Subserosal and intramural ectopic pregnancy: toward a new classification for improved management

Ectopic pregnancies, while predominantly tubal, are increasingly recognized in non-tubal locations such as interstitial, cervical, abdominal, and intramural sites, largely due to assisted reproductive technologies and advanced maternal age. Intramural pregnancy (IMP) is rare, with heterogeneous clinical presentation and limited standardized management guidelines. Accurate classification and early diagnosis are essential, yet current nomenclature and imaging criteria inadequately capture the spectrum of intramural and subserosal variants. Recent evidence highlights that a significant proportion of pregnancies initially classified as intramural exhibit subserosal extension, indicating a progression toward the outer uterine wall rather than confinement within the myometrium. This distinction carries important clinical implications, as subserosal pregnancies are associated with higher risks of uterine rupture, hemorrhage, and failure of conservative medical therapy. The lack of refined subclassification can delay recognition, misguide treatment selection, and complicate outcome interpretation. Introducing a "subserosal pregnancy" subtype-defined by implantation originating within the myometrium, extending beyond 50% of the outer uterine wall, with residual myometrium ≤4 mm, and no continuity with the uterine cavity or fallopian tube-enables earlier identification, optimized surgical planning, and preservation of reproductive potential. Subclassification also improves reproducibility in reporting, facilitates registry-based research, and enhances multidisciplinary communication. Adoption of this framework aligns clinical terminology with pathophysiologic reality, guides risk stratification, and informs counseling for patients undergoing assisted reproduction. The International Intramural Pregnancy Data Registry will provide critical prospective data to refine diagnosis, management strategies, and long-term reproductive outcomes in this rare but clinically significant condition.