Table 1 CSP types and diagnostic criteria [12]

I

Partial implantation of the gestational sac in the uterine scar, thinning of the myometrium between the gestational sac and the bladder, thickness > 3 mm

II

Partial implantation of the gestational sac in the uterine scar, thinning of the myometrium between the gestational sac and the bladder, thickness ≤ 3 mm

III

Completely implantation of the gestational sac in the uterine scar and convex toward the bladder; or a mixed echogenic mass be seen in the lower uterine scar, with the mass bulging toward the bladder, CDFI shows a rich blood flow signal around the mass; significantly thinning or even absent of the myometrium between the gestational sac and the bladder, thickness ≤ 3 mm