Advanced rectal cancer with multiorgan metastasis detected after single fetal death in twin pregnancy: a case report.

Background: Detection of colorectal cancer (CRC) during pregnancy is rare; moreover, its diagnosis is often delayed because its symptoms overlap with the physiological changes that occur during gestation. Reports of pregnancies complicated by advanced malignancy in which non-reassuring fetal status (NRFS) occurred are rare. Case Description: Herein, we report a case involving a twin pregnancy in which single fetal death served as a crucial clue for the detection of advanced CRC with multiorgan metastasis. A 36-year-old pregnant woman was admitted at 26 weeks and 3 days with suspected preterm contractions, a NRFS with elevation of inflammatory markers or activated coagulation. Despite thorough monitoring, intrauterine fetal death (IUFD) was observed for Fetus I at 28 weeks and 0 days. Imaging studies performed to investigate the fetal death and maternal inflammation revealed multiple masses in the liver. At 28 weeks and 2 days of gestation, findings suggestive of NRFS were observed for Fetus II. Emergency cesarean section was performed on the same day. Histopathology of both placentas demonstrated extensive infarctions. Following delivery, a thorough examination of the maternal liver led to a diagnosis of advanced CRC with multiple metastases. The patient underwent chemotherapy but succumbed to progressive disease 13 months later. Placental dysfunction due to maternal malignancy-associated hypercoagulability was considered the likely mechanism of IUFD. Conclusions: In cases of advanced cancer during pregnancy, attention must also be paid to fetal-placental function. In pregnant women, when IUFD occurs accompanied by unexplained maternal inflammatory response elevation and coagulation activation, thorough investigation for malignant tumors is necessary.