Urological complications in women undergoing Cesarean section for placenta accreta spectrum disorders: systematic review and meta-analysis.

OBJECTIVE: To report on the occurrence of urological complications in women undergoing Cesarean section for placenta accreta spectrum disorders (PAS). METHODS: MEDLINE, EMBASE and the Cochrane databases were searched electronically up to 1 November 2022. Studies reporting on the urological outcome of women undergoing Cesarean section for PAS were included. Two independent reviewers performed data extraction using a predefined protocol and assessed the risk of bias using the Newcastle-Ottawa scale for observational studies, with disagreements resolved by consensus.The primary outcome was the overall occurrence of urological complications. Secondary outcomes were the occurrence of any cystotomy, intentional cystotomy, unintentional cystotomy, ureteral damage, ureteral fistula and vesicovaginal fistula. All outcomes were explored in the overall population of women undergoing surgery for PAS. In addition, we performed subgroup analyses according to the type of surgery (Cesarean hysterectomy, or conservative surgery or management), severity of PAS at histopathology (placenta accreta/increta and placenta percreta), type of intervention (planned vs emergency) and number of cases per year. Random-effects meta-analyses of proportions were used to analyze the data. RESULTS: There were 62 studies included in the systematic review and 56 were included in the meta-analysis. Urological complications occurred in 15.2% (95% CI, 12.9-17.7%) of cases. Cystotomy complicated 13.5% (95% CI, 9.7-17.9%) of surgical operations. Intentional cystotomy was required in 7.7% (95% CI, 6.5-9.1%) of cases, while unintentional cystotomy occurred in 7.2% (95% CI, 6.0-8.5%) of cases. Urological complications occurred in 19.4% (95% CI, 16.3-22.7%) of cases undergoing hysterectomy and 12.2% (95% CI, 7.5-17.8%) of those undergoing conservative treatment. In the subgroup analyses, urological complications occurred in 9.4% (95% CI, 5.4-14.4%) of women with placenta accreta/increta and 38.5% (95% CI, 21.6-57.0%) of those described as having placenta percreta, and included mainly cystotomy (5.5% (95% CI, 0.6-15.1%) and 22.0% (95% CI, 5.4-45.5%), respectively). Urological complications occurred in 15.4% (95% CI, 8.1-24.6%) of cases undergoing a planned procedure and 24.6% (95% CI, 13.0-38.5%) of those undergoing an emergency intervention. In subanalysis of studies reporting on ≥ 12 cases per year, the incidence of urological complication was similar to that reported in the primary analysis. CONCLUSIONS: Women undergoing surgery for PAS are at high risk of urological complication, mainly cystotomy. The incidence of these complications was particularly high in women described as having placenta percreta at birth and in those undergoing emergency surgical intervention. The high heterogeneity between the included studies highlights the need for a standardized protocol for the diagnosis of PAS to identify prenatal imaging signs associated with the increased risk of urological morbidity at delivery. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Risk factors, histopathology and diagnostic accuracy in posterior placenta accreta spectrum disorders: systematic review and meta-analysis.

OBJECTIVE: To elucidate the risk factors, histopathological correlations and diagnostic accuracy of prenatal imaging in pregnancies complicated by posterior placenta accreta spectrum (PAS) disorders. METHODS: MEDLINE, EMBASE and CINAHL were searched for studies reporting on women with posterior PAS. Inclusion criteria were women with posterior PAS confirmed either at surgery or on histopathological analysis. The outcomes explored were risk factors for posterior PAS, histopathological correlation and the diagnostic accuracy of ultrasound and magnetic resonance imaging (MRI) in detecting posterior PAS. Random-effects meta-analysis of proportions was used to analyze the data. RESULTS: Twenty studies were included. Placenta previa was present in 92.8% (107/114; 17 studies) of pregnancies complicated by posterior PAS, while 76.1% (53/88; 11 studies) of women had had prior uterine surgery, mainly a Cesarean section (CS) or curettage and 82.5% (66/77; 10 studies) were multiparous. When considering histopathological analysis in women affected by posterior PAS, 77.5% (34/44; 11 studies) had placenta accreta, 19.5% (8/44; 11 studies) had placenta increta and 9.3% (2/44; 11 studies) had placenta percreta. Of the cases of posterior PAS disorder, 52.4% (31/63; 12 studies) were detected prenatally on ultrasound, while 46.7% (32/63; 12 studies) were diagnosed only at birth. When exploring the distribution of the classic ultrasound signs of PAS, placental lacunae were present in 39.0% (12/30; seven studies), loss of the clear zone in 41.1% (13/30; seven studies) and bladder-wall interruption in 16.6% (4/30; seven studies) of women, while none of the included cases showed hypervascularization at the bladder-wall interface. When assessing the role of MRI in detecting posterior PAS, 73.5% (26/32; 11 studies) of cases were detected on prenatal MRI, while 26.5% (6/32; 11 studies) were discovered only at the time of CS. CONCLUSIONS: Placenta previa, prior uterine surgery and multiparity represent the most commonly reported risk factors for posterior PAS. Ultrasound had a very low diagnostic accuracy in detecting these disorders prenatally. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Interobserver agreement in MRI assessment of severity of placenta accreta spectrum disorders.

OBJECTIVE: To evaluate the level of agreement in the prenatal magnetic resonance imaging (MRI) assessment of the presence and severity of placenta accreta spectrum (PAS) disorders between examiners with expertise in the diagnosis and management of these conditions. METHODS: This was a secondary analysis of a prospective study including women with placenta previa or low-lying placenta and at least one prior Cesarean delivery or uterine surgery, who underwent MRI assessment at a regional referral center for PAS disorders in Italy, between 2007 and 2017. The MRI scans were retrieved from the hospital electronic database and assessed by four examiners, who are considered to be experts in the diagnosis and surgical management of PAS disorders. The examiners were blinded to the ultrasound diagnosis, histopathological findings and clinical data of the patients. Each examiner was asked to assess 20 features on the MRI scans, including the presence, depth and topography of placental invasion. Depth of invasion was defined as the degree of adhesion and invasion of the placenta into the myometrium and uterine serosa (placenta accreta, increta or percreta) and the histopathological examination of the removed uterus was considered the reference standard. Topography of the placental invasion was defined as the site of placental invasion within the uterus in relation to the posterior bladder wall (posterior upper bladder wall and uterine body, posterior lower bladder wall and lower uterine segment and cervix or no visible bladder invasion) and the site of invasion at surgery was considered the reference standard. The degree of interrater agreement (IRA) was evaluated by calculating both the percentage of observed agreement among raters and the Fleiss kappa (κ) value. RESULTS: Forty-six women were included in the study. The median gestational age at MRI was 33.8 (interquartile range, 33.1-34.0) weeks. A final diagnosis of placenta accreta, increta and percreta was made in 15.2%, 17.4% and 50.0% patients, respectively. There was excellent agreement between the four examiners in the assessment of the overall presence of a PAS disorder (IRA, 92.1% (95% CI, 86.8-94.0%); κ, 0.90 (95% CI, 0.89-1.00)). However, there was significant heterogeneity in IRA when assessing the different MRI signs suggestive of a PAS disorder. There was excellent agreement between the examiners in the identification of the depth of placental invasion on MRI (IRA, 98.9% (95% CI, 96.8-100.0%); κ, 0.95 (95% CI, 0.89-1.00)). However, agreement in assessing the topography of placental invasion was only moderate (IRA, 72.8% (95% CI, 72.7-72.9%); κ, 0.56 (95% CI, 0.54-0.66)). More importantly, when assessing parametrial invasion, which is one of the most significant prognostic factors in women affected by PAS, the agreement was substantial and moderate in judging the presence of invasion in the coronal (IRA, 86.6% (95% CI, 86.5-86.7%); κ, 0.69 (95% CI, 0.59-0.71)) and axial (IRA, 78.6% (95% CI, 78.5-78.7%); κ, 0.56 (95% CI, 0.33-0.60)) planes, respectively. Likewise, interobserver agreement in judging the presence and the number of newly formed vessels in the parametrial tissue was moderate (IRA, 88.0% (95% CI, 88.0-88.1%); κ, 0.59 (95% CI, 0.45-0.68)) and fair (IRA, 66.7% (95% CI, 66.6-66.7%); κ, 0.22 (95% CI, 0.12-0.37)), respectively. CONCLUSIONS: MRI has excellent interobserver agreement in detecting the presence and depth of placental invasion, while agreement between the examiners is lower when assessing the topography of invasion. The findings of this study highlight the need for a standardized MRI staging system for PAS disorders, in order to facilitate objective correlation between prenatal imaging, pregnancy outcome and surgical management of these patients. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Value of first-trimester ultrasound in prediction of third-trimester sonographic stage of placenta accreta spectrum disorder and surgical outcome.

OBJECTIVES: To explore whether early first-trimester ultrasound can predict the third-trimester sonographic stage of placenta accreta spectrum (PAS) disorder and to elucidate whether combining first-trimester ultrasound findings with the sonographic stage of PAS disorder can stratify the risk of adverse surgical outcome in women at risk for PAS disorder. METHODS: This was a retrospective analysis of prospectively collected data from women with placenta previa, and at least one previous Cesarean delivery (CD) or uterine surgery, for whom early first-trimester (5-7 weeks' gestation) ultrasound images could be retrieved. The relationship between the position of the gestational sac and the prior CD scar was assessed using three sonographic markers for first-trimester assessment of Cesarean scar (CS) pregnancy, reported by Calí et al. (crossover sign (COS)), Kaelin Agten et al. (implantation of the gestational sac on the scar vs in the niche of the CS) and Timor-Tritsch et al. (position of the center of the gestational sac below vs above the midline of the uterus), by two different examiners blinded to the final diagnosis and clinical outcome. The primary aim of the study was to explore the association between first-trimester ultrasound findings and the stage of PAS disorder on third-trimester ultrasound. Our secondary aim was to elucidate whether the combination of first-trimester ultrasound findings and sonographic stage of PAS disorder can predict surgical outcome. Logistic regression analysis and area under the receiver-operating-characteristics curve (AUC) were used to analyze the data. RESULTS: One hundred and eighty-seven women with vasa previa were included. In this cohort, 79.6% (95% CI, 67.1-88.2%) of women classified as COS-1, 94.4% (95% CI, 84.9-98.1%) of those with gestational-sac implantation in the niche of the prior CS and 100% (95% CI, 93.4-100%) of those with gestational sac located below the uterine midline, on first-trimester ultrasound, were affected by the severest form of PAS disorder (PAS3) on third-trimester ultrasound. On multivariate logistic regression analysis, COS-1 (odds ratio (OR), 7.9 (95% CI, 4.0-15.5); P < 0.001), implantation of the gestational sac in the niche (OR, 29.1 (95% CI, 8.1-104); P < 0.001) and location of the gestational sac below the midline of the uterus (OR, 38.1 (95% CI, 12.0-121); P < 0.001) were associated independently with PAS3, whereas parity (P = 0.4) and the number of prior CDs (P = 0.5) were not. When translating these figures into diagnostic models, first-trimester diagnosis of COS-1 (AUC, 0.94 (95% CI, 0.91-0.97)), pregnancy implantation in the niche (AUC, 0.92 (95% CI, 0.89-0.96)) and gestational sac below the uterine midline (AUC, 0.92 (95% CI, 0.88-0.96)) had a high predictive accuracy for PAS3. There was an adverse surgical outcome in 22/187 pregnancies and it was more common in women with, compared to those without, COS-1 (P < 0.001), gestational-sac implantation in the niche (P < 0.001) and gestational-sac position below the uterine midline (P < 0.001). On multivariate logistic regression analysis, third-trimester ultrasound diagnosis of PAS3 (OR, 4.3 (95% CI, 2.1-17.3)) and first-trimester diagnosis of COS-1 (OR, 7.9 (95% CI, 4.0-15.5); P < 0.001), pregnancy implantation in the niche (OR, 29.1 (95% CI, 8.1-79.0); P < 0.001) and position of the sac below the uterine midline (OR, 6.6 (95% CI, 3.9-16.2); P < 0.001) were associated independently with adverse surgical outcome. When combining the sonographic coordinates of the three first-trimester imaging markers, we identified an area we call high-risk-for-PAS triangle, which may enable an easy visual perception and application of the three methods to prognosticate the risk for CS pregnancy and PAS disorder, although it requires validation in large prospective studies. CONCLUSIONS: Early first-trimester sonographic assessment of pregnancies with previous CD can predict reliably ultrasound stage of PAS disorder. Combination of findings on first-trimester ultrasound with second- and third-trimester ultrasound examination can stratify the surgical risk in women affected by a PAS disorder. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Prenatal ultrasound staging system for placenta accreta spectrum disorders.

OBJECTIVES: To develop a prenatal ultrasound staging system for placenta accreta spectrum (PAS) disorders in women with placenta previa and to evaluate its association with surgical outcome, placental invasion and the clinical staging system for PAS disorders proposed by the International Federation of Gynecology and Obstetrics (FIGO). METHODS: This was a secondary retrospective analysis of prospectively collected data from women with placenta previa. We classified women according to the following staging system for PAS disorders, based upon the presence of ultrasound signs of PAS in women with placenta previa: PAS0, placenta previa with no ultrasound signs of invasion or with placental lacunae but no evidence of abnormal uterus-bladder interface; PAS1, presence of at least two of placental lacunae, loss of the clear zone or bladder wall interruption; PAS2, PAS1 plus uterovescical hypervascularity; PAS3, PAS1 or PAS2 plus evidence of increased vascularity in the inferior part of the lower uterine segment potentially extending into the parametrial region. We explored whether this ultrasound staging system correlates with surgical outcome (estimated blood loss (EBL, mL), units of packed red blood cells (PRBC), fresh frozen plasma (FFP) and platelets (PLT) transfused, operation time (min), surgical complications defined as the occurrence of any damage to the bladder, ureters or bowel, length of hospital stay (days) and admission to intensive care unit (ICU)) and depth of placental invasion. The correlation between the present ultrasound staging system and the clinical grading system proposed by FIGO was assessed. Prenatal and surgical management were not based on the proposed prenatal ultrasound staging system. Linear and multiple regression models were used. RESULTS: Two-hundred and fifty-nine women were included in the analysis. Mean EBL was 516 ± 151 mL in women with PAS0, 609 ± 146 mL in those with PAS1, 950 ± 190 mL in those with PAS2 and 1323 ± 533 mL in those with PAS3, and increased significantly with increasing severity of PAS ultrasound stage. Mean units of PRBC transfused were 0.05 ± 0.21 in PAS0, 0.10 ± 0.45 in PAS1, 1.19 ± 1.11 in PAS2 and 4.48 ± 2.06 in PAS3, and increased significantly with PAS stage. Similarly, there was a progressive increase in the mean units of FFP transfused from PAS1 to PAS3 (0.0 ± 0.0 in PAS1, 0.25 ± 1.0 in PAS2 and 3.63 ± 2.67 in PAS3). Women presenting with PAS3 on ultrasound had significantly more units of PLT transfused (2.37 ± 2.40) compared with those with PAS0 (0.03 ± 0.18), PAS1 (0.0 ± 0.0) or PAS2 (0.0 ± 0.0). Mean operation time was longer in women with PAS3 (184 ± 32 min) compared with those with PAS1 (153 ± 38 min) or PAS2 (161 ± 28 min). Similarly, women with PAS3 had longer hospital stay (7.4 ± 2.1 days) compared with those with PAS0 (3.4 ± 0.6 days), PAS1 (6.4 ± 1.3 days) or PAS2 (5.9 ± 0.8 days). On linear regression analysis, after adjusting for all potential confounders, higher PAS stage was associated independently with a significant increase in EBL (314 (95% CI, 230-399) mL per one-stage increase; P < 0.001), units of PRBC transfused (1.74 (95% CI, 1.33-2.15) per one-stage increase; P < 0.001), units of FFP transfused (1.19 (95% CI, 0.61-1.77) per one-stage increase; P < 0.001), units of PLT transfused (1.03 (95% CI, 0.59-1.47) per one-stage increase; P < 0.001), operation time (38.8 (95% CI, 31.6-46.1) min per one-stage increase; P < 0.001) and length of hospital stay (0.83 (95% CI, 0.46-1.27) days per one-stage increase; P < 0.001). On logistic regression analysis, increased severity of PAS was associated independently with surgical complications (odds ratio, 3.14 (95% CI, 1.36-7.25); P = 0.007), while only PAS3 was associated with admission to the ICU (P < 0.001). All women with PAS0 on ultrasound were classified as having Grade-1 PAS disorder according to the FIGO grading system. Conversely, of the women presenting with PAS1 on ultrasound, 64.1% (95% CI, 48.4-77.3%) were classified as having Grade-3, while 35.9% (95% CI, 22.7-51.6%) were classified as having Grade-4 PAS disorder, according to the FIGO grading system. All women with PAS2 were categorized as having Grade-5 and all those with PAS3 as having Grade-6 PAS disorder according to the FIGO system. CONCLUSION: Ultrasound staging of PAS disorders is feasible and correlates with surgical outcome, depth of invasion and the FIGO clinical grading system. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

First-trimester detection of abnormally invasive placenta in high-risk women: systematic review and meta-analysis.

OBJECTIVES: The primary aim of this systematic review was to ascertain whether ultrasound signs suggestive of abnormally invasive placenta (AIP) are present in the first trimester of pregnancy. Secondary aims were to ascertain the strength of association and the predictive accuracy of such signs in detecting AIP in the first trimester. METHODS: An electronic search of MEDLINE, EMBASE, CINAHL and Cochrane databases (2000-2016) was performed. Only studies reporting on first-trimester diagnosis of AIP that was subsequently confirmed in the third trimester either during operative delivery or by pathological examination were included. Meta-analysis of proportions, random-effects meta-analysis and hierarchical summary receiver-operating characteristics curve analysis were used to analyze the data. RESULTS: Seven studies, involving 551 pregnancies at high risk of AIP, were included. At least one ultrasound sign suggestive of AIP was detected in 91.4% (95% CI, 85.8-95.7%) of cases with confirmed AIP. The most common ultrasound feature in the first trimester of pregnancy was low implantation of the gestational sac close to a previous uterine scar, which was observed in 82.4% (95% CI, 46.6-99.8%) of cases. Anechoic spaces within the placental mass (lacunae) were observed in 46.0% (95% CI, 10.9-83.7%) and a reduced myometrial thickness in 66.8% (95% CI, 45.2-85.2%) of cases affected by AIP. Pregnancies with a low implantation of the gestational sac had a significantly higher risk of AIP (odds ratio, 19.6 (95% CI, 6.7-57.3)), with a sensitivity and specificity of 44.4% (95% CI, 21.5-69.2%) and 93.4% (95% CI, 90.5-95.7%), respectively. CONCLUSIONS: Ultrasound signs of AIP can be present during the first trimester of pregnancy, even before 11 weeks' gestation. Low anterior implantation of the placenta/gestational sac close to or within the scar was the most commonly seen early ultrasound sign suggestive of AIP, although its individual predictive accuracy was not high. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Outcome of Cesarean scar pregnancy managed expectantly: systematic review and meta-analysis.

OBJECTIVE: To explore the outcome in women managed expectantly following the diagnosis of Cesarean scar pregnancy (CSP). METHODS: An electronic search of MEDLINE, EMBASE and ClinicalTrials.gov databases was performed utilizing combinations of relevant medical subject headings for 'Cesarean scar pregnancy' and 'outcome'. Reference lists of relevant articles and reviews were hand-searched for additional reports. Observed outcomes included: severe first-trimester vaginal bleeding; clinical symptoms (abdominal pain, vaginal bleeding) requiring treatment; uncomplicated miscarriage; complicated miscarriage requiring intervention; first- or second-trimester uterine rupture or hysterectomy; third-trimester bleeding, uterine rupture or hysterectomy; maternal death; incidence of abnormally invasive placenta (AIP); prevalence of placenta percreta; ultrasound signs suggestive of AIP; and live birth. Meta-analyses of proportions using a random-effects model were used to combine data. Cases were stratified based on the presence or absence of embryonic/fetal heart activity at the time of diagnosis. RESULTS: A total of 17 studies (69 cases of CSP managed expectantly, 52 with and 17 without embryonic/fetal heart beat) were included. In women with CSP and embryonic/fetal heart activity, 13.0% (95% CI, 3.8-26.7%) experienced an uncomplicated miscarriage, while 20.0% (95% CI, 7.1-37.4%) required medical intervention. Uterine rupture during the first or second trimester of pregnancy occurred in 9.9% (95% CI, 2.9-20.4%) of cases, while hysterectomy was required in 15.2% (95% CI, 3.6-32.8%) of all cases. Forty (76.9% (95% CI, 65.4-86.5%)) women progressed to the third trimester of pregnancy, of whom 39.2% (95% CI, 15.4-66.2%) experienced severe bleeding. Finally, 74.8% (95% CI, 52.0-92.1%) had a surgical or pathological diagnosis of AIP at delivery and around two-thirds (69.7% (95% CI, 42.8-90.1%)) of them had placenta percreta. In women with CSP but no embryonic/fetal cardiac activity, an uncomplicated miscarriage occurred in 69.1% (95% CI, 47.4-87.1%) of cases, while surgical or medical intervention during or immediately after miscarriage was required in 30.9% (95% CI, 12.9-52.6%). Uterine rupture during the first trimester of pregnancy occurred in 13.4% (95% CI, 2.7-30.3%) of cases, but hysterectomy was not required in any case. CONCLUSIONS: CSP with positive embryonic/fetal heart activity managed expectantly is associated with a high burden of maternal morbidity including severe hemorrhage, early uterine rupture, hysterectomy and severe AIP. Despite this, a significant proportion of pregnancies complicated by CSP may progress to, or close to, term, thus questioning whether termination of pregnancy should be the only therapeutic option offered to these women. Expectant management of CSP with no cardiac activity may be a reasonable option in view of the low likelihood of maternal complications requiring intervention, although close surveillance is advisable to avoid adverse maternal outcome. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Natural history of Cesarean scar pregnancy on prenatal ultrasound: the crossover sign.

OBJECTIVE: Advances in prenatal imaging techniques have led to an increase in the diagnosis of Cesarean scar pregnancy (CSP). However, antenatal counseling when CSP is diagnosed is challenging, and current evidence is derived mainly from small series reporting high rates of adverse maternal outcomes. The aim of this study was to ascertain the performance of prenatal ultrasound in predicting the natural history of CSP using a new sonographic sign, the crossover sign (COS). METHODS: This was a retrospective analysis of early first-trimester (6-8 weeks' gestation) ultrasound images in women with morbidly adherent placenta (MAP) managed in the third trimester of pregnancy. The relationship between the gestational sac of the CSP, anterior uterine wall and Cesarean scar, defined as the COS, was analyzed to determine whether it could predict evolution in these cases. Odds ratios (ORs) were calculated and logistic regression analysis was performed to investigate the association between different types of COS (COS-1, COS-2+ or COS-2-) and the occurrence of MAP. RESULTS: Sixty-eight pregnancies with MAP were included. The risk of placenta percreta was significantly higher in pregnancies with COS-1 than in those with COS-2 (OR, 6.67 (95% CI, 1.3-33.3)). When evaluating the two variants of COS-2 separately, the risk of placenta percreta was significantly higher in pregnancies with COS-1 vs COS-2+ (OR, 5.83 (95% CI, 1.1-30.2)) and this risk was even higher when comparing cases with COS-1 vs COS-2- (OR, 12.0 (95% CI, 1.9-75.7)). Logistic regression analysis showed that COS-1 was associated independently with severe forms of MAP, such as placenta percreta and increta (OR, 12.85 (95% CI, 2.0-84.0)), while COS-2+ was associated independently with placenta accreta (OR, 4.37 (95% CI, 1.1-17.0)). CONCLUSIONS: Ultrasound assessment of the relationship between the gestational sac of a CSP and the endometrial line (the COS) may help to determine whether a CSP will progress towards a less severe form of MAP, amenable to postnatal treatment, and successful pregnancy outcome. Large prospective studies are needed to confirm our findings and elucidate the natural history of this condition. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Counseling in fetal medicine: evidence-based answers to clinical questions on morbidly adherent placenta.

Although the incidence of morbidly adherent placenta (MAP) has risen progressively in the last two decades, there remains uncertainty about the diagnosis and management of this condition. The aim of this review is to provide up-to-date and evidence-based answers to common clinical questions regarding the diagnosis and management of MAP. Different risk factors have been associated with MAP; however, previous Cesarean section and placenta previa are the most frequently associated. Ultrasound is the primary method for diagnosing MAP and has a good overall diagnostic accuracy for its detection. When considering the different ultrasound signs of MAP, color Doppler seems to provide the best diagnostic performance. Magnetic resonance imaging has the same accuracy in diagnosing MAP as does ultrasound examination; its use should be considered when a resective procedure, such as hysterectomy, is planned as it can provide detailed information about the topography of placental invasion and predict difficulties that may arise in surgery. The optimal gestational age for delivery in pregnancies with MAP is yet to be established; planning surgery between 34 and 36 weeks of gestation provides the best balance between fetal maturity and the risk of unexpected episodes of heavy bleeding, which are more likely to occur with delivery after this timepoint, especially in severe cases of MAP. The optimal surgical approach to MAP depends on multiple factors, including availability of an experienced team, specific surgical skills and hospital resources. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Prenatal identification of invasive placentation using magnetic resonance imaging: systematic review and meta-analysis.

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.

Cesarean scar pregnancy and early placenta accreta share common histology.

OBJECTIVE: To determine, by evaluation of histological slides, images and descriptions of early (second-trimester) placenta accreta (EPA) and placental implantation in cases of Cesarean scar pregnancy (CSP), whether these are pathologically indistinguishable and whether they both represent different stages in the disease continuum leading to morbidly adherent placenta in the third trimester. METHODS: The database of a previously published review of CSP and EPA was used to identify articles with histopathological descriptions and electronic images for pathological review. When possible, microscopic slides and/or paraffin blocks were obtained from the original researchers. We also included from our own institutions cases of CSP and EPA for which pathology specimens were available. Two pathologists examined all the material independently and, blinded to each other's findings, provided a pathological diagnosis based on microscopic appearance. Interobserver agreement in diagnosis was determined. RESULTS: Forty articles were identified, which included 31 cases of CSP and 13 cases of EPA containing histopathological descriptions and/or images of the pathology. We additionally included six cases of CSP and eight cases of EPA from our own institutions, giving a total of 58 cases available for histological evaluation (37 CSP and 21 EPA) containing clear definitions of morbidly adherent placenta. In the 29 cases for which images/slides were available for histopathological evaluation, both pathologists attested to the various degrees of myometrial and/or scar tissue invasion by placental villi with scant or no intervening decidua, consistent with the classic definition of morbidly adherent placenta. Based on the reviewed material, cases with a diagnosis of EPA and those with a diagnosis of CSP showed identical histopathological features. Interobserver correlation was high (kappa = 0.93). CONCLUSIONS: EPA and placental implantation in CSP are histopathologically indistinguishable and may represent different stages in the disease continuum leading to morbidly adherent placenta in the third trimester.

Role of three-dimensional power Doppler in the antenatal diagnosis of placenta accreta: comparison with gray-scale and color Doppler techniques.

OBJECTIVE: To assess the role of three-dimensional (3D) power Doppler in the antenatal diagnosis of placenta accreta and compare its diagnostic performance with gray-scale and color Doppler ultrasonography. METHODS: One hundred and seventy pregnant women with persistent placenta previa totalis (after 28 weeks' gestation) were prospectively enrolled into this study. Gray-scale transabdominal ultrasound examination was performed to detect loss of the subendometrial echolucent zone and other abnormalities suggestive of placenta accreta. Color flow mapping was used to scan the whole placenta to detect any newly formed vessels at the serosa-bladder border or the presence of abnormal lacunae. Finally a targeted examination of angioarchitecture in the basal and lateral views of the placenta was carried out using 3D power Doppler. The ultrasound findings were analyzed with reference to the final diagnosis made during Cesarean delivery. RESULTS: Placenta accreta and its variants (including increta and percreta) were confirmed in 39 patients at the time of Cesarean delivery. Based on receiver-operating characteristics analysis, 'numerous coherent vessels' visualized using 3D power Doppler in the basal view was the best single criterion for the diagnosis of placenta accreta, with a sensitivity of 97% and a specificity of 92%. If we considered the presence of at least one criterion to be diagnostic when using each ultrasound technique, then 3D power Doppler would have the best positive predictive value (76%), followed by gray-scale (51%) and color Doppler (47%). The majority of patients with placenta accreta showed multiple characteristic features on ultrasound imaging. In contrast, those patients with a false-positive diagnosis (i.e. the final diagnosis was placenta previa alone) tended to show isolated ultrasound markers of the condition. CONCLUSION: 3D power Doppler may be useful as a complementary technique for the antenatal diagnosis or exclusion of placenta accreta.