Natural History of Low Implantation and Cesarean Scar Pregnancy

To evaluate the natural history of low implantation and cesarean scar pregnancy and the prognostic features given professional organization recommendations against expectant management. Since 2013 the nomenclature has evolved from low implantation to the more recent cesarean scar pregnancy. Low implantation and cesarean scar pregnancies were identified from a maintained obstetric sonography database between 3/1/2013 and 12/31/2021. Inclusion criteria were CSP identified on sonogram and outcome information available. Ultrasounds (US) were reviewed blinded to clinical outcome for identification of niche, smallest myometrial thickness (SMT), and location of basalis (CY and DT). Clinical outcomes of interest including pregnancy outcome, need for intervention, hysterectomy, transfusion, pathologic findings, and morbidities were obtained by chart review. 101 pregnancies were identified (Table 1). Of these, 46% (n=46) failed prior to 20 weeks of gestation, 65% (n=30) required no intervention, 16 (35%) required intervention with 6 hysterectomies. There were 55 (55%) that progressed beyond 20 weeks. Of these, 39(71%) did not require a hysterectomy. In the overall cohort, 22 (21.8%) required hysterectomy and 16 (15.8%) required some type of intervention, thus 66.7% required no intervention. Of the 101 pregnancies, 43 met SMFM ultrasound criteria < 10 weeks and 28 at 10-14 weeks. The sensitivity, specificity, positive and negative predictive values (Table 2) suggest these US parameters do not identify significant invasion accurately enough to determine management. Over two thirds of cases require no intervention with expectant management of low implantation and cesarean scar pregnancy. Of those meeting SMFM criteria, the sensitivity, specificity, PPV and NPV have limitations in discerning clinical management.View Large Image Figure ViewerDownload Hi-res image Download (PPT)