Plasenta previa
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Understanding Placenta Previa: Risk Factors, Diagnosis, and Management
Introduction to Placenta Previa
Placenta previa is a condition where the placenta partially or completely covers the internal cervical os, leading to significant bleeding during the third trimester of pregnancy. This condition is a major cause of maternal and perinatal morbidity and mortality4. The prevalence of placenta previa varies, with studies reporting rates between 0.28% and 2.0%, or approximately 1 in 200 deliveries1.
Risk Factors for Placenta Previa
Previous Cesarean Deliveries and Abortions
A history of cesarean delivery significantly increases the risk of developing placenta previa in subsequent pregnancies. Women with at least one prior cesarean delivery are 2.6 times more likely to develop placenta previa, with the risk increasing with the number of cesarean deliveries1. For instance, the relative risk is 4.5 for one prior cesarean, 7.4 for two, and 44.9 for four or more1. Similarly, a history of spontaneous or induced abortion also elevates the risk, with relative risks of 1.6 and 1.7, respectively1 9.
Maternal Age, Multiparity, and Substance Use
Advancing maternal age, multiparity, and substance use such as smoking and cocaine during pregnancy are additional risk factors for placenta previa7. These factors contribute to the overall prevalence rate of 4.0 per 1000 births, with variations based on study design and population7.
Male Fetus
Interestingly, there is a higher incidence of placenta previa in pregnancies with male fetuses. Studies have shown a 14% excess of placenta previa when the fetus is male compared to female8.
Diagnosis and Management
Ultrasound Imaging
Ultrasound imaging is a critical tool for the prenatal diagnosis of placenta previa and placenta accreta spectrum (PAS). It is highly sensitive and specific when performed by skilled operators, with a diagnostic accuracy of 90.9% for placenta previa accreta3. The development of standardized prenatal screening protocols is essential to improve outcomes3.
Histopathological Changes
Histopathological studies reveal significant degenerative changes in placentas affected by placenta previa and accreta. These include dysfunctional endothelial cells, congestion, edema, and dense erythrocyte accumulation in the intervillous areas4. Such findings underscore the severe impact of these conditions on placental health.
Prophylactic Interventions
Prophylactic internal iliac artery balloon occlusion has been shown to reduce intraoperative blood loss, decrease the need for hysterectomy, and improve gestational outcomes in patients with placenta previa or PAS6. This intervention can be a valuable tool in managing these high-risk pregnancies.
Clinical Guidelines
The Society of Obstetricians and Gynaecologists of Canada (SOGC) provides guidelines for the diagnosis and management of placenta previa. These guidelines emphasize the importance of accurate diagnosis, appropriate management strategies, and the potential benefits of both inpatient and outpatient care depending on the severity of the condition5.
Conclusion
Placenta previa is a serious obstetric condition with significant implications for maternal and fetal health. Understanding the risk factors, such as previous cesarean deliveries and abortions, and utilizing effective diagnostic tools like ultrasound imaging are crucial for managing this condition. Prophylactic interventions and adherence to clinical guidelines can further improve outcomes for affected women. Continued research and standardized protocols are essential to address the complexities of placenta previa and enhance maternal-fetal care.
Sources and full results
Most relevant research papers on this topic
The association of placenta previa with history of cesarean delivery and abortion: a metaanalysis.
Placenta previa is 2.6 times more likely in women with a history of at least one prior cesarean delivery compared to those with no prior cesarean deliveries.
Meta-Analysis
Highly CitedEpidemiology of placenta previa accreta: a systematic review and meta-analysis
Standardized protocols for diagnosing placenta previa and placenta accreta spectrum are needed to improve consistency in data and reduce the risk of misdiagnosis.
Meta-Analysis
Rigorous JournalHighly CitedPrenatal ultrasound diagnosis and outcome of placenta previa accreta after cesarean delivery: a systematic review and meta‐analysis
Prenatal ultrasound is accurate in diagnosing placenta previa accreta, with its depth impacting individual management in women with a history of previous cesarean deliveries.
Meta-AnalysisRigorous JournalHighly CitedHistopatological Changes in Plasenta Previa, Plasenta Acreata and Normotensive Plasentas in the 3rd Trimestry of Pregnancy
Placenta previa and placenta acreata cause serious degenerations on placentas during the third trimester of pregnancy.
Guideline No. 402: Diagnosis and Management of Placenta Previa.
Optimizing diagnosis and management protocols for placenta previa can potentially improve maternal, fetal, and postnatal outcomes.
Systematic ReviewThe effect prophylactic internal iliac artery balloon occlusion in patients with placenta previa or placental accreta spectrum: a systematic review and meta‐analysis
Prophylactic internal iliac artery balloon occlusion in patients with placenta previa or placenta accreta spectrum reduces intraoperative blood loss, hysterectomy, and increases gestation.
Meta-Analysis
Very Rigorous JournalEtiology and risk factors for placenta previa: an overview and meta-analysis of observational studies
Placenta previa is associated with increased risk factors such as maternal age, multiparity, previous Cesarean delivery and abortion, smoking and cocaine use during pregnancy, and male fetuses.
Meta-AnalysisHighly CitedPlacenta previa: preponderance of male sex at birth.
Placenta previa is strongly associated with a higher male-to-female ratio at birth, but the mechanism for this association remains unclear.
Meta-AnalysisHubungan antara Riwayat Abortus Komplet dan Inkomplet dengan Kejadian Plasenta Previa di Rumah Sakit Umum Daerah Al-Ihsan Provinsi Jawa Barat Periode 2017-2018
Placenta previa is significantly associated with a history of complete or incomplete abortion, with damage to the endometrium during previous labor, and both complete and incomplete abortions being possible mechanisms.
Abnormal Placentation: Placenta Previa, Vasa Previa, and Placenta Accreta.
Placental disorders like placenta previa, placenta accreta, and vasa previa can cause serious fetal and maternal morbidity and mortality, and antenatal diagnosis is crucial for optimal obstetric management.
Literature ReviewRigorous JournalHighly Cited