The following is a summary of “Decreased percent change in renal pelvis diameter on diuretic functional magnetic resonance urography following administration of furosemide may help characterize unilateral ureteropelvic junction obstruction,” published in the December 2023  issue of Pediatrics by Janssen, et al.

No clear definition of blockage in congenital hydronephrosis exists. Several imaging modalities and radiographic criteria may indicate ureteropelvic junction obstruction (UPJO). Furosemide and pyeloplasty were used to assess the change in anterior-posterior renal pelvic diameter (APRPD) in unilateral hydronephrosis patients with UPJO on functional magnetic resonance urography (fMRU). Inclusion criteria were 49 patients (11 females, 38 males; average age 2.2 years, SD 3.4 years) diagnosed with unilateral hydronephrosis (SFU Grade 3–4) who received fMRU before pyeloplasty for verified UPJO from February 2006 to September 2020. 29 individuals had post-pyeloplasty fMRUs. 

The weight-adjusted intravenous furosemide dosage was 1 mg/kg (max 20 mg/kg). Two board-certified pediatric radiologists assessed the APRPD of the obstructed and non-dilated kidneys before pyeloplasty and the hydronephrotic kidneys on post-pyeloplasty fMRUs. Images were measured before and 30 min after furosemide injection. Before furosemide administration, the average APRPD in obstructed kidneys was 26.3mm (SD 9.0mm) compared to 5.1mm (SD 3.6mm) in non-obstructed kidneys (P < 0.001). After furosemide treatment, the average APRPD was 31.4mm (SD 8.8mm) in the obstructed kidney and 7.8 mm (SD 4.1mm) in the non-dilated kidney (P < 0.001). 

Post-pyeloplasty, pre-furosemide APRPD was substantially lower than pre-pyeloplasty (P < 0.001), measuring 17.8mm (SD 11mm). Post-pyeloplasty, post-furosemide APRPD was 25.8mm (SD 12mm), substantially lower than pre-pyeloplasty (P = 0.02). APRPD in the blocked kidney changed by 5.1mm (SD 3.5mm) before pyeloplasty and 8mm (SD 4.6mm) thereafter (P = 0.002). APRPD changed 2.7mm (SD 2.3mm) in the non-dilated kidney. The APRPD change in the obstructed kidney was 22.9% (SD 18.5%), substantially lower than the post-pyeloplasty kidney (33.3%, SD 22.1%) (P = 0.028) and the non-dilated kidney (82.8%, SD 87.9%) (P < 0.001). A lesser decrease in APRPD on fMRU after furosemide in UPJO may also indicate blocked kidneys.

Source: sciencedirect.com/science/article/abs/pii/S1477513123003297