Contrast-enhanced ultrasonography: a potential way for diagnosing cesarean scar pregnancy

Cesarean scar pregnancy (CSP) is a condition in which the gestational sac implants within the scar tissue of a previous cesarean section uterine incision. This potentially life-threatening condition can result in severe, uncontrollable bleeding for the patient. Early and definite diagnosis is crucial. This study aims to investigate the imaging characteristics and the diagnostic performance of contrast-enhanced ultrasonography (CEUS) on CSP.

This retrospective study included patients suspected of having CSP by transvaginal ultrasound (TVUS) between October 2012 and October 2023 at our Hospital. The clinical data, TVUS findings, CEUS images, and intraoperative findings were obtained. Based on surgical and pathological findings, patients were classified into CSP and non-CSP groups. The CSP group was further subdivided into gestational sac-type CSP and mass-type CSP according to TVUS findings.

A total of 124 patients for whom we performed both TVUS and CEUS were included for the final analysis, among them, 102 were confirmed as CSP and 22 as non-CSP by surgical and pathological findings. The diagnostic accuracy of TVUS was 83.1%. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of CEUS were 100% (95% CI: 0.964-1.000), 95.45% (95% CI: 0.849-0.999), 99.03% (95% CI: 0.969-0.999), 100% (95% CI: 0.855-1.000), and 99.19% (95% CI: 0.969-0.999). On CEUS, the CSP group showed significant differences in the initial site of contrast enhancement and myometrial thickness compared with the non-CSP group (0.15±0.12 cm vs. 0.27±0.13 cm, P=0.005). The gestational sac-type and mass-type CSP subgroups demonstrated significant differences in enhancement time, initiation site, enhancement pattern, and contrast agent washout time (all P<0.05). Early enhancement in gestational sac-type CSP typically appeared as arcuate high enhancement, while mass-type CSP showed irregular high enhancement. The overall diagnostic accuracy of CEUS for CSP classification reached 99.2%.

In patients with high suspicion of CSP, CEUS could help provide better characterization of lesion's vascular features and classification of different CSP subtypes.