title: Natural history of Cesarean scar pregnancy on prenatal ultrasound: the crossover sign.
abstract: 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.
authors.affiliation: Department of Obstetrics and Gynaecology, Arnas Civico Hospital, Palermo, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Cali
authors.affiliation: Department of Obstetrics and Gynaecology, Arnas Civico Hospital, Palermo, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Forlani
authors.affiliation: Department of Obstetrics and Gynaecology, Division of Maternal-Fetal Medicine, New York University SOM, New York, NY, USA.
authors.forename: I E
authors.initials: IE
authors.lastname: Timor-Tritsch
authors.affiliation: Centre for Medical Education and Clinical Research (CEMIC), University Hospital, Buenos Aires, Argentina.
authors.forename: J
authors.initials: J
authors.lastname: Palacios-Jaraquemada
authors.affiliation: Department of Obstetrics and Gynaecology, Arnas Civico Hospital, Palermo, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Minneci
authors.affiliation: Department of Clinical Medicine, Faculty of Health Sciences, UiT-The Arctic University of Norway, Tromsø, Norway.
authors.forename: F
authors.initials: F
authors.lastname: D'Antonio
mesh_terms: D000328:Adult; D002585:Cesarean Section / Q000009:adverse effects; D002921:Cicatrix / Q000000981:diagnostic imaging* / Q000209:etiology; D005260:Female; D006801:Humans; D011237:Predictive Value of Tests; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011271:Pregnancy, Ectopic / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D012306:Risk; D016216:Ultrasonography, Prenatal
keywords: Cesarean scar pregnancy; morbidly adherent placenta; ultrasound