Early ultrasound diagnosis and management of intramural pregnancy: a case series report utilizing the FIGO leiomyoma classification system and 3D sonographic mapping
Intramural pregnancy, a rare ectopic pregnancy with the gestational sac implanted within the myometrium, poses significant diagnostic and therapeutic challenges. Current diagnostic criteria lack anatomical precision, leading to delayed management and high morbidity. This study proposes a novel diagnostic framework integrating the International Federation of Gynecology and Obstetrics (FIGO) leiomyoma classification system and advanced 3D transvaginal ultrasound, enabling anatomical risk stratification and individualized management. We retrospectively analyzed four intramural pregnancies, assessing clinical history, laboratory results, 2D/3D sonographic findings, treatment methods and outcomes. All cases underwent comprehensive evaluation using high-resolution transvaginal 2D/3D ultrasound (GE Voluson E8 or S8 systems with 5-6.5 MHz transvaginal probes). Lesions were systematically mapped according to the FIGO leiomyoma classification system, with particular attention to their spatial relationship with the uterine cavity and surrounding myometrium. Treatment strategies were tailored based on lesion characteristics, β-hCG levels, and fertility goals. Two distinct sonographic patterns were identified: gestational sac-type (Cases 1-2) and heterogeneous mass-type (Cases 3-4). The FIGO classification system (Types 2-5) effectively predicted the depth of myometrial invasion and guided therapeutic decisions. Type 3 (Case 1): Medical management with methotrexate (MTX) achieved resolution. Type 2-5 (Case 2): Ultrasound-guided fetal reduction preserved intrauterine pregnancy to term. Type 4 and Type 5 (Cases 3-4): Laparoscopic excision prevented uterine rupture, with lesions demonstrating significant myometrial thinning or serosal protrusion. High risk factors and key sonographic features are summarized, and diagnostic criteria are proposed. The integration of FIGO-based anatomical staging with advanced 3D sonographic evaluation provides a robust framework for early diagnosis and risk-stratified management of intramural pregnancy. This innovative approach significantly enhances diagnostic accuracy, facilitates appropriate treatment selection, and optimizes fertility preservation outcomes.