Management of Complex Myometrial Cyst in Pregnancy: Case Report [12G]

INTRODUCTION: Acquired myometrial cysts have been associated occasionally with endometriosis, adenomyosis, endosalpingiosis or degenerative leiomyomas. These conditions do not usually pose a danger to the mother or fetus if conception occurs. There are two reports in the literature of benign cystic myometrial masses unrelated to any of the above conditions. METHODS: A 33 y.o. female was found to have a cystic mass on the posterior uterine wall during a first trimester ultrasound. An MRI revealed a mass arising from the endometrial cavity extruding cranially and laterally through a right myometrial wall defect partially contained within the uterine serosa, unconnected with the gestational sac. Diagnostic laparoscopy confirmed a large, reducible cystic structure. Following extensive counseling about the possibility of uterine rupture later in gestation, the patient chose to terminate the pregnancy. A laparoscopic-guided dilation and evacuation was performed. The cyst was separately drained, and clear fluid aspirated. Five months postoperatively, the myometrial defect was repaired with a hysterorrhaphy. Histopathology of the excised cyst revealed benign mesothelium without evidence of adenomyosis, endometriosis or leiomyoma. The patient conceived five months later, delivering by repeat caesarean section without any complications. CONCLUSION: There are no prior reported cases of complex cystic myometrial masses or herniations unrelated to endosalpingiosis, endometriosis, adenomyosis or leiomyomas; nor of the effects of such a mass on current pregnancy or future fertility. This desired pregnancy was terminated to avoid the potential risk of uterine rupture and associated hemorrhage. Clinicians should be aware of this rare entity.