The Northeastern Society of Plastic Surgeons

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PRENATAL HYDRONEPHROSIS SAFE DISCHARGE PARAMETERS
Orchid Djahangirian, MD, FRCSC1, Antoine Khoury, MD, FRCSC2.
1Ste-Justine/University of Montreal, Montreal, QC, Canada, 2CHOC/University of California, Irvine, Irvine, CA, USA.

BACKGROUND: With the advent of routine fetal ultrasonography, the entity of antenatal hydronephrosis has become a steady source of urology referrals. To date, there are no known guidelines for patient follow-up but it is known that most will resolve. Our goal is to define safe parameters with which patients can be discharged early and avoid unnecessary follow-up with the associated parental anxiety.
METHODS:
We retrospectively reviewed all patients referred to a single children's referral hospital center for hydronephrosis between 2010 and 2012. We excluded all patients with postnatal hydronephrosis, less than 2 postnatal ultrasounds with available images for interpretation by the authors, the presence of hydroureter or a duplicated renal system, associated neurogenic bladder or syndromes encompassing hydronephrosis. We divided the patients and renal units into 2 groups for comparison. Our analysis endpoint is progression or non-resolution. That is, if the initial postnatal APD is less than 10mm in a renal unit or in both units of the patient, progression occurs if the APD increases to 10mm or above upon follow-up. Conversely, if the initial APD is 10mm or more in at least one renal unit, non-resolution occurs if the APD remains at 10mm or above upon follow-up. Univariate and multivariate regression models are computed. RESULTS:
There are 186 patients and 308 renal units included in the analysis, with the majority of them being in the APD less than 10mm group. Most renal units in the APD of less than 10mm group are of SFU grades 0-2 (92.1%) and the majority of the renal units in the APD of 10mm or greater group are of SFU grades 3-4 (60%). Only 19 renal units (6.2%) underwent pyeloplasty, and they are all from the APD of 10mm or greater group and classified as SFU grade 3-4. No renal unit with an APD of 10mm or greater and a SFU grade 0-2 underwent surgical correction, nor did any renal unit with an APD of less than 10mm. More than half of the renal units' hydronephrosis resolved in the APD of 10mm or greater group, in comparison to 96.1% of the APD of less than 10mm group that did not progress. On multivariate analysis adjusting for gender, laterality, and SFU grade, patients with an APD of 10mm or greater are 7.76 times more likely to progress, when compared to those with an APD of less than 10mm (p=0.0006). However, no variable proved to be an independent predictor of progression.
CONCLUSIONS: An initial postnatal APD of 10mm or greater does not necessarily predict surgery, but patients in this group with a SFU grade 3-4 merit follow-up. More importantly, all patients with an APD of less than 10mm, especially those with a SFU grade 1-2, can be safely discharged as they will most likely not suffer any complications. Without being able to guarantee non-progression, the benefits of minimal follow-up in this large group of patients with mild hydronephrosis surely outweigh the risks.


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