Urinary stone disease results from an abnormal crystallization of urine components in the urinary tract [1] . That disease is more frequent in patients above the age of 60 years [2] . Still, it is more and more affecting younger populations [3] [4] . Its incidence is variable: 7% to 13% in northern America, 5% to 9% in Europe, and 1% to 5% in Asia [5] . In Burkina Faso, the prevalence of urinary stone disease is 12.5% [6] . Obesity, diet modifications, and climate changes make urinary stone disease increase in the world [7] [8] [9] .

Computed tomography has dramatically bettered the diagnosis of urinary stone [9] [10] [11] [12] which treatment is turning mini-invasive by using extracorporeal shock wave lithotripsy, percutaneous nephrolithotomy, ureteroscopy, and cystolitholapaxy [13] [14] .

Still, open surgery remains the main stone treatment modality in Benin and other developing countries.

Studies on urinary stone disease have been performed in Benin, [15] [16] but its overall status has not yet been evaluated.

This study aims to determine epidemiologic, diagnostic, and therapeutic features of urinary stone disease in northern Benin from 2018 to 2023.

We performed an observational and descriptive study. We retrospectively collected urinary stone data from medical records of patients managed from February 1, 2018, to February 1, 2013, in the Surgical Department of the “Centre Hospitalier Universitaire Départmental Borgou Alibori or CHUD-BA”. The CHUD-BA is the university teaching hospital in Parakou, the biggest town in northern Benin. We made an exhaustive census of patients and systematically collected data from their medical records. Were included patients with imaging-confirmed urinary stones. Were excluded, urinary stone patients with no confirmatory imaging or incomplete medical record.

Data collected were age, gender, ethnicity, provenance, profession, marital status, dietary behavior, symptoms, history, type of imaging, stone location, type of treatment, treatment outcome.

Collected data were analyzed with Excel® 2019 and EPI Info 7.2. The means and the proportions were used to describe respectively the quantitative and qualitative variables.

4522 patients were managed in the Department of Surgery. 75 of them were urinary stone-affected, which yielded a hospital prevalence of 1.7%. Their age ranged from 9 to 80 years. Their mean age was 41 years (standard deviation = 3.98). Eight patients (10.7%) including 7 males and 1 female, were less than 20 years old. Among the 75 urinary stone-affected patients, there were 55 males (73.3%) et 20 females (26.7%). The sex ratio was 2.75.

Table 1 presents the patients’ profession, provenance, and ethnicity. Regarding the profession there were 20% public service officers, 14.7% craftsmen, 13.3% traders, and 9.3% students. Most of the patients, i.e., 72%, came from Borgou, the geographical area sheltering the CHUD-BA hospital. The most frequent ethnic groups were the Fon (32%) and the Batonu (21.3%).

Stone locations and main symptoms in the patients are presented on Table 2. There were 23 (30.7%) renal, 35 (46.7%) ureteral, and 17 (22.7%) vesical stones. 43 patients (57.3%) complained about pain which was either lumbar (52%), iliac (4%), or pelvic (1.3%). 11 (14.7%), 9 (12%) et 4 (5.3%) patients had respectively a hematuria, a dysuria, and a fever. The stones’ size ranged from 1 to 30 mm. Yet the main complaint varied according to the stone’s location.

18 in the 23 patients with renal stone experienced pain as lumbar pain (47.8%) or renal colic (30.4%). The symptoms in the others were dysuria, hematuria,

*CBRU = Complete Bladder Retention of Urine.

pollakiuria and painful micturition.

Among 35 patients with ureteral stone, 25 patients (71.4%) had a pain which was lumbar (60%), iliac (8.6%), and pelvic (2.9%). The pain was a renal colic type in 18 cases (51.4%) of ureteral stones. The other main complaints in ureteral stones patients were hematuria (14.7%), dysuria (12.0%), and fever (5.3%).

Of the 17 cases of bladder stones, 8 (47.1%), 5 (29.4%), 1 (5.9%), 1 (5.9%), 1 (5.9%) et 1 (5.9%) were respectively revealed by dysuria, hematuria, pollakiuria, painful micturition, complete bladder urinary retention and pyuria. 11 in the 17 bladder stone patients, i.e., 64.7% had a bladder outlet obstructing disease: benign prostate hyperplasia (7 cases, i.e., 41.2%), urinary schistosomiasis (3 cases, i.e., 17.6%), prostate cancer (1 case, i.e., 5.9%).

Table 3 presents disease and dietary history in the stone-affected patients. 38.7% patients had some disease history: diabetes mellitus (6.7%), high blood pressure (6.7%), benign prostate hyperplasia (8%), urinary schistosomiasis (6.7%), ureteropelvic junction obstruction (2.7%), prostate cancer (1.3%). Dietary behavior was evaluated in 19 patients (25.3%). The diet in all 19 patients was rich in dairy products. 16 (84.2%), 10 (52.6%) et 6 (31.6%) of those 19 patients had respectively a diet rich in animal proteins (i.e., meat, fish), hot drinks (i.e., coffee, tea), and green vegetables (cabbage).

Imaging tools utilized to diagnose the stones were ultrasonography of the urinary system (69.3%), kidneys-ureters-bladder (KUB) non-contrast enhanced tomography (2.7%) and computed tomographic urography (37.3%). There were 1 to 2 stones in the upper urinary tract (kidney, ureter) and 1 to 10 stones in the bladder. The stones size ranged from 1 to 30 mm.

Stone diagnostic imaging in 14 (60.9%), 8 (34.7%), and 1 (4.3%) patients were respectively ultrasonography, computed tomographic urography and KUB tomography. 6 patients (26.1%) had a calyceal stones, 5 patients (21.7%) had pelvic stones; intrarenal stone location was not specified in the other patients. Kidney stones were unilateral and obstructive in 60.9% of the patients, bilateral and obstructive with renal failure in 30.4% of the patients (Table 4).

For the diagnosis of ureteral stones, KUB tomography with or without ultrasonography and computed tomography were used respectively in 18 (51.4%) and 17 (48.6%) patients. Ureteral stone was bilateral and obstructive in 22.9% cases, unilateral and obstructive in 40% cases, unilateral and non-obstructive in 37.1% cases (Table 4). Among 40 affected ureteral units the stone location was lumbar, iliac, pelvic, and intramural respectively in 25% (n = 10), 5% (n = 2), 32.5% (n =

BPH = Benign Prostate Hyperplasia – UPJO = Uretero-Pelvic Junction Obstruction.

13) et 15% (n = 6) cases. The stone’s segmentary location was not indicated in 9 patients (22.5%).

The stone’s treatment varied according to its location. Renal stones were treated by pyelolithotomy in 12 patients (52.2%), nephrolithotomy in 5 patients (21.7%), ureteral pigtail stent in 1 patient (4.3%). Ureteral stones were treated by alpha-blockers in 14 patients (40%), ureterolithotomy in other 14 patients (40%), and ureteral pigtail stent in 7 patients (20%). Each one of the 17 cases of bladder stone was treated by cystolithotomy.

Overall, 47 patients in 75 had received a medical therapy: alpha-blocker (29 cases, i.e., 38.7%), non-steroidal anti-inflammatory drug (24 cases, i.e., 32%), antispasmodic (2 cases, i.e., 2.7%). The use of alpha-blocker aimed the medical expulsion of ureteral stone, but data were not available on the achieved rate of stone’s expulsion.

The hospital prevalence of stone disease was 1.7% in CHUD-BA i.e., nearly half that of 3.7% computed at Cotonou in 2015 [16] . The difference may be linked to the fact that life standards are higher and the tendency to higher consumption of animal protein and dairy products in southern than in northern Benin. Besides, the climate is hot and humid in the south while it is hot and dry in the north: body hydration challenges are discrepant between the two regions.

The mean age was 41 years. It is similar to 39.6 ans [16] , 47 ans [9] , and 40.5 ans [17] found in other regional studies.

10.7% patients (7 males and 1 female) were less than 20 years old. Urinary stone disease is rare in childhood and adolescence where it is often associated with obstructive malformations of the urinary tract or genetic anomalies [18] [19] [20] .

We observed a masculine predominance among the stone-affected patients. The sex ratio was 2.75. Several studies have demonstrated the masculine predominance in urinary stone disease with variable sex-ratio: 2 [21] , 1.4 [22] and 1.61 [23] . The masculine predominance may be linked to the higher tendency to urinary tract obstruction in aging males or the estrogens’ promoting effect on urine citrate’s stone formation inhibiting activities [24] [25] .

Most of the patients (72%) came from Borgou, the geographical area that sheltered the CHUD-BA. The remaining patients came from other neighboring areas with no urologist. The patients belonged to several ethnic and professional groups. Some professions such as craftsmen and agriculturalists which necessitate physical activity do contribute to body dehydration. Still, none of the patients were agriculturalists or herders despite the region was one of high animal and agricultural production activity. Some authors have founded that stone-affected patients were agriculturalists and students [26] .

An obstructive uropathy was present in 18.7% of the patients: benign prostate hyperplasia (8%, n = 6), urinary schistosomiasis (6.7%, n = 5), ureteropelvic junction obstruction (2.7%, n = 2), prostate cancer (1.3%, n = 1) [6] [27] . In several studies, benign prostate hyperplasia is the main urological disease associated with urinary lithiasis. According to Bah et al. [26] , benign prostate hyperplasia (42.2%) and urethral stenosis are the main obstructive causes of urinary stone disease. Urological tumors especially prostate tumors are associated with urinary lithiasis in 31.4% cases [28] . 31.4% and 60.5% urinary stones cases are respectively associated with urological tumors, mainly prostate tumors [28] , and with urogenital schistosomiasis [29] .

Stone disease in our patients was diagnosed with ultrasonography (69.3%) and computed tomography (37.3%). Nowadays, non-contrast enhanced computed tomography of abdomen and pelvis is the gold standard imaging tool for the diagnosis of urinary stone. An alternative tool is the ultrasonography combined with KUB non-contrast enhanced tomography [24] [25] . The situation in CHUD-BA is similar to that in most of the sub-regional care units [6] [16] [26] [28] [30] . Often patients cannot afford the cost of computed tomography which limits its usage.

46.7%, 30.7% et 22.7% of the stones were respectively ureteral, renal, and vesical. In two other studies, there were 54.3% and 43.5% renal stones, 34.1% and 39.1% ureteral stones, 11.5% and 17.4% bladder stones [16] [30] .

57.3% of the urinary stones were revealed by pain, 33.3% cases of which was a renal colic. Renal colic was present in 51.4% ureteral stones versus 30.4% renal stones. The pain is the main symptom according to several studies. Diallo et al. [9] have reported 94.9% pain, 28.8% of which being a renal colic. Renal colic reveals 67.5% [17] and 79.4% [16] of ureteral stones. The literature also signals 5% hematuria and 13% fever [31] . Complications of renal stones were hydronephrosis (60.9%) and obstructive renal failure (30.4%). That proportion of obstructive renal failure is higher than the ones observed elsewhere: 17.4% [32] , 13.5% [9] . Voiding or storage troubles such as dysuria and pollakiuria were associated with bladder stones. That fact is also observed in several other studies [33] [34] .

56 patients (74.7%) underwent a surgical treatment: 48 open surgeries (64%) and 8 drainages by pigtail ureteral stent (10.7%). Mini-invasive surgery is not yet introduced into CHUD-BA. Hounnasso et al. apply open surgery to 50.8% cases [16] and Coulibaly et al. perform open surgery in 100% cases [32] .

We could not evaluate the expulsion rate of ureteral stone treated with alpha-blocker. Yet the efficacy of alpha-blockers as a medical expulsive therapy for ureteral stones have been demonstrated [35] [36] [37] .

The prevalence of urinary stone disease was 1.7% at CHUD-BA, northern Benin in 2023. There was a masculine predominance: the sex ratio was 2.75. The patients’ mean age was 41 years. Computed tomography was available, but its high cost hindered its usage. Open surgery was the only treatment tool available.

Some medical records were not available, some other were incomplete. Infrared cristallography or other tool being unavailable, it was impossible to determine the chemical composition of the urinary stones collected after their surgical removal.

The Ethics Committee in CHUD-BA had authorized the study to be performed.

The authors declare no conflicts of interest regarding the publication of this paper.

Isidore, G., Jean, S., Rafiou, T.S., Emmanuel, D., Alexandre, A. and Georges, A.D.J. (2024) Epidemiologic, Diagnostic, and Therapeutic Features of Urinary Stone Disease in Northern Benin from 2018 to 2023. Open Journal of Urology, 14, 128-137. https://doi.org/10.4236/oju.2024.142013