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Placenta previa and placental abruption
Published in Hung N. Winn, Frank A. Chervenak, Roberto Romero, Clinical Maternal-Fetal Medicine Online, 2021
Placenta previa is defined as abnormal placental implantation over the cervical os. There are several variants of this definition. A low-lying placenta occurs when the placenta implants in the lower uterine segment; the placental edge lies near, but not over the cervical os. A low-lying placenta is not considered a category of placenta previa, but it is a form of irregular placentation, which may cause vaginal bleeding when the lower uterine segment develops during labor. When the edge of the placenta lies exactly at the internal cervical os, a marginal placenta previa is present. A complete placenta previa occurs when the internal cervical os is completely covered by the placenta. Clinicians refer to a “central previa” when the center of the placenta is covering the internal os of the cervix (Figs. 1 and 2). The term “partial placenta previa” in which part of the placenta covers the internal os of the cervix is not clinically useful, given the above definitions.
Bioengineering Aids to Reproductive Medicine
Published in Sujoy K. Guba, Bioengineering in Reproductive Medicine, 2020
Placenta is also clearly delineated in MRI. Powell et al.37 examined by MRI cases diagnosed by ultrasound as having placenta previa. They scanned with a 0.15 T field by T2 weighted spin echo as well as by T1 weighted inversion recovery. Spin echo pulse sequence with long TR and TE were found to yield good signal from both placental tissue and the internal os. Placental tissue has a moderately short T2 relaxation time giving a high intensity signal while amniotic fluid gives low level signal and the myometrium somewhere in between. So relative positions of the placenta and the internal os become clear and a number of positive diagnosis by ultrasound were found to be in error. Grades of placenta previa can be determined too. This investigation suggests that MRI has a role in diagnosis of placenta previa other than for total placenta previa for which ultrasound is adequate.
Perinatal Social Work and the High Risk Obstetrics Patient
Published in Regina Furlong Lind, Debra Honig Bachman, Fundamentals of Perinatal Social Work, 2012
Debra Honig Bachman, Regina Furlong Lind
Though one clear cause has not been identified, the following may be associated with placenta previa: multigravida pregnancy, previous Cesarean sections, advanced maternal age, poor uterine circulation, uterine scarring, fibroids, multiple gestation pregnancy, tobacco or cocaine use during pregnancy and living at high altitudes (Berger et al., 1990; Giacoia, 1990; Harrison, 1983; Naeye & Tafari, 1983; Pilliteri, 1992).
Determinants of low birth weight among newborns delivered in China: a prospective nested case-control study in a mother and infant cohort
Published in Journal of Obstetrics and Gynaecology, 2023
Zhuomin Huang, Quanfu Zhang, Litong Zhu, Haishan Xiang, Depeng Zhao, Jilong Yao
In the present study, the frequency of LBW was significantly increased in mothers with a diagnosis of placenta previa, consistent with some previous findings (Moeini et al.2021) in which placenta previa with abnormal placentation occurs more frequency in LBW than in controls. Antepartum haemorrhage is attributed to placenta previa (Crane et al.2000) and leads to maternal anaemia, which has been linked with an increased risk of delivering LBW babies (Figueiredo et al.2019) due to reduced oxygen-carrying capacity (Savaliya et al.2021). Furthermore, placenta previa is an independent risk factor for the placenta accreta spectrum (Liu et al.2021b). The abnormal attachment of the placenta causes dysfunction of maternal vascular remodelling and may result in LBW. Placenta previa is therefore also an important independent risk factor for preterm infant birth (Huang et al.2021). The routine strategy for high-risk pregnancies such as women with placenta previa and other maternal comorbidities is iatrogenic preterm birth, however preterm delivery such as emergency caesarean delivery is linked with LBW. Consistent with this, the present results suggest an overall higher rate of LBW for women with placenta previa.
Prospective comparative analysis for application and selection of FIESTA sequence and SSFSE sequence in MRI for prenatal diagnosis of placenta previa accreta
Published in Journal of Obstetrics and Gynaecology, 2022
Gan Tian, Zhaofa Liu, Dawei Zhang, Pin Wang
Placenta previa is the most common cause of vaginal bleeding in the third trimester of pregnancy (Zhang et al. 2017; Advani et al. 2020; Peng et al. 2020). The risk of placental adhesion, implantation or penetration is significantly increased, and the case fatality rate can reach 10% in placenta previa, therefore, which belongs to critical and severe obstetrics (Chen et al. 2019). Clinically, the ultrasound is the main screening method for placenta previa with implantation (Happe et al. 2020). However, magnetic resonance imaging (MRI) is superior to ultrasound in the diagnosis of placental abnormalities in pregnant women, such as placental location in the posterior wall, maternal obesity, foetal oversize and oligohydramnios (Eshkoli et al. 2013; Song et al. 2018). The MRI large field imaging can find various uterine diseases (Barral et al. 2017; Ker et al. 2018).
Risk of preterm delivery in singletons conceived by in vitro fertilization
Published in Gynecological Endocrinology, 2019
Puyu Yang, Huixian Kang, Caihong Ma, Yuan Wei, Liyuan Tao, Zhangxin Wu
According to the International Association of Diabetes and Pregnancy Study Groups criteria, all patients underwent a 2-h 75 g oral glucose tolerance test between 24 and 28 weeks of gestation. Gestational diabetes mellitus (GDM) was diagnosed if one or more of the three plasma glucose concentrations equaled or exceeded the following values: fasting glucose 5.1 mmol/L, 1-h level 10.0 mmol/L, and 2-h level 8.5 mmol/L [14]. The diagnosis of pregnancy-induced hypertension syndrome (PIH) was made if systolic blood pressure >140 mmHg and/or diastolic blood pressure >90 mmHg persisted for two measurements, with or without proteinuria of >300 mg in a 24-h urine collection at a gestational age of >20 weeks [15]. Premature rupture of membranes (PROM) refers to rupture of the fetal membranes prior to the onset of labor and can occur at any gestational age-even at 42 weeks’ gestation [16]. Preterm birth was delivery before 37 completed weeks of gestation. Placenta previa was a complete coverage of the internal cervical. Confirmation of the diagnosis of placenta previa was based on transvaginal ultrasonography with empty bladder performed within 1 week before delivery.