The urachus is an embryologic remnant of the cloaca that usually degenerates after birth, resulting from the obliteration of the allantois, whose role is to connect the bladder to the umbilicus. Incomplete removal of the lumen may give rise to different malformations of the median umbilical ligament after birth. Although in the pediatric population urachus are common, most cases are asymptomatic and may go unrecognized until adulthood and give rise to cysts, rarely reported in the literature. Thus, in this manuscript we present the circumstances of a 43-year-old Romanian woman showing hypogastric pain of moderate intensity for three weeks, radiation in the left lower limb, menstrual cycle abnormalities, and dysmenorrhea. Based on the initial examinations, a paraovarian cyst measuring 80 mm was noted. Through the subsequent magnetic resonance imaging (MRI) conducted, a hypoechoic mass was detected, and the patient underwent a tumorectomy and partial cystectomy. A 9.7/7.5-cm tumor was excised, and the anatomopathological result was urachal mucinous cystadenoma. It came to our attention that relatively scarce data were found in the literature, with only seven studies with the diagnosis of the urachal cyst.