Objective: To investigate the genetic etiology, ultrasonic characterization and prognosis of obstructive diseases, such as fetal hydronephrosis, posterior urethral valve and giant bladder. Methods： The clinical data of 359 fetuses (23 of them were one of twins, others were singleton) with urinary obstructive lesions diagnosed by prenatal ultrasound from January 2014 to June 2020 were analyzed, including 156 cases with interventional prenatal diagnosis. The prognosis of all cases was tracked. Results: There were 314 cases of hydronephrosis (87.46%), 36 cases of giant bladder (10.03%), and 9 cases of posterior urethral valve (2.51%). Among 359 cases of urinary obstructive diseases, 319 cases were single disease and 40 cases were complicated with other system abnormalities. Chromosomal microarray analysis of fetal samples from 156 cases showed that 10 cases (6.41%) were the abnormalities of chromosome number, 3 cases were pathogenic CNVs and 8 cases were CNVs of unknown clinical significance, including 2 cases of 21 trisomy with the simple hydronephrosis under ultrasonic examination. Among 267 live born newborns, 251 newborns with hydronephrosis, 211 newborns with hydronephrosis showed normal micturition after delivery, 40 cases were diagnosed with severe hydronephrosis and underwent further urinary obstruction-relief surgery, in which 36 cases exhibited good effects after surgery. Among the giant bladder cases diagnosed by prenatal ultrasound, 9 cases of 15 live births were found the giant bladder in the early pregnancy, and returned to normal in the middle and late stage of pregnancy, which suggested a transient bladder enlargement. One case recovered well from the ureterectomy surgery on the affected side due to left hydronephrosis and left ureteral malformation after birth. The other 5 cases had normal urination and did not undergo the follow-up ultrasound examination. Among 9 cases of posterior urethral valve, 8 cases were terminated pregnancy and 1 case got a live birth. This case was diagnosed as posterior urethral valve at 28 weeks of pregnancy, no operation performed after birth, and the growth and development was normal. Conclusions： The rate of adverse pregnancy with hydronephrosis is low and the prognosis is good in obstructive diseases of urinary system. In some cases of the giant bladder found in the early pregnancy and with the ultrasonic imaging returned to normal in the middle and late pregnancy, the risk of chromosomal abnormalities related to giant bladder was increased. When the fetal giant bladder was found before delivery, chromosomal karyotype analysis and gene detection were needed. The prognosis of posterior urethral valve is related to the gestational age of definite diagnosis. The prognosis may be better if the posterior urethral valve happened after 24 weeks of pregnancy.
