Diagnostic accuracy of first-trimester ultrasound in detecting abnormally invasive placenta in high-risk women with placenta previa

OBJECTIVES: To ascertain the diagnostic accuracy of ultrasound in detecting AIP during the first trimester (11-14 weeks of gestation) of pregnancy in women at risk of these conditions. METHODS: Retrospective analysis on prospectively collected data on women at risk for AIP based upon the presence of at least one prior CS and/or uterine surgery and placenta previa who had an ultrasound assessment for AIP since the 11-14 weeks scan. The ultrasound signs explored in the present study were: loss of clear zone, placental lacunae, bladder wall interruption, uterovescical hypervascularity. The potential of ultrasound and different ultrasound signs to predict the different types of AIP was assessed computing the summary estimates of sensitivity, specificity, diagnostic odd ratio, positive and negative likelihood ratios. RESULTS: One hundred and eighty-eight women with placenta previa and at least one previous caesarean section or uterine surgery were included in the study. All the ultrasound signs explored where significantly associated with the occurrence of AIP. Overall, ultrasound had a sensitivity of 84.3% (95% CI 74.7-91.4), a specificity of 61.9 (95% CI 51.9-71.2), a DOR of 8.6 (95% CI 4.1-19.3), a LR+ of 2.2 (95% CI 1.7-2.9) and a LR- of 0.3 (95% CI 0.1-0.4) in detecting AIP, when at least one ultrasound sign was used to make the diagnosis. Using two ultrasound signs to label a case as positive, increased the diagnostic accuracy in terms of specificity, while it did not affect sensitivity. Among the different ultrasound signs, the loss of the clear zone had a sensitivity of 84.4% (95% CI 74.7-91.4) and a specificity of (81.9% (95% CI 73.2-88.7) in detecting AIP, while the corresponding figures for placental lacunae and bladder wall interruption were 78.3% (95% CI 67.9-86.6) and 75.9% (95% CI 65.3-84.) and 81.0% (95% CI 72.1-88.0) and 99.1 (95% CI 94.8-100) respectively. The optimal combination of sensitivity and specificity was achieved when at least two imaging signs of AIP were used in the diagnostic algorithm. CONCLUSION: AIP can be detected since the first trimester of pregnancy in women at risk for this condition and that ultrasound performed between 11 and 14 weeks of gestation has an overall good diagnostic accuracy for detecting all types of AIP. However, these findings are applicable only to women with major placenta previa and prior uterine scar

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

OBJECTIVES: The primary aim of this systematic review was to ascertain whether ultrasound (US) signs suggestive of abnormally invasive placenta (AIP) are present in the first trimester. The secondary aims were to ascertain the strength of association and the predictive accuracy of such signs in detecting AIP in the first trimester of pregnancy. METHODS: MEDLINE, EMBASE, CINAHL and Cochrane databases (2000-2016) were searched. Only studies reporting the first trimester diagnosis of AIP that was subsequently confirmed in the third trimester either during operative delivery or by pathology were included. Meta-analysis of proportion, random-effect meta-analysis and hierarchical summary receiver operating characteristic curve (HSROC) analysis were used to compute the data. RESULTS: Seven studies (551 pregnancies at risk for 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 a low implantation of the gestational sac close to the previous uterine scar which was observed in 82.4% (95% CI 46.6-99.8) of the 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) cases affected by AIP. Pregnancies with a low implantation of the gestational sac had a significantly higher risk of AIP, (OR:19.6, 95% CI 6.7-57.3), with a sensitivity and a 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 are already present during the first trimester of pregnancy, especially before 11 weeks of gestation. Low anterior implantation of the placenta/sac close to or within the scar was the most common early US signs suggestive of AIP, although its individual predictive accuracy is not high

Diagnostic accuracy of ultrasound in detecting the depth of invasion in women at risk of abnormally invasive placenta: A prospective longitudinal study

Introduction: The aim of this study was to assess the diagnostic accuracy of ultrasound in detecting the depth of abnormally invasive placenta in women at risk. Material and methods: Prospective longitudinal study including women with placenta previa and at least one prior cesarean delivery or uterine surgery. Depth of abnormally invasive placenta was defined as the degree of trophoblastic invasion through the myometrium and was assessed with histopathological analysis. The ultrasound signs explored were: loss of clear zone, placental lacunae, bladder wall interruption, uterovesical hypervascularity, and increased vascularity in the parametrial region. Results: In all, 210 women were included in the analysis. When using at least one sign, ultrasound had an overall sensitivity of 100% (95% CI 96.5-100) and overall specificity of 61.9 (95% CI 51.9-71.2) for all types of abnormally invasive placenta. Using two ultrasound signs increased the diagnostic accuracy in terms of specificity (100%, 95% CI 96.5-100) but did not affect sensitivity. When stratifying the analysis according to the depth of placental invasion, using at least one sign had a sensitivity of 100% (95% CI 93.7-100) and 100% (95% CI 92.6-100) for placenta accreta/increta and percreta, respectively. Using three ultrasound signs improved the detection rate for placenta percreta with a sensitivity of 100% (95% CI 92.6-100) and a specificity of 77.2% (95% CI 69.9-83.4). Conclusion: Ultrasound has a high diagnostic accuracy in detecting the depth of placental invasion when applied to a population with specific risk factors for anomalies such as placenta previa and prior cesarean delivery or uterine surgery

Changes in ultrasonography indicators of abnormally invasive placenta during pregnancy

Objective: To ascertain whether the prevalence of ultrasonography signs of abnormally invasive placenta (AIP) changes during pregnancy. Methods: The present retrospective analysis included women with a prenatal diagnosis of AIP that was confirmed at delivery between January 1, 2007, and April 30, 2017, at the Department of Obstetrics and Gynaecology, Arnas Civico Hospital, Palermo, Italy. Ultrasonography signs of AIP were recorded at four different intervals during pregnancy: early first (6\ue2\u80\u939\uc2\ua0weeks), first (11\ue2\u80\u9314\uc2\ua0weeks), second (15\ue2\u80\u9324\uc2\ua0weeks), and third trimester (25\ue2\u80\u9336\uc2\ua0weeks). Results: There were 105 pregnancies included. Low implantation of the gestational sac was present on all ultrasonography images from the early first trimester compared with on 23 of 83 (27.7%) images from 11\ue2\u80\u9314\uc2\ua0weeks of pregnancy. The identification of loss of the clear space, placental lacunae, bladder wall interruption, and uterovesical hypervascularity all increased (all P<0.001) from the early first trimester onwards; these could all be identified in a majority of patients at 11\ue2\u80\u9314\uc2\ua0weeks of pregnancy. Conclusions: The prevalence of ultrasonography signs suggestive of AIP varied throughout pregnancy. During the early first trimester, indicators of AIP were similar to those of a cesarean scar pregnancy; classical ultrasonography signs of AIP were already present at 11\ue2\u80\u9314\uc2\ua0weeks of pregnancy for most patients