Clinical Score Application for Abdominopelvic Computed Tomography Used in the Diagnosis of Renal Colic Patients

Abstract

Background To develop risk scoring for the use of computed tomography (CT) imaging using the visual analog scale (VAS), physical examination, and laboratory findings of renal colic patients admitted to the emergency department (ED).

Materials and Methods This is prospective observational study. Among the patients who presented to the ED with abdominal or flank pain, patients who were scheduled for CT imaging for urolithiasis were included in the study. The mean VAS pain scores, physical examination findings, laboratory parameters, and macroscopic and microscopic values in urinalysis were compared between the two groups with and without stones on CT.

Results Of the 196 urolithiasis patients included in the study, 165 had ureteral stones, 76 had renal stones, and 45 had renal and ureteral stones. While the difference between the urine erythrocyte averages of the two groups was borderline significant (p = 0.04), there was a high difference between the urinary hemoglobin amounts (p < 0.001). In patients with urinary system stone disease, hydronephrosis, and ureteral dilatation, hemoglobin ++ and above were more significant (p < 0.001). For ureteral stones, pain intensity increased as the size increased (r = 0.34 p < 0.001). White blood cells > 10,000 10³/mL, and C-reactive protein (CRP) ≤ 5 mg/L were more significant in patients with acute renal colic.

Conclusions Although we cannot develop a clinical scoring system for renal colic patients, the meaningful results we found for urinary stone disease can be used in a newly developed scoring system. It can be used in new scoring systems in the ED using a high VAS score, presence and amount of urine hemoglobin, CRP) ≤ 5 mg/L, and creatinine value.

Keywords

renal colic - parameters - urinary stone - visual analog scale - computed tomography

Introduction

Renal colic is a urological emergency that is one of the most common reasons for admission to the ED. It is characterized by severe flank pain that often develops due to kidney stone disease (nephrolithiasis). The disease is diagnosed and treated with physical examination, clinical findings and imaging methods. The aim of the treatment is to relieve the pain effectively and to relieve the obstruction without causing loss of kidney function.[1]

Suspected renal colic accounts for nearly 2% of adult visits to the ED in the United States, and its economic cost is ∼2.1 million dollars per year. Many imaging methods are used in patients with suspected urolithiasis, mainly ultrasonography (USG), computed tomography (CT), and direct radiography. There is no widely agreed management protocol for diagnosing and treating patients with suspected renal colic.[2] [3] While the diagnostic sensitivity of CT, which is one of the most common imaging methods used in urolithiasis patients, is 96%, the specificity is between 94 and 100%, the sensitivity of USG varies between 12 and 44%, and the specificity is between 79 and 100%.[4] CT radiation exposure, despite the high economic cost, the rate of use in the first diagnosis of urolithiasis patients reaches 90%.[5] We aimed to develop a clinical scoring system for CT use by compiling the influencing factors in patients admitted to the ED with renal colic.

Patients and Methods

Study Design and Settings

In this prospective observational study, patients who applied to the ED of a tertiary university hospital with flank and/or abdominal pain between October 2019 and February 2020 were included.

Study Participants

The ethics committee approved this study of the Health Science University Antalya Training and Research Hospital (Ethics code: 2019–23/13). Informed consent was obtained from the patients or their first-degree relatives who accepted to participate in the study after the ethics committee's approval. The inclusion criteria were patients who presented with flank and/or abdominal pain and were thought to have renal colic, were older than 18 years, had abdominal CT planned for diagnostic purposes, and gave consent to participate. We excluded patients with a history of the surgical procedure due to urolithiasis, urolithiasis previously diagnosed with pain in our hospital or another center, those with kidney disease associated with pain, or with known chronic kidney disease. Renal colic was considered a preliminary diagnosis, but patients for whom abdominal CT was not planned, patients who did not consent to the study, and patients who were pregnant. The study's sample size based on similar studies was calculated at 214 by power analysis, and 300 people were included.[6]

Methodology

Gender, age, visual analog scale (VAS), examination finding, percentage of white blood cells (WBCs), and neutrophils in complete blood count, kidney function tests (blood urea nitrogen [BUN]/blood urea nitrogen, creatinine, glomerular filtration rate), C-reactive protein (CRP) value was measured. Urinalysis included urine color (macroscopic appearance), protein, hemoglobin, leukocyte esterase, nitrite, erythrocyte, leukocytes, calcium oxalate crystals (calcium oxalate monohydrate/dihydrate), uric acid crystals, ascorbic acid, bacteria, amorphous, renal epithelium, presence or absence of calculus in abdomen CT, calculus size and location were recorded. In the VAS score included in the study form, the value at which the patient's pain was most severe was questioned. The intensity of pain up to the mark, marked by the patient himself, measured from 0 (no pain) to 10 (most severe pain) 0–10 cm. Blinded radiologists routinely interpreted abdominopelvic CT imaging results, and the results were recorded. WBCs and neutrophil % values in the complete blood count were performed in the biochemistry laboratory of our hospital in the Sysmex XN-1000 SA-01 (Sysmex Corp., Kobe, Japan) device, kidney function tests, and CRP in the Sysmex AU680 (Beckman-coulter AU680) device, urine analysis in the Sysmex UC-data studied on 3500, UF-4000 and UD-10 devices. Groups were analyzed by counting a cut-off of 10,000 10³/mL (> or ≤) for WBCs, more than 60% (> or ≤) for neutrophil %, and 5 mg/L (> or ≤) for CRP from laboratory values. Negative, trace positive, 1 + , 2 + , 3 + , and 3+ and above groups were formed for hemoglobin/protein/leukocyte esterase/nitrite values in urine analysis. Bacterial positivity or negativity was evaluated in the complete urinalysis. Hydronephrosis and ureteral dilatation were recorded as mild, moderate, and severe.

Statistical Analysis

Statistical analysis of data was performed with SPSS for Windows 22 package program. Descriptive statistics are shown as mean ± standard deviation for continuous and discrete numerical variables and the number of cases and percentage (%) for categorical variables. Before comparing the means, their conformity to the normal distribution was evaluated with the Kolmogorov–Smirnov test. In the study, with grouped variables such as gender, age group, physical examination findings, and laboratory evaluation results, the Chi-square test was used when examining the relationship between the presence of renal, ureter, or urinary stones. When comparing patients with and without renal, ureter, or urinary stones with measurement data, t-tests in independent groups and Mann–Whitney U tests were used when parametric conditions were not met. One-way analysis of variance (ANOVA) was applied when comparing more than two groups for continuous variables (comparing the mean of laboratory parameters according to the degree of hydronephrosis in those with urinary calculus). Correlation coefficient r value was accepted as < 0.20 very weak, 0.20–0.40 weak, 0.40–0.60 moderate, 0.60–0.80 high, >0.80 very high correlation. A logistic regression model was used to construct a multivariate model explaining the presence of urinary stones. In the last step, the remaining variables in the model have presented with odds ratio and 95% confidence intervals. Results for p < 0.05 were considered statistically significant.

Results

Three hundred patients who met the inclusion criteria were included in the study. Of these patients, 65% (196 patients) were male, and 35% (104 patients) were female. As expected, there was a positive correlation between the male sex and urolithiasis (p < 0.001). Patients with urinary tract stones were divided into four groups according to their age: under 30 years old (29 patients, 15%), 30–45 years old (95 patients, 48%), 46–65 years old (59 patients, 30%), over 65 years old (13 patients, 7%). Urolithiasis, in our study, was seen mostly between the ages of 30 and 45 years.

Of the 300 patients included in the study, 11 had no physical examination findings. Urinary system stone disease was present in 7 (4%) patients with no physical findings. Costovertebral angle tenderness (CVAT) was present in 90.7% (69 patients) of patients with renal stones. One hundred fifty-two patients (92.1%) with ureteral stones had CVAT. Lower quadrant findings accompanied the CVAT (tenderness in the right or left lower quadrant; tenderness or defense or rebound) in 51% (84%) patients. The mean VAS score of patients with stones in the urinary system was 8.44 ± 1.86 cm. The mean score of those without stones was 7.01 ± 1.75 cm (p < 0.001). The median VAS score of the stones detected in the ureter was calculated as 8.5 cm for the proximal one-third ureter, 7.7 cm for the middle one-third ureter, and 10 cm for the distal one-third ureter. The mean VAS pain score for renal stones was 7.92 ± 2.03 cm. There was no significant difference between urine colors in urine microscopic analysis between those with and without stones in the urinary system (p = 0.161). There was no significant difference in the number of urinary leukocytes between the two groups (p = 0.945). While 137 (69.8%) of the patients with urinary tract stones were positive and above in trace amounts, 59 (56.7%) were protein-negative. When the presence of protein was compared with the two groups, it was more significant for urinary system stone disease if the protein was positive and above trace amount (p < 0.001). In 78.5% (154 patients) of the patients who were found to have stones in the urinary system, the amount of hemoglobin in the urine was two positive and above, and the urinary hemoglobin was negative in 14% (28 patients). In urolithiasis patients, the presence of hemoglobin in the urine, especially two positive or more, was more significant (p < 0.001). The relationship between the laboratory parameters and with/without urinary stone disease is shown in [Table 1].

Table 1 Clinical and laboratory characteristics of patients with and without stone disease

Variables	With urinary stone disease (n = 196)	Without urinary stone disease (n = 104)	P-value
Age	45.27 ± 14.28	42.57 ± 15.82
Male n (%)	141 (71.9)	55 (52.8)	<0.001
Location n (%)
Ureter	165 (84.1)
Renal	76 (38.7)
Both ureter/renal	45 (22.9)
Physical examination n (%)
CVAT (ureter)	152 (77.5)
CVAT (renal)	69 (35.2)
CVAT + lower abdominal pain	84 (42.8
None	7 (3.6)	4 (3.8)
VAS score	8.44 ± 1.86	7.01 ± 1.75	<0.001
Laboratory parameter
WBC > 10,000 n (%)	112 (57.1)	46 (44.2)	0.033
Neutrophil > %60 n (%)	125 (63.7)	64 (61.5)	0.703
CRP < 5 n (%)	130 (66.3)	56 (53.8)	0.034
Blood urea nitrogen	16.53 ± 5.97	14.43 ± 4.49	0.001
Creatinine	1.06 ± 0.32	0.86 ± 0.19	<0.001
Glomerular filtration rate	85.20 ± 22.63	98.37 ± 19.97	<0.001
Urine analysis
Protein n (%)	137 (69.8)	59 (56.7)	<0.001
Hemoglobin trace or + n (%)	14 (7.1)	17 (16.3)	<0.001
Hemoglobin ++ and above n (%)	154 (78.5)	37 (9.2)	<0.001
Uric acid	0.43 ± 2.36	0.09 ± 0.24	0.042

Abbreviations: CRP, C-reactive protein; CVAT, costovertebral angle tenderness; VAS, visual Analog scale; WBC, white blood cell.

Hydronephrosis severity and creatinine, GFR, BUN, WBC, and CRP averages were compared in patients with urinary stones. The mean and difference of the data were analyzed in three groups without hydronephrosis, mild, and moderate-severe. There was borderline significance between BUN, creatinine, GFR, WBC, and the presence and severity of hydronephrosis (p = 0.050, p = 0.01, p < 0.01, p < 0.01). The change of CRP with hydronephrosis severity was not significant. As the severity of hydronephrosis increased, BUN, creatinine, and WBC increased, while GFR decreased. The relationship between laboratory parameters and hydronephrosis is shown in [Table 2].

Table 2 Laboratory parameters according to the degree of hydronephrosis in those with urinary calculi

		N	Mean	Std. deviation	P-value
Blood urea nitrogen	None				0.05
	Mild
	Medium-severe	51	18.27	6.11
	total	196	16.53	5.97
Creatinine	None	45	0.96	0.40	0.01
	Mild	100	1.05	0.26
	Medium-severe	51	1.17	0.33
	total	196	1.06	0.32
GF	None	45	95.73	23.36	<0.001
	Mild	99	86.64	20.03
	Medium-severe	51	73.12	21.62
	total	196	85.20	22.63
C-reactive protein	None	45	12.83	28.54	0.11
	Mild	100	11.46	34.19
	Medium-severe	51	24.66	49.49
	total	196	15.21	37.91
WBC	None	45	9746.67	3715.24	<0.001
	Mild	100	10666.00	3256.70
	Medium-severe	51	12109.80	3681.75
	total	196	10830.61	3562.00

Abbreviations: GFR, glomerular filtration rate; WBC, white blood cell.

In patients with urinary system stones, ureteral dilatation, and hydronephrosis, the VAS score was higher, and the difference between groups was significant (8.66 ± 1.79 cm vs. 7.22 ± 1.82 cm; p < 0.001).There was a positive linear, weak, but statistically significant correlation between ureteral calculi size and VAS pain score (r = 0.34 p < 0.001); as the stone's size increases, the pain score increases. There is no linear relationship between renal calculi size and VAS score (r = − 0.027, p = 0.64).

Significant values to develop a clinical score system from all these data; gender (male, female), VAS pain score, urine protein (absent, trace, +, ++ + ), hemoglobin (absent, trace/+ , ++), bacteria (absent, present), WBC (10000 10³/mm³) and below, 10,000 10³/³ above), CRP (5 mg/L and below, over 5 mg/L), BUN, creatinine, GFR, uric acid crystal were taken continuously. For all these significant results, logistic regression analysis was performed. In the last step, the remaining variables in the model are presented with odds ratio and 95% confidence intervals. However, the variables remaining in the last step of the model explain 44% of the variance in the presence of urinary stones. (Nagelkerke R square = 0.44). With this model, urolithiasis was diagnosed in only 44% of the patients with urinary stones on CT, so the scoring system could not be developed ([Table 3]).

Table 3 The logistic regression model explains the presence of stones in the urinary system

	B	Odds ratio	%95 Cl	P-value
VAS score		1.44	1.23–1.69	<0.001
Urine hemoglobin
None	1			<0.001
Urine hemoglobin trace or + n	0.77	2.15	0.78–5.95	0.14
Urine hemoglobin ++ and above	1.86	6.40	3.25–12.64	<0.001
C-reactive protein
≤5	1			<0.001
> 5	−1.07	0.34	0.18–0.65	<0.001
Creatinine	3.34	28.13	6.51–121.43	<0.001
Regression constant	−6.09	0.002		<0.001

Discussion

CT imaging is frequently used in patients presenting to the ED with renal colic. Although the European Urology Association recommends using USG as an imaging method, it is the first diagnostic method, especially in countries such as the USA. The use of CT does not significantly alter patient-centered outcomes, including admission to hospital in patients with renal colic or the identification of alternative diagnoses.[4] [7] Cupisti et al in the study of 696 patients with renal colic who applied to the ED, reported that the most common admission were between the ages of 25 and 40 years.[8] Among the developing countries, the male-female ratio in Iran varies from 1.15:1 to 2.5:1 in Iraq.[9] Similar data were available in our study. The most frequent application of renal colic was in the age range of 30 to 45 years, similar to developing countries. The male-female ratio was evaluated as 2.6:1.

In the study conducted by Guru et al. on patients who applied to the ED with complaints of pain, they defined the patients as mild-moderate-severe pain according to the VAS pain score. Renal colic patients were included in the severe pain group, with a VAS score of 8 to 10 cm.[10] In our study, the mean and standard deviation VAS pain score of patients with urinary tract stones was 8.44 ± 1.86 cm, and the difference between the mean and VAS pain scores of other causes of abdominal pain was statistically highly significant (p < 0.001). Papa et al. found a relationship between VAS pain score (7.2 ± 2.9 cm), stone size (6 mm and above), and stone localization (middle ureter) in renal colic patients admitted to the ED.[11] However, Jennifer et al studied 650 patients with ureteral stones and found no significant correlation between stone size, localization, or pain severity.[12] In our study, while the size of the ureteral stones increased in correlation with the VAS pain score, this correlation was not seen for renal stones (r =0.34 p < 0.001, r =–0.027, p = 0.64). In the comparison of stone localization and pain severity, while the distal ureteral stones were the most painful (VAS score 10 cm), the decrease in pain intensity was listed as proximal (VAS score 8.5 cm) - middle ureter (VAS score 7.7 cm) (p < 0.001).

Urinary findings are essential in admissions to the ED due to renal colic. The most common urinary finding accompanying patients is hematuria.[13] Perez et al, in his study, hematuria, found that 90.4% (132 patients) patients had renal colic.[14] Eskelinen et al found that erythrocyte count > 10 P/HPF was more indicative of urolithiasis in patients with renal colic.[15] Similar findings were found in the literature. In our study, the number of patients presenting with hematuria (erythrocyte> 3 P/HPF) was 207 (69%), of which 65% (134 patients) had an erythrocyte count above 10 P/HPF in the urine analysis. Among those with an erythrocyte count of 10 P/HPF and below, 62 individuals had stones in the urinary system.

Furthermore, Argyropoulos et al compared urine dipstick test (UDT) and urinalysis in a retrospective study, in which 609 urolithiasis patients admitted to the ED with renal colic were screened. At the end of the study, he showed that the urine dipstick test has a high sensitivity in renal colic patients and suggested that it can be used as a screening test. In the urinalysis of the study, UDT-positive were 92.9% (566 patients) and negative were 7.1% (43 patients) were found. Of the 43 negative patients confirmed by urinalysis, 2% were false negatives.[16] In our study, results supporting this study were obtained. The hemoglobin of 168 out of 196 stone patients whose urinary hemoglobin amount is positive and urinary stone disease cannot be detected as positive. A highly significant difference was found between the two groups regarding hemoglobin positivity (p < 0.001). Hemoglobin ++ and above was more significant for stone patients (p < 0.001).

Proteinuria results from either increased glomerular permeability or decreased tubular reabsorption. Physiological such as muscle exercise, pregnancy, and orthostatic proteinuria may be seen due to pathological causes such as fever, renal hypoxia, hypertension, glomerulonephritis, nephrotic syndrome, kidney tumor and infection, cystitis, urethritis, prostatitis, and contamination.[17] [18] In another study by Bratt et al that included urolithiasis patients, the presence of proteinuria showed distal tubule damage.[19] In our study, hydronephrosis was detected in 151 of 196 patients with urinary stones, and protein positivity was found to be statistically high in stone patients (p < 0.001). Changes in GFR, creatinine, and BUN were significant with stone disease.

Other parameters evaluated for the presence of stones in urine analysis were leukocytes, leukocyte esterase, and renal epithelium. For these values, no significant difference was found between the two groups explaining the presence of stones in the urinary system. They were also not significant for hydronephrosis and ureteral dilatation. While the presence or absence of nitrate in the urine was not significant in comparing the two groups, the absence of bacteria was more significant for the urinary stone group (p = 0.030). Another significant result was the amount of urinary uric acid crystals compared with patients with stones in the urinary system and the other group. Uric acid crystals were found to be 0.43 ± 2.36 P/HPF in the patient group with stones and 0.09 ± 0.24 P/HPF in those without stones. The difference between the two groups was significant (p = 0.042). In the study of Pak et al,[20] in the group with only uric acid stones, the uric acid fractional excretion was 0. 080 ± 0.029, 0.052 ± 0.028 in the group without uric acid stones, and the difference between the two groups was significant (p < 0.001).[20] In our study, it can be predicted that uric acid stones, limited but parallel to the excretion of uric acid metabolites, are widespread in the Mediterranean region because they do not include stone analysis and are single-centered.

Sfoungaris et al studied 156 patients who were thought to have renal colic due to stones and concluded that WBC count and neutrophil count increased in the acute period during spontaneous resolution of the stones. A high WBC count (over 10,000 10³/mL) in patients may not necessarily result from a urinary tract infection. It may be the result of a preclinical urinary tract infection condition, ureteral mucosal inflammation caused by the stone, or simply the pain and stress caused by the ureteral stone.[21] In our study, while neutrophil percentage was not significant between groups (p = 0.703), WBC > 10,000 10³/mL was found to be more significant for stone probability (p = 0.033), CRP < 5 mg/L was also found to be more significant for stone patients (p = 0.034).

Our results are similar to those of Yan et al, the change in the mean creatine in patients with ureteral stones was not associated with the severity of hydronephrosis.[22] In our study, the mean creatinine values (1.09 ± 0.29 mg/dL) of patients with both hydronephrosis and ureteral dilatation (149 individuals) were found to be significantly higher than those without hydronephrosis and ureteral dilatation (0.9 ± 0.28 mg/dL) (p < 0.001). In the study by Kim et al, the presence and absence of hydronephrosis and GFR were compared in patients with urolithiasis. Hydronephrosis was more common in patients with a GFR below 60 mL/min/1.73 m². In the same study, WBC elevation (>10,000 10³/mL) was significant in patients with GFR< 60 mL/min/1.73 m² (p < 0.001).[23] In our study, however, WBC increased with the presence and severity of hydronephrosis. At the same time, unlike in this study, GFR decreased as the severity of hydronephrosis increased.

Eskelinen et al developed a scoring system to diagnose ureteral stones by evaluating the history, physical examination, and laboratory findings of 1,333 patients who presented to the ED with acute abdominal pain. Data from patients with stones in IVP were compared with other abdominal pain groups. Abdominal pain lasting less than 12 hours, low back or kidney tenderness, hematuria (erythrocyte > 10 P/HPF), and anorexia were the most important findings for renal colic. The specificity of the developed score was 89%, and the sensitivity was 99% in patients with renal colic. Nevertheless, this study was poor in distinguishing patients with obstructive urolithiasis accompanied by pyelonephritis. Therefore, it was recommended to be used in cases where the diagnosis of renal colic could not be distinguished.[15] Our study was designed similarly to this, but with the data in the logistic regression model, only 44% of the patients with urolithiasis on CT could be diagnosed correctly. Discontinuous and limited data among the variables found to be significant in our study were eliminated in the last step of the model, and sufficient diagnostic specificity and sensitivity could not be achieved with the remaining data.

Conclusion

Although we could not develop a clinical scoring system for renal colic patients, the meaningful results we found for urinary stone disease can be used in a newly developed scoring system. It can be used in new scoring systems in the ED using a high VAS score, presence and amount of urinary hemoglobin, CRP 5 mg/L and below, and creatinine value.

Conflict of Interest

None declared

Authors' Contributions

All authors contributed to the manuscript's conception, data collection, analysis, drafting, and revising. They all accept responsibility for the contents of the study.

Compliance with Ethical Principles

The ethics committee approved this study of the Health Science University Antalya Training and Research Hospital (Ethics code: 2019–23/13). Informed consent was obtained from the patients.

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Publication History

Article published online:
20 September 2022