Clautice-Engle T, Anderson N G, Allan R B, Abbott G D
Department of Radiology, Christchurch Hospital, New Zealand.
AJR Am J Roentgenol. 1995 Apr;164(4):963-7. doi: 10.2214/ajr.164.4.7726057.
The purpose of this study was to compare the usefulness of renal sonograms obtained 6 days and 6 weeks after birth in differentiating obstruction from nonobstruction in patients with antenatal pyelocaliceal dilatation shown by sonography and to establish sonographic criteria to determine the degree of postnatal pyelocaliceal dilatation that warrants further investigation.
Criteria for an infant to enter the study were fetal pyelectasis of 4 mm or greater, two postnatal sonograms with the second showing persisting pyelectasis extending at least into the infundibula, and a voiding cystourethrogram showing normal findings. One hundred thirty kidneys in 100 infants met the study criteria. The first postnatal sonogram was obtained at a mean age of 6 days (range, 1-14 days) and the second at a mean age of 6.6 weeks (range, 3-16 weeks). The degree of pyelectasis was measured in the anteroposterior direction on the transverse postnatal sonograms. The diagnosis of obstruction was made by excretory urography in 99 infants and nephrostography in one infant. Kidneys were categorized as definitely obstructed, possibly obstructed (anatomic features of obstruction on excretory urogram but functionally not obstructed), or not obstructed. Receiver-operating-characteristic (ROC) curves based on renal pelvic diameters were plotted for both sonograms; the ability to detect definite obstruction or possible obstruction was compared for the two time periods; and optimal cutoff points were determined.
The mean diameter of the renal pelvis was not significantly different between the sonogram obtained at 6 days and the sonogram obtained at 6 weeks for the 86 nonobstructed kidneys. For the 27 kidneys that were obstructed, the mean pelvic diameter increased from 18 mm (range, 5-54 mm) on the sonogram obtained at 6 days to 22 mm (range, 11-60 mm) on the sonogram obtained at 6 weeks. The mean pelvic diameter of 17 kidneys categorized as possibly obstructed increased from 6 mm (range, 0-11 mm) to 10 mm (range, 6-20 mm) between the first and second sonograms. The ROC curves for all sonograms obtained at 6 weeks provided cutoff points with greater sensitivity and specificity than did the curves for the sonograms obtained at 6 days. The optimal cutoff points were 6 mm for possible obstruction (sensitivity, 100%; specificity, 57%) and 11 mm for definite obstruction (sensitivity, 100%; specificity, 57%) and 11 mm for definite obstruction (sensitivity, 100%; specificity, 96%).
Renal obstruction may be underestimated or missed on a renal sonogram obtained 6 days after birth. A sonogram obtained 6 weeks after birth is more specific for detecting obstruction.
本研究旨在比较出生后6天和6周时获得的肾脏超声检查结果，以鉴别产前超声显示肾盂肾盏扩张患者的梗阻与非梗阻情况，并建立超声检查标准，以确定出生后肾盂肾盏扩张程度，判断是否需要进一步检查。
纳入本研究的婴儿标准为：胎儿肾盂扩张4mm或以上；出生后两次超声检查，第二次显示肾盂扩张持续存在且至少延伸至漏斗部；排尿性膀胱尿道造影结果正常。100例婴儿的130个肾脏符合研究标准。出生后首次超声检查的平均年龄为6天（范围1 - 14天），第二次超声检查的平均年龄为6.6周（范围3 - 16周）。在出生后横向超声图像上沿前后方向测量肾盂扩张程度。99例婴儿通过排泄性尿路造影、1例婴儿通过肾造瘘术诊断梗阻情况。肾脏分为明确梗阻、可能梗阻（排泄性尿路造影有梗阻的解剖特征但功能上无梗阻）或无梗阻。基于肾盂直径绘制两次超声检查的受试者操作特征（ROC）曲线；比较两个时间段检测明确梗阻或可能梗阻的能力；确定最佳截断点。
86个无梗阻肾脏在出生后6天和6周获得的超声图像上，肾盂平均直径无显著差异。27个梗阻肾脏的肾盂平均直径从出生后6天超声图像上的18mm（范围5 - 54mm）增加到出生后6周超声图像上的22mm（范围11 - 60mm）。17个分类为可能梗阻的肾脏在首次和第二次超声图像之间，肾盂平均直径从6mm（范围0 - 11mm）增加到10mm（范围6 - 20mm）。出生后6周获得的所有超声图像的ROC曲线提供的截断点比出生后6天获得的超声图像曲线具有更高的敏感性和特异性。可能梗阻的最佳截断点为6mm（敏感性100%；特异性57%），明确梗阻的最佳截断点为11mm（敏感性100%；特异性96%）。
出生后6天获得的肾脏超声检查可能低估或漏诊肾梗阻。出生后6周获得的超声检查对检测梗阻更具特异性。
