Prenatal ultrasound staging system for placenta accreta spectrum disorders

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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. L...

Section: Introductionmentioning

confidence: 99%

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

Finazzo¹,

D’Antonio

Masselli

et al. 2020

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“…Advances in prenatal imaging have led to an increase in the detection rate of PAS, which in turn has improved the surgical and maternal outcome. We recently described a prenatal ultrasound staging system for PAS disorders which is based on a number of ultrasound signs in women at high risk for these disorders. However, this staging system did not take into account first‐trimester ultrasound findings.…”

Section: Introductionmentioning

confidence: 99%

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

Calì

Timor‐Tritsch

Forlani

et al. 2020

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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 <...

“…Assessing the trophoblastic invasion of this area is crucial to planning an appropriate surgical strategy. According to a recently proposed ultrasound staging system for PAS disorders, all cases of placenta previa with evidence of increased vascularity in the inferior part of the lower uterine segment, potentially extending into the parametrial region (PAS3 in the proposed system), had been categorized as Stage 6 according to the FIGO postnatal clinical grading system, with good correlation between this ultrasound finding and surgical outcome. However, the assessment of this finding on color Doppler ultrasound is highly subjective and technically challenging, especially beyond 30 weeks of gestation.…”

Section: Discussionmentioning

confidence: 99%

Intracervical lakes as sonographic marker of placenta accreta spectrum disorder in patients with placenta previa or low‐lying placenta

Pasquo

Ghi

Calì

et al. 2020

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Objective To evaluate the diagnostic accuracy of a new ultrasound sign, intracervical lakes (ICL), in predicting the presence of placenta accreta spectrum (PAS) disorder and delivery outcome in patients with placenta previa or low‐lying placenta. Methods This was a retrospective multicenter study of women with placenta previa or low‐lying placenta at ≥ 26 weeks' gestation, who were referred to three Italian tertiary units from January 2015 to September 2018. The presence of ICL, defined as tortuous anechoic spaces within the cervix which appeared to be hypervascular on color Doppler, was evaluated on ultrasound images obtained at the time of referral. The primary aim was to explore the diagnostic accuracy of ICL in detecting the presence and depth of PAS disorder. The secondary aim was to explore the accuracy of this sign in predicting total estimated blood loss, antepartum bleeding, major postpartum hemorrhage at the time of Cesarean section and need for Cesarean hysterectomy. The diagnostic accuracy of ICL in combination with typical sonographic signs of PAS disorder, was assessed by computing summary estimates of sensitivity, specificity, positive and negative predictive values, positive and negative likelihood ratios and diagnostic odds ratios (DOR). Results A total of 332 women with placenta previa or low‐lying placenta were included in the analysis, with a median maternal age of 33.0 (interquartile range, 29.0–37.0) years. ICL were noted in 15.1% of patients. On logistic regression analysis, the presence of ICL was associated independently with major postpartum hemorrhage (odds ratio (OR), 3.3 (95% CI, 1.6–6.5); P < 0.001), Cesarean hysterectomy (OR, 7.0 (95% CI, 2.1–23.9); P < 0.001) and placenta percreta (OR, 2.8 (95% CI, 1.3–5.8); P ≤ 0.01), but not with the presence of any PAS disorder (OR, 1.6 (95% CI, 0.7–3.5); P = 0.2). Compared with the group of patients without ultrasound signs of PAS disorder, the presence of at least one typical sonographic sign of PAS disorder in combination with ICL had a DOR of 217.2 (95% CI, 27.7–1703.4; P < 0.001) for placenta percreta and of 687.4 (95% CI, 121.4–3893.0; P < 0.001) for Cesarean hysterectomy. Conclusion ICL may represent a marker of deep villus invasion in women with suspected PAS disorder on antenatal sonography and anticipate the occurrence of severe maternal morbidity. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.