| Background and aim The ductus venosus(DV)is an hourglass-shaped structure which plays a important role in the fetal circulation by directly connecting the portal sinus to the subdiaphragmatic vestibulum.It shunts 20-30%of the oxygenated blood from the placenta and the umbilical vein(UV)directly to the important organs such as the fetal heart and brain,bypassing the fetal liver.Agenesis of ductus venosus(ADV)is a rare anomaly and its etiology is unknown which may be related to the " critical anastomosis" that is not formed or overabsorbed.ADV is usually divided into two types:intrahepatic shunt and extrahepatic shunt,which has been reported to be highly associated with structural malformations,chromosomal malformations,agenesis of the portal venous system and persistent portosystemic shunts.At present,the prenatal diagnosis of ADV at home and abroad is mostly a retrospective study of a small series of cases.Therefore,A meta-analysis of the Chinese and English articles diagnosed as fetal ADV in the past 18 years is performed in this study for providing the basis for prenatal consultation and clinical decision-making,and the basis for evidence-based medicine.Materials and Methods All related Chinese and English literature published from 2000 to 2017 in the CBM,CNKI,Wanfang,Pubmed,and Embase databases were searched.Two investigators screened and evaluated the retrieved literature based on inclusion and exclusion criteria,and excluded literature that did not meet the purpose and criteria of the study.Two researchers extracted data from the included literature.A meta-analy sis of proportions was performed using R 3.3.1 software,and the forest plots and funnel plots were drawn.According to the location of the umbilical vein shunt,ADV of fetuses was classified into two subgroups:intrahepatic and extrahepatic shunt,and the combined rate and the corresponding 95%CI were respectively calculated.Results According to the inclusion and exclusion criteria of the literature,a total of 17 articles were included in this systematic review and meta-analysis,including 3 in Chinese and 14 in English.There are results of meta-analysis of ADV of intrahepatic shunt:The incidence of structural malformations in the intrahepatic shunt was 43.99%(95%CI:30,19-58.78),and the frequency of chromosomal malformations was 25.76%(95%CI:13.71-41.11).The rate of induction with a prenatal diagnosis of intrahepatic shunt was 34.38%(95%CI:23.12-47.74),and the mortality rate of fetuses was 25.02%(95%CI:14.19-40.23),and the survival rate was 49.59%(95%CI:36.84-62.40).However,no isolated cases of death were found in the isolated intrahepatic shunt.Intrahepatic shunts were analyzed for subgroups based on whether they had other abnormalities.The incidence of non-isolated and isolated intrahepatic shunts were 57.99%(95%CI:46.11-69.00)and 42.01%(95%CI:31.00-53.89),respectively,and the rates of induction were 46.34%(95%CI:30.43-63.02)and 24.46%(95%CI:12.65-42.00),respectively,and the survival rates were 34.31%(95%CI:21.59-49.77)and 75.54%(95%CI:58.00-87.35),respectively.The results of meta-analysis of ADV with extrahepatic shunt:According to the location of shunting of umbilical vein,meta-analysis showed that the incidence of subflow into RA,IVC,iv,and CS was 42.21%(95%CI:32.62-52.44),42.54%(95%CI:31.28-54.63),17.22%(95%Cl:11.61-24.77),and 9.21%(95%CI:5.32-15.47),respectively.The incidence of structural malformations was 45.80%(95%CI:36.40-55.50);and the incidence of chromosomal malformations was 19.97%(95%CI:12.56-30.23).Agenesis of the portal system was present in 38.40%(95%CI::19.05-62.28)of extrahepatic shunt.Induction rate was 33.79%(95%CI:24.16-44.98);and mortality was 21.89%(95%CI:14.55-31.57);and survival rate was 49.73%(95%Cl:40.98-58.50).Extrahepatic shunts were analyzed by subgroups based on whether they had other abnormalities.The incidence of non-isolated and isolated intrahepatic shunts were 56.88%(95%CI:48.21-65.15),and 43.12%(95%CI:34.85-51.79);and the rates of induction were 50.92%(95%CI:40.53-61.24)and 20.46%(95%Cl:12.38-31.91),respectively;and the mortality rates were 26.88%(95%Cl:18.81-36.86)and 27.93%,respectively.95%CI:17.61-41.26);and the survival rates were 37.25%(95%CI:27.83-47.76)and 65.85%(95%CI:53.32-76.50),respectively.Conclusion ADV is not only a single anomaly,but is a group of anatomical developmental abnormalities including abnormal development of the umbilical vein,ductus venosus and portal vein system.ADV is significantly associated with structural abnormalities,chromosomal abnormalities,,portal vein system dysplasia and intrahepatic portosystemic shunt,which are the main influencing factor of ADV prognosis.The prognosis of isolated intrahepatic ADV is better than that of extrahepatic type.In the cases of isolated ADV,sonographic assessment of the cardiac function should be followed-up closely in order to find signs of cardiac compromise. |
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