In Utero Ultrasonography: Impact on Urology

Postnatal management of infants with antenatally detected hydronephrosis

With the increasing use of antenatal sonography, fetal hydronephrosis has been reported more frequently. Because of the lack of consensus regarding treatment of these infants, the postnatal approach toward fetal renal pelvis enlargement remains controversial. The aim of this prospective study is to demonstrate the postnatal investigation, treatment, and outcome of infants with prenatally diagnosed hydronephrosis. Infants whose antenatal ultrasound scan showed a fetal renal pelvis of 5 mm or greater were investigated postnatally using ultrasound (US) and voiding cystourethrography. When indicated, isotope studies and intravenous urograms were also performed. We followed prospectively neonates with antenatally diagnosed hydronephrosis and recommended management guidelines on the basis of our findings. In 156 neonates (193 kidney units) that were found to have hydronephrosis, the average gestational age at which the diagnosis was made was 32.94+/-5.10 weeks. The mean duration of postnatal follow-up was 26.3+/-13.56 months (range 3-60 months). The mean APPD of the fetal renal pelvis was 10.35+/-3.24 mm (5-9 mm in 84 kidneys, 10-14 mm in 96 kidneys and > or =15 mm in 13 kidneys). Of the 193 kidney units, 145 units were found to be pathological. The most common detected underlying abnormalities were ureteropelvic junction obstruction (in 91 kidneys; 62.7%) and vesicoureteral reflux (in 24 kidneys; 16.6%). Postnatally, 23 (45%) of 51 patients whose first US was normal were diagnosed postnatally as having urinary tract abnormality. There was a negative correlation between APPD and the rate of spontaneous resolution and positive correlation between APPD and the rate of surgery (P<0.01). In conclusion, because it is not possible to determine an upper limit of normal for the antenatal renal pelvis, any baby with AH should not be considered clinically insignificant. Infants with antenatal renal pelvis measurements > or =5 mm should be investigated postnatally. A normal postnatal ultrasound scan does not preclude the presence of urinary tract abnormality.

Antenatal hydronephrosis. Fetal and neonatal management

As many as 1% of newborn infants have a prenatal diagnosis of hydronephrosis or significant renal pelvic dilation. Hydronephrosis often is caused by nonobstructive conditions. The likelihood of significant urologic pathology is directly related to the size of the fetal renal pelvis, and 90% with an anteroposterior diameter more than 2 cm need surgery or long-term urologic medical care. Following delivery, antibiotic prophylaxis should be administered and a renal sonogram and voiding cystourethrogram should be obtained. If there is grade 3 or 4 hydronephrosis, usually a diuretic renogram is recommended also. Pediatric urologic or pediatric nephrologic consultation usually is helpful in planing evaluation and treatment. Prenatal recognition of hydronephrosis allows neonatal diagnosis and treatment of urologic pathology, preventing complications of pyelonephritis and obstruction.

Outpatient nephrectomy for nonfunctioning kidneys

We describe a surgical approach that allows multicystic dysplastic and nonfunctioning hydronephrotic kidneys to be removed on an outpatient basis through a 2.5 to 3 cm. subcostal incision. In the last 5 years 40 children (age 4 months to 5 years, mean 8.2 months) were scheduled for outpatient nephrectomy in an ambulatory surgical unit in a hospital setting. Of the 40 patients 30 had a multicystic kidney. Renal size ranged from 3 x 2 to 9.5 x 7.2 cm. Operative time ranged from 20 to 70 minutes (mean 45.4). In 34 cases (85%) an intercostal block was also performed to provide analgesia for 18 to 24 hours. Nephrectomy was done on an outpatient basis in 39 of the 40 children (98%). Mean pain score (range 0 to 5) in the last 19 patients who underwent an intercostal block was 0.68 at discharge from the hospital, 0.85 at bedtime and 0.95, 24 hours later. We conclude that nephrectomy may be performed through a small incision on an outpatient basis with minimal morbidity, and that this approach offers an alternative to laparoscopic nephrectomy and nonsurgical management of these kidneys.

Renal histological changes secondary to ureteropelvic junction obstruction

The treatment of children with apparent ureteropelvic junction obstruction is controversial. In an asymptomatic infant or child the decision to recommend pyeloplasty usually is based on interpretation of the renal scan. We retrospectively analyzed the renal biopsy obtained during pyeloplasty in 55 children. Histological changes were compared to the differential renal function revealed on the preoperative renal scan. Histological changes were graded on a scale of I to V; I--normal, II--mild dilatation of the collecting tubules or Bowman's space and III to V--progressively severe changes of obstructive uropathy, including reduced glomerular number, glomerular hyalinization, cortical cysts and interstitial inflammation. Patient age ranged from 4 days to 19 years (mean 4.8 years). Mean differential function according to histological grade was I--49%, II--43%, III--42%, IV--30% and V--25%. Of 33 patients with a differential function of 40% or greater 26 (79%) had a grade I or II biopsy, while 21% had a more significant alteration in renal histology. In contrast when the differential function was less than 40% 6 of 18 patients (33%) had grade I or II disease on biopsy. In conclusion, in approximately 25% of children with ureteropelvic junction obstruction there is a disparity between preoperative differential renal function computed during diuretic renography and renal biopsy.