Adverse outcome in Cesarean scar pregnancy continuing into mid-to-late gestation: systematic review and meta-analysis

To review systematically and assess quantitatively the incidence and risk of placenta accreta spectrum (PAS) disorders and hysterectomy in Cesarean scar pregnancy (CSP) continuing into mid-to-late gestation.

A comprehensive literature search was performed in PubMed, EMBASE, Cochrane Library, ClinicalTrials.gov, China National Knowledge Infrastructure (CNKI) and Yiigle databases from inception to 12 February 2025. Studies reporting the rates of PAS and/or hysterectomy in women with a singleton CSP that continued ≥ 14 weeks' gestation were eligible for inclusion. Data extracted included information on medical history, CSP classification and clinical manifestation, gestational age at delivery and pregnancy outcome. Data were synthesized as pooled incidences and odds ratios with 95% CIs, and random-effects models were used owing to high heterogeneity. Subgroup analyses were performed according to CSP subtype (Type I vs Type II vs Type III; and endogenous vs exogenous) and residual myometrial thickness (RMT) (≤ 3 mm vs > 3 mm).

Among 61 studies included in the systematic review, 20 studies (432 cases) were eligible for inclusion in the meta-analysis. Qualitative synthesis captured severe clinical phenotypes, including spontaneous uterine rupture and massive hemorrhage during Cesarean section. The pooled incidences of PAS and hysterectomy were 0.90 (95% CI, 0.81-0.96) and 0.39 (95% CI, 0.22-0.57), respectively. Marked heterogeneity was observed across CSP subtypes: Type-III and exogenous CSPs were associated with significantly higher odds of invasive PAS, hysterectomy and preterm delivery compared with Types-I/II and endogenous subtypes, respectively. Reduced RMT was associated significantly with increased odds of overall PAS and invasive PAS, and was predictive of hysterectomy on receiver-operating-characteristics-curve analysis. The pooled incidence of reaching ≥ 28 weeks' gestation was 0.85 (95% CI, 0.73-0.94), whereas the pooled incidence of reaching term (≥ 37 weeks) was 0.19 (95% CI, 0.10-0.30). Among studies that reported uterine rupture, the pooled incidence of this outcome was 0.05 (95% CI, 0.02-0.10).

Type-III and exogenous CSPs that progress into mid-to-late gestation present substantial risks for PAS and hysterectomy, with a low likelihood of term delivery. Type-I, Type-II and endogenous CSPs are associated with a comparatively lower risk of adverse outcome. CSP subtype and RMT are key determinants for risk stratification and individualized counseling. © 2026 International Society of Ultrasound in Obstetrics and Gynecology.