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Combined Parameter Surveillance Protocol for High Grade Congenital Hydronephrosis
Brian Stotter, M.D., Rachel Engelberg, M.D., Jeremy Wiygul, M.D..
Tufts Medical Center, Boston, MA, USA.
BACKGROUND: The optimal management algorithm for congenital high grade hydronephrosis is still unclear. We present a surveillance protocol for patients with high grade unilateral congenital hydronephrosis that uses a combination of clinical and radiologic parameters.
METHODS: Since 2012, patients at our institution with congenital unilateral hydronephrosis have been managed according to a protocol that includes both periodic renal ultrasounds and a mercaptoacetyltriglycine (MAG-3) renal scan obtained at baseline, as well as urine protein/creatinine ratios, serum creatinine and blood pressure measurements. Repeat MAG-3 was obtained after 12 months if SFU grade 3 or higher hydronephrosis persisted. Pyeloplasty was indicated if there were evidence of deterioration on MAG-3 of more than 10% and/or high grade obstruction indicated by a drainage time of greater than 20 minutes on either the initial or followup MAG-3, with the presence of at least one of the following: hypertension, elevated serum creatinine, failure of growth of the ipsilateral kidney, or proteinuria. For our purposes, only infants with SFU grade 3 or 4 were included.
RESULTS: A total of 31 infants were included in the study, with a mean followup of 14 months. 12 patients (39%) presented with SFU grade 4, 18 (58%) with SFU grade 3, and one with SFU grade 2 that then increased to grade 4. 25 patients underwent baseline MAG-3, with five patients' hydronephrosis resolving before the initial MAG-3, and one family declining any MAG-3, despite persistent SFU grade 3 hydronephrosis at over 3 years of followup. Out of these 25, 9 patients underwent repeat MAG-3 scan (with a mean time between MAG-3 scans of 15 months), 8 experienced lessening of hydronephrosis to SFU grade II or less in the interval, 6 patients with high grade hydronephrosis are awaiting repeat MAG-3 and 2 others were lost to followup. 13 patients presented with high grade obstruction on initial MAG-3, with another patient having a T1/2 of 19 subsequently increasing to 26 on follow up MAG-3. Eight then underwent at least one follow up MAG-3 scan due to persistent high grade hydronephrosis (Table 1), with obstruction persisting in seven (including the one patient that developed obstruction on follow up renal scan) and resolving in one. No obstructed kidney experienced a drop in differential function greater than 5.6% on repeat scan, and average change in the affected kidney in this group was -1%. 12 patients had a non-obstructive pattern on initial renal scan (though one was subsequently reclassified to obstructed), and eight were followed for more than 8 months, with all 8 experiencing lessening of the hydronephrosis to SFU Grade II or less. No child fulfilled criteria for surgical intervention, and one child underwent pyeloplasty due to parental desire.
CONCLUSIONS: Although larger numbers of patients are needed to confirm, even highly obstructed kidneys do not appear to lose significant function early in life, and most unobstructed kidneys experience eventual improvement of hydronephrosis.
Initial and Followup Renal Scans for Obstructed Kidneys
|Initial % Function / T 1/2||Final % Function/ T 1/2||Time between scans (days)|
|Patient 1||47% / 33 min||53% / 58 min||154|
|Patient 2||49% / 31 min||44.5% / 42 min||1096|
|Patient 3||53% / 19 min||55% / 26 min||261|
|Patient 4||53% / 20 min||50.4% / 50 min||482|
|Patient 5||52% / 31 min||53.6% / 10 min||511|
|Patient 6||47.5% / 72 min||45.3% / 24 min||402|
|Patient 7||29% / 84 min||26.3% / 45 min||411|
|Patient 8||55% / 28 min||49.4% / 33 min||366|
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