Prenatally diagnosed hydronephrosis and infants/evaluating and managing Flashcards
What is the most common abnormality found on routine screening at the prenatal ultrasound?
Genitourinary and kidney abnormalities.
What is the most common genitourinary abnormality identified on prenatal ultrasounds?
Hydronephrosis or dilation of the proximal urinary collecting system occurs in up to 0.6% of all prenatal ultrasounds.
In a stable infant found to have hydronephrosis, or genitourinary, or kidney abnormalities on prenatal ultrasound, when should a follow-up ultrasound be obtained?
Wait until 1 week of age, if however, there is a concern of being unable to follow-up at 1 week, then obtain at discharge and at 4 to 6 weeks of age.
If the patient is unstable or oliguric at birth then when should an ultrasound be obtained?
+At greater than or equal to 48 hours after birth
What percentage of prenatal hydronephrosis demonstrates resolution postnatally??
50% postnatal ultrasounds demonstrate resolution
What percentage of prenatal hydronephrosis postnatally is not associated with urinary tract obstruction?
15% of postnatal ultrasounds show persistent hydronephrosis not associated with urinary tract obstruction. Of these only 10% will require surgery due to development of obstruction, the rest will resolve entirely by age 3 years.
What percentage of prenatal hydronephrosis postnatally is associated with obstructive or refluxing?
35% of postnatal ultrasounds show obstructive or refluxing causes.
What are some of the underlying etiologies for obstructive or refluxing causes of hydronephrosis?
- Ureteropelvic junction obstruction or UPJ
- Vesicoureteral reflux or VUR
- Posterior urethral valves or PUV
- Megaureter
- Ureterocele
How is the severity of hydronephrosis graded?
It is based on measuring the anterior posterior pelvic diameter
What constitutes a normal or mild hydronephrosis?
Less than 10 mm AP pelvic diameter
What constitutes moderate hydronephrosis?
10 to 15 mm AP pelvic diameter
What constitutes severe hydronephrosis?
Greater than 15 mm AP pelvic diameter
In an infant who has not urinated in the first 48 hours or oligoanuria, what is strongly suggested diagnosis?
Genitourinary obstructive lesion.
What physical exam findings may be present in an infant or newborn with genitourinary or kidney abnormalities?
Palpable abdominal or flank mass: UPJ or multicystic, dysplastic kidney
Distended bladder: PUV or urethral stricture
Absent abdominal musculature and undescended testes: Prune-belly syndrome
When should a voiding cystourethrogram or VCUG be obtained?
If postnatal hydronephrosis is present on ultrasound and for evaluating VUR, ureterocele, urethral stricture, or PUV.
What is a MAG-3 study?
Diuretic renography
When should a MAG3 study be done?
In patients with hydronephrosis and a UPJ obstruction is suspected
How should a patient with normal or mild hydronephrosis be managed?
Clinically with no further evaluation needed
How should the patient with moderate hydronephrosis be managed?
A repeat ultrasound at 4 to 6 months of age is recommended.
With the 4 to 6-month ultrasound results what further management is necessary for patients with resolution, no change or increasing hydronephrosis?
- With resolution of hydronephrosis no further management needed, most will resolve by 18 months of age.
- No change in hydronephrosis continue to monitor with an ultrasound at 1 year of age followed by an ultrasound at 3 to 5 years of age. May need to obtain a mag–3 renography if symptomatic, pain with urination or increasing urinary frequency to rule out obstructive process.
- Increasing hydronephrosis, obtain a mag–3 study to look for obstructive process.
How should the patient with severe hydronephrosis be managed?
Obtain diuretic renography or mag–3 at 6 weeks of age and refer to pediatric urologist.
Should a child be circumcised routinely if found to have hydronephrosis?
Circumcision should not routinely be recommended for neonates with hydronephrosis, there is no evidence of negative renal outcomes and uncircumcised children with hydronephrosis.
Although controversy in prophylactic management for hydronephrosis what antibiotics are used for what patient age and degree of hydronephrosis.
Amoxicillin or cephalexin is used in infants less than 3 months of age
TMP sulfa or nitrofurantoin is used in children greater than 3 months of age. Generally antibiotic prophylaxis is not used in infants with low-grade or moderate grade hydronephrosis.
What 4 circumstances would most centers opt for providing antibiotic prophylaxis in neonates or children with hydronephrosis?
- Dilated ureters
- Enlarged bladder due to PUV
- Bilateral UPJ obstruction
- Giant hydronephrosis: Renal pelvis diameter greater than 30 mm
