The production of intrauterine ureteral obstruction and vesico-ureteric reflux and their effect on the foetal kidney

Abstract

The unborn foetuses of sheep have been used as an experimental model in the study of certain congenital renal anomalies. Monoestrous ewes were bred on a farm and radiographed at about 60 days gestation for confirmation of pregnancy. Using epidural anaesthesia, each ewe was submitted to hysterotomy at about 90 days gestation to perform one of two types of studies on the foetus. -- The first experiment, that of ureteral obstruction, involved delivery of the caudal half of the foetus into the wound and approaching the left ureter from the back, lateral to the lumbar vertebrae. A silk ligature was placed on the ureter and the foetus and maternal wounds were closed separately. -- The second experiment was one of creating vesico-ureteral reflux in the unborn foetus. The foetus was delivered and a lower vertical midline, or in the male paramedian, incision was made anteriorly and the bladder entered. The ureteral orifice was unroofed adequately to leave a gaping hole. The bladder and foetal wound were closed separately and the closing procedure was carried on as in the first experiment. -- The experience gained in these studies suggested that preliminary radiography provided both an excellent confirmation of pregnancy in the ewe and also the number of foetuses present. Adequate premedication with Chlorpromazine and the use of epidural anaesthesia avoided inhalation of vomitus, jeopardizing the foetus with drugs that cross the placental barrier, and provide good anaesthesia. Amniotic fluid loss could be circumvented by using the method adopted here. Because of the friable gelatinous nature of the foetal tissue, surgery is not practicable before 70 days gestation. Whereas hydronephrosis resulted from ureteral ligation in these cases, earlier ureteral ligation may result differently. Creation of vesico-ureteral reflux was accomplished in utero and the effects of this are yet to be evaluated.