The Cesarean Scar of Pregnancy: Ultrasound Findings and Expectant Management Outcomes

Abstract

Background: The nomenclature has evolved from low implantation to cesarean scar pregnancy and criteria are recommended for identification. Management guidelines include pregnancy termination due to life-threatening complications. Objective: To apply ultrasound (US) parameters recommended by the Society for Maternal Fetal Medicine to terminate CSP pregnancies in women with who were expectantly managed. Study Design: Pregnancies were identified between 3/1/2013 and 12/31/2020. Inclusion criteria were women with CSP or low implantation identified on US. Studies were reviewed for niche, smallest myometrial thickness (SMT), and location of basalis blinded to clinical data. Clinical outcomes: pregnancy outcome, need for intervention, hysterectomy, transfusion, pathologic findings, and morbidities, were obtained by chart review. Results: Of 101 pregnancies with low implantation, 43 met Society for Maternal Fetal Medicine (SMFM) criteria <10 weeks and 28 at 10-14 weeks for CSP. At < 10 weeks, SMFM criteria identified 45/76 women; of these 13 required hysterectomy; there were 6 who required hysterectomy who did not meet SMFM criteria. At 10-<14 weeks, SMFM criteria identified 28/42 women; of these 15 required hysterectomy. US parameters yielded significant differences in women requiring hysterectomy, at<10 weeks and 10<14weeks gestational age epochs, but the sensitivity, specificity, positive and negative predictive values of these US parameters have limitations in identifying invasion to determine management. Of the 101 pregnancies, 46 (46%) failed < 20 weeks, 16 (35%) required medical/surgical management including 6 hysterectomies; 30 (65%) required no intervention. There were 55 pregnancies (55%) that progressed beyond 20 weeks. Of these, 16 required hysterectomy (29%) while 39 (71%) did not. In the overall cohort of 101, 22 (21.8%) required hysterectomy and an additional16 (15.8%) required some type of intervention, while 66.7% required no intervention. Conclusion: SMFM US criteria were positive in yielding significant findings, but the sensitivity, specificity, PPV and NPV have limitations in discerning clinical management