Prenatal Monitoring And Early Prediction Of Inconsistent Twin Growth Based On Doppler Ultrasound

Objectives The purpose of this study was to monitor the hemodynamics of fetus and placenta with inconsistent twin growth and to explore the early prediction method of inconsistent twin growth.Methods1.Epidemiology of twins in our hospital:Pregnancy cases examined by ultrasound in the outpatient department of our hospital and pregnancy cases delivered in hospital from January 2019 to December 2020,including single pregnancy,twin pregnancy and triple pregnancy.The software ultrasound medical image management and transmission system was queried,and the number of examinations was checked with the ultrasound diagnosis of"intrauterine pregnancy"as the search term,and the number of cases was respectively checked with the search term indicating"single pregnancy,twin pregnancy,and third pregnancy",and the same person was checked multiple times as a case,and the name was repeated.The number of single,twin and triplet pregnancies treated by ultrasound examination was recorded.The complications of twins were investigated by disease name and the number of cases were recorded.2.Study on fetal hemodynamic characteristics of inconsistent growth of twins in late pregnancy.（I）Study on the difference of brain placenta ratio in inconsistent growth of twins.A total of 401 pregnant women with twin pregnancies were selected from October 2020 to September 2022,of which 250 were double chorionic twins（DCT）and151 were single chorionic sac twins（MCT）.Exclusion criteria:（1）one or both twins died in utero;（2）One of the twins or twins with severe structural malformations;（3）twins or chromosomal abnormalities that cause intrauterine growth restriction in one of the twins and serious intrauterine infections;（4）Complicated monochorionic twin pregnancies other than s IUGR,including TTTS,TRAPS,TAPS,and conjoined twins;（5）Twins who underwent elective reduction（including reduction of one or two pregnancies in triplets and twin pregnancies）or intrauterine interventions such as placental vessel communication branch coagulation.Grouping:（1）DCT was divided into normal development group（control group）and twin growth inconsistent group（case group）.（2）Monochorionic twins（MCT）were divided into normal development group（control group）and selective one-child growth restriction（s IUGR）group（case group）.Contents of ultrasound examination:（1）Routine fetal biological measurement.（2）Doppler blood flow parameters:twin fetal umbilical artery systolic peak velocity（UA-PSV）,umbilical artery pulse index（UA-PI）,middle cerebral artery systolic peak velocity（MCA-PSV）,middle cerebral artery pulse index（MCA-PI）.Venous catheter（DV）flow spectrum is low,absent or reversed a wave.At the same time,brain-placental blood flow ratio（CPR）and the differences of the above mentioned umbilical artery and middle cerebral artery Doppler parameters（disc）between twins were calculated.The formula for calculating the differences of each parameter in twins was:（larger parameter-smaller parameter）/larger parameter×100%.In this part of the study,the data of the last prenatal ultrasound examination were obtained no more than 3 weeks ago.Clinical data were collected,including age,mode of pregnancy,body mass index（BMI）,pregnancy complications,etc.Perinatal follow-up:placental characteristics were examined immediately after delivery and birth weight（BW）was recorded.（II）Study on the difference of placental microblood flow in twins with inconsistent growth.The study subjects,exclusion criteria,grouping,collection of clinical data and follow-up of perinatal outcomes are the same as in the previous part.Contents of ultrasound examination:（1）Routine fetal biological measurement.（2）Activate MV-Flow to optimize the image and obtain a good placental vascular tree image.Carefully define the sample frame size,always maintain a fixed size area of interest（ROI）,select the oval sample frame automatically set by the instrument to obtain the placental vascular index(VI^MV),sample and save the image at the point where the placental villus vascular tree is most clearly displayed.Identification of chorionic plate vessels（CPV）,placental primary villous vessels（PVV）,secondary villous vessels（SVV）,and tertiary villous vessels（TVV）.CPV peak systolic flow rate（CPV-PSV）and pulsation index（CPV-PI）,PVV peak systolic flow rate（PVV-PSV）and pulsation index（PVV-PI）,SVV peak systolic flow rate（SVV-PSV）and pulsation index（SVV-PI）were respectively measured.TVV systolic peak velocity（TVV-PSV）and pulsation index（TVV-PI）.All parameters were calculated for their intertwin differences（disc）.3.Exploratory research on early prediction of inconsistent twin growth.DCT placental microblood flow was observed at 12-15 weeks of gestation and 16-19 weeks of gestation respectively,and the microblood flow parameters of the branch blood flow of the placental villus vascular tree were measured,including CPV-PSV,CPV-PI,PVV-PSV,PVV-PI,SVV-PSV,SVV-PI,VI^MV,and the differences between twins were calculated.DCT case group and control group were divided into 12-15 week group and16-19 week groupResults1.Epidemiology of twins:In the past two years,there were 40,099 cases of intrauterine pregnancy examined by outpatient ultrasound,of which 38,195 were single pregnancies,accounting for 95.25%,1825 were twin pregnancies,accounting for 4.55%,and 79 were triplets,accounting for 0.02%.Among 1825 cases of twin pregnancy,37 cases（2.03%）of DCT twins were inconsistent in growth,and 26 cases（1.42%）of DCT twins were abnormal in structure.DCT complications accounted for 3.45%of twin pregnancies.Fetal complications of MCT included structural malformation in one of the twins in 28cases（1.53%）.TTTS in 10 cases（0.54%）;There were 14 cases（0.76%）with s IUGR.TAPS in 3 cases（0.16%）;TRAPS in 6 cases（0.32%）;Conjoined twins were found in 2cases（0.11%）,and umbilical cord entangling was found in 3 cases（0.16%）.MCT complications accounted for 3.51%of twin pregnancies.2.Study on fetal hemodynamic characteristics of inconsistent growth of twins in late pregnancy（1）Study on the difference of brain placenta ratio in inconsistent growth of twins:Among 250 cases of DCT,44 cases of inconsistent growth of twins and 44 cases of normal development were used as control group.ROC curve showed that the sensitivity（79.5%）and specificity（61.4%）of CPR disc in diagnosing twin growth discordances were higher,AUC area was 0.743,and cutoff value was 12.36%.Multivariate Logistic regression analysis showed that CPR disc had diagnostic value for DCT twin growth discordance（P=0.001）.Among 151 MCT cases,49 cases of s IUGR were used as the case group and 49 cases of normal development were used as the control group.ROC curves showed that the sensitivity（65.3%）and specificity（79.6%）of CPR disc for diagnosis of s IUGR were higher,the AUC area was 0.736,and the cutoff value was 27.23%.Multivariate Logistic regression analysis showed that CPR disc had diagnostic value for s IUGR（P=0.007）.（2）Study on differences in placental microblood flow in twins’growth discordance:Taking the last ultrasound microblood flow parameters during middle and late pregnancy,there were statistically significant differences in SVV-PSV disc,VI^MVdisc and BW disc between the DCT case group and the control group.The ROC curve showed that the specificity of TVV-PSV disc and VI^MVdisc for the diagnosis of s IUGR was higher（77.3%,70.5%）,and the sensitivity was better（52.3%,61.4%）.Multivariate Logistic regression analysis showed that VI^MVdisc had diagnostic value for DCT twin growth discordance（P=0.001）.（2）There was no significant difference in all blood flow parameters between the MCT patients and the control group.ROC curve showed that all blood flow parameters could not be sensitive and specific for the diagnosis of s IUGR.Multivariate Logistic regression analysis showed that all blood flow parameters had no diagnostic efficacy.3.Exploratory study on early prediction of inconsistent twin growth.In terms of placental microblood flow parameters at 12-15 weeks,there was no significant difference in CPV-PSV disc,CPV-PI disc,PVV-PSV disc,PVV-PI disc,VI^MVdisc and BW disc between the DCT case group and the control group.In terms of placental microblood flow parameters at 16-19 weeks,there were statistically significant differences in VI^MVdisc and BW disc between the DCT case group and the control group.There was a moderate correlation between VI^MVdisc and BW disc at 16-19weeks,and the difference was statistically significant.There was no correlation between BW disc and parameters at 12-15 weeks.ROC curve showed that VI^MVdisc had good specificity（65.6%）and sensitivity（87.5%）for the diagnosis of DCT twin growth inconsistencies at 16-19 weeks,with an AUC area of 0.806.No diagnostic efficacy was found in all parameters at 12-15 weeks.Conclusion1.The incidence of twin pregnancy is low and the risk of mother and child is high.The most common complication of twins is inconsistent twin growth.2.CPR disc can be used as an intrauterine monitoring index for the difference in birth weight between DCT and MCT twins.3.Ultrasound imaging of placental microflow based on MV-Flow can clearly display blood flow in at least three branches of the placental villus vascular tree in late pregnancy,and can quantitatively measure vascular index,making up for the deficiency of conventional color Doppler in displaying placental blood perfusion.4.Placental VI^MVdisc can be combined with CPR disc as an intrauterine detection index for growth inconsistencies in DCT twins,and placental microblood flow parameters have no significance in monitoring s IUGR intrauterine development of MCT.5.MV-flow-based ultrasound imaging of placental can show the 1-3 branches of the placental villus vascular tree at 12-19 weeks of pregnancy,reflecting the gradual development and maturity of the chorionic vascular tree in early and middle pregnancy.6.VI^MVdisc at 16-19 weeks of gestation has early predictive value for the growth inconsistencies of DCT twins,and is expected to provide theoretical reference for clinical intervention to improve placental blood perfusion before growth restriction of one of the twins occurs.