[Prenatal diagnosis and prognostic factors analysis of fetal sacrococcygeal teratoma].

Objective: To investigate the prenatal diagnosis and prognostic factors of fetal sacrococcygeal teratoma (SCT). Methods: A retrospective analysis was performed on 41 pregnant women who were diagnosed with fetal SCT by prenatal ultrasound at the Women's Hospital, Zhejiang University School of Medicine from January 2014 to September 2021. The prenatal imaging features and pregnancy outcomes, including tumor volume to fetal weight ratio (TFR), proportion of solid tumor, tumor growth rate (TGR), fetal hydrops, placentomegaly and polyhydramnios were analyzed. Receiver operating characteristic (ROC) curve was used to determine the critical values of TFR and TGR for predicting adverse fetal outcomes. Results: (1) Among the 41 pregnant women with fetal SCT, the diagnostic gestational week of ultrasound was (24.2±2.9) weeks (range: 18-28 weeks). Among them, 1 case progressed to fetal hydrops and induced labor at 22 weeks of gestation, 1 case developed intrauterine death and induced labor at 29 weeks of gestation, and 39 pregnancies continued until delivery. Among the 39 cases of continued pregnancy, 1 case underwent cesarean section at 31 weeks of gestation due to malignant polyhydramnios and increased fetal cardiothoracic ratio in the third trimester, 1 case underwent cesarean section at 32 weeks of gestation due to fetal heart failure, and 1 case underwent cesarean section at 32 weeks of gestation due to fetal heart failure and hydrops. The other 36 cases underwent surgical resection of tumor within 3 weeks after birth with good prognosis. (2) TFR>0.12 before 28 weeks of gestation could predict poor fetal prognosis, with a sensitivity of 100.0%, a specificity of 86.1% and an area under curve (AUC) of 0.922 (P<0.01). Among the fetuses with TFR>0.12, 5/10 had poor prognosis, while the fetuses with TFR≤0.12 all had good prognosis (100%,31/31), and the difference between the two groups was statistically significant (P<0.001). (3) TGR>48 cm3/week could predict poor fetal prognosis with a sensitivity of 100.0%, a specificity of 78.3% and an AUC of 0.880 (P<0.05). (4) Among the 28 SCT fetuses delivered in our hospital, the incidence rate of poor fetal prognosis was 0 (0/20) in those with solid tumor component<50%, and 5/8 in those with solid tumor component ≥50%, and the difference between the two groups was statistically significant (P<0.01). The incidence rate of poor fetal prognosis was 2/2 in those with placentomegaly (all with fetal hydrops), and 12% (3/26) in those without placentomegaly. The risk of poor fetal prognosis was 8.67 times higher in those with placentomegaly than those without placentomegaly, and the difference between the two groups was statistically significant (P<0.05). The incidence rate of poor fetal prognosis in those with polyhydramnios was 3/7, and 10% (2/21) in those without polyhydramnios, but there was no statistically significant difference between the two groups (P>0.05). Conclusion: TFR combined with solid tumor morphology, TGR, and presence of placentomegaly could predict the adverse pregnancy outcomes of fetal SCT.