Department of Urology, The Second Xiangya Hospital, Central South University, Changsha, 410011, Hunan, China.
Department of Ultrasound Diagnosis, The Second Xiangya Hospital, Central South University, 139 Renmin Road (M), Changsha, 410011, China.
BMC Pregnancy Childbirth. 2020 Dec 11;20(1):774. doi: 10.1186/s12884-020-03480-z.
The fetal adrenal gland is a highly vascularized organs and develops two recognizable distinct zones in uetro, inner fetal zone (FZ) and outer definitive zone (DZ). Based on the region supplied, middle adrenal artery (MAA) mainly contribute to FZ while inferior adrenal artery (IAA) mainly to the inferior part of DZ. The purpose of this study was to establish reference ranges of adrenal artery Doppler indices of IAA and MAA, and assess zonal difference of blood supply to fetal adrenal gland.
The pulsatility index (PI), resistance index (RI), and systolic:diastolic ratio (S/D) of the IAA and MAA were obtained serially at 4-week intervals in normal fetuses. The MAA and IAA were referred based on the course and location in the gland: IAA referring the artery that mainly branches from the renal artery and walks along the renal upper pole, distributing the inferoposterior part of DZ in the adrenal gland while MAA as arterial blood flowing along the single central adrenal vein in the medial part of the gland. Multilevel modeling was performed to establish the gestational age-associated reference ranges for IAA and MAA. Differences in Doppler indices between the IAA and MAA were assessed.
One hundred sixty-eight fetuses with 843 observations were included. The IAA had a higher detection rate than the MAA (100% vs 89.2%, p < 0.05). The resistance of IAA had a reduction around 35 weeks of gestation and that of MAA remained unchanged throughout the second half of pregnancy. Lower PI, RI and S/D were observed in the MAA than in the IAA (p < 0.05) from 752 paired measurements.
There is a zonal difference in blood supply in favor of the fetal zone, which may correspond to its unique function. Reference ranges of Doppler parameters in adrenal artery maybe beneficial for further evaluation of fetal hemodynamics.
胎儿肾上腺是一个高度血管化的器官，在子宫内发育出两个可识别的不同区域，即内胎儿区（FZ）和外终末区（DZ）。根据供应区域，中间肾上腺动脉（MAA）主要为 FZ 供血，而下方肾上腺动脉（IAA）主要为 DZ 的下部供血。本研究旨在建立 IAA 和 MAA 肾上腺动脉多普勒指数的参考范围，并评估胎儿肾上腺的血液供应区域差异。
在正常胎儿中，每隔 4 周连续测量 IAA 和 MAA 的搏动指数（PI）、阻力指数（RI）和收缩期/舒张期比值（S/D）。根据在肾上腺内的走行和位置，将 MAA 和 IAA 定义为：IAA 指主要发自肾动脉并沿肾上极行走，分布在肾上腺 DZ 的后下方的动脉；而 MAA 指沿肾上腺中部单一中央肾上腺静脉流动的动脉血液。采用多水平模型建立 IAA 和 MAA 的与胎龄相关的参考范围。评估 IAA 和 MAA 之间的多普勒指数差异。
纳入 168 例胎儿，共 843 次观察。IAA 的检测率高于 MAA（100% vs 89.2%，p<0.05）。IAA 的阻力在 35 孕周左右下降，而 MAA 在整个妊娠后半期保持不变。从 752 对测量值中可以看出，MAA 的 PI、RI 和 S/D 均低于 IAA（p<0.05）。
胎儿区的血液供应存在区域差异，这可能与其独特的功能相对应。肾上腺动脉多普勒参数的参考范围可能有助于进一步评估胎儿的血液动力学。
