Work

Euro-Chinese consensus on accessory cavitated uterine malformation

Year: 2025

Type: article

Abstract: Accessory cavitated uterine malformation (ACUM) is a rare obstructive uterine anomaly that remains poorly understood, posing challenges for clinical management. The aetiopathogenesis is hypothesised to involve the duplication and persistence of ductal Müllerian tissue usually near the round ligament attachment, potentially related to gubernaculum dysfunction. ACUM is specifically classified by Acién’s system, though rare variants necessitate continued international research to refine classification frameworks. This consensus aims to develop good clinical practice recommendations for the pathophysiology, terminology, clinical presentation, diagnosis, and treatment of ACUM. A working group consisted of Chinese and European experts, after approval from the European Society for Gynaecological Endoscopy, developed recommendations based on the best available evidence and experts’ opinion. Patients with ACUM present with typical symptoms such as dysmenorrhea and dyspareunia, and atypical symptoms, including gastrointestinal and generalized pelvic pain. Diagnostic criteria include isolated cavitated lesions in the anterolateral myometrium near the round ligament, lined by endometrial tissue and filled with haemorrhagic fluid, surrounded by a myometrial mantle with concentric orientation of myometrial fibres, and typically associated with a normal uterine cavity. Diagnosis is most accurately made through ultrasound and magnetic resonance imaging. Surgical excision of the ACUM is considered the definitive treatment offering near-complete symptom resolution, and a minimally invasive approach should be preferred when possible. The timing of surgery and the interval before attempting pregnancy remain unclear. The mode of delivery post-surgery is individualised based on the degree of myometrial involvement. The current consensus summarises the existing evidence on ACUM, providing good clinical practice recommendations for its management. Existing gaps in the understanding and management of ACUMs, highlight the need for further research to guide clinical decision-making. The key points of the consensus are summarized below. For the full content, please refer to the supplementary file, https://links.lww.com/CM9/C525. Part I: Embryology of the Internal Genitalia Key question: What are the current theories on the etiopathogenesis of ACUM? Key point: ACUMs could be caused by the duplication and persistence of ductal Müllerian tissue in the critical area at the attachment level of the round ligament, possibly related to a gubernaculum dysfunction or abnormal traction.[1,2] Key question: What is the most appropriate terminology for accessory cavitated uterine malformation? Key point: Accessory cavitated uterine malformation (ACUM) is the preferred terminology. Key question: How is accessory cavitated uterine malformation classified according to the existing classification systems? Key points: (1) Acién’s classification is the only system which specifically refers to the ACUM.[3] (2) Clinicians who care for patients with Müllerian anomalies should be mindful of existence of other rare, unique and potentially very complex variants. (3) Continued international efforts are needed to conduct high-quality studies that offer evidence-based data to improve the classification systems and their applicability in clinical practice. Part II: Clinical Presentation, Diagnosis and Differential Diagnosis Key question: What are the typical and atypical symptoms in patients with ACUM? Key points: (1) Typical symptoms: dysmenorrhea, dyspareunia and recurrent pelvic pain. (2) Atypical symptoms: gastrointestinal pain and generalised pelvic pain as can be seen in any chronic/recurrent pain problem. (3) ACUMs should be considered in all young women presenting with severe menstrual pain symptoms after menarche. Key question: What are the diagnostic criteria for an ACUM? Key points: In order to diagnose ACUM, the following criteria should be fulfilled: (1) An isolated cavitated lesion located in the anterolateral myometrium, in the proximity of the round ligament. (2) The cavity is lined by endometrial tissue and typically filled with haemorrhagic/menstrual fluid. (3) The cavity is surrounded by a myometrial mantle with concentric orientation of myometrial fibres. (4) They are typically associated with a normal uterine cavity. Additional notes: While large ACUMs may enlarge to involve the posterolateral myometrium, because they are thought to originate from the gubernaculum. They should predominantly be within the anterolateral myometrium. ACUMs are found within the myometrium but the extent of their involvement with the myometrium can vary. They can be completely embedded within the myometrium or substantially outside the myometrium with minimal myometrial involvement. A grading system could be used to describe this based on the International Federation of Gynecology and Obstetrics (FIGO) classification of type 4, type 5 and type 6 fibroids as this will inform the extent of surgical dissection necessary as well as the risk of uterine cavity breach. Key question: What are the diagnostic tools for diagnosing accessory cavitated uterine malformation? Key points: (1) In expert hands, the diagnosis of ACUM can confidently be made on transvaginal or transrectal ultrasound.[4] (2) If there is diagnostic uncertainty after ultrasound examination, consideration should be given to using MRI. (3) Not all histopathologists are familiar with ACUMs so it is important to let them know that you suspect an ACUM and ensure they are aware of their histopathological features. Differential diagnoses: The main differential diagnoses of ACUM are listed in Table 1. Table 1 - Features of accessory congenital uterine malformations and relevant differential diagnoses. Items Accessory cavitated uterine malformations Cystic adenomyomas Rudimentary horn with functioning endometrial cavity Complete septate uterus with unilateral cervical aplasia (Robert uterus) Degenerated fibroids Location Located in the anterolateral myometrium, in proximity to the round ligament Located in the myometrium Located at the lateral cornual aspect or lateral and distinct to the myometrium Located in the lateral aspect of the uterus with a thin septum between cavities that can be bulging Can be located anywhere in the myometrium Pathophysiology Having a myometrial mantle and endometrial lining Absence of myometrial mantle No myometrial mantle Will not have a myometrial mantle that is distinct from surrounding myometrium Fibroid pseudo capsule and heterogeneous aspect Relation to the uterine corpus Typically bulge outside the uterine corpus Typically entirely within the myometrium Can be separated from the main uterine body or not, but the uterine cavity will be unicornuate. Typically within the uterine corpus Could be within the body of the uterus or pedunculated Content Typically echogenic cavity content Often anechoic cavity content There is usually not hematometra found because the content refluxes into the abdomen Typically echogenic content Can be echogenic or anechoic content Age Commonly found in young women or teenagers Commonly found in older parous women Can be found in any age group Commonly found in young women or teenagers Can be found in any age group Key point: As exclusion of other uterine anomalies is crucial to the diagnosis, in the rare circumstances where ultrasound and MRI have failed to clarify the morphology of the uterine cavity, consideration could be given to more invasive tests such as saline infusion sonohysterography, Hysterosalpingo-Contrast Sonography/Hysterosalpingo-Foam Sonography or hysteroscopy. Part III: Treatment and Counselling Key question: What are the clinical indications and available treatment options for ACUM? Key points: (1) Treatment aims to restore uterine anatomy through excision of the ACUM and to alleviate symptoms. (2) ACUM typically requires treatment in case of severe dysmenorrhea or chronic/recurrent pelvic pain. (3) Surgical management, consisting of ACUM removal from the myometrium and suturing of the uterine defect, is the definitive treatment and it has shown nearly complete remission of symptoms. Options include laparotomy, laparoscopy, and robot-assisted laparoscopy. A minimally invasive approach should be preferred when possible.[5] (4) Medical management including administration of Non-Steroidal Anti-Inflammatory Drugs, Oral Contraceptive Pill, Levonorgestrel-Releasing IntraUterine System, and Gonadotropin-Releasing Hormone agonists; Medical management provides temporary relief but is often not a definitive solution. (5) Sclerotherapy is an alternative for those who wish to avoid surgery, though it may lead to recurrence. Key question: What are the optimal skills and facilities to remove the ACUM while protecting the uterine myometrium wall? Key points: (1) Ability to accurately estimate the penetration depth in the myometrium to remove the lesion while minimizing risks. (2) Use of intraoperative ultrasound, including 3D ultrasonography, for precise localization and excision of the ACUM. (3) Surgical skills and experience to apply proper surgical techniques including careful enucleation of the ACUM using mechanical, monopolar or bipolar energy, with various tools assisting in the dissection and suturing (especially for laparoscopy/robotics) Key question: What is the best timing of surgery for ACUM? Key point: There is no direct evidence to guide the timing of ACUM surgery. Key question: What is the recommended interval before attempting pregnancy after surgery? Key point: After surgery for ACUM, a recommended waiting period of 4–6 months is advised before attempting pregnancy; this allows the proper healing of the myometrium. Key question: What is the recommended mode of delivery for future pregnancy? Key point: There are no data to determine the optimal mode of delivery after ACUM excision; Caesarean sections and vaginal deliveries are described in literature. In determining the mode of delivery after ACUM excision, consideration should be given to the depth of myometrial involvement/FIGO type of ACUM. In conclusion, there remains a great deal that is unknown about ACUMs, which provides challenges for clinicians managing patients with this malformation. The embryological origin remains unclear although it is possibly related to a gubernaculum dysfunction or abnormal traction. Existing classification systems except for Acién’s, while widely utilised, do not adequately incorporate ACUM. To diagnose an ACUM, the following criteria should be fulfilled: to be an isolated cavitated lesion located in the anterolateral myometrium, in the proximity of the round ligament with a cavity lined by endometrial tissue and typically filled with haemorrhagic/menstrual fluid. They should be surrounded by a myometrial mantle with typical concentric orientation of the myometrial fibres with a normal uterine cavity. Current management strategies prioritise complete surgical excision of the lesion, preferably via minimally invasive techniques, to achieve symptom resolution. There is a paucity of high-quality evidence to guide clinical decision-making regarding aspects of optimal surgical intervention and more specifically regarding the management of future pregnancies. Funding This work was supported by grants from the National Key Clinical Specialty Construction Project (No. U114000) and the National Natural Science Foundation of China (No. 82271656). Conflicts of Interest None.

Source: Chinese Medical Journal

DOI: 10.1097/cm9.0000000000003717