探讨产前超声及磁共振成像（MRI）诊断胎儿泌尿生殖系统畸形的应用指征和临床作用。

对产前超声诊断为泌尿生殖系统畸形的227例胎儿均于24 h内行MRI检查，与产后检查和临床随访结果对照，对产前超声漏误诊病例的图像特征进行分析。

产前超声检出泌尿生殖系统畸形的227例胎儿中包括肾脏囊性病变70例、梗阻性尿路疾病41例、肾缺如40例、肾位置异常24例、融合肾18例、重复肾17例、肾肿瘤8例、双肾体积小3例、膀胱病变5例、阴茎短小1例。与产后检查及临床随访结果对照，产前超声正确诊断胎儿泌尿生殖系统畸形194例（85.5%，194/227）；漏误诊33例（14.5%，33/227），其中15例（1例输尿管息肉）梗阻性尿路疾病不能显示输尿管狭窄或梗阻部位、3例梗阻性尿路疾病不能明确诊断（1例巨输尿管、2例肾积水）、3例梗阻性尿路疾病误诊为重复肾；其余12例漏误诊病例包括3例肾位置异常、2例重复肾合并囊性肾发育不良、2例肾缺如、2例融合肾、1例多囊肾合并重度积水、1例重复肾、1例阴茎短小。产前MRI正确诊断224例（98.7%，224/227）；漏诊3例（1.3%，3/227）。另外，3例泌尿系统异常伴发的生殖器异常，产前超声、MRI均未显示，均为产后发现。

产前超声及MRI对胎儿泌尿系统畸形有较高显示率；但超声及MRI对胎儿生殖器畸形的显示率均不高。明确MRI应用指征有助于产前合理选用影像学检查方法，对诊断和佐证胎儿泌尿生殖系统畸形有重要临床作用。

To explore the indications of prenatal ultrasound and magnetic resonance imaging (MRI) in diagnosing fetal genitourinary abnormalities.

Two hundred and twenty-seven fetuses with genitourinary abnormalities detected by prenatal ultrasound received MRI examination within 24 hours after ultrasound. The final diagnosis was confirmed by autopsy or clinical follow-up. The results of prenatal ultrasound and MRI were analyzed retrospectively and compared with follow-up results. And the misdiagnosis of prenatal ultrasound in fetal genitourinary abnormalities were also analyzed.

In 227 fetuses with genitourinary abnormalities, there were 70 fetuses with renal cystic lesions, 41 with urinary obstruction, 40 with renal agenesis, 24 with ectopic kidney, 18 with horseshoe kidney, 17 with renal duplication, 8 with kidney neoplasm, 3 with small kidney, 5 with bladder anomaly, and 1 with small penis. The diagnostic accuracy rates of ultrasound and MRI were 85.5% (194/227) and 98.7% (224/227) respectively. There were 33 cases of fetal genitourinary abnormalities misdiagnosed by prenatal ultrasound as follows: failed to detect the location of ureteral stricture or obstruction in 15 cases of urinary obstruction (including 1 ureteral polyp); failed to diagnose definitely in 3 cases of urinary obstruction (including 1 megaureter and 2 cases of hydronephrosis); 3 cases of urinary obstruction misdiagnosed as renal duplication; and the rest 12 misdiagnosed cases including 3 ectopic kidney, 2 renal duplication associated with cystic renal dysplasia, 2 renal agenesis, 2 horseshoe kidney, 1 polycystic kidney associated with severe hydronephrosis, 1 renal duplication and 1 small penis. There were 3 cases of fetal genitourinary abnormalities misdiagnosed by prenatal MRI. Neither prenatal ultrasound nor MRI could show the genitalia anomaly detected by postnatal examine, in all 3 cases of urinary system abnormalities associated with genitalia anomaly.

In fetal urinary system abnormalities, prenatal ultrasound and MRI have high diagnostic accuracy rates. However, ultrasound and MRI are both difficult to show genitalia anomaly. The indications of MRI in detecting fetal genitourinary abnormalities need to be defined to guide a reasonable use of fetal MRI.