Diagnosis and Management of Struma Ovarii in Pregnancy: A Case Report

Abstract

Adnexal tumors during pregnancy are rare, with a prevalence ranging from 0.05% to 3%, and in most cases, they are benign. Struma ovarii, a monodermal teratoma, consists of over 50% thyroid tissue and accounts for 2.7% of ovarian teratomas. It typically affects women aged 40–60 and is exceptionally rare during pregnancy. Diagnosis is often only established after surgical intervention and histological examination. We present the case of a 39-year-old pregnant woman (gravida 2, para 1) at 19 weeks of gestation who presented with acute lower abdominal pain. At her first visit at 11 weeks, ultrasound revealed a 12 cm multilocular left adnexal mass. Initial conservative management was followed by emergency laparoscopy due to suspected ovarian torsion, resulting in a left oophorectomy. Histopathology confirmed struma ovarii. Thyroid function tests (TSH, FT4) remained within normal limits throughout pregnancy. The pregnancy continued without further complications, culminating in a spontaneous vaginal delivery at 40 + 4 weeks of a healthy female infant weighing 3800 g. Due to the rarity of this condition, treatment guidelines remain undefined, with management decisions relying on limited case reports and clinical judgment. This report highlights the importance of detailed evaluation and individualized management in such uncommon presentations during pregnancy.