EFFICACY OF ULTRASOUND IN DETECTING RENAL CALCULI KEEPING NON-ENHANCED COMPUTED TOMOGRAPHY AS A REFERENCE STANDARD

Abstract

Background: Renal calculi is an emergency condition and must be diagnosed to evaluate the presence and location of renal calculi as early as possible.
Objective: To evaluate the efficacy of ultrasound in detecting renal calculi keeping non-enhanced computed tomography as a reference standard.
Methodology: An analytical cross-sectional study was performed at Gurki Trust Hospital, Lahore. All patients with suspicion of renal calculi were included, while patients with polycystic disease, dialysis, ureteric stricture, and those who refused to give informed consent were excluded. Ultrasound was performed bilaterally, focusing on ureters. 16 slice Computer tomography scanner was used to perform computer tomography scan.
Results: Out of 121 patients, 46 (38%) females and 75 (62%) males were examined, on ultrasound, 74 (61.2%) patients had no evidence of renal calculi, while 47 (38.8%) were reported with presence of renal calculi, on contrary, CT scan was performed on same patients showing, 108 (89.3%) with renal calculi and 13 (10.7%) with no evidence of renal calculi. The transabdominal ultrasonography showed an accuracy 83.47%, sensitivity 74.6%, specificity 69.6%, PPV (positive predictive value) 97.8% and NPV (negative predictive value) 37.9%.
Conclusion: Efficacy of ultrasound is comparable to CT, therefore can be considered as an alternative method when CT scan is unavailable or cannot be performed, i.e.; pregnant female. Moreover, ultrasound is cost effective, easily available modality and without radiation exposure, hence making it more appropriate for both initial and follow-up evaluations.