Avoiding CT by Using US to Evaluate Pediatric Renal Colic
Avoiding CT by Using US to Evaluate Pediatric Renal Colic
The use of POCUS to evaluate renal colic in the pediatric patients is sparse in the medical literature. Although US is slightly less sensitive and specific in identifying individual stones than CT, the difference between the two imaging studies has been shown not to be clinically significant, given that the average size of stones missed by US are 2–3 mm, which usually do not require procedural intervention and should pass spontaneously. Additionally, the secondary signs, such as the twinkling artifact, and reduced or absent ureteral jets on color Doppler are complementary findings that improve detection of urolithiasis on sonography. These color Doppler techniques (twinkling artifact and ureteral jets) can increase overall accuracy of ultrasound for nephrolithiasis and may reduce CT scan utilization and radiation exposure beyond the reductions obtained in the multicenter randomized controlled trial by Smith-Bindman et al. that did not employ these methods. Another study showed that nearly 90% of pediatric patients treated for symptomatic urolithiasis could have completed their evaluation and treatment without undergoing CT. The American College of Radiology also rates US as equivalent to CT in the appropriateness criteria for recurrent renal colic. The multicenter randomized controlled trial by Smith-Bindman et al. also demonstrated that there were no significant differences between the initial use of POCUS, radiology US, or CT in missed or delayed high-risk diagnoses with complications, serious adverse events, pain scores, return to ED visits, or hospitalizations. US performed by the radiology department, however, may require a prolonged ED length of stay, while POCUS may allow for a rapid diagnosis of urolithiasis.
In case 1, the POCUS examination showed a 6.6-mm stone identified in the right ureterovesical junction with twinkling artifact and right hydronephrosis. The POCUS diagnosis of urolithiasis allowed for more efficient management of the patient's renal colic without obtaining a CT. His previous renal colic was also diagnosed with POCUS, which allowed him to avoid two CTs thus far.
In case 2, POCUS examination revealed right hydroureteronephrosis with diminished right ureteral jet compared to the left side and was consistent with the findings on US performed by radiologist. Although the patient did receive a repeat US performed by the radiologist, POCUS did provide valuable information regarding the severity of the obstruction and CT was avoided. This was important, as she had received a CT in the past to evaluate for an earlier episode of renal colic.
In case 3, POCUS examination identified the migration of a left ureteral stent into the bladder with hydronephrosis of the left kidney and intrarenal stones with twinkling artifact. Rapid diagnosis expedited her care and avoided a third CT scan, as she had previously received two CTs scans with earlier episodes of renal colic.
In case 4, POCUS showed a 10-mm stone in the right ureterovesical junction in a 3-year-old boy with persistent dysuria, despite antibiotic treatment for a urinary tract infection. POCUS identified a rare infected bladder stone as the reason for persistent symptoms despite antibiotic treatment.
In case 5, POCUS was more challenging because the patient had polycystic kidney disease. In such patients, hydronephrosis may be difficult to appreciate. However, the enlargement of the left polycystic kidney relative to the right kidney along with the relative difference in the quality of ureteral jets was useful in diagnosing renal colic and avoiding a CT. Specifically, the decreased ureteral jet on the left was consistent with partial obstruction of the left ureter. This is important, given that she had already received two previous CTs.
In each of these cases, urolithiasis was confirmed by using POCUS, and CT was avoided in all 5 patients with renal colic.
This report is a limited, nonconsecutive case series. Four out of five cases included adolescents or young adults, who may have different US findings of urolithiasis compared to those in younger children. Therefore, the accuracy of POCUS for evaluating pediatric renal colic cannot be inferred from our case series, and care must be taken when extrapolating adult data to pediatric patients. Prospective research examining the accuracy of POCUS for evaluating renal colic in pediatric ED patients is needed, especially if the trend in prevalence of urolithiasis in the pediatric population continues to increase.
Discussion
The use of POCUS to evaluate renal colic in the pediatric patients is sparse in the medical literature. Although US is slightly less sensitive and specific in identifying individual stones than CT, the difference between the two imaging studies has been shown not to be clinically significant, given that the average size of stones missed by US are 2–3 mm, which usually do not require procedural intervention and should pass spontaneously. Additionally, the secondary signs, such as the twinkling artifact, and reduced or absent ureteral jets on color Doppler are complementary findings that improve detection of urolithiasis on sonography. These color Doppler techniques (twinkling artifact and ureteral jets) can increase overall accuracy of ultrasound for nephrolithiasis and may reduce CT scan utilization and radiation exposure beyond the reductions obtained in the multicenter randomized controlled trial by Smith-Bindman et al. that did not employ these methods. Another study showed that nearly 90% of pediatric patients treated for symptomatic urolithiasis could have completed their evaluation and treatment without undergoing CT. The American College of Radiology also rates US as equivalent to CT in the appropriateness criteria for recurrent renal colic. The multicenter randomized controlled trial by Smith-Bindman et al. also demonstrated that there were no significant differences between the initial use of POCUS, radiology US, or CT in missed or delayed high-risk diagnoses with complications, serious adverse events, pain scores, return to ED visits, or hospitalizations. US performed by the radiology department, however, may require a prolonged ED length of stay, while POCUS may allow for a rapid diagnosis of urolithiasis.
In case 1, the POCUS examination showed a 6.6-mm stone identified in the right ureterovesical junction with twinkling artifact and right hydronephrosis. The POCUS diagnosis of urolithiasis allowed for more efficient management of the patient's renal colic without obtaining a CT. His previous renal colic was also diagnosed with POCUS, which allowed him to avoid two CTs thus far.
In case 2, POCUS examination revealed right hydroureteronephrosis with diminished right ureteral jet compared to the left side and was consistent with the findings on US performed by radiologist. Although the patient did receive a repeat US performed by the radiologist, POCUS did provide valuable information regarding the severity of the obstruction and CT was avoided. This was important, as she had received a CT in the past to evaluate for an earlier episode of renal colic.
In case 3, POCUS examination identified the migration of a left ureteral stent into the bladder with hydronephrosis of the left kidney and intrarenal stones with twinkling artifact. Rapid diagnosis expedited her care and avoided a third CT scan, as she had previously received two CTs scans with earlier episodes of renal colic.
In case 4, POCUS showed a 10-mm stone in the right ureterovesical junction in a 3-year-old boy with persistent dysuria, despite antibiotic treatment for a urinary tract infection. POCUS identified a rare infected bladder stone as the reason for persistent symptoms despite antibiotic treatment.
In case 5, POCUS was more challenging because the patient had polycystic kidney disease. In such patients, hydronephrosis may be difficult to appreciate. However, the enlargement of the left polycystic kidney relative to the right kidney along with the relative difference in the quality of ureteral jets was useful in diagnosing renal colic and avoiding a CT. Specifically, the decreased ureteral jet on the left was consistent with partial obstruction of the left ureter. This is important, given that she had already received two previous CTs.
In each of these cases, urolithiasis was confirmed by using POCUS, and CT was avoided in all 5 patients with renal colic.
Limitations
This report is a limited, nonconsecutive case series. Four out of five cases included adolescents or young adults, who may have different US findings of urolithiasis compared to those in younger children. Therefore, the accuracy of POCUS for evaluating pediatric renal colic cannot be inferred from our case series, and care must be taken when extrapolating adult data to pediatric patients. Prospective research examining the accuracy of POCUS for evaluating renal colic in pediatric ED patients is needed, especially if the trend in prevalence of urolithiasis in the pediatric population continues to increase.
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