History of renal stones or renal obstruction. Initial imaging. CT Abdomen and Pelvis Renal stones or renal obstruction can be a source of APN [1,8,11,15,18,19]. CT of the abdomen and pelvis is highly sensitive for detection of stones and hydronephrosis [8,11]. Furthermore, CT is a useful imaging study to diagnose APN if symptoms persist or worsen after 72 hours have passed [1,8,14-21]. CT imaging should include the pelvis to identify stones in the distal ureters or urinary bladder, congenital abnormalities of the distal ureters, and abnormalities of the urinary bladder, among other potential sources of APN. Both unenhanced and contrast-enhanced CT are able to detect urolithiasis, perinephric fluid, renal swelling, and hydronephrosis [1,8,14,17-19]. However, contrast-e nhanced CT has been shown to improve detection of APN parenchymal changes, a renal abscess, and extrarenal acute conditions that may clinical present as suspicious for APN [19]. Of note, unenhanced CT has higher sensitivity than contrast-enhanced CT for detection of small renal calculi. Acute Pyelonephritis In a prospective nonrandomized data collection study of patients with a final diagnosis of APN (n = 827), the detection rate of APN was 84.4% (445/527) by abdominal CT and only 40% (72/180) by abdominal US [10]. Although the detection rate of urolithiasis and hydronephrosis were similar by abdominal CT and abdominal US, the rate of detection of renal abscess was 4.0% (21/527) by abdominal CT and only 1.1% (2/180) by US [10]. CT and US have similar detection rates for renal stones and hydronephrosis. Advantages of abdominal CT and US over abdominal MRI may include superior detection of small urothelial stones [1,14,15,18]. In a small retrospective study of adult patients with clinical and laboratory suspicion of APN who all underwent triphasic abdominal CT (n = 100), the accuracy of the nephrographic phase among 2 readers for diagnosis of APN was 90% to 92% and for diagnosis of urolithiasis was 96% to 99% [22].
Acute Pyelonephritis. History of renal stones or renal obstruction. Initial imaging. CT Abdomen and Pelvis Renal stones or renal obstruction can be a source of APN [1,8,11,15,18,19]. CT of the abdomen and pelvis is highly sensitive for detection of stones and hydronephrosis [8,11]. Furthermore, CT is a useful imaging study to diagnose APN if symptoms persist or worsen after 72 hours have passed [1,8,14-21]. CT imaging should include the pelvis to identify stones in the distal ureters or urinary bladder, congenital abnormalities of the distal ureters, and abnormalities of the urinary bladder, among other potential sources of APN. Both unenhanced and contrast-enhanced CT are able to detect urolithiasis, perinephric fluid, renal swelling, and hydronephrosis [1,8,14,17-19]. However, contrast-e nhanced CT has been shown to improve detection of APN parenchymal changes, a renal abscess, and extrarenal acute conditions that may clinical present as suspicious for APN [19]. Of note, unenhanced CT has higher sensitivity than contrast-enhanced CT for detection of small renal calculi. Acute Pyelonephritis In a prospective nonrandomized data collection study of patients with a final diagnosis of APN (n = 827), the detection rate of APN was 84.4% (445/527) by abdominal CT and only 40% (72/180) by abdominal US [10]. Although the detection rate of urolithiasis and hydronephrosis were similar by abdominal CT and abdominal US, the rate of detection of renal abscess was 4.0% (21/527) by abdominal CT and only 1.1% (2/180) by US [10]. CT and US have similar detection rates for renal stones and hydronephrosis. Advantages of abdominal CT and US over abdominal MRI may include superior detection of small urothelial stones [1,14,15,18]. In a small retrospective study of adult patients with clinical and laboratory suspicion of APN who all underwent triphasic abdominal CT (n = 100), the accuracy of the nephrographic phase among 2 readers for diagnosis of APN was 90% to 92% and for diagnosis of urolithiasis was 96% to 99% [22].