Division of Obstetrics and Gynecology, Department of Clinical Science, Intervention and Technology (CLINTEC), Karolinska Institutet and Center for Fetal Medicine Karolinska University Hospital, 14186, Stockholm, Sweden.
Women's Health and Perinatology Research Group, Department of Clinical Medicine, Faculty of Health Sciences, UiT-The Arctic University of Norway, Tromsø, Norway.
BMC Pregnancy Childbirth. 2021 Feb 23;21(1):158. doi: 10.1186/s12884-021-03635-6.
Fetal superior vena cava (SVC) is essentially the single vessel returning blood from the upper body to the heart. With approximately 80-85% of SVC blood flow representing cerebral venous return, its interrogation may provide clinically relevant information about fetal brain circulation. However, normal reference values for fetal SVC Doppler velocities and pulsatility index are lacking. Our aim was to establish longitudinal reference intervals for blood flow velocities and pulsatility index of the SVC during the second half of pregnancy.
This was a prospective study of low-risk singleton pregnancies. Serial Doppler examinations were performed approximately every 4 weeks to obtain fetal SVC blood velocity waveforms during 20-41 weeks. Peak systolic (S) velocity, diastolic (D) velocity, time-averaged maximum velocity (TAMxV), time-averaged intensity-weighted mean velocity (TAMeanV), and end-diastolic velocity during atrial contraction (A-velocity) were measured. Pulsatility index for vein (PIV) was calculated.
SVC blood flow velocities were successfully recorded in the 134 fetuses yielding 510 sets of observations. The velocities increased significantly with advancing gestation: mean S-velocity increased from 24.0 to 39.8 cm/s, D-velocity from 13.0 to 19.0 cm/s, and A-velocity from 4.8 to 7.1 cm/s. Mean TAMxV increased from 12.7 to 23.1 cm/s, and TAMeanV from 6.9 to 11.2 cm/s. The PIV remained stable at 1.5 throughout the second half of pregnancy.
Longitudinal reference intervals of SVC blood flow velocities and PIV were established for the second half of pregnancy. The SVC velocities increased with advancing gestation, while the PIV remained stable from 20 weeks to term.
胎儿上腔静脉（SVC）基本上是将血液从身体上部回流到心脏的单一血管。由于大约 80-85%的 SVC 血流量代表脑静脉回流，因此对其进行检查可能会提供有关胎儿脑循环的临床相关信息。然而，胎儿 SVC 多普勒速度和搏动指数的正常参考值却缺乏。我们的目的是建立妊娠后半期 SVC 血流速度和搏动指数的纵向参考区间。
这是一项对低危单胎妊娠的前瞻性研究。大约每 4 周进行一次连续多普勒检查，以在 20-41 周时获得胎儿 SVC 血流速度波形。测量收缩期峰值速度（S）、舒张期速度（D）、平均时间最大速度（TAMxV）、平均时间加权平均速度（TAMeanV）和心房收缩末期速度（A-速度）。计算静脉搏动指数（PIV）。
成功记录了 134 例胎儿的 SVC 血流速度，得到了 510 组观察结果。随着胎龄的增加，血流速度显著增加：平均 S 速度从 24.0 增加到 39.8cm/s，D 速度从 13.0 增加到 19.0cm/s，A 速度从 4.8 增加到 7.1cm/s。平均 TAMxV 从 12.7 增加到 23.1cm/s，TAMeanV 从 6.9 增加到 11.2cm/s。PIV 在妊娠后半期一直稳定在 1.5。
建立了妊娠后半期 SVC 血流速度和 PIV 的纵向参考区间。随着胎龄的增加，SVC 速度增加，而 PIV 从 20 周至足月保持稳定。
