Placenta accreta in Kuwait: does a discrepancy exist between fundal and praevia accreta?

Uterine body placenta accreta spectrum: A detailed literature review

Placenta accreta spectrum (PAS) is a major obstetrical problem whose incidence is rising. Current guidelines recommend screening of all women with placenta previa and risk factors for PAS between 20 and 24 weeks. Risk factors, diagnosis, and management of previa PAS are well established, but an apparently normal location of the placenta does not exclude PAS. Literature data are scarce on uterine body PAS, which carries a high risk of maternal and neonatal adverse outcome, but is still easily missed on prenatal ultrasound. We conducted a comprehensive review to identify possible risk factors, clinical presentations, and diagnostic modalities of uterine PAS. A total of 133 cases were found during a 70-year period (1949-2019). The vast majority of them presented with signs of uterine rupture, even prior to the viability threshold of 24 weeks (up to 45%). Major risk factors included previous cesarean delivery, uterine curettage, uterine surgery, Asherman's syndrome, manual removal of the placenta, endometritis, high parity, young maternal age, in vitro fertilization, radiotherapy, uterine artery embolization, and uterine leiomyoma. Diagnosis was pre-symptomatic in only 3% of cases. Future studies should differentiate between previa PAS and uterine body PAS.

Prevalence and main outcomes of placenta accreta spectrum: a systematic review and meta-analysis

OBJECTIVE DATA

The objective of this study was to evaluate the prevalence of placenta accreta spectrum in general population studies and the main maternal outcomes at delivery.

STUDY

We searched PubMed, Google Scholar, clinicalTrials.gov, and MEDLINE between 1982 and 2018. Articles that provided data on the number of cases of placenta accreta spectrum per pregnancies, births, or deliveries in a defined population were used.

STUDY APPRAISAL AND SYNTHESIS METHODS

Study characteristics were evaluated by 2 independent reviewers who used a predesigned protocol. Primary outcomes were the prevalence of placenta accreta spectrum and clinical diagnostic data at birth; the pathologic criteria were used to confirm the diagnosis. Secondary outcomes included cases that required transfusion, incidence of peripartum hysterectomy, and maternal mortality rates. Heterogeneity between studies was analyzed with the Cochran's Q-test and the I² statistics.

RESULTS

Of the 98 full-text studies that were identified, 29 articles met the defined criteria and included 22 retrospective and 7 prospective studies comprising 7001 cases of placenta accreta spectrum of 5,719,992 births. Prevalence rates ranged from 0.01-1.1% with an overall pooled prevalence of 0.17% (95% confidence interval, 0.14-0.19). Only 10 studies provided detailed histopathologic data. The pool prevalence for the adherent vs the invasive grades was 0.5 (95% confidence interval, 0.3-0.36) and 0.3 (95% confidence interval, 0.2-0.4) per 1000 births, respectively. The pooled incidence for peripartum hysterectomy was 52.2% (95% confidence interval, 38.3-66.4; I²=99.8%) and 46.9% (95 % confidence interval, 34-59.9; I²=98.8%) for hemorrhage that required transfusion. The pooled estimate of maternal death was 0.05% (95% confidence interval, 0.06-0.69; I²=73%). We found large amounts of heterogeneity between studies for all parameters and further quantification was limited because of methodologic inconsistencies between studies with regards to clinical criteria that were used for the diagnosis of the condition at birth and the histopathologic confirmation of the diagnosis and differential diagnosis between adherent and invasive accreta placentation.

CONCLUSION

This meta-analysis indicated wide variation between studies for the prevalence rate of placenta accreta spectrum and for the different grades of accreta placentation that highlighted the need for consistency in definitions that are used to describe placenta accreta spectrum at birth and in the reporting of this increasing common obstetric complication.