[Clinical characteristics of accessory cavitated uterine malformation]

Accessory cavitated uterine malformation (ACUM) is a congenital Müllerian duct developmental anomaly. Clinically, it is commonly observed in young women presenting with progressive lower abdominal pain. Due to the small size of the lesions and insufficient awareness of this condition among clinicians, the rates of missed diagnosis and misdiagnosis are relatively high, often leading to delayed treatment. This study aims to explore the clinical characteristics, diagnostic and therapeutic approaches, and prognosis of ACUM, summarize relevant clinical experience, and provide references for clinical diagnosis and management.

A retrospective analysis was conducted on the clinical data of 16 patients with ACUM who were admitted to the Department of Gynecology, the Third Xiangya Hospital of Central South University from May 2023 to November 2025. The collected data included age, clinical manifestations, medical history, menstrual and reproductive history, tumor markers, imaging findings, treatment methods, pathological results, and prognosis. The Kappa test was used to evaluate the diagnostic consistency between two auxiliary imaging modalities.

The age at diagnosis ranged from 23 to 53 years [(32.00±7.56) years], and the disease duration ranged from 5 months to 12 years. All 16 patients presented with lower abdominal pain, including left lower abdominal pain in 6 cases, right lower abdominal pain in 3 cases, and ipsilateral pelvic pain in 2 cases. Dysmenorrhea occurred in 10 patients, pain initially associated with menstruation that later became non-menstrual pain occurred in 1 patient, and non-menstrual pain occurred in 5 patients. All 16 patients underwent gynecologic color Doppler ultrasonography. Lesions were located within the myometrium beneath the uterine cornual region of the left anterior uterine wall in 12 cases and the right anterior uterine wall in 4 cases. The nodules showed hypoechoic signals in 4 cases and mixed echogenicity in 12 cases. Clear boundaries were observed in 13 cases, while indistinct boundaries were observed in 3 cases. The maximum diameter of the nodules ranged from 17 to 38 mm [(28.31±6.04) mm] and the maximum diameter of the anechoic area within the cyst ranged from 5 to 29 mm [(18.63±6.77) mm]. Endometrium-like echoes within the cyst wall were detected in 12 cases. All 16 patients underwent pelvic magnetic resonance imaging (MRI) with plain and contrast-enhanced scans. The nodular lesions showed short T₁ and long T₂ signals in 7 cases, slightly shorter T₂ signals with equal T₁ values in 5 cases, equal T₁ and T₂ signals in 1 case, long T₁ and short T₂ signals in 2 cases, and long T₁ and long T₂ signals in 1 case. Among them, short T₁ and long T₂ signals were indicated within the nodules in 7 cases. The diagnostic coincidence rate for ACUM was 81.25% with gynecological ultrasonography and 56.25% with pelvic MRI. The agreement between the 2 diagnostic modalities was weak (Kappa=0.186, P=0.375). A total of 13 patients underwent cancer antigen 125 (CA125) testing, with values ranging from 12.90 to 91.80 U/mL. Among them, 10 cases had CA125≤35 U/mL and 3 cases had CA125> 35 U/mL. A total of 15 patients underwent laparoscopic resection of uterine lesions (including hysteroscopy in 6 cases), while 1 patient underwent laparoscopic total hysterectomy with bilateral salpingectomy due to advanced age and no reproductive requirement. Based on pathological examination combined with clinical and imaging findings, all 16 patients were diagnosed with ACUM, including 3 cases suspected of concomitant focal adenomyosis. The postoperative follow-up duration ranged from 2 to 28 months [(13.50±8.12) months]. Postoperative pain symptoms disappeared in 15 patients and were significantly relieved in 1 patient. 1 patient achieved full-term vaginal delivery after surgery.

ACUM is a special type of obstructive disease that can easily be confused with cystic adenomyosis or cystic degeneration of uterine fibroids. When young women present with progressive lower abdominal pain, especially unilateral pain accompanied by referred pelvic pain, ACUM should be highly suspected. Three-dimensional gynecological ultrasonography and pelvic MRI are recommended for auxiliary diagnosis. Laparoscopic resection of uterine lesions is the preferred treatment for radical management of this condition, and hysteroscopy may be performed when necessary for differential diagnosis.