucial role in the generation of plasmin-dependent proteolysis, which takes place in the surface of trophoblast. Penetration of the villi into the tissues is controlled by plasminogen activator inhibitors--plasminogen activator inhibitor 1 (PAI-1) and plasminogen activator inhibitor 2 (PAI-2), mainly by PAI-2. PAI-2 inactivates uPA/uPAR complexes forming triplicate complexes. If the PAI-2 concentration in placenta and myometrium is low, the invasion of placenta villi is excessive. CONCLUSION: Disturbance of balance between plasminogen activator and their inhibitors (PAI-1 and PAI-2) in placenta and myometrium can lead to the formation of placenta accreta.

Adult↗