Background and Objectives: Choriocarcinoma is an aggressive oncological disease that manifests as trophoblast tissue proliferation. The vast majority of primary lesions affect the uterus, with primarily extrauterine lesions being a rarity. Choriocarcinoma with an ongoing pregnancy is extremely rare because fetuses usually do not survive the third trimester. Case Report: We present a case of heterotopic tubal choriocarcinoma coexisting with a viable intrauterine pregnancy. A 30-year-old, 39-week pregnant woman (gravida 2, para 2) came to our hospital complaining of acute upper abdominal pain. During routine prenatal screening in the first trimester, no pathological ultrasound findings were detected. Similar abdominal pain episodes had been recorded at 18, 27, and 32 weeks of gestation, when patient was hospitalized for examination and observation, but the cause of symptoms at that time of gestation remained unclear. The patient underwent an emergency caesarean section due to severe abdominal pain and fetal compromise. She delivered a live male infant. During the surgery, around 1000 mL of blood clots were evacuated, and the excision of the right fallopian tube and masses, as well as the control of significant blood loss was performed. Postoperative serum beta-hCG was elevated to 139 482 IU/L, while imaging studies showed no metastasis. The histological examination of the excised tissue samples confirmed a diagnosis of tubal choriocarcinoma. With a FIGO score of 8, the patient received three courses of the EP/EMA regimen. After more than a year, the patient showed no radiographic signs of distant metastasis and is now in complete remission. Conclusions: This case highlights the diagnostic complexity of such extremely rare scenarios. Even though such cases are rare, it demonstrates the necessity for improved diagnostic measures to enhance patient outcomes in similar clinical situations.