Objectives: To estimate procedure‐related risks of miscarriage following amniocentesis and chorionic villus sampling (CVS) based on a systematic review of the literature and a meta‐analysis.Methods: A search of MEDLINE, EMBASE, CINHAL and The Cochrane Library (2000–2014) was performed to review relevant citations reporting procedure‐related complications of amniocentesis and CVS. Only studies reporting data on more than 1000 procedures were included in this review to minimize the effect of bias from smaller studies. Heterogeneity between studies was estimated using Cochran's Q, the I² statistic and Egger bias. Meta‐analysis of proportions was used to derive weighted pooled estimates for the risk of miscarriage before 24 weeks' gestation. Incidence–rate difference meta‐analysis was used to estimate pooled procedure‐related risks.Results: The weighted pooled risks of miscarriage following invasive procedures were estimated from analysis of controlled studies including 324 losses in 42 716 women who underwent amniocentesis and 207 losses in 8899 women who underwent CVS. The risk of miscarriage prior to 24 weeks in women who underwent amniocentesis and CVS was 0.81% (95% CI, 0.58–1.08%) and 2.18% (95% CI, 1.61–2.82%), respectively. The background rates of miscarriage in women from the control group that did not undergo any procedures were 0.67% (95% CI, 0.46–0.91%) for amniocentesis and 1.79% (95% CI, 0.61–3.58%) for CVS. The weighted pooled procedure‐related risks of miscarriage for amniocentesis and CVS were 0.11% (95% CI, –0.04 to 0.26%) and 0.22% (95% CI, –0.71 to 1.16%), respectively.Conclusion: The procedure‐related risks of miscarriage following amniocentesis and CVS are much lower than are currently quoted. Copyright © 2014 ISUOG. Published by John Wiley & Sons Ltd.

Objective The accuracy of prospective sonographic prenatal detection of invasive placentation is unclear. The objective of this study was to conduct a systematic review and meta‐analysis to assess the performance of ultrasound in at‐risk women for prenatal identification of invasive placentation. Methods MEDLINE, EMBASE, The Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects (DARE) and The Cochrane Central Register of Controlled Trials (CENTRAL) were searched using the search terms ‘placenta accreta’, ‘placenta increta’, ‘placenta percreta’, ‘ultrasound’, ‘magnetic resonance imaging (MRI)’, ‘invasive placenta’ and ‘infiltrative placenta’. Two authors independently abstracted data from the articles. Sensitivity, specificity, positive and negative likelihood ratios (LR+ and LR–), the diagnostic odds ratio (DOR) and their 95% CIs for each study were calculated. Forest plots and summary receiver–operating characteristics curves were produced. Between‐study heterogeneity was explored both graphically and statistically. The MOOSE (meta‐analysis of observational studies in epidemiology) guidelines were followed. Results Twenty‐three studies involving 3707 pregnancies at risk for invasive placentation were included. The overall performance of ultrasound for the antenatal detection of invasive placentation was as follows: sensitivity, 90.72 (95% CI, 87.2–93.6)%; specificity, 96.94 (95% CI, 96.3–97.5)%; LR+, 11.01 (95% CI, 6.1–20.0); LR–, 0.16 (95% CI, 0.11–0.23); and DOR, 98.59 (95% CI, 48.8–199.0). Among the different ultrasound signs, color Doppler had the best predictive accuracy (sensitivity, 90.74 (95% CI, 85.2–94.7)%; specificity, 87.68 (95% CI, 84.6–90.4)%; LR+, 7.77 (95% CI, 3.3–18.4); LR–, 0.17 (95% CI, 0.10–0.29); and DOR, 69.02 (95% CI, 22.8–208.9)). Conclusions Ultrasound has a high accuracy for prenatal diagnosis of disorders of invasive placentation in high‐risk women. The use of color Doppler improves the test performance. Copyright © 2013 ISUOG. Published by John Wiley & Sons Ltd.

Objective To assess systematically the performance of prenatal magnetic resonance imaging (MRI) in diagnosing the presence, degree and topography of disorders of invasive placentation and to explore the role of the different MRI signs in predicting these disorders. The diagnostic accuracy of ultrasound and MRI in the detection of invasive placentation was also compared. Methods MEDLINE, EMBASE, CINAHL and The Cochrane Library, including The Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects and The Cochrane Central Register of Controlled Trials, were searched electronically utilizing combinations of the relevant medical subject heading terms, keywords and word variants for ‘invasive placentation’ and ‘magnetic resonance imaging’. Only prospective studies reporting a diagnosis of invasive placentation at the time of MRI and retrospective studies in which the radiologist was blinded to the final results were included in the analysis. The MRI signs explored were: uterine bulging, heterogeneous signal intensity, dark intraplacental bands on T2 weighted sequences, focal interruption of the myometrium and tenting of the bladder. Summary estimates of sensitivity, specificity, positive and negative likelihood ratios (LR+, LR–) and diagnostic odds ratio (DOR) were based, depending on the number of studies, upon DerSimonian–Laird random‐effect or hierarchical summary receiver–operating characteristics models. Results A total of 18 studies involving 1010 pregnancies at risk for invasive placentation were included. The overall diagnostic accuracy of MRI in detecting the presence of invasive placentation was: sensitivity, 94.4% (95% CI, 86.0–97.9%); specificity, 84.0% (95% CI, 76.0–89.8%); LR+, 5.91 (95% CI, 3.73–9.39); LR–, 0.07 (95% CI, 0.02–0.18); DOR, 89.0 (95% CI, 22.8–348.1). MRI had a high predictive accuracy in assessing both the depth and topography of placental invasion. All five MRI signs showed good predictive accuracy in the diagnosis of disorders of invasive placentation. There was no difference in either the sensitivity (P = 0.24) or the specificity (P = 0.91) between ultrasound and MRI for the detection of invasive placentation. Conclusions Prenatal MRI is highly accurate in diagnosing disorders of invasive placentation. Ultrasound and MRI have comparable predictive accuracy. Large population‐based studies are needed in order to assess whether ultrasound can predict the depth and topography of placental invasion as reliably as can MRI. Copyright © 2014 ISUOG. Published by John Wiley & Sons Ltd.