Acute obstructive renal failure is characterized by a sudden and significant deterioration of renal function. Obstructive ARF usually results in phenomena of compression of the ureters (retroperitoneal hematoma, retroperitoneal edema) or phenomena of obstruction (edema of the ureteral mucosa or ureteral meat). Rarely, acute obstructive renal failure is the result of accidental ureteral ligation (uterine surgery). Two particular forms nevertheless deserve to be mentioned: by precipitation of uric acid or calcium phosphate crystals linked to reductive tumor surgery; ureteral mucosal edema by major hyponatremia (resorption syndrome linked to transvesical prostatic resection, for example) [1] .

Acute obstructive renal failure (AORF) is a life-threatening medical and surgical emergency. Any uncorrected obstruction of urinary flow can lead to acute and then chronic renal failure. Obstruction causes irreversible renal failure if bilateral and various tubular abnormalities if incomplete, but early elimination of the obstruction allows complete recovery. In order to improve the management of AORF, we conducted this study with the main objective of studying the clinical-biological, ultrasound, etiological and therapeutic profile of AORF in our nephrology dialysis department of the Brazzaville University Hospital (CHU).

We conducted a retrospective and descriptive study. The study period was 15 months (from January 1, 2022 to March 15, 2023). The study was carried out in the nephrology and dialysis department of the Brazzaville University Hospital. Information was collected from hospitalization registers and medical records of patients hospitalized for IRAO during the study period.

Included in the study were the files of patients who presented

-impaired renal function with a blood creatinine level greater than 120 µmol/L

-evidence of obstructive uropathy (clinical and/or ultrasound).

The files of subjects with chronic renal failure (CRF) already known as well as unusable files were excluded.

Data processing and analysis were carried out using Microsoft Office Excel 2021 software. The various tables and figures were generated using Microsoft Office Excel 2021 software. Quantitative variables were expressed as mean with standard deviation or as median with the first and third quartiles. The median was used when 10% of the integer part of the mean was greater than the standard deviation. Qualitative variables were expressed as numbers and percentages.

1) We retained 35 patient files out of 615, or 5.69% of the population studied. The incidence of IRAO at the CHU is 5.69%. On the other hand, in Mali, Sy et al. in 2017 found 7.32% [2] ; identical in Benin in 2015, Kokou et al. found 10.5% [3] . In Mali, the results and methodology were identical to ours while Kokou et al. had done work over 5 years, which would explain the difference between our results (see Table 1 ).

2) The average age was 48.9 years in Mali but the extremes went from 7 to 102 years. This is identical to the work carried out in Casablanca Morocco 63.11 years [4] and we found 59.91 years in Niger [5] .

The sex ratio was 3 men for 1 woman. In all our research the sex ratio is identical and in favor of men. This was found by Lanzy A and collaborator 3 years earlier in urology at CHUB [6] [7] .

3) The circumstances of discovery.

The circumstances of discovery were dominated by dysuria 37.14%. On the other hand, Table 2 below compares with other studies.

4) The causes of IRAO ( Figure 2 ).

5) The mean creatinine level was 111.9 mg/L or 986.95 micromol/L (range: 11 - 325). Mean creatinine level was 143.31 mg/L or 1264 micromol/l. (Mabrouk in Morocco) the mean levels of admission would be high on admission.

6) Renal ultrasound showed hydronephrosis in 31.42% of cases; dilation was bilateral in 25.71% of cases. (our work). Hydronephrosis is 61.5%, and ureterohydronephrosis is 38.5% (Sy S in Mali).

7) The indication for hemodialysis.

The indication for hemodialysis was: hyperkalemia, acidosis, severe uremia and OAP in 83.1%; 34.57%; 21.49% and 11.21% of cases respectively. (Mabrouk et al. in Morocco [4] and Chavez-Iniguez et al. [7] )

The incidence of IRAO was 5.69%.

The mean age was 62.6 years; the interest in uroMRI for early diagnosis is obvious.

The predominant obstacle was prostatic in 45.71%, followed by lithiasis in 17.14%.

The indication for hemodialysis was: severe uremia, threatening hyperkalemia and acute pulmonary edema, respectively: 37.14%, 5.71% and 2.85%.

The delay in consultation and the delay in performing the nephrostomy and the double J catheterization constitute an obstacle to the recovery of normal renal function and vital prognosis.

Thank 6th-year students and nephrology interns for helping compile medical records.