Novel cross-over sign in cesarean scar pregnancy helps predicts the risk of invasive placentation

power-point slide by ISUOG

First trimester ultrasound scan evaluating the relationship between the gestational sac and the endometrial line in women with cesarean scar pregnancy(CSP) helps predicts the development of abnormally invasive placenta (AIP) and consecutive intra and post-operative surgical morbidities reports the results of a retrospective case series published in Journal of International Society of Ultrasound in Obstetrics and Gynecology.

Recent advances in prenatal imaging and increase rate of cesarean sections have led to increased diagnosis of CSP. Although, most of the patients with CSP present with severe hemorrhage or rupture uterus, that requires emergency surgical management, few advance further, evolving into AIP.

There is no reliable marker that can predict whether a woman with CSP will end up in early abortion or further progress to develop placenta percreta or other less severe forms of AIP.

A novel ultrasound cross-over sign (COS) has recently been thought to predict the evolution of CSP into different forms of AIP so that the intraoperative and postoperative risk can be stratified.

A straight line is drawn from internal cervical os to the fundus of the uterus in sagittal view through the endometrium. The gestational sac is identified, and its superior-inferior diameter measured. The COS is classified according to the relationship of ectopic sac diameter with the endometrial straight line into COS-1 and COS-2.

This case series identified 102 women over a period of 8 years with AIP diagnosis confirmed by histopathological examination (HPE), of whom 68 patients had a first-trimester ultrasound with a diagnosis of CSP. The scans were read by sonographers who did not have any idea about the pregnancy outcome and pathology reports.  

COS sign was assessed as mentioned, and all patients received counseling regarding the prognosis, risk, and post-operative complications. Women with severe AIP were delivered early, as compared to less severe variants.

All women underwent cesarean hysterectomy with temporary occlusion of the internal iliac artery and ureteric stent in place. At HPE, 34 cases were diagnosed with placenta percreta, 13 with placenta increta and 21 with placenta accreta.

Pregnancies with COS-1 had early deliveries, longer operating time, more blood loss and required much more packed red blood cells during surgery mean as compared with those with COS-2+ or COS-2–.

Thus, predicting the likely course CSP diagnosed by COS sign in the first trimester can improve shared decision making between the patient and provider about the surgical difficulties endured, amount of blood loss and need for cesarean hysterectomy.

Large, multi-center studies to determine the role of COS sign in predicting the severity of AIP in CSP is needed in future.

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