Proposed section structure
For this topic, a clinically appropriate structure includes: clinical background and unmet need; study design and registry methods; patient population and outcome definitions; major maternal and pregnancy outcomes; prognostic ultrasound findings; clinical interpretation and counseling implications; strengths and limitations; and a practical conclusion for specialists managing these high-risk pregnancies.
Highlights
Expectant management of live cesarean scar ectopic pregnancy was associated with substantial maternal morbidity in this international registry, including peripartum hysterectomy in 43.5% of cases.
Although 67.0% of pregnancies reached at least 23 weeks and resulted in live birth, 33.0% ended in pregnancy loss between 13+0 and 22+6 weeks.
A first-trimester residual myometrial thickness below 2.5 mm and enhanced subplacental vascularity were associated with higher hysterectomy risk.
The findings reinforce the value of expert early ultrasound for diagnosis, risk stratification, referral planning, and counseling.
Background
Cesarean scar ectopic pregnancy is an uncommon but increasingly recognized form of abnormal implantation in which the gestational sac implants within the fibrous and myometrial defect of a previous cesarean delivery scar. Its clinical importance lies not only in the immediate first-trimester risks of bleeding and uterine rupture, but also in the possibility that if the pregnancy continues, it may evolve into severe placenta accreta spectrum with catastrophic hemorrhage at miscarriage, delivery, or hysterectomy.
As cesarean delivery rates have risen globally and first-trimester transvaginal ultrasound has become more refined, the reported incidence of cesarean scar pregnancy has increased. Yet evidence guiding counseling remains limited because most publications are small case series, often focused on termination techniques rather than the natural history of pregnancies that continue. This creates a difficult counseling gap when a patient declines termination or when clinicians are trying to estimate the likelihood of fetal survival versus major maternal morbidity.
The International CSEP Registry study by Agten and colleagues addresses that gap by describing outcomes in viable first-trimester cesarean scar ectopic pregnancies managed expectantly and by identifying early ultrasound features associated with peripartum hysterectomy. For clinicians, this is one of the most practically relevant questions in the field: when a live cesarean scar pregnancy is continued, what are the realistic maternal and neonatal trade-offs, and can first-trimester imaging identify women at highest risk?
Study design
This was an analysis of an international registry established to collect anonymized ultrasound and clinical data on the diagnosis and management of cesarean scar ectopic pregnancy. Twenty-one centers across 13 countries contributed data for this report, offering broader geographic representation than most prior series.
The study included first-trimester live cases recorded between August 29, 2018, and December 31, 2023, in which the pregnancy was managed expectantly or the patient declined pregnancy termination. Cases that were terminated or were nonviable were excluded from this analysis. The primary descriptive outcomes were progression to viability, pregnancy loss, development of placenta accreta spectrum, and need for peripartum hysterectomy. The investigators also examined first-trimester ultrasound findings, particularly residual myometrial thickness and scar-area vascularity, in relation to hysterectomy risk.
The report is observational and descriptive rather than comparative. There was no randomized intervention, no formal control group, and no multivariable causal model to adjust for confounding. That is important when interpreting associations. Still, in a rare condition where randomized data are not realistically available, well-curated registry evidence can be highly informative.
Study population
Among 708 registered cesarean scar ectopic pregnancies, 593 were excluded because the pregnancy was terminated or not viable. The final study cohort comprised 115 viable first-trimester pregnancies that were continued.
This denominator matters. The paper does not describe the overall prognosis of all cesarean scar pregnancies, but rather the subgroup in which a live first-trimester cesarean scar implantation was allowed to continue. That makes the findings especially relevant to counseling after diagnosis, once expectant management is being considered or has already been chosen.
Key findings
Pregnancy continuation was possible, but often at high maternal cost
Of the 115 pregnancies, 77 cases, or 67.0%, progressed to at least 23+0 weeks. Live birth likewise occurred in 77 of 115 cases, again 67.0%. On the surface, this indicates that continuation to viability is possible in a majority of selected viable first-trimester cases.
However, this should not be mistaken for reassuring prognosis. Thirty-eight of 115 pregnancies, or 33.0%, ended in pregnancy loss between 13+0 and 22+6 weeks. That rate of midtrimester loss is strikingly high. In practical terms, roughly one in three women continuing such a pregnancy did not reach conventional viability, despite having a live pregnancy in the first trimester.
Peripartum hysterectomy was common
The most sobering finding was the frequency of hysterectomy. Overall, 50 of 115 women, or 43.5%, underwent peripartum hysterectomy. Seven of these hysterectomies, representing 6.1% of the full cohort, occurred before 23 weeks. This indicates that severe maternal morbidity was not confined to late gestation or delivery; catastrophic clinical deterioration may occur even before viability.
For counseling purposes, the hysterectomy rate is arguably the most important single number in the paper. A risk approaching one in two radically changes the ethical and clinical framework of expectant management. Hysterectomy implies not only major blood loss and surgical complexity, but also permanent loss of fertility, potential urinary tract injury, intensive care use, and long-term psychological consequences.
Placenta accreta spectrum is the likely biological bridge
The authors report collection of placenta accreta spectrum outcomes, consistent with current understanding that ongoing cesarean scar pregnancy can evolve into severe morbidly adherent placentation. Although the abstract foregrounds hysterectomy more than the exact placenta accreta spectrum proportion, the biological continuum is central to interpretation: implantation into a deficient scar with little or no normal decidua allows abnormal trophoblastic invasion into myometrium and beyond, predisposing to placenta accreta, increta, or percreta and to uncontrollable bleeding at separation or attempted removal.
This concept is well established in prior literature and is strongly consistent with the present findings. In effect, the paper provides multicenter outcome data confirming that the danger of continued cesarean scar pregnancy is not hypothetical. It materializes clinically as second-trimester loss, invasive placentation, major hemorrhage, and hysterectomy.
Ultrasound markers associated with hysterectomy
The most clinically actionable aspect of the study was the analysis of first-trimester ultrasound features associated with hysterectomy.
A residual myometrial thickness below 2.5 mm identified 80% of women requiring peripartum hysterectomy, based on 16 of 20 cases. The test characteristics reported were a sensitivity of 64%, specificity of 75%, and positive predictive value of 76%.
These numbers deserve careful interpretation. The positive predictive value of 76% means that in this selected high-risk cohort, a woman with residual myometrial thickness below 2.5 mm had a high observed probability of hysterectomy. The specificity of 75% is moderate, suggesting the marker has useful discriminatory ability, though not enough to stand alone. The sensitivity of 64% indicates that more than one-third of hysterectomies would not be identified by this threshold, so a myometrium measuring 2.5 mm or more cannot be considered reassuring.
Enhanced subplacental vascularity in the scar area was also significantly more frequent in women who underwent hysterectomy than in those who retained their uterus: 25 of 29 cases, or 86.2%, versus 13 of 22 cases, or 59.1%. The odds ratio was 4.13 with a 95% confidence interval of 1.09 to 18.4 and a p value of 0.04.
This association is biologically plausible. Marked low-segment or subplacental vascularity on color Doppler likely reflects active trophoblastic invasion and neovascular remodeling at the scar implantation site, features that would be expected in placenta accreta spectrum and severe hemorrhagic risk.
Clinical interpretation
Several messages emerge for maternal-fetal medicine specialists, early pregnancy units, sonologists, and gynecologic surgeons.
First, early diagnosis is essential, but diagnosis alone is not enough. Once a live cesarean scar pregnancy is identified, clinicians should move rapidly from detection to structured risk assessment. This includes careful evaluation of implantation site, direction of sac growth, residual myometrial thickness, placental position, and color Doppler vascularity, preferably by an operator experienced in cesarean scar pregnancy and placenta accreta spectrum.
Second, counseling must be frank and numerically grounded. Patients who continue a viable cesarean scar pregnancy should understand that live birth may occur in about two-thirds of cases in this registry, but against a background of one-third midtrimester loss and nearly 44% hysterectomy. These are not competing outcomes in the abstract; they represent a genuine maternal-fetal conflict in which the chance of neonatal survival coexists with major risk of hemorrhage, uterine loss, and complex surgery.
Third, women with residual myometrial thickness below 2.5 mm and pronounced subplacental vascularity should be treated as particularly high risk. Although these markers are not perfect predictors, they can help triage referral to tertiary centers with expertise in placenta accreta spectrum, blood product access, interventional radiology when appropriate, anesthetic support, and multidisciplinary surgical teams.
Fourth, the paper supports the concept that continued cesarean scar pregnancy belongs on the placenta accreta spectrum pathway early in gestation, rather than being treated as a routine pregnancy with delayed specialist involvement. In practice, that means serial expert ultrasound, anticipatory planning for hemorrhage, individualized timing of delivery or intervention, and preparedness for cesarean hysterectomy.
How this fits with existing literature and guidance
Prior studies and expert reviews have suggested that cesarean scar pregnancy and placenta accreta spectrum may represent different stages of the same pathophysiologic process. Timor-Tritsch, Jurkovic, and others have emphasized the central role of transvaginal ultrasound in diagnosis and the severe maternal risks of continuation. The current registry strengthens that framework by providing multicenter outcome estimates focused specifically on viable pregnancies managed expectantly.
Available guideline and consensus documents, including publications from expert ultrasound and obstetric groups, generally support early diagnosis and individualized counseling, often favoring active treatment because of the risk of hemorrhage, uterine rupture, and placenta accreta spectrum. This study does not compare termination with continuation, but its results explain why many centers recommend intervention once the diagnosis is secure.
At the same time, the paper is valuable because it avoids reducing counseling to a simplistic directive. Some patients decline termination for personal, ethical, religious, or fertility-related reasons. For those patients, clinicians need real-world numbers and credible prognostic markers. This registry begins to supply them.
Strengths
The study has several important strengths. It draws on a relatively large international dataset for a rare disorder, includes only live first-trimester cases relevant to expectant management decisions, and reports clinically meaningful outcomes rather than surrogate imaging endpoints alone. The focus on ultrasound markers is especially useful because these findings are available at the point of care and can be incorporated into counseling and referral planning.
The international multicenter design also improves external relevance. Cesarean scar pregnancy is rare enough that single-center experience can be misleading. By aggregating data across 21 centers in 13 countries, the registry provides a broader snapshot of real-world practice.
Limitations
Important limitations should temper interpretation. This was a registry-based observational analysis, so selection bias is unavoidable. Cases entered into the registry may overrepresent more severe or more specialized referrals. Management protocols, imaging definitions, and thresholds for intervention likely varied across centers. The abstract does not provide full detail on central image review, interobserver variability, or standardized criteria for placenta accreta spectrum and hysterectomy decisions.
Sample size becomes smaller in the ultrasound subgroup analyses, as reflected by denominators such as 20, 29, and 22. That reduces precision and explains the wide confidence interval around the odds ratio for vascularity. The 95% confidence interval of 1.09 to 18.4 suggests uncertainty in the exact magnitude of effect, even though the direction of association is clinically plausible.
Because only pregnancies that were continued were analyzed, the study cannot estimate the comparative effectiveness or safety of expectant management versus active treatment. Nor can it determine whether early intervention guided by ultrasound findings would reduce hysterectomy risk. Those remain open questions.
Finally, neonatal outcomes beyond live birth are not detailed in the abstract. For comprehensive patient counseling, information on gestational age at delivery, neonatal morbidity, NICU stay, and long-term infant outcomes would be highly valuable.
Practical implications for clinicians
For front-line clinicians, the immediate takeaway is to recognize viable cesarean scar pregnancy as a time-sensitive, high-risk diagnosis requiring expert imaging and multidisciplinary discussion.
When the pregnancy is continued, early transvaginal ultrasound should document residual myometrial thickness and scar-area vascularity, among other anatomic features. Findings of less than 2.5 mm residual myometrium or markedly increased subplacental vascularity should heighten concern for severe placenta accreta spectrum and eventual hysterectomy.
Patients should be referred early to centers capable of managing massive obstetric hemorrhage. Counseling should explicitly address the possibility of second-trimester loss, previable emergency surgery, blood transfusion, bladder or adjacent organ involvement, preterm delivery, and permanent loss of fertility through hysterectomy.
In highly selected cases where expectant management proceeds, the clinical team should frame care as ongoing surveillance of a pregnancy at major risk, not reassurance after the first trimester. This conceptual shift may help avoid underestimating danger during periods of apparent fetal well-being.
Conclusion
The International CSEP Registry analysis provides some of the clearest evidence to date that viable cesarean scar ectopic pregnancy continued beyond the first trimester is associated with major maternal risk. While about two-thirds of pregnancies in this cohort reached viability and resulted in live birth, one-third ended in second-trimester loss and nearly half of women underwent peripartum hysterectomy. A first-trimester residual myometrial thickness below 2.5 mm and enhanced subplacental vascularity were associated with increased hysterectomy risk, underscoring the role of expert ultrasound in early risk stratification.
For practice, the message is straightforward: continuation of cesarean scar pregnancy may lead to neonatal survival, but often at a very high maternal price. Counseling should be individualized, data-driven, and delivered early, with prompt referral to specialized multidisciplinary care.
Funding and trial registration
The abstract provided does not report a ClinicalTrials.gov registration number. Specific funding details are not included in the abstract and should be confirmed from the full article.
References
Agten AK, Brunnschweiler E, Timor-Tritsch I, Jurkovic D, Huirne J, Bartels HC, El-Haieg D, Coutinho CM, Agostini A, Nieto-Calvache AJ, Prefumo F, Buonomo F, Cordoba M, Ross J, Pateisky P, Ajjawi S, Manegold-Brauer G, CSEP collaborative network. Outcome of cesarean scar ectopic pregnancy continued to viability: Data from the International CSEP Registry. American Journal of Obstetrics and Gynecology. 2026-06-04. PMID: 42248443. https://pubmed.ncbi.nlm.nih.gov/42248443/
Timor-Tritsch IE, Monteagudo A, Cali G, Palacios-Jaraquemada J, Maymon R, Arslan AA. Cesarean scar pregnancy and early placenta accreta share common histology. Ultrasound in Obstetrics and Gynecology. 2014;43(4):383-395.
Jurkovic D, Hillaby K, Woelfer B, Lawrence A, Salim R, Elson CJ. First-trimester diagnosis and management of pregnancies implanted into the lower uterine segment Cesarean section scar. Ultrasound in Obstetrics and Gynecology. 2003;21(3):220-227.
Cali G, Timor-Tritsch IE, Palacios-Jaraquemada J, Monteagudo A, Buca D, Forlani F, Minneci G, Foti F, Familiari A, Scambia G, D’Antonio F. Outcome of Cesarean scar pregnancy managed expectantly: systematic review and meta-analysis. Ultrasound in Obstetrics and Gynecology. 2018;51(2):169-175.
Society for Maternal-Fetal Medicine (SMFM), Miller R, Gyamfi-Bannerman C, et al. Publications and expert guidance on placenta accreta spectrum and cesarean scar pregnancy provide relevant context for referral and multidisciplinary management; readers should consult current SMFM and international ultrasound society documents for local practice integration.