Diagnostic accuracy of ultrasonography compared to unenhanced CT for stone and obstruction in patients with renal failure

BACKGROUND: To determine accuracy of ultrasound (US) kidney, ureter and bladder (KUB) compared to un-enhanced helical CT (UHCT) in patients with renal failure in the diagnosis of stone and obstruction. METHODS: This is a case controlled study conducted in the period from June 2000 to July 2003 at a university hospital. All patients had both US and UHCT scan. Patients with serum creatinine ≥ 1.8 mg/dl were included in the study. Only direct visualization of stone was considered as confirmatory. In both the studies, UHCT and US, presence of stone and obstruction were noted. The relevant biochemicals, radiological and clinical records of all the patients were analyzed. Data was analyzed using commercially available software. RESULTS: During the period of study 864 patients had UHCT for evaluation of the urinary tract in patients presenting with flank pain. Out of these 34 patients had both UHCT and US done within a span of one day and had serum creatinine of ≥1.8 mg/dl. Mean age was 48 ±15.8 years and 59% of patients were males. UHCT identified renal stones in 21 (62%), whereas 17 of these were identified on US, with a sensitivity of 81%. Of the four patients with renal stones missed on US, three were identified on plain x-ray; the mean size of stones missed was 6.3 mm. Of the 22 (65%) patients with ureteric stone on UHCT, US could only identify 10; a further 7 were identified on x-ray KUB, giving a sensitivity of 45% (US alone) and 77% (US with x-ray KUB). CONCLUSIONS: US is sensitive and specific for renal stones, 81% and 100% and for hydronephrosis, 93% and 100%, respectively. Its sensitivity to pick ureteric stone (46%) and to identify hydroureter (50%) is low. Addition of x-ray KUB abdomen increases the sensitivity for ureteric stones to 77%

Non-contrast CT in the Evaluation of Urinary Tract Stone Obstruction and Haematuria

Non-contrast computed tomography (CT) abdomen has emerged as a first line investigation in suspected upper urinary tract obstruction. Underlying causes can usually be ascertained on computed tomography of kidneys, ureters and bladder (CT KUB). However, further investigations may be required to delineate/confirm underlying pathology like ureteropelvic junction obstruction (UPJ), differentiation between obstruction and residual dilatation. Actual protocol of CT KUB for evaluation of stone disease and haematuria vary on institutional guidelines. CT KUB is not only extremely sensitive and specific in the diagnosis of stone; it is now used in the pre-operative nomograms in predicting success of various endourological interventions like percutaneous nephrolithotomy (PCNL) and shock wave lithotripsy (SWL). Determination of stone density, stone volume, stone composition, skin to stone distance, presence of ureteral wall oedema, perinephric oedema are highly predictive of stone free rate. CT recognition of various anomalies, presence of retro-renal colon, horse-shoe kidney, malrotation, etc. can help in better planning to avoid complications. One of the major limitations of CT is the radiation dose, besides cost and availability. Modification in technique and technological innovation has resulted in significant dose reduction from 4.5 to about 1 mSv

Comparison of secondary signs as shown by unenhanced helical computed tomography in patients with uric acid or calcium ureteral stones

AbstractUnenhanced helical computed tomography (UHCT) has evolved into a well-accepted diagnostic method in patients with suspected ureterolithiasis. UHCT not only shows stones within the lumen of the ureter, it also permits evaluation of the secondary signs associated with ureteral obstruction from stones. However, there we could find no data on how secondary signs might differ in relation to different compositions of ureteral stones. In this study, we compared the degree of secondary signs revealed by UHCT in uric acid stone formers and in patients forming calcium stones. We enrolled 117 patients with ureteral stones who underwent UHCT examination and Fourier transform infra-red analysis of stone samples. Clinical data were collected as follows: age, sex, estimated glomerular filtration rate (eGFR), urine pH, and radiological data on secondary signs apparent on UHCT. The uric acid stone formers had significantly lower urine pH and eGFR in comparison to calcium stone formers, and on UHCT they also had a higher percentage of the secondary signs, including rim sign (78.9% vs. 60.2%), hydroureter (94.7% vs. 89.8%), perirenal stranding (84.2% vs. 59.2%) and kidney density difference (73.7% vs. 50.0%). The radiological difference was statistically significant for perirenal stranding (p=0.041). In conclusion, we found that UHCT scanning reveals secondary signs to be more frequent in patients with uric acid ureteral stones than in patients with calcium stones, a tendency that might result from an acidic urine environment

Role of ultrasonography in diagnosis of urological lesions: hospital based study

Background: Ultrasound examination is considered to be a very useful imaging modality for the diagnosis of renal colic as well as other renal or extra-renal diseases. One of the major advantages of ultrasound examination is the avoidance of radiation exposure. However, it is reported to be operator dependent and less accurate when compared with Computed Tomography. Present study describes role of ultrasonography in assessment of suspected urological disease in patients referred to radiodiagnosis department of Nair Hospital, Mumbai during the study period.Methods: This observational descriptive study was conducted during June 2006 to June 2008 at Department of Radiology, BYL Nair Hospital, Mumbai, India. 84 patients with clinical features suggestive of urological disease and referred to the department for ultrasound examination were enrolled. Ultrasonography was done on a TOSHIBA ECCOCEE duplex Doppler ultrasound machine with 3.5-5 MHz curvilinear transducer. USG findings were correlated with the final diagnosis and USG examination findings were considered diagnostic if they resulted in correct histopathological diagnosis or correct identification of malignant tumours along with organ site. They were considered contributory when either the organ site was correctly identified without histology diagnosis or when malignancy was identified but without proper organ site. If the lesion was not detected, USG findings were marked as false negative and they were marked as false positive when the predicted disease was found to be incorrect on confirmatory diagnosis.Results: Age of the patients ranged from 0 to 76 years. Out of 84 patients studied, 49 were males and 35 were females. Overall ultrasound examination findings were found to be diagnostic in 48 cases (57.14%), contributory in 26 cases (30.95%), false negative in 10 cases (11.9%) whereas there were no false positive reports. There were 56 cases in which there were kidney lesions. Ultrasound examination findings were found to be diagnostic in 35 cases (62.5%), contributory in 17 cases (30.35%) and false negative in 4 cases (7.14%) whereas there were no false positive reports. There were 10 cases in which there were lesions involving both kidney and ureters. Ultrasound examination findings were found to be contributory in 8 cases (80%) and false negative in 2 cases (20%).There were 4 cases in which there were lesions involving ureters. Ultrasound examination findings were found to be false negative in all 4 cases (100%). There were 14 cases in which there were lesions involving urinary bladder. Ultrasound examination findings were found to be diagnostic in 4 cases (28.57%), contributory in 9 cases (64.28%) and false negative in 1 case (7.14%).Conclusions: Ultrasound examination was found to be diagnostic or contributory in diagnosis in most of the cases (88.1%). However there were a sizeable proportion of cases (11.9%) with false negative results on ultrasonography

Scintigraphic Demonstration of Urine Extravasation Secondary to Acute Ureteral Obstruction: A Case Report and Some Considerations about Acute Ureteral Obstruction

Acute ureteral obstruction produces renal damage and complications that are proportional to the severity and length of the obstruction. Anatomic diagnosis of the obstruction may be insufficient to manage the patient. Intravenous urogram (IVU) is the method usually advised by radiologists to obtain functional information, but requires iodinated contrast agents. IVU anatomic information is superior to anatomic information obtained with renal scintigraphy, but normally the physician already has the anatomic information (unenhanced CT or ultrasound). A renal scan offers better physiologic information than the IVU, has neither adverse effects nor complications, is accurate to confirm or discard significant ureteral obstruction, and depicts obstruction complications. This paper presents a patient with spontaneous urine extravasation secondary to acute renal obstruction who is diagnosed with renal scintigraphy. The authors describe the scintigraphic signs of extraperitoneal, diffuse perinephric, urine extravasation and emphasize the role of renal scintigraphy in diagnosis and follow-up of renal colic

Comparison Between Computed Tomography and Ultrasonography in Detection of Urinary Tract Calculi

Introduction: In the past decade, developments in CT technology have changed the trend of imaging modalities used in the evaluation of urinary system. The present study was undertaken to compare between Computed Tomography (CT) and Ultrasonography (USG) in detection of urinary tract calculi.  Methods: The prospective, cross-sectional and observational research design was used. The study was conducted in Department of Radiology and Imaging of Tribhuvan University Teaching Hospital from June 2017 to September 2017 in 96 patients. Patients who underwent plain CT abdomen (CT KUB) with suspicion of urolithiasis after performing USG were enrolled in the study. Ultrasound and CT findings were compared on the basis of age, gender, clinical complaints, number of stones and their locaton (site of occurrence). Similarly, specificity, sensitivity, positive predictive value and negative predictive value of USG were calculated using CT as gold standard.  Results: A total number of 96 patients were studied from June 2017 to September 2017. Among them 56 were males and 40 were females with male to female ratio of 1.4:1. The mean age among the males was 34±14.79 years and  females was 38±18.74 years. Flank pain was the commonest complaint recorded in 35.41% of patients. On the CT scan, 80% patients had renal calculi, 15.60% of stones were found in vesico-ureteric junction (VUJ) and 41.66% stones were seen bilaterally. Out of the 22 cases with ureteric calculi, USG detected calculi only in 5 cases and the sensitivity of USG in diagnosing ureteric calculi in comparision to CT was 22.72% with 100 % specificity, 100% PPV and 81% NPV.  Conclusion: Ultrasound has lower sensitivity for the detection of ureteric calculi. CT helps in precise detection of calculi during initial evaluation which is critical for clinical decision making and patient counselling.

Is an excretory urogram mandatory in patients with small to medium-sized renal and ureteric stones treated by extra corporeal shock wave lithotripsy?

Background: An intravenous urogram (IVU) has traditionally been considered mandatory before treating renal and ureteric stones by extracorporeal shock wave lithotripsy (ESWL). This study was designed to see whether there is a difference in complications and the need for ancillary procedures in patients managed by ESWL for renal and ureteric calculi, according to preoperative imaging technique. Methods: This retrospective study compared 133 patients undergoing ESWL from January 2001 to July 2002. Patients were divided into three groups according to the preoperative imaging technique used: i) IVU; ii) non-contrast enhanced helical computed tomography (UHCT); and iii) ultrasound (US) + X-ray kidney, ureter and bladder (KUB). The groups were matched in terms of age and gender, as well as location, side and size of stones. Results: There was no statistically significantly difference for number of ESWL sessions, number of shock waves and use of ancillary procedures between the three groups. The stone-free rate was 98% for the IVU and UHCT groups, and 97% for the US + X-ray KUB group. Conclusions: The complication rate and need for ancillary procedures was comparable across the three groups. Patients imaged by UHCT or US + X-ray KUB prior to ESWL for uncomplicated renal and ureteric stones do not require IVU

Diagnostic Accuracy of IVU Compared to Unenhanced CT KUB for Detection of Urinary Tract Calculi

Objective: To compare the diagnostic Accuracy of IVU to unenhanced CT KUB for detection of urinary tract calculi. Patients and Methods: This cross-sectional study was carried out at department of Radiology, Aziz Fatimah Hospital Faisalabad, from October 2016 to July 2017. All the patients having suspected Urolithiasis or ureteric colic indicating urolithiasis and referred to the Radiology department for IVU or CT KUB were selected in study sample. All the patients were briefly described about the study and informed written consent was obtained. A sample of 83 suspected patients of urolithiasis were included in the study sample. All patients in study sample who were referred for CT KUB or IVU were offered the other test free of cost. All the information including demographics, IVU and CT KUB were recorded on a predesigned performa. The data was entered and analyzed on SPSS version 21. Results: There were 48 (57.83%) males and 35 (42.17%) female patients. The mean age of the patients was 46.58 ± 9.42 years, ranging from 25 to 60 years. The final diagnosis showed that there were 59 (71.10%) positive patients for renal or ureteric stone. On the basis of IVU screening test 45 (54.21%) patients were positive, 38 (45.78%) were negative and 21.69% (16/83) patients had inconclusive results. CT KUB diagnosed 58 (69.87%) positive and 25 (30.12%) negative patients. The diagnostic parameters of IVU were considerably poor as compared with the CT KUB having sensitivity (72.08%), specificity (91.67%), PPV (95.56%), NPV (57.89%) and accuracy of 78.31%. The sensitivity, specificity, PPV, NPV and accuracy of 96.61%, 95.83%, 98.28%, 92.00% and 96.39% respectively. Conclusion: CT KUB provides more efficient information about the patients, presenting with acute renal colic. It has significantly higher rate of diagnosing urolithiasis in comparison of IVU.&nbsp

Diagnostic Accuracy of Trans-Abdominal Ultrasonography in Urolithiasis, keeping CT KUB as Gold Standard

Objective: To determine the diagnostic accuracy of trans-abdominal ultrasonography in urolithiasis, keeping CT KUB as gold standard.Material and Methods: This cross-sectional validation study was conducted at Armed Forces Institute of Radiology and Imaging, Military Hospital (MH) Rawalpindi from 15 July 2015 to 14 July 2016. In total 115 patients with expected urolithiasis were evaluated with transabdominal ultrasonography and the findings were documented. CT KUB of these patients was carried out. The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of transabdominal ultrasonography were calculated, keeping findings of CT KUB as gold standard.Results: Among total of 115 patients, 54.78% (n=63) were males and 45.22% (n=52) were females. Mean age was 35.69 ± 5.91 years. Frequency of urolithiasis on CT KUB was recorded in 62.61% (n=72). The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of transabdominal ultrasonography in urolithiasis was calculated as 65.27%, 72.09%, 79.66%, 55.36% and 67.83% respectively.Conclusion: The diagnostic accuracy of trans-abdominal ultrasonography in urolithiasis is acceptable for diagnosing urolithiasis and hence it may serve as an alternative in case of unavailability or contraindication to CT scan

Diagnostic Accuracy of Ultrasound for the Evaluation of Ureteric Calculi Taking Non-enhanced Computed Tomography as a Gold Standard

Objective: To find the diagnostic accuracy of ultrasound for the evaluation of ureteric calculi taking non enhanced Computed Tomography as gold standard. Study Design: An analytical cross-sectional prospective study was performed. Settings: The study was performed in National Hospital and Medical Center, Lahore. Period: An analytical cross-sectional study was conducted from 15 October, 2020 to 15 January, 2021. Material & Methods: In our study, all those patients with suspected ureteric calculi presenting to radiology department were included. Patients on dialysis, those with polycystic disease and ureteric stricture, as well as patients who declined to give consent and those who were uncooperative, were all excluded. Ultrasound was performed on both sides of the patient's kidney, concentrating on the ureters. Then were sent to a 64 slice CT scanner for a non-enhanced CT scan. Results: Total 121 Patients were reviewed in this research. Females were 82 (67.8%) while male was 39 (32.2%). On Ultrasound 61(50.4%) were positive for ureteric calculi while 60 (49.6%) were negative for stone in the ureter. On CT scan 110 (90.9%) patients were positive for ureteric calculi while 11 (9.1%) were negative for stone in ureter (p= 0.05). The trans-abdominal ultrasound with sensitivity 58.62%, Specificity 56.76%, Positive predictive value 51.52% and Negative predictive value of 63.64% and accuracy of 57.68%. Conclusion: The sensitivity of ultrasound is comparable to Computed Tomography findings, hence, it can be used as an option in cases where CT scans are not available or is contraindicated, such as in pregnant women. Moreover, Ultrasound modality is cheap, with no radiation dose and is readily available in our setups, making it suitable for initial diagnosis as well as for follow-up scans. Keywords: Non-enhanced Computed Tomography, Ultrasound, Ureteric Calculi, radiation, Computed Tomography. DOI: 10.7176/JHMN/90-04 Publication date:June 30th 2021