Prevalence and Etiologies of Obstructive Renal Failure in the Nephrology Department of the University Hospital Center of Point G, Bamako, Mali

Introduction: Obstructive renal failure (ORF) or obstructive uropathy is defined by the simultaneous presence of impaired renal function and urinary excretory tract dilatation on medical imaging. It accounts for 2% to 10% of the causes of acute renal failure (ARF). Objective: To determine the prevalence and etiologies of ORF in the nephrology department of the University Hospital Center of Point G. Methodology: This was a descriptive study with retrospective data collection conducted from January 1, 2017 to June 30, 2018. All patients hospitalized with renal failure due to urinary tract obstruction were included. The parameters studied were age, gender, etiology, type of renal impairment, procedures performed, surgical outcomes of the procedure, pre-and post-management creatinine levels. Information on these clinical and paraclinical variables was collected from individual hospitalization and patient follow-up records. Results: Among 1133 patients, 83 had obstructive renal failure, a prevalence of 7.32%. The sex ratio was 1.86. The mean age was 48.99 ± 6.81 years with extremes of 7 and 102 years. Signs suggestive of lower urinary tract obstruction were, in order of frequency: dysuria (50.6%), urinary burns (44.6%), urinary frequency (44.6%), pollakiuria (44.6%), macroscopic hematuria (25.3%), low back pain (21.6%), total anuria (18.1%). The etiologies were dominated by lithiasis 36 cases (43.4%), tumours 32 cases (38.55%) followed by sequelae of bilharziasis 12 cases (14.50%). Conclusion: Obstructive renal failure is becoming more and more common. The etiology is essentially of lithiasic and tumor origin. It must be treated early to allow total or partial recovery of renal function.


Introduction
Obstructive renal failure is defined as acute or chronic obstruction of the urinary tract, occurring bilaterally or in a single anatomical or functional kidney.This type of renal failure is called post-renal, because its etiology is downstream of the kidneys.It accounts for 2% to 10% of the causes of ARF.[1].Early removal of the obstacle conditions its reversibility [1].Their severity lies in the reduced capacity of the kidneys to ensure their sodium excretion functions leading to the risk of hydrosodium overload on the one hand and acute pulmonary oedema on the other hand with the risk of threatening hyperkalaemia.Their diagnostic and therapeutic management has been improved by advances in imaging and endo-urology.However, this form of renal failure continues to pose many problems in facilities with limited technical facilities, more so than in developing countries [2].
The aim of this work was to determine the prevalence and etiologies of obstructive renal failure in the nephrology department of the UHC of Point G.

Patients and Methods
This was a descriptive retrospective data collection study of patients managed for obstructive kidney disease in the Nephrology Department of Point G University Hospital from January 1, 2017 to June 30, 2018 (16 months).Patients were included in this study without distinction of sex, age or nationality, hospitalized for renal failure whose cause is an obstacle in the urinary tract and having a medical record including clinical variables, paraclinical variables, procedures performed, surgical results, creatinine levels before and after drainage.
Clinical variables sought included dysuria, anuria, acute urine retention, bladder globe, low back pain, macroscopic hematuria.Abdominal pelvic ultrasound, uroscanner or abdominal-pelvic CT scan looked for hydronephrosis, uretero-hydronephrosis or causes of obstruction such as lithiasis, tumours of the bladder or prostate, sequelae of bilharzia or extra-renal tumours, among others.Information on these clinical and paraclinical variables was collected from individual hospitalization and patient follow-up records.

Definition Criteria Used
 Chronic kidney disease (CKD) is defined as the chronic (>3 months) and ir-reversible decrease in glomerular filtration rate (GFR) < 60 ml/min/1.73m 2 [3].Chronicity was selected in front of:  A history of previous pathologic creatinine or the existence of hematuria and/or proteinuria for at least 3 months;  On ultrasound, small kidneys (<10 cm), poorly differentiated;  An aregenerative normocytic normocytic anemia;  Hypocalcemia associated with hyperphosphatemia. Definition of acute renal failure (Table 1): The obstructive nature of renal failure was retained by the presence of an obstacle in the urinary tract either on clinical examination (anuria, bladder goblet, urine retention, dysuria, lumbar pain, macroscopic hematuria, urinary frequency or burns) or on medical imaging (hydronephrosis or ureterohydronephrosis, lithiasis, tumour) and/or improvement in renal function after removal of the obstacle.
The evolution was considered favourable if there was an improvement in renal function.
Strict adherence to the anonymity of each patient's medical record was observed.
Data entry and analysis were carried out with the SPSS 20 software (French version).The statistical test used was the Pearson Chi2 with a significant value P < 0.05.

Discussion
The ORF, once an uncommon or rather underestimated situation in the institution, has become relatively common nowadays.The prevalence of urinary obstruction is difficult to establish.This prevalence was 7.32% in our study.In Ouagadougou in 2011 and in Benin in 2017, obstructive kidney disease accounted for 17% and 34% of cases respectively [2] [5].The male predominance was clear (65.1% vs 34.9%).Many authors have also reported this male predominance [5].failure is symptomatic and mainly manifests itself as pain [1].In the majority of our patients, the clinical picture was dominated by signs suggestive of a uremic syndrome, namely asthenia (81.9%), vomiting (74.4%) and anorexia (66.3%).
Renal ultrasonography, carried out as an emergency procedure, revealed dilatation of the upper excretory tract and sometimes the etiology.Dilatation of the upper excretory tract was observed in all our patients (100%).A dilatation rate of 74.5% and 92% was reported in Benin in 2015 and 2017 respectively [5] [10].
Although ultrasound is still the first-line examination in developing countries, it is increasingly being surpassed by CT, which in addition to dilatation allows visualization of the cause and study of renal parenchyma.In our study, the CT scan performed in 42 patients showed dilatation of the excretory tract in 90% of cases.Govani et al. reported 54% excretory tract dilatation diagnosed on first-line CT in their series [15].Although there are recommendations from learned societies regarding the management of renal failure in general, none to our knowledge provide specific recommendations to guide clinical decision making in the specific case of obstructive AKI [1].
Despite this lack of recommendations, our patients received antibiotic therapy (72.3%), water intake (51.8%), urinary catheterization (38.6%), percutaneous nephrostomy (34.9%), antihypertensive treatment (32.5%), blood transfusion (32.50%) and urological surgery (22.9%).Twenty-two percent (22%) of patients received dialysis.In the presence of ARF, the KDIGOs recommend initiating emergency extrarenal dialysis when hydroelectrolytic complications or overload are life-threatening in the short term [4].A double J ureteral endoprosthesis, a percutaneous nephrostomy catheter or the Detour system for extra-anastomotic internal urinary diversion should be used for a high barrier [18] [19].The time to reversibility of the lesions is difficult to specify.Recovery would not be related to the extent of dilatation [20].
Wu believes that kidney function impaired by an obstruction never normalizes after surgical removal.The procedure relieves pain, prevents further deterioration and infection [21].
Limitations of the study: patients whose records were incomplete or even unusable due to lack of financial means to carry out radiological and biological explorations, return home against medical advice, non-consent of some but also the early occurrence of death during the study, contributed to significantly reduce the size of our sample.

Conclusion
Obstructive renal failure is becoming increasingly common.The etiology is essentially of lithiasis and tumour origin.It must be treated early to allow total or partial recovery of renal function.

Figure 1 .
Figure 1.Distribution according to functional signs.

Figure 2 .
Figure 2. Distribution according to physical signs.

Figure 3 .
Figure 3. Abdomino-pelvic ultrasound: homogeneous hypertrophy of the prostate (a) associated with localized thickening of the bladder wall in favor of bilharzia cystitis (b) with impact on the upper urinary tract (bilateral uretero-hydronephrosis) (c).(arrows).

Figure 4 .
Figure 4. Abdominal CT scan of right lateral pseudotumour thickening of the bladder with calcification areas (arrow).

Figure 6 .
Figure 6.Abdominal CT scan: expansive process at the expense of the right renal cortex measuring 28 mm long axis (arrow).
*We used the creatinine criterion in this study.

Table 2 .
Distribution of patients by urinary tract ultrasound result (n = 83).

Table 3 .
Distribution of patients by CT scan result (n = 42).

Table 4 .
Distribution of patients by etiology of obstruction on abdominopelvic ultrasound (N = 83).

Table 5 .
Distribution of patients by etiology of CT obstruction (n = 51).