A primary fistula connecting a broad ligament leiomyoma to the cervix.

A 35-year-old woman presented with irregular vaginal bleeding persisting for over 3 months. The patient is unmarried and has a sexual history (Gravida 0, Para 0). The gynecological examination revealed no significant abnormalities. She had no history of surgery or trauma, nor any notable family history. The serum β-hCG level was measured at 0.5 IU/L. The transvaginal ultrasound revealed features initially interpreted as a bicornuate unicollis uterus according to the ASRM 2021 classification [ 3 ], with 2 distinct uterine cavities communicating with a single cervix ( Fig. 1 A). The left myometrium demonstrated heterogeneous echogenicity, and a heterogeneous hypoechoic mass was identified within the left uterine cavity ( Fig. 1 B). The right myometrium exhibited homogeneous echogenicity, with the endometrium in the right uterine cavity appearing centrally located. Both ovaries were clearly visualized, with no apparent abnormalities. Hysteroscopy revealed a prominent cavity on the left side of internal os of the cervical canal, containing aged clots and mucus ( Fig. 1 D). Following irrigation, no significant endometrium were observed. Another channel was identified at the same level on the right side, inside which a normally shaped uterine cavity appeared, with the bilateral fallopian tube openings visible. The patient underwent laparoscopic resection of the pelvic lesion and hysterography. During the procedure, the uterus appeared to be normal size. A solid mass measuring approximately 8 × 7 cm was identified in the anterior lobe of the left broad ligament, with its pedicle located on the left side of uterine isthmus. The pedicle was excised, and the mass was resected. A fistula was found connecting the mass to the cervix ( Fig. 1 E). Postoperative pathology confirmed the mass to be a leiomyoma with hyaloid degeneration. The patient experienced an uneventful postoperative recovery and was well at 6-mouth follow-up. Fig. 1 Transvaginal 3-dimensional ultrasound imaging revealed 2 distinct uterine cavities communicating with a single cervix (A). A solid mass was observed within the left cavity. Color Doppler ultrasound indicated no evident blood flow signal within the mass (B). Two-dimensional ultrasound images of the uterine fundus in revealed a smooth and flat uterine fundus without obvious serosal indentation, the right uterine cornu exhibits a well-defined contour, whereas the left uterine cornu demonstrates a blurred outline (C). Hysteroscopy findings exhibited horizontally visible dual channels at the internal os of the cervical canal (arrow) (D). Intraoperative observations of broad ligament leiomyoma displayed a large cavity (E). Fig 1 Transvaginal 3-dimensional ultrasound imaging revealed 2 distinct uterine cavities communicating with a single cervix (A). A solid mass was observed within the left cavity. Color Doppler ultrasound indicated no evident blood flow signal within the mass (B). Two-dimensional ultrasound images of the uterine fundus in revealed a smooth and flat uterine fundus without obvious serosal indentation, the right uterine cornu exhibits a well-defined contour, whereas the left uterine cornu demonstrates a blurred outline (C). Hysteroscopy findings exhibited horizontally visible dual channels at the internal os of the cervical canal (arrow) (D). Intraoperative observations of broad ligament leiomyoma displayed a large cavity (E).

Written informed consent was obtained from the patient for publication of this case report and any accompanying images.

Gynecologists and sonographers should be aware that atypical imaging findings in a bicornuate unicollis uterus may suggest rare pathological conditions, such as broad ligament leiomyoma associated with a primary fistulous tract communicating with the cervix. A systematic evaluation of key uterine anatomical structures is essential to minimizing diagnostic errors.

This study presents a rare case of a primary fistula connecting the broad ligament leiomyoma to the cervix, a condition that has been previously documented as a potential complication arising from uterine artery embolization(UAE) [ [4] , [5] , [6] , [7] ]. However, the precise mechanism underlying the formation of such a fistula remains undetermined. Some scholars propose that fistulation likely occurs after myoma degeneration and adjacent tissue necrosis and breakdown [ 7 ]. In contrast to the previously mentioned cases, the patient in question had no history of UAE, ablation therapy, recent miscarriage, or GnRH agonists use, and these negative findings further support the diagnosis of a primary fistula case. The potential mechanisms of fistula formation in this case may include hyaline degeneration of the broad ligament leiomyoma, followed by central necrosis of the tumor mass and subsequent erosion of adjacent cervical tissues. This rare case of misdiagnosis offers valuable insights for both clinical practice and imaging diagnostics. While the majority of broad ligament leiomyomas typically present as asymptomatic pelvic masses, a subset may initially manifest with vaginal bleeding as their primary clinical symptom. The preoperative misdiagnosis in this case underscores the critical importance of identifying key anatomical landmarks in gynecological ultrasonography. Specifically, it involves the following aspects: First, precise localization of the uterine cornua are essential. On the transverse ultrasound plane, the uterine cornua are situated bilaterally at the fundus, appearing as triangular or obtuse-angled protrusions. These structures mark the openings of the uterine ostia of the fallopian tubes and serve as critical anatomical landmarks for differentiating intrauterine from extrauterine pathologies. Retrospective analysis of the 2-dimensional ultrasound images of the uterine fundus in this case revealed a smooth and flat uterine fundus without obvious serosal indentation ( Fig. 1 C). The right uterine cornu exhibits a well-defined contour, whereas the left uterine cornu demonstrates a blurred outline due to compression and displacement by the large lesion located posterolaterally on the left. This alteration in morphology and position serves as the primary diagnostic clue, suggesting that the lesion likely originated within the uterus and subsequently extended into the broad ligament region. Although the bilateral fallopian tubes were not clearly visualized on the ultrasound images in this case, subsequent hysteroscopic examination clearly demonstrated the ostia of both fallopian tubes, thereby excluding the initial diagnosis of a Müllerian anomaly. Second, accurate assessment of endometrial cavity morphology is crucial. In transverse section, the normal endometrial cavity typically appears as a linear or fusiform hyperechoic structure, with symmetry serving as a key indicator for evaluating uterine compression or invasion. In this case, the true endometrial cavity is situated anterolaterally to the right, whereas a pseudocavity resulting from central necrosis of a broad ligament leiomyoma is located posterolaterally on the left, the pseudocavity exerts compressive effects on the true endometrial cavity, leading to morphological asymmetry and mild rightward deviation. This finding strongly suggests a close anatomical relationship between the lesion and the uterine myometrium, constituting the second key imaging feature that shifts diagnostic consideration from an ``adnexal mass'' to a uterine origin. Third, accurate determination of uterine orientation provides the foundation for precisely delineating the spatial relationships among lesions and the uterus, cervix, and vagina. Here, a substantial mass is situated in the left posterior aspect of the uterus, exerting marked compression on the left lateral wall of the normally positioned uterus, leading to midline deviation. This positional change aids in distinguishing the condition from disorders characterized by diffuse uterine enlargement, such as adenomyosis. Although 3-dimensional ultrasound provides more comprehensive spatial information and enables clearer, more intuitive visualization of uterine cavity morphology as well as the spatial relationship between the uterine cavity and the fundus [ 8 , 9 ], its clinical application has not yet achieved the same level of widespread adoption as 2-dimensional ultrasound. In cases exhibiting typical 2-dimensional ultrasound findings, meticulous 2-dimensional scanning remains sufficient for establishing an accurate diagnostic assessment. Magnetic resonance imaging (MRI) is generally not employed as a routine diagnostic modality due to substantial time requirements and high economic costs. However, owing to its superior soft tissue contrast resolution, MRI plays a pivotal role in the definitive diagnosis of complex cases and preoperative planning [ 10 ]. Hysterosalpingography and hysteroscopy are valuable tools for the accurate diagnosis of uterine malformations. Laparoscopic myomectomy is the preferred surgical approach. Although the majority of patients have a favorable prognosis, they require strict contraception for an extended period postoperatively.

Intraligamental myomas represent a rare subtype of uterine fibroids that originate from the lateral uterine wall and extend into the broad ligament [ 1 ]. Due to their unique growth patterns, these tumors may displace critical pelvic structures such as uterine vessels and ureters, leading to anatomical distortion and increasing the complexity and risk of surgical intervention [ 2 ]. Accurate preoperative diagnosis is therefore crucial to prevent intraoperative complications. However, atypical clinical presentations can complicate diagnostic efforts. This report presents a rare case of a primary fistula connecting a broad ligament leiomyoma to the cervix that mimicked bicornuate unicollis uterus on both clinical examination and sonographic imaging, leading to initial diagnostic uncertainty.