This is a prospective, descriptive and analytical study conducted over a 12-month period, from August 1, 2023 to July 31, 2024, in the nephrology-hemodialysis department of the Hôpital National Amirou Boubacar Diallo (HNABD) in Niamey, Niger.

All chronic hemodialysis patients with an arteriovenous fistula (AVF), functional or not, who agreed to participate in the study were included.

Inclusion criteria were:

Non-inclusion criteria included:

Data were collected using a standardized form including ( Table 1 ):

Each patient underwent a complete clinical examination, carried out in the dialysis room by the medical team. Doppler ultrasound of the AVF was performed on the ward for patients who had access to it, using a Mindray device with a high-frequency linear probe.

This study was performed using a Mindray ultrasound machine.

The Doppler ultrasound examination follows a specific methodology:

Doppler ultrasound allowed us to measure blood flow and obtain a precise anatomical and hemodynamic analysis of arteriovenous fistulas, particularly to detect venous hypoperfusion or hyperperfusion, stenosis, false aneurysms, or thrombosis ( Table 2 ).

The quality criteria for an arteriovenous fistula were divided into two groups:

Our study was conducted after submitting a research authorization request to the Dean of the Faculty of Health Sciences (FSS) at Abdou Moumouni University (UAM). We then obtained approval from the Dean of the FSS and the Director of the HNABD.

The informed consent of each patient included in the study was obtained.

Data were entered using Microsoft Excel 2013 and analyzed with Epi Info version 7.2.5.0 and SPSS version 25.0.

Of a total of 225 patients on chronic hemodialysis during the study period, 126 were included, representing an inclusion rate of 56%.

The mean age of the patients was 46 years ± 14 years (extremes: 13 to 70 years). The most common age group was 40 to 49 (30.2%). Males predominated, accounting for 65.9% of cases (n = 83), giving an M/F sex ratio of 1.93.

Hypertension was the most frequent comorbidity (95.2%, n = 120), followed by diabetes (11.1%) and heart failure (10.3%). Regarding the etiology of CKD, chronic glomerulonephritis was the most common (34.9%), followed by undetermined nephropathy (32.5%) and hypertensive nephropathy (22.2%).

The mean duration of hemodialysis treatment was 36.1 months ± 25.2 months (extremes: 3 to 204 months). The vast majority of patients (96%) received 2 weekly sessions.

Native arteriovenous fistula (AVF) was the predominant vascular approach, found in 99.2% of cases (n = 121). Only one patient had a prosthetic fistula.

Fistulas were predominantly radiocephalic (61.1%, n = 77), followed by humerocephalic (38.9%, n = 49). The most frequent site of creation was the distal left arm (50.8%), followed by the proximal left arm (30.9%).

Right laterality was dominant in 81.8% of cases. The mean lifespan of the AVFs was 33.1 months ± 24.8 months (extremes: 2 to 196 months).

On examination, more than half of AVFs were clinically normal (55.6%). The most frequent abnormalities were:

Thrill was present and satisfactory (>10 cm) in 80.9% of cases.

Biologically, the majority of patients were anemic, with mild to moderate anemia in 86.7% of cases.

Doppler ultrasound was performed in 51.6% of patients (n = 65). Of these, the examination was normal in 40% (n = 26).

Complications were observed in 42.9% of patients (n = 54). The main complications were

Of patients presenting complications, 24.1% (n = 13) received treatment. Treatment was drug-based in 92.3% of cases (n = 12), and mainly involved:

Thrombosis was the complication requiring the most treatment (76.9% of cases treated).

Post-treatment outcome was favorable in 38.5% of cases, while loss of AVF was observed in 61.5% of treated cases.

This situation can be explained by a lack of technical facilities. In most cases, fistulas are closed by surgeons in the event of fistula rupture or significant hyperflow leading to heart failure.

The statistically significant relationships identified were as follows:

In multivariate logistic regression, age, diabetes, age at dialysis, hemoglobin, anemia, and female sex remain independent predictors ( Figure 1 ).

In multivariate logistic regression, age, diabetes, age at dialysis, and gender remain independent predictors ( Figure 2 ).

In our study, the native arteriovenous fistula was the most commonly used vascular approach (99.2%), with a predominance of radio-cephalic AVFs (61.1%). This practice is in line with international recommendations, which favor native AVF as the first choice of vascular approach due to its longevity, low infection rate, and reduced cost [1] [2] .

Our results concur with those of Karar et al. in Algeria [15] , who reported a similar proportion of native AVFs, and confirm the rarity of using prosthetic grafts in resource-limited countries, due to economic constraints and an insufficient technical platform.

The frequency of complications in our series (42.9%) is high, but remains consistent with African data reporting significant morbidity associated with AVFs [15] - [17] . This frequency may be linked to inadequate monitoring, repeated puncture at the same site, the absence of a structured Doppler follow-up program, and insufficient training of nursing staff.

Contrary to many studies in the literature, in which thrombosis is the most frequent complication [16] [17] , our series shows a predominance of false aneurysms (46.3%). This specificity could be explained by repeated punctures at the same site, poor needling technique, and lack of systematic rotation of puncture sites, exacerbated by the absence of prior ultrasound identification.

Thrombosis, although in 3rd place, remains a dreaded complication, occurring in 18.5% of cases. In our study, thrombosis was significantly associated with anemia (p = 0.03) and female gender (p = 0.04). This latter finding is in line with several publications suggesting a greater susceptibility of women to thrombosis, in relation to vascular caliber and hormonal factors [17] - [21] .

Primary failure accounted for 22.2% of complications. Contrary to some publications [18] [19] , we found no significant association between primary failure and diabetes (p = 0.15), although this comorbidity is known to favor diffuse arterial damage and mediacalcosis, which impede AVF maturation. This result may be linked to the modest size of our sample or to an underestimation of associated vascular lesions.

We found a significant association between prolonged AVF lifespan and certain degenerative complications such as stenosis (p = 0.0005), false aneurysm (p = 0.0001), and hyperflow (p = 0.0001). These results reinforce the idea that prolonged exposure to high arterial pressures and repeated punctures induces vascular structural remodeling [20] .

Doppler ultrasonography was performed in only 51.6% of patients, despite being a fundamental tool for detecting silent or sub-clinical complications [1] [3] . Its limited access reflects the structural constraints of our healthcare system. The development of a systematic Doppler screening strategy, even if targeted, could significantly improve the early detection and longevity of AVFs.

Most complications were treated with drugs (92.3%), mainly anti-inflammatories and anticoagulants. This finding is in line with data from Baldé et al. in Guinea [17] . However, this approach often remains palliative. The failure rate (loss of AVF in 61.5% of cases treated) underlines the need to integrate vascular surgery and interventional radiology into the local therapeutic arsenal.

This study has certain limitations: