Department of Radiology, Seoul National University College of Medicine, Seoul, Korea.
Ultrasound Obstet Gynecol. 2009 Nov;34(5):515-20. doi: 10.1002/uog.7336.
To assess the usefulness of sonographic evaluation of compensatory hyperplasia of the contralateral kidney for the differential diagnosis of fetal unilateral empty renal fossa (ERF).
We retrospectively measured the ratio of the anteroposterior (AP) and transverse (TR) diameters of the contralateral kidney in 24 fetuses with unilateral ERF including 12 cases of unilateral renal agenesis, six cases of a unilateral pelvic kidney and six cases of a unilateral ectopic multicystic dysplastic kidney (MCDK). For the normal reference value, we calculated the AP : TR diameter ratios of both kidneys in 20 normal fetuses in the second and third trimesters. We calculated the accuracy of the AP : TR ratio to detect contralateral compensatory hyperplasia.
The median (range) AP : TR diameter ratios of the normal kidneys were 0.84 (0.72-0.89) in the second trimester and 0.81 (0.65-0.89) in the third trimester. All cases of unilateral renal agenesis and ectopic MCDK showed the presence of compensatory hyperplasia, while no case of renal ectopy was seen with compensatory hyperplasia. The median (range) ratios for unilateral renal agenesis and ectopic MCDK were 1.0 (0.95-1.02) and 1.1 (1-1.25) in the second and third trimesters, respectively. The median ratios for a unilateral pelvic kidney were 0.8 (0.74-0.85) and 0.77 (0.74-0.84) in the second and third trimesters, respectively. Using 0.9 as the discriminating value, the sensitivity, specificity, and accuracy of the AP : TR diameter ratio for the prenatal diagnosis of compensatory renal hyperplasia was 100%.
Sonographic evaluation of compensatory hyperplasia of the contralateral kidney may be useful for the differential diagnosis of a fetal unilateral ERF. Prospective studies are warranted.
评估对侧肾脏代偿性增生的超声评估在单侧空肾窝（ERF）胎儿的鉴别诊断中的作用。
我们回顾性地测量了 24 例单侧 ERF 胎儿（包括 12 例单侧肾发育不全、6 例单侧盆腔肾和 6 例单侧异位多囊性发育不良肾（MCDK））对侧肾脏的前后（AP）和横径（TR）的比值。对于正常参考值，我们计算了 20 例在第二和第三孕期的正常胎儿的双侧肾脏的 AP：TR 直径比值。我们计算了 AP：TR 比值检测对侧代偿性增生的准确性。
正常肾脏的中位（范围）AP：TR 直径比值在第二孕期为 0.84（0.72-0.89），在第三孕期为 0.81（0.65-0.89）。单侧肾发育不全和异位 MCDK 的所有病例均显示存在代偿性增生，而无肾脏异位的病例则无代偿性增生。单侧肾发育不全和异位 MCDK 的中位（范围）比值在第二和第三孕期分别为 1.0（0.95-1.02）和 1.1（1-1.25）。单侧盆腔肾的中位比值在第二和第三孕期分别为 0.8（0.74-0.85）和 0.77（0.74-0.84）。使用 0.9 作为鉴别值，AP：TR 直径比值对产前诊断代偿性肾增生的灵敏度、特异性和准确性均为 100%。
对侧肾脏代偿性增生的超声评估可能有助于单侧 ERF 胎儿的鉴别诊断。需要进行前瞻性研究。
