The role of ultrasonography in the evaluation of renal pathologies

INTRODUCTION

The kidneys are essential organs that control fluid volume, waste elimination, and electrolyte balance to maintain internal homeostasis. Early identification of renal diseases is crucial to preventing permanent structural and functional damage, as they constitute a substantial worldwide health burden.^[1,2] Clinical management and therapeutic decision-making are guided by imaging, which is essential in the diagnostic assessment of renal disorders. Due to its non-invasiveness, real-time visualization, lack of ionizing radiation, and accessibility, ultrasonography (USG) continues to be the primary imaging modality for renal evaluation.^[3] Important details about renal size, cortical thickness, echotexture, and collecting system morphology are provided by conventional B-mode USG, which helps detect anomalies such as hydronephrosis, cystic illness, renal calculi, chronic parenchymal damage, and pyelonephritis.^[4-6]

Renal ultrasonography’s diagnostic potential has greatly increased with the use of Doppler methods. Renal perfusion, vascular resistance indices, and the identification of renal artery stenosis or thrombosis may all be evaluated using color and spectral Doppler imaging.^[7-9] Contrast-enhanced USG also offers dynamic vascular imaging, which enhances the assessment of renal transplant perfusion and helps distinguish between benign and malignant kidney tumors.^[10-12] Pointof-care ultrasonography, which enables quick evaluation of renal function, obstruction identification, and procedural guidance during procedures such as biopsy and catheter placement, has emerged as a useful tool in nephrology and critical care in recent years.^[13,14] For pediatric, elderly, and pregnant patients who need to avoid ionizing radiation exposure, USG’s mobility and safety profile make it especially beneficial.^[15]

Artificial intelligence-assisted picture interpretation and ultrasonic elastography are examples of emerging technologies that have further improved diagnostic accuracy by allowing for the early detection of fibrosis, cortical thinning, and functional changes before irreversible harm.^[16-18] In renal imaging, these developments are turning USG from a merely morphological method into a quantitative, functional, and predictive diagnostic tool.^[19-21] Even with the development of more sophisticated modalities such as computed tomography (CT) and magnetic resonance imaging, USG remains the most accessible, affordable, and adaptable imaging method for renal assessment.^[22,23] However, interpretation variability and diagnostic accuracy are still operator-dependent, underscoring the necessity of continued study and standardized procedures.^[14]

This study aims to evaluate the role of ultrasound (USG) in the assessment of renal pathologies. Specifically, it seeks to analyze sonographic findings to detect structural abnormalities in patients with renal disease. In addition, the study aims to assess the diagnostic accuracy of USG in distinguishing between various causes of renal dysfunction, thereby supporting clinical decision-making and enhancing patient care.

MATERIALS AND METHODS

This prospective study was conducted over a span of 6 months at our institution. The study aimed to investigate renal pathologies in a cohort of 40 patients, encompassing both the inpatient department and outpatients department, of varying ages and both sexes. The patients were enrolled in this study following the inclusion and exclusion criteria listed in Table 1. Ethical approval for the study was obtained from the institutional ethics committee of the same institution vide IEC-3369 dated March 08, 2025. High-resolution USG imaging was performed on a Philips USG machine using a range of transducers—convex (3–5 MHz) for deeper structures, linear (5–12 MHz) for superficial or pediatric cases, and phased-array probes as needed. Standard scanning protocols were followed, with patients positioned on an examination bed and USG gel applied as a coupling medium. Two board-certified radiologists performed the USG examinations following the standardized protocol. The scans were interpreted by radiologists, and the findings and patient data were recorded in a structured Microsoft Excel spreadsheet.Patients were categorized by age group, sex, and clinical presentation. The sonographic parameters recorded included kidney size, shape, structural abnormalities, and signs of hydronephrosis and other pathologies. Data analysis employed descriptive statistical tools. Collected variables were summarized using measures of frequency, mean, and percentages. The results were presented in demographic charts elucidating distributions across age, sex, and clinical findings. The study excluded patients with an inability to fast, severe abdominal pain, recent renal surgery, medico-legal complications, or uncooperative behavior, ensuring data quality and patient safety.

RESULTS

A total of 40 patients undergoing USG evaluation for suspected renal pathologies were included in the study. Among the study population, 24 patients (60%) were male, and 16 patients (40%) were female [Table 2, Figure 1]. This indicates a male predominance in individuals presenting with renal complaints.

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Figure 1: Sex-wise distribution of patients.

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Distribution of patients by chief complaints

The most frequently reported clinical symptom was flank pain, observed in 22 (55%) patients. Hematuria was reported in 20 (50%) patients, while dysuria occurred in 19 patients (47.5%). Anuria and hypertension were each noted in 15 (37.5%) patients [Table 3, Figure 2]. These findings highlight that flank pain and hematuria are the most common presenting complaints among patients evaluated for renal pathology.

Table 3: Distribution of patients as per chief complaints

Chief complaints	Number	Percentage
Flank pain	22	55
Dysuria	19	47.5
Hematuria	20	50
Anuria	15	37.5
Hypertension	15	37.5

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Figure 2: Distribution of patients as per chief complaints.

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Distribution of patients based on renal pathologies

USG evaluation revealed that renal calculus was the most common pathology, detected in 35 (87.5%) patients. Renal cysts were identified in 14 (35%) cases, followed by hydronephrosis in 13 (32.5%) cases. Pyelonephritis was the least prevalent finding, present in 3 (7.5%) patients [Table 4, Figure 3]. These results demonstrate the high diagnostic yield of USG in detecting a wide spectrum of renal abnormalities, particularly renal calculi.

Table 4: Distribution of patients on the basis of common pathologies

Pathologies	Number	Percentage
Calculus	35	87.5
Renal cyst	14	35
Hydronephrosis	13	32.5
Pyelonephritis	3	7.5

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Figure 3: Distribution of patients on the basis of common pathologies.

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Severity of hydronephrosis

Among the 13 patients diagnosed with hydronephrosis, 9 (69.23%) cases were classified as mild, 3 (23.08%) cases as moderate, and 1 (7.69%) case as severe [Table 5, Figure 4]. Mild hydronephrosis was thus the most frequently observed grade, with significantly fewer cases of moderate and severe obstruction pathology.

Table 5: Distribution of cases of hydronephrosis based on severity

Hydronephrosis	No. of cases	Percentage
Mild	9	69.23
Moderate	3	23.08
Severe	1	7.69
Total	13	100

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Figure 4: Distribution of cases of hydronephrosis on the basis of severity.

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Site-wise distribution of renal calculi

Analysis of the anatomical location of renal calculi revealed that the lower calyx was the most commonly affected site, accounting for 13 (37.14%) cases. The middle calyx harbored 10 stones (28.57%), followed by the pelvis with 5 (14.29%) cases and the upper calyx with 4 cases (11.43%). The minor calyx showed the least involvement with 3 (8.57%) cases [Table 6, Figure 5]. These findings reflect a higher concentration of calculi in the lower and middle calyceal regions.

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Figure 5: Distribution of the calculi on the basis of site of obstruction.

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Table 6: Distribution of the calculi according to the site of obstruction

Location	Number	Percentage
Minor calyx	3	8.57
Upper calyx	4	11.43
Middle calyx	10	28.57
Lower calyx	13	37.14
Pelvis	5	14.29
Total	35	100

DISCUSSION

The current study assessed the use of USG in evaluating renal pathology in 40 patients. Males made up 60% of the study population, while women made up 40%. The age group most impacted was 21–40 years old. Hematuria (50%), flank discomfort (55%), and dysuria (47.5%) were the main clinical manifestations, underscoring the importance of USG in identifying underlying renal disorders. Comparing our study to that of Park et al. (2008), who examined 318 patients with probable ureteral stones, we found that flank pain was a common symptom. Although Park et al. discovered ureteral calculi in 291 out of 296 verified cases, renal calculi were the main focus of our investigation, appearing in 87.5% of cases.^[24] In addition, Park et al. found that 68.7% of patients had hydronephrosis, while 20% of patients in our study had it, with 69.23% being classified as mild, 23.08% as moderate, and 7.69% as severe. According to these results, USG is useful for identifying stones, but it may not be as sensitive for ureteral calculi as it is for renal calculi, necessitating secondary imaging techniques such as CT in certain situations. The significance of USG in renal disease is further supported by a comparison with Omer et al. 2015.^[25] They found that kidney stones (23%) and ureteric stones (31%) were the main causes of hydronephrosis, which occurred in 53% of cases. In identifying calculi as a primary source of renal disease, our study concurs with their findings. In contrast, our study found a higher percentage of renal calculi (87.5%), which suggests that intrarenal stone production is more common. In addition, the location of stones varied; Park et al. reported the majority of stones in the ureterovesical junction (38.6%), while our study revealed the lower calyx (37.14%) to be the most prevalent region. Overall, the findings of Park et al. in 2008 and Omer et al.^[25] in 2015 that USG is a crucial technique for assessing renal pathology, specifically for identifying renal calculi and determining the severity of hydronephrosis, are supported by our work. Although USG is still the first imaging modality of choice since it is accessible and non-invasive, its inability to detect tiny ureteral calculi highlights the necessity for supplementary imaging methods in some situations.^[24]

CONCLUSION

In this prospective study of 40 patients, USG proved to be a dependable and practical tool for evaluating a wide range of renal pathologies. Most of the cases were seen in males, and the age group between 21 and 40 years was more commonly affected. Patients presented with complaints such as flank pain, hematuria, dysuria, anuria, and even hypertension, many of which are vague, yet significant, when it comes to renal issues. Among the findings, renal calculi were the most common pathology. Most of these stones were located in the lower and middle calyces, showing how well USG can detect and localize even small calculi. Hydronephrosis was another frequent diagnosis, with the majority of cases being mild. USG helped not only in detecting it but also in grading its severity, which is essential for timely intervention. Renal cysts and a few cases of pyelonephritis were also picked up, again showing the versatility of USG in differentiating between different types of renal diseases. Overall, the results clearly show that USG is highly effective in correlating clinical symptoms with imaging findings. It is non-invasive, safe, and quick, making it ideal as a first-line investigation. Especially in routine setups or emergency cases, USG can offer vital diagnostic information without delay or risk to the patient.