Avoiding unnecessary intervention in pregnancy: an ultrasound-based decision algorithm for acute flank pain.

Background: Chronic kidney disease (CKD) in cats often progresses silently, making early diagnosis challenging. Symmetric dimethylarginine (sSDMA) is a sensitive biomarker for early renal dysfunction, while the resistive index (RI), obtained via Doppler ultrasonography, reflects renal vascular resistance. Combining these tools may improve early CKD detection. This study aimed to evaluate the correlation of RI with sSDMA in asymptomatic cats. Materials, Methods & Results: A prospective, blinded cohort study assessed the correlation between renal RI and sSDMA in 101 clinically asymptomatic cats. Examinations were performed without sedation, with manual restraint, and approved by the Federal University of Paraná's Animal Ethics Committee. Triplex Doppler ultrasonography used a GE Logic 5 machine with a 7.5-12 MHz linear transducer. B-mode assessed renal morphology, followed by color and pulsed Doppler for vasculature and interlobar arteries. RI was automatically calculated from three waveforms per kidney. An RI ≥0.59 (left) or ≥0.54 (right) was considered elevated. Blood samples were collected from the jugular vein. Creatinine and sSDMA were measured at IDEXX Laboratories (São Paulo, Brazil) using liquid chromatography-mass spectrometry. Urine was collected via cystocentesis. sSDMA values ≥ 14 μg/dL were considered elevated. Cats were grouped by sSDMA levels. Statistical analysis used SPSS 21.0, with P < 0.05 set as significant. Reliable RI measurements were obtained in 91 cats; 10 were excluded due to poor waveform acquisition (e.g., patient movement, panting, poor corticomedullary definition). Mean RI was 0.61 ± 0.07 (left) and 0.62 ± 0.07 (right), with no significant difference. Increased RI was seen in 55.9% (47/84) of left kidneys and 86% (74/86) of right kidneys. Elevated sSDMA was detected in 14.9% (15/101) of cats. A statistically significant correlation was found between elevated RI in the right kidney and increased sSDMA (P = 0.001), but not the left (P = 0.246). Creatinine also positively correlated with elevated sSDMA (P = 0.022), supporting the link between renal hemodynamic changes and early biochemical markers. These results suggest RI, particularly in the right kidney, may be a useful non-invasive parameter for early CKD detection in cats, especially with sSDMA. Discussion: While renal ultrasonography is common in cats, few studies explore RI's diagnostic potential in asymptomatic animals. Doppler ultrasonography was feasible but sometimes limited by patient stress, obesity, and altered renal morphology, affecting waveform quality. No significant difference was found between right and left kidney RI values, though some cats showed inter-kidney discrepancies, possibly indicating unilateral disease. Mean RI values were normal but near early CKD values.The significant correlation between elevated RI in the right kidney and increased sSDMA was not observed in the left. The asymmetry is unclear, but extrarenal factors and comorbidities might influence both RI and sSDMA. Despite limitations, creatinine also correlated positively with sSDMA, supporting its reliability in early renal assessment. RI should not be a standalone CKD screening method but a complementary tool, especially with sSDMA. Bilateral assessment is recommended, and interpretation should be cautious with morphological abnormalities or poor patient cooperation. Overall, RI measurement is feasible in unsedated cats and may aid early detection of renal changes in subclinical disease. Keywords: feline, resistive index, doppler, kidney, SDMA.

We investigated the influence of age on intrarenal arterial resistive index (RI) measurement in 135 normal subjects (71 male, 64 female; age range = 17-68 years, median age = 37 years). Each subject underwent color Doppler measurement of the intrarenal RI from three distinct interlobar arteries in the superior, middle, and inferior parts of both kidneys. The mean of six RI values obtained from both kidneys was used for analysis. The correlation of RI with different variables was investigated by linear regression and stepwise multiple linear regression. Variables analyzed were age, systolic blood pressure, diastolic blood pressure, mean blood pressure, pulse pressure, and pulse rate. The results of linear regression showed that age had a significantly positive correlation ( r = 0.276, p = 0.0012) and diastolic blood pressure had a significantly negative correlation ( r = -0.186, p = 0.0311) with the RI. The results of stepwise multiple linear regression showed that the combination of age and diastolic blood pressure could explain approximately 15% of the RI changes ( r(2) = 0.1535). Although there is a statistically significant positive correlation between intrarenal RI and age, the correlation is weak. This suggests that the influence of age on RI measurement is small and may be of no clinical importance.

To determine the intrinsic sampling variability of measurements of hepatic artery resistive index and systolic acceleration time in healthy subjects and to estimate the components of variability attributable to the sonographer, individual measurement, and subject. In a randomized, controlled (blinded) fashion, nine sonographers measured hepatic artery resistive index and systolic acceleration time in five healthy subjects by using Doppler ultrasound (US). Analysis of variance was used to estimate the contribution of several factors to the observed variability in measurements. The standard deviation for a single measurement was 0.08 for resistive index and 39 msec for systolic acceleration time. For resistive index, the estimated variance components were 0.0012 (18%), 0.0004 (6%), and 0.0050 (76%) for the subject, sonographer, and intrinsic variability, respectively. For systolic acceleration time, the estimated variance components were 59 msec (4%), 264 msec (17%), and 1,250 msec (79%) for the subject, sonographer, and intrinsic variability, respectively. Because of substantial variability in hepatic arterial measures, caution is indicated when interpreting small changes in the measurement of these Doppler US indexes.

Doppler Resistive Index in Benign Prostatic Hyperplasia: Correlation with Ultrasonic Appearance of the Prostate and Infravesical Obstruction

The aim of this study was to evaluate the influence of elevated ureteral pressure on renal arterial distention, and thereby on the Doppler resistive index. Seven isolated rabbit kidneys were subjected to a pulsatile perfusion while the renal pelvis was pressurized via the ureter. Renal vascular pressure, flow, resistance (pressure/flow) and conductance (flow/pressure) were compared to simultaneous resistive index measurements using linear regression analysis. Changes in the Conductance Index (systolic conductance - diastolic conductance/systolic conductance) were likewise compared to the resistive index. Elevations in ureteral pressure were significantly correlated with (1) increased resistive index values, (2) increased mean renal vascular resistance, (3) decreased mean conductance, and (4) increased conductance index values (for all correlations P < 0.05). The increases in the resistive index correlated significantly with increases in the conductance index. This study shows that elevated ureteral pressure, likely acting via interstitial pressure, diminishes the conductance of the renal vascular bed. Because this effect is more dramatic at diastole, the cyclic patterns of flow are altered, resulting in elevated resistive index values. The results indicate the importance of the interaction between vascular distensibility and pulsatile flow, rather than overall mean renal vascular resistance, in determining resistive index values.

To determine the usefulness of sonographically obtained resistive indexes (RIs) in the diagnosis of pancreas allograft rejection. Findings were studied from 78 transduodenal pancreas allograft biopsies that were ultrasound-guided and cystoscopically directed. The 78 biopsies included 40 that were compared directly with baseline RI data. Biopsies were categorized by result and correlated with concurrent RIs (including 26 RIs obtained within 24 hours of biopsy) with the chi2 test for categoric variables and the Student t test for continuous variables. Sensitivity, specificity, and positive and negative predictive values were calculated with standardized formulas. The mean RIs between the no rejection, mild acute rejection, and moderate acute rejection groups were not statistically significantly different; however, the mean RI associated with chronic rejection was statistically significantly higher (P < .05) than that in the other groups. The sensitivity, specificity, and positive and negative predictive values of either an elevated RI (> 0.70) or greater than 10% increase in the RI above the baseline value in the diagnosis of acute rejection were approximately 50%. Neither the absolute level of the RI nor the relative increase was correlated with acute rejection proved at biopsy. Changes in RIs after pancreas transplantation were a poor indicator of acute rejection, but the absolute value of the RI was elevated in cases of chronic rejection.

Acute flank pain from suspected urolithiasis is a common presenting complaint in the Emergency Department. Multiple computed tomography (CT) has traditionally been the standard imaging modality used to diagnose obstructive kidney stones, however point of care ultrasound (PoCUS) can play an important role in the diagnostic algorithm and risk stratification of acute flank pain. Here, we present the case of a 29-year-old female with suspected urolithiasis, who underwent PoCUS that revealed right-sided hydronephrosis and normal left kidney, bladder, and aorta. A subsequent KUB was negative. As the clinical course failed to improve with therapy, an abdominal and pelvic CT was ordered revealing a 5 mm distal obstructing ureteric calculus at the right vesico-ureteric junction and another 5 mm left mid ureteric calculus. To the best of our knowledge, this is the first case in which a patient presenting with acute right-sided flank pain demonstrated unilateral hydronephrosis on PoCUS, but had clinically significant bilateral ureteric stones on CT. Emergency physicians who employ PoCUS for evaluation of flank pain must be aware of its benefits and drawbacks and how they apply to each patient. As such, we have developed a script emergency physicians can use for shared decision-making with renal colic patients when deciding on the appropriate imaging modality.

Aim: In this study, we aimed to assess the diagnostic accuracy and cost effectiveness of a first-step evaluation form, which we improved for patients administrat ed to the emergency department (ED) with non-traumatic acute abdominal and flank pain. Materials and Methods: Patients presenting with non-traumatic acute abdominal and flank pain complaints to the ED were included in this prospective cross-sectional cohort study in two consecutive months. Control group patients were evaluated with forms currently in use in our ED in the first month, whereas the evaluation of the test group was perfromed with the standardized evaluation form specifically designed for acute abdominal and flank pain in the second month. Results: Throughout both sessions, 1224 patients in total presented with non-traumatic abdominal and flank pain. Out of these, 285 of those enrolled in the first session, and 335 enrolled in the second session. Both control and test groups, which were similar demographically and with respect to vital symptoms/ findings, did not show any significant difference with respect to the examination/test and treatment. However, we observed a significant decrease in ED patient care expenses in the group evaluated with the new standardized form. Among them, those who were evaluated with the standardized form had relatively fewer complaints than those evaluated with the currently available evaluation form. Conclusion: Our results showed that utilization of a new standardized form for patients presenting with non-traumatic acute abdominal and flank pain significantly decreased patient care expenses for ED care; furthermore, they experienced relatively fewer complaints after discharge from the ED. (Eurasian J Emerg Med 2016; 15: 20-3)

To determine the variability in resistive index (RI) in normal kidneys, possible causes of variability, and consequences of reporting a single value. Doppler ultrasound RI measurements were obtained in the upper, middle, and lower regions of 118 kidneys in 58 healthy subjects (aged 24-70 years; 35 women, 23 men) who subsequently underwent angiography. The effects of sampling a particular parenchymal region, vascular territory, or kidney were assessed. Kidney region, vascular territory, and right versus left kidney had no consistently significant effect (P < or = .05) on RI. Age had a statistically significant effect. RI readings were highly correlated with each other both within a subject and within a kidney. The probability that a single RI value would exceed 0.70 in a healthy 45-year-old subject was 6%; this decreased to 3% when three readings were averaged. The variability of RI measurements in a kidney suggests that a number of RI readings should be averaged before a single representative value is reported.

Acute flank pain: A modern approach to diagnosis and management

The choice of the most suitable technique for radiologic evaluation of upper urinary tract stones depends on the precise clinical questions that have to be answered. Many of these questions can still be answered by plain films of the abdomen and excretory urography. This review addresses the value of ultrasonography and computed tomography (CT) with respect to the two most important clinical questions, i.e. 1) presence/extent of obstruction/hydronephrosis and perinephric abscess in patients with acute flank pain; and 2) precise location, number and size of calculi. Because its sensitivity is comparable with CT and it is widely available, ultrasonography in the hands of experienced clinicians/radiologists may be preferred for evaluation of patients with acute flank pain. However, it must be emphasized that ultrasonography may totally miss acute ureteral obstruction/hydronephrosis within the first 12-24 hours. In children as well as in pregnant women, ultrasonography is still the technique of choice, but it may be replaced by magnetic resonance urography in the future. For precise stone location or detection of calcifications, however, the speed, safety and accuracy of unenhanced helical CT make this the most sensitive method and therefore the technique of choice. It also detects urinary calculi more accurately and exposes patients to less radiation than the traditional combined plain abdominal film/intravenous urography. Furthermore, CT can most readily reveal alternative diagnoses in patients with acute flank pain and other intraabdominal pathologies than stones.

Pelviureteric junction obstruction (PUJO) is the most common cause of pediatric hydronephrosis; however, distinguishing obstructive and non-obstructive dilatation remains challenging. Existing diagnostic modalities are limited by the lack of validation against objective measures of renal injury. Preoperative imaging is critical for guiding surgical decision-making; however, its correlation with histopathologic renal damage has not been fully elucidated. To evaluate the association between preoperative sonographic and nuclear scintigraphy parameters and intraoperative renal histopathology in children with congenital PUJO and to identify imaging predictors of significant renal parenchymal damage. A prospective observational study was conducted on 60 children (< 16years) with unilateral PUJO who underwent Anderson-Hynes pyeloplasty. Preoperative ultrasound parameters, including Society for Fetal Urology (SFU) grade, anterior-posterior pelvic diameter (APD), cortical thickness, and Doppler resistive index (RI), as well as nuclear scintigraphy parameters, including differential renal function (DRF), drainage half-time (T½), and renogram curve were recorded. Renal lower pole cortical biopsies were graded using Elder's histopathology scoring system, with significant histologic damage defined as moderate-to-severe injury (score of ≥ 6). Statistical correlations and receiver operating characteristic analyses were performed to assess the predictive value of imaging parameters for histologic injury. High-grade hydronephrosis (SFU grade III-IV) was observed in 70.0% of patients, an anteroposterior diameter (APD) ≥ 20mm in 66.7%, and an elevated Doppler resistive index (RI ≥ 0.70) in 45.0%. Nuclear scan parameters demonstrated reduced differential renal function (DRF < 40%) in 48.3% of patients and prolonged drainage half-time (T½ ≥ 20min) in 56.7% of patients. Histopathological examination revealed significant renal damage in 73.3% of kidneys. Significant associations, with histologic injury were observed for APD ≥ 20mm (p = 0.017), SFU grade ≥ III (p = 0.018), RI ≥ 0.70 (p = 0.030), DRF < 40% (p = 0.008), and T½ ≥ 20min (p = 0.021). Receiver operating characteristic analysis demonstrated fair predictive accuracy across parameters, with area under the curve (AUC) values of 0.707 for SFU grade, 0.697 for RI, 0.640 for APD, 0.702 for DRF, and 0.673 for T½. SFU grade ≥ III showed the highest sensitivity (79.5%) but moderate specificity (56.2%), while DRF < 40% demonstrated the highest specificity (81.2%) and positive predictive value (89.7%). Doppler RI ≥ 0.68 and T½ ≥ 20min exhibited balanced diagnostic performance, with sensitivities of 70.5% and 65.9% and specificities of 68.8% each. Negative predictive values were modest across all parameters (41.9-50.0%). Ultrasonographic and nuclear imaging parameters correlate significantly with histopathologic injury in pediatric PUJO and serve as practical, noninvasive predictors of renal parenchymal damage. While ultrasonography provides higher sensitivity, nuclear scan indices offer greater specificity and predictive value, supporting a combined imaging approach for optimal evidence-based decision-making to preserve renal function in affected children.

Intrarenal and carotid hemodynamics in patients with essential hypertension

The purpose of this study is to investigate the temporal relation between the change in the resistive index (RI) from renal Doppler sonography and that of serum creatinine values in the course of experimentally induced reversible acute renal failure (ARF) in rabbits. Reversible ARF was induced in 10 New Zealand white rabbits by injecting a glycerol solution (6.0 mL/kg) into the thigh muscle. Doppler sonography was performed before injection, and 6, 12, and 24 hours, and 3, 5, 7, and 14 days after injection of glycerol. Blood samples for measuring serum creatinine levels were obtained in the same time sequence. Three rabbits, which died during the course of the experiment, were excluded from the study group. The RI elevated rapidly after glycerol injection, peaked at 12 hours, and then decreased to normal values by 7 days. Conversely, serum creatinine values were elevated and peaked at 1 day and then decreased to normal by 14 days. The change in the RI preceded the change in serum creatinine levels in the course of reversible ARF. There was a weak linear correlation between RI and serum creatinine levels, with a correlation coefficient of 0.33. Doppler sonography with measurement of resistive index may be useful in predicting the course of ARF.

THE VALUE OF UNENHANCED HELICAL COMPUTERIZED TOMOGRAPHY IN THE MANAGEMENT OF ACUTE FLANK PAIN