BACKGROUND: The Demons-Meigs syndrome should usually be evoked in case of 
presence of a typical triad: abdominopelvic mass, ascites and hydrothorax. Its 
diagnosis appears crucial to prevent the realization of unnecessary surgical 
procedures.
CASE PRESENTATION: A 32-year-old woman presented in April 2012 to the emergency 
department of our maternity unit (General Hospital, Thiers, France) with an 
abdominal distension mimicking the symptoms of a pregnancy at term. Physical 
examination revealed a voluminous painful abdominopelvic mass, extended from the 
pelvis to the upper abdomen with a large right pleural effusion. Ultrasound and 
computed tomography showed it was a tumor measuring more than 300 mm in diameter 
with a right hydrothorax. Serum CA-125 level was 289 U/ml. Cytologic analysis of 
the pleural effusion didn't show any malignant cells. In this study, 
Demons-Meigs syndrome was recognized. A laparoscopico-laparotomic management 
permitted an aspiration of 23 liters of a brownish liquid and an unilateral 
adnexectomy after pleural paracentesis was performed. Frozen section 
demonstrated benign mucinous cystadenoma. The final histologic findings 
objectified intracystic intestinal type ovarian mucinous borderline tumor. After 
multidisciplinary consultation, the patient was re-operated one month later. The 
exploration didn't reveal any suspected lesions and appendectomy and omentectomy 
were performed. The postoperative course was uneventful. Serum CA-125 level was 
normal at the time of the reoperation and 24 months after the initial surgery.
CONCLUSION: The preoperative recognition of a Demons-Meigs syndrome or a Demons' 
pseudosyndrome is essential to avoid useless surgical procedures.