In patients with acute abdomen, especially during pregnancy, it is difficult to suspect myoma torsion initially due to its rarity. However, when these patients have a solid mass in the pelvis, torsion of uterine fibroids or adnexa and large infarct inside leiomyoma are the main diagnoses that must be differentiated. We report a case of uterine myoma torsion mimicking ovarian torsion in the second trimester of pregnancy that was successfully managed by laparoscopic myomectomy. A 31-year-old pregnant woman with severe right lower abdominal pain at 21 + 2 weeks of gestation was transferred. On ultrasonography, the appendix appeared normal but a solid mass (7.0×4.0 cm) containing a cystic portion was observed on the right side of the uterus. The mass had no blood flow and tenderness appeared on the transducer pressure. Pelvic magnetic resonance imaging revealed a 7 cm edematous mass with low signal intensity on T2-weighted image, instead of a normal-looking right ovary. These findings led to suspicion of right ovarian torsion. One day after admission, the patient's symptoms worsened with acute elevation in C-reactive protein (CRP) (4.55 mg/dL) and neutrophile-to-lymphocyte ratio (NLR) (10.1), despite the use of analgesics and tocolytics, and uterine contractions were not controlled. Emergency surgery was performed, and the final diagnosis was a uterine leiomyoma torsion. Laparoscopic myomectomy was successfully performed, and symptoms were relieved after operation. She had full term vaginal delivery without complication. The differential diagnosis between myoma torsion and ovarian torsion is challenging in patients with acute abdomen during pregnancy. To exclude ovarian torsion, a comparison with an asymptomatic contralateral normal ovary will be very helpful. When fibroids are found in mothers with an acute abdomen, follow-up of NLR and CRP is related to preterm labor and can be a reference point for considering surgery.