| Abstract|| |
This retrospective study was conducted to determine the prevalence of urinary calculi in the indigenous population of Saudi Arabia and compare it with expatriates of different nationalities working in Saudi Arabia with emphasis on the anatomic location of the calculi and the role of ultrasound in the detection and management. The study included 5371 patients (both sexes, mean age 36.6 years) examined by us from September 2004 to February 2008. The patients hailed from 30 countries, which included Bangladesh (42.3%), Pakistan (18.3%), Yemen (17.5%), India (6.5%), Sudan (3.4%), Saudi Arabia (2.8%), Egypt (2.3%) and Eritrea (1.7%). All patients were referred for abdominal/renal ultrasonography. Urinary calculi were detected in 1029 patients. The distribution of calculi was as follows: Renal 73.3%, pelviureteric junction 2.3%, proximal, middle and distal thirds of the ureter 13%, vesicouretic junction 9.8%, vesical 1.1% and urethral 0.5%. The prevalence of urinary calculi according to ethnic origin in descending order of frequency was Egyptians (29.5%), Pakistani (24.9%), Indian (23.3%),Yemeni (20.5%), Sudanese (17.6%), Bangladeshi (16.2%), Eritrean (15.4%) and Saudi Arabian (7.4%). Urinary calculi were found in 19.1% of the studied population. Approximately three-quarters of the calculi were located within the kidney. The nationalities with the highest prevalences were Egyptian, Pakistani and Indian.
|How to cite this article:|
Ahmad F, Nada MO, Farid AB, Haleem M A, Razack S. Epidemiology of urolithiasis with emphasis on ultrasound detection: A retrospective analysis of 5371 cases in Saudi Arabia. Saudi J Kidney Dis Transpl 2015;26:386-91
|How to cite this URL:|
Ahmad F, Nada MO, Farid AB, Haleem M A, Razack S. Epidemiology of urolithiasis with emphasis on ultrasound detection: A retrospective analysis of 5371 cases in Saudi Arabia. Saudi J Kidney Dis Transpl [serial online] 2015 [cited 2021 May 18];26:386-91. Available from: https://www.sjkdt.org/text.asp?2015/26/2/386/152557
| Introduction|| |
Urinary calculus disease is a common reason for referral of patients to imaging clinics in Saudi Arabia. The majority of these patients are referred for abdominal ultrasonography (US) because of the non-specific nature of symptoms. A variety of imaging techniques are available to detect urinary calculi. These include conventional radiograph (KUB), US, computed tomography (CT) scan and magnetic resonance imaging (MRI). US has the added advantage of its universal availability, safety and low cost, with a reasonable sensitivity in the detection of urinary calculi. Renal calculus disease is common, affecting 12% of the population during their life span  . A sensitivity of 100% has been reported with US in the detection of calculi 5 mm or larger.  The addition of a Doppler US study may further enhance the sensitivity of US detection of urinary calculi. ,, Patients presenting with a renal/ureteric colic need a rapid non-invasive and accurate diagnosis. US fits the bill perfectly where diagnosis can be achieved rapidly. We conducted this study to determine the prevalence of urinary calculi in the indigenous population of Saudi Arabia and compare it with expatriates of different nationalities working in Saudi Arabia with emphasis on the anatomic location of the calculi and the role of US in the detection and management of urinary calculi.
| Materials and Methods|| |
This was a retrospective study conducted during the period from 25/9/04 to 19/2/2008 at the Elixir International Polyclinic, Riyadh, Saudi Arabia, where 5371 consecutive patients were enrolled in the study, of whom 4871 (90.7%) patients were male and 500 (9.3%) patients were female. Age distribution of the patients is shown in [Figure 1].
The male to female ratio was 9.7:1. Ages ranged from 12-65 years. The mean age of the patients was 36.6 years, having bimodal distribution with peaks at 30 and 40 years and median age 35 years with standard deviation 10.2 [Figure 1]. Patients were referred from inside the clinic as well as outreach clinics for abdominal/renal ultrasonography. Patients examined hailed from 30 countries including Bangladesh, Pakistan, India, Yemen, Saudi Arabia, Egypt, Sudan, Eritrea, Sri Lanka, Nepal, Philippines, Afghanistan, Somalia, Palestine, Guinea, Syria, Chad, Ethiopia, Jordan, Morocco, Lebanon, Nigeria, Liberia, Turkey, Canada, Mali, Kenya, Tunisia, Indonesia and Qatar. The highest number of patients were of Bangladeshi (42.3%) and Pakistani origin (18.3%). [Table 1] enumerates the distribution of various ethnic origins. Most patients were manual workers.
|Table 1: Distribution of patients according to nationalities (n = 5371).|
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Examinations were conducted using a Shimadzu SDU-350A and DC6 US machines with 3.5 MHZ and 5 MHZ curvilinear probes and a Doppler facility. The kidneys were scanned in the coronal, sagittal and transverse planes in the supine, oblique, lateral decubitus and, occasionally, prone positions where required. The proximal part of the ureter was scanned in the coronal oblique position using the kidney as an acoustic window and continued downward to the bladder maintaining the same position. When examining the ureters, both supine and prone positions were used. The distal ureters were examined in both supine and coronal oblique positions. Doppler scanning was added when required to differentiate dilated ureters from blood vessels. Urinary bladder and urethra were scanned in sagittal and transverse planes. Moderate filling of the urinary bladder was taken as a prerequisite before starting the examination. Data entry and analysis were performed by Minitab.
| Results|| |
Of the 5371 patients, 1029 (19.1%) patients had calculi in the urinary tract. Among 1029 patients, 1000 (97.2%) patients were male and 29 (2.8%) patients were female. The prevalence of urinary calculi in males was 20.5% and that in females was 5.8%.The total number of anatomic sites of urinary calculi recorded were 1236 in 1029 patients (73.3% renal and 13% ureteric) [Figure 2].
Calculi at multiple sites including bilateral renal calculi and bilateral or unilateral renal calculi with calculi at the pelviureteric junction, ureter, vesicoureteric junction or urinary bladder were recorded in 225 (22%) patients.
In 161 (13%) cases, the calculi were ureteric and mostly in the distal third (84.5%), while the rest of the calculi were in the middle third (11; 6.8%) and proximal third (14; 8.7%) of the ureter.
The size of the calculi varied from 0.4-6 cm in renal, 11-19 mm at the pelviureteric junction, 4-16 mm at the proximal, middle and distal thirds of the ureter, 5-18 mm at the vesico-ureteric junction, 5-25 mm in vesical and 8-10 mm in the urethral calculi.
In 98 (1.8%) patients, there was dilatation of the pelvicalyceal systems, renal pelvis and ureters associated with acute flank pain and in some cases, with hematuria. However, the causes of obstruction were not identified. 35.8% calculi were found in Bangladeshi and 23.7% in Pakistani patients as shown in [Table 2].
|Table 2: Proportions of patients of different nationalities having urinary calculi (n = 1029).|
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The prevalence of urinary calculi was highest in Egyptian (29.5%), Pakistani (24.9%) and Indian (23.3%) patients [Figure 3].
|Figure 3: Prevalence of urinary calculi among patients of different nationalities.|
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| Discussion|| |
Urinary calculi are solid concretions found in the kidneys, ureters, urinary bladder and urethra. These stones are formed in the urinary tract from dissolved urinary minerals. Biochemical analysis reveals six varieties of renal calculi, of which 90% are radiopaque, mostly calcium oxalate and phosphate, and the remaining are struvite, cysteine and mix matrix,  while the other 10% are radiolucent, comprising of uric acid and xanthine calculi  . Most bladder calculi are visible on plain film and bladder calculi usually consist of magnesium ammonium phosphate and apatite and urate calculi. 
In the studied patients attending our US clinic for abdominal US, 19.1% had urinary calculi although the cohort may not be representative of the general population as the majority of patients were male and manual laborers. However, our findings concur with the earlier reports where a worldwide variation of the prevalence of renal calculus disease have been observed. Studies have shown a 1-5% incidence in Asia, 5-9% in Europe, 13% in North America and 20% in Saudi Arabia.  Our study also concurs with the previous findings of male preponderance of renal calculus disease. , Men on average have a larger body size and a three-fold higher lifetime risk of stone formation than women. 
The prevalence of urinary calculi was found to be higher in Egyptians (29.5%), Pakistanis (24.9%) and Indians (23.3%) than in others such as Yemenis (20.5%), Sudanese (17.6%), Bangladeshis (16.2%), Eritreans (15.4%) and Saudis (7.4%). This study concurs with an earlier study where a higher prevalence was recorded in the Pakistani population.  It also correlates with other findings where it is found that calculi, especially calcium-containing calculi, are more common in the Europeans compared with the other ethnic groups.  Genetic factor, body size and diet seem to be responsible for these variations. ,
US is very helpful in detecting urinary calculi as bowel preparation is not required, can be carried out in any emergency situation and both radio-opaque and radiolucent calculi can be detected. In the present study, 73.3% of the calculi were renal calculi, which approximates with a previously published study where 67.4% of the calculi fell in this range.  A few calculi (2.3%) were found in the pelviureteric junction with or without dilatation of the pelvicalyceal system. These findings correlate with previous data that in an acute PUJ obstruction, there is often no dilatation of calyceal or pelvicalyceal system until 8-12 h have passed.  The ability to detect renal calculus by US depends on the size of the calculus and is independent of the location of the calculus or patient size.  To diagnose renal calculi, ultrasonic scanning of the kidney is indicated as an initial modality of choice as US is more sensitive than plain film abdominal radiography in detecting renal calculi showing sensitivity of 96%.  If size of the calculus is more than 5 mm, sensitivity in detecting renal calculi is 100%.  In the present study, the numbers of the total ureteric calculi including calculi at the vesicoureteric junction are at variance with previous studies at 22.8% and are nearly twice the numbers in an earlier report at 12.5%.  The calculi at the proximal, middle and distal third of the ureter were 13% of the total urinary calculi. The anatomically normal ureter allows over 95% of calculi of less than 4 mm in diameter to pass unhindered into the bladder and onwards through the urethra.  Nevertheless, US is of limited value in imaging the ureter as it fails to demonstrate a significant proportion of ureteric calculi.  However, application of Doppler US may enhance the sensitivity of ureteric calculus detection. A calculus can obstruct any part of the ureter, but the distal ureter is the most common site of obstruction, brilliantly depicted by an unenhanced CT scan.  In this study, 84.5% of ureteric calculi detected by US were found in the distal third of the ureter. The sensitivity of detecting ureteric calculus by US is 61%. 
Non-contrast helical CT scan is the gold standard in detecting ureteric calculus (sensitivity 96%).  In this study, vesical calculi were found in 1.1% of the cases. With the help of US, a reliable diagnosis of bladder calculi can be achieved and phleboliths and prostatic calculi can be excluded. Urethral calculi are rare. Most urethral calculi (59-63%) are located in the anterior urethra, while 42% may be impacted at the posterior urethra.  In the present study, we found only six calculi (0.5%) at the posterior urethra. The study reveals that renoureteral calculi (98.4%) are much more frequent while bladder calculi account for only 1.1%. Studies have shown that upper urinary tract calculi appear to be related with life style, being more frequent among people living in developed countries with high animal protein intake.  Bladder calculus disease is more an infliction of the developing world and poor socioeconomic conditions. In this study, several factors may be responsible for the higher prevalence of renoureteral calculi. These may be dietary, environmental and racial factors and genetic predisposition. ,,
To the best of our knowledge, this is the largest retrospective study on the epidemiology and the role of ultrasonography in urolithiasis. It confirms some previously held beliefs and adds some new observations.
Conflict of interest: None
| References|| |
Thruston W, Wilson SR. The urinary tract. In: Romack CM, Wilson SR, Charboneau JW, eds. Diagnostic Ultrasound, 3 rd
edition, Vol. 1. Netherlands: Elsevier Mosby; 2005. p. 344-50.
Dublin PA. The kidney. In: Allan PL, Dubbins PA, Prozniak MA, McDicken WR, eds. Clinical Doppler Ultrasonography. London: Churchill Livingstone; 2000. p. 169-90.
Burge HJ, Middleton WD, McClennan BL, Hildebolt CF. Ureteral jets in healthy subjects and in patients with unilateral ureteral calculi: Comparison with colour Doppler US. Radiology 1991;180:437-42.
Kabala JE. The kidneys and ureters. In: Sutton D, edr. A Textbook of Radiology and Imaging, 7th ed, Vol. 2. London: Churchill Livingstone; 2003. p. 929-87.
Kabala JE. The bladder and Prostrate. In: Sutton D, edr. A Textbook of Radiology and Imaging, 7 th
ed, Vol. 2. London: Churchill Livingstone; 2003. p. 997.
Romello A, Vitale C, Marangella M. Epidemiology of nephrolithiasis. J Nephrol 2000; 13:45- 50.
Romero Parez P, Amat Ceilla M. Epidemiology of urinary calculi in the Marina Alta region. Actas Urol Esp 1992;16:455-61.
Curhan GC, Willet WC, Rimm EB, Speizer FE, Stampfer MJ. Body size and risk of kidney stones. J Am Soc Nephrol 1998;9:1645-5.
Buchhole NP, Abbes F, Afzal M, Khan R, Rizvi I, Tateli J. The presence of silent stonesan ultrasonographic screening study. J Pak Med Assoc 2003;53:24-5.
Spirnak JP, Resnick MI. Urinary stones. In: Tanagho EA, McAninch JW, eds. Smith's General Urology, 13 th
ed. USA: Appleton and Lange; 1992. p. 271-98.
Qaddar DS, Yousif SY, Mahdi LK. Prevelance and etiology of urinary stones in hospitalized patients in Baghdad. East Meditarr Health J 2006;12:853-61.
Dubbins PA. The Kidney: In: Allan PL, Dubbins PA, Prozniak MA, McDicken WR, eds. Clinical Doppler Ultrasound, 1 st
edition. London: Churchill Livingstone; 2004. p. 186-7.
Middleton WD. DoddsWJ, Lawson TL, Foley WD. Renal calculi; sensitivity for detection with ultrasound. Radiology 1988;167:239-44.
Karabackakoglu A, Karakose S, Ince O, Cobankara OE, Karalazli G. Diagnostic value of diuretic enhanced excretory MR urography in patients with obstructive uropathy. Eur J Radiol 2004;52:320-7.
Lorberboym M, Kaputsin Z, Elias S, Nikolov G, Ketz R. The role of renal scintigraphy and unhenced helical computerized tomography in patients with ureterolithiasis. Eur J Nucl Med 2000;27:441-6.
Sheafor DH, Hertzberg BS, Freed KS, et al. Non enhanced helical CT and US in emergency evaluation of patients with renal calculi: Prospective comparison. Radiology 2000;217: 792-7.
Boridy IC, Nikolaidis P, Kawashima A, Sandler CM, Goldman SM. Non contrast helical CT for ureteral stones. World J Urol 1998;16:18-21.
Trinchier A. Epidemiology of urolithiasis. Arch Ital Urol Androl 1996;68:203-49.
Dr. Farid Ahmad
Elixir International Polyclinic, P. O. Box 335066, Riyadh 11341
[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2]