4.1. Summary of Main Results
This retrospective study evaluated the clinical characteristics and treatment outcomes of 107 patients with tubal ectopic pregnancy managed at the University Hospital of Parma.
The MTX success rate was 72%, aligning with published data. The patients treated surgically presented with significantly higher β-hCG levels, larger gestational sacs, and more frequent symptoms, including pelvic pain and hemodynamic instability, consistent with institutional criteria. A sixfold difference in initial β-hCG levels was observed between the patients treated medically and those undergoing primary surgery, reflecting the pre-established selection criteria that stratify patients into two clinically distinct groups (see
Table 5).
The demographic and obstetric variables were comparable between the treatment groups. A previous ectopic pregnancy did not influence treatment allocation or outcome.
Gestational sac diameter was the strongest predictor of MTX failure. The ROC curve analysis identified a threshold of >20 mm (AUC 0.82, sensitivity 60%, specificity 93%).
Among the patients receiving MTX, 20 responded to a single dose, and 6 required retreatment. No significant associations were found between MTX failure and age, BMI, β-hCG level, or gestational age. Notably, some successful cases involved β-hCG levels > 5000 mIU/mL, suggesting that MTX may remain a viable option in selected cases beyond conventional thresholds.
Approximately one-third of the patients required retreatment. No demographic or clinical variables were associated with this need. Conditions such as endometriosis, fibroids, or prior pelvic surgery were not statistically significant but may warrant further study.
4.2. Results in the Context of the Published Literature
Despite the availability of evidence on the efficacy of both medical and surgical approaches in the management of tubal ectopic pregnancy, the selection criteria for MTX remain inconsistent across international guidelines, particularly regarding β-hCG thresholds and gestational sac dimensions [
5,
11,
14]. While β-hCG levels below 1500 mIU/mL are considered optimal for medical management due to their association with lower retreatment rates [
23], robust evidence supports the safety of repeated MTX dosing. This has allowed treatment to be safely extended to patients with levels up to 5000 mIU/mL who meet appropriate clinical criteria [
7].
Our study contributes to this discussion by reporting real-world outcomes from a referral center applying standardized protocols. We also explored clinical and sonographic predictors of medical treatment success that may support the refinement of current eligibility criteria.
An important aspect emerging from our analysis concerns the evaluation of predictive factors for MTX success. Although the existing literature suggests that elevated β-hCG levels (>5000 mIU/mL) are associated with increased risk of treatment failure [
23,
24], and current guidelines discourage MTX use in this setting [
5,
11,
14], our results support the need for an integrated evaluation of treatment eligibility. In our cohort, the patients who responded successfully to MTX had, on average, higher initial β-hCG levels compared to those who experienced treatment failure. However, this difference was not statistically significant and should be interpreted as a descriptive finding rather than a clinically relevant association. Given the substantial overlap in β-hCG values between responders and non-responders, mean levels alone are not appropriate as decision-making thresholds. Nevertheless, these findings suggest that while higher β-hCG levels may reduce MTX efficacy, they do not entirely preclude successful medical management [
24]. Consequently, rigid exclusion criteria based solely on β-hCG may unnecessarily restrict patient eligibility for conservative treatment. Notably, our data indicated that, in this cohort, only gestational sac diameter appeared to predict failure of a single MTX administration. However, we acknowledge that the small sample size limits the power of this finding, and the role of β-hCG cannot be definitively excluded.
We hypothesize that due to the wide range of β-hCG values and the variability in metabolic activity of trophoblastic tissue, β-hCG alone may not accurately reflect the biological behavior or maturity of the ectopic pregnancy. In contrast, gestational sac diameter might more reliably indicate the developmental stage and sensitivity to MTX therapy. The diameter of the gestational sac likely reflects the trophoblastic mass more accurately than β-hCG levels and may better predict the likelihood of successful resolution with systemic Methotrexate, particularly in the absence of an embryonic pole. Recently, a nomogram for the prediction of MTX success was proposed by Zeevi et al. based on a retrospective series of more than 300 patients treated with MTX for EP [
25]. In this cohort, the presence of a fetal pole was associated with an odds ratio (OR) for MTX failure of 4.25 (95% CI: 1.05–17.2). The only other factor associated with MTX failure in the multivariable analysis was β-hCG level on day 1 after treatment administration; however, the clinical utility of this parameter is limited by its post-exposure nature. Interestingly, the impact of gestational sac diameter was not demonstrated [
25] However, the mean gestational sac diameters in the population of the previous study were significantly smaller than in ours—14 mm and 13 mm in the success and failure groups, respectively. This may suggest that, in the clinical setting in [
25], patients with smaller gestational sacs are more often selected for MTX treatment, possibly reflecting different selection criteria compared to our institution [
25]. Nevertheless, supporting our hypothesis, the presence of a fetal pole may be a marker of a more metabolically active and viable ectopic pregnancy, possibly indicating reduced responsiveness to MTX more accurately than β-hCG levels alone. In fact, it was previously reported that, even in intrauterine pregnancies, gestational sac dimensions correlate more strongly with viability than single-point β-hCG measurements, as both endogenous and analytical factors can influence β-hCG levels [
26,
27].
Given the increasing attention to fertility preservation, particularly in young women of reproductive age affected by both non-oncologic and oncologic conditions [
28,
29], the comparative effectiveness of medical versus surgical management has been widely investigated, especially in terms of reproductive outcomes. The DEMETER trial, a randomized controlled study involving 400 patients conducted in France, found no significant differences in two-year spontaneous pregnancy rates between patients treated with MTX and those managed surgically, with live birth rates of 67% and 64–70%, respectively. Moreover, no advantage was found in salpingostomy vs. salpingectomy [
30]. Similarly, the European Surgery in Ectopic Pregnancy (ESEP) multicenter trial compared salpingectomy and salpingostomy in women with a healthy contralateral tube, showing comparable cumulative pregnancy rates of 56.2% and 60.7%, respectively, and concluded no clear advantage of one surgical approach over the other [
31]. In addition to limited evidence supporting its benefits, salpingostomy also has a non-negligible risk of persistent trophoblastic tissue (TRAP), which occurs in approximately 10% of cases [
32]. In light of these findings, in our center, salpingectomy is the preferred surgical approach and was the treatment of choice in patients elected for surgery in our cohort.
Recent data from Düz et al. further confirmed the comparability of reproductive outcomes across treatment modalities [
33]. Their 2022 study reported no significant differences in intrauterine pregnancy rates between patients treated with MTX, those undergoing primary surgery, and those requiring surgery following medical treatment failure. These findings support the notion that, in appropriately selected patients, conservative management is not inferior to surgical treatment in terms of fertility preservation.
Our findings are consistent with this study. Among the 50 patients in our cohort with available follow-up data, 68% achieved a term live birth, with no statistically significant difference between the MTX (52.9%) and surgical (75.8%) groups. Most of the pregnancies occurred spontaneously, and only 10% required assisted reproductive techniques. The numerically higher rate in the surgical group was not statistically significant, in line with the non-inferiority of MTX compared to radical surgery reported in the existing literature.
Over the course of the study period, we observed a progressive increase in the use of MTX, particularly after 2019. In 2019, only 11% of patients were treated medically, whereas this proportion rose to 46% by 2023. This trend suggests growing clinical confidence and institutional familiarity with conservative protocols. Furthermore, half of the surgical conversions following MTX failure occurred in 2019, while only one or two such cases were recorded annually in the subsequent years. These data reflect increased experience and protocol adherence, but also the implementation of international guidelines and growing evidence supporting the efficacy of repeated MTX administration, contributing to more accurate patient selection and improved treatment outcomes [
34,
35].
Taken together, these findings reinforce the growing consensus that both MTX and salpingectomy are valid and effective treatment options for tubal ectopic pregnancy, offering comparable fertility outcomes when applied according to clear clinical criteria. They also highlight the importance of individualized care, supported by accurate ultrasound assessment and appropriate counseling, in optimizing both clinical results and patient-centered goals.
4.3. Strengths and Limitations
The main strengths of this study include the homogeneity of clinical management, ensured by shared protocols within a single center, and the consistent application of eligibility criteria. The flexibility in β-hCG thresholds reflects real-life clinical reasoning and enhances the generalizability of the findings.
Another strength is the longitudinal observation of practice trends over five years, documenting the progressive adoption of conservative management and improved selection of candidates for MTX.
Finally, follow-up data on fertility outcomes, available for nearly half of the cohort, provide additional value by linking treatment strategies with long-term reproductive results. The follow-up data on fertility outcomes were collected through structured telephone interviews and included only pregnancies resulting in live births, a clinically meaningful endpoint in reproductive medicine.
Nonetheless, several limitations must be acknowledged. As a retrospective study, it is subject to potential data omissions and selection bias, including possible recall bias from follow-up interviews. The observed imbalance in the treatment groups may reflect a greater inclusion of patients not eligible for MTX during the study period, as well as the centralization of complex and emergency cases at our institution from nearby hospitals. Moreover, the relatively small sample size limits the statistical power, particularly for subgroup comparisons. Future prospective studies with larger cohorts would help validate our findings and refine treatment algorithms.
4.4. Implications for Future Research and Clinical Practice
Our findings suggest that sonographic parameters, particularly gestational sac diameter, are the strongest predictors of successful medical treatment. A diameter < 2 cm appears to be a strong predictor of MTX success, potentially improving the accuracy of pre-treatment counseling regarding the likelihood of resolution with medical therapy, and guiding subsequent decisions in the event of single-dose failure. Conversely, β-hCG levels above 5000 mIU/mL may unjustifiably discourage MTX use, despite favorable clinical conditions in selected patients. These findings provide a rationale for future prospective studies and may prompt a reconsideration of current guideline-endorsed criteria for choosing between MTX and salpingectomy. If validated, a broader eligibility framework for MTX could be proposed, wherein elevated β-hCG levels alone would not preclude conservative management in the presence of a permissive gestational sac diameter.
Given its accessibility and non-invasive nature, transvaginal ultrasound plays a key role in the initial evaluation and therapeutic planning of ectopic pregnancy [
36]. Its routine use can enhance patient selection for conservative treatment and improve individualized care.
Future studies should aim to validate this cut-off in larger, prospective cohorts, and to explore additional clinical or biochemical predictors of MTX response. Long-term outcomes, including both reproductive and psychological well-being, should also be assessed. Incorporating these elements into patient counseling may support more individualized, fertility-preserving treatment strategies, aligned with patient values and reproductive goals.