Can preoperative parameters and histopathology of the vessels affect arteriovenous fistula outcomes? A prospective observational study

Abstract

BACKGROUND

Arteriovenous fistula (AVF) is the preferred vascular access for maintenance hemodialysis in patients with chronic kidney disease; however, early failure remains common.

AIM

To determine clinical, biochemical, Doppler ultrasound and histopathological predictors of early AVF outcomes.

METHODS

In this single-center prospective observational study, 69 adult patients undergoing AVF creation were evaluated preoperatively using clinical assessment, laboratory investigations (lipid profile and serum calcium), and Doppler ultrasonography. Intraoperative edge biopsies of the artery and vein were obtained for histopathological analysis. Patients were followed at 1, 6, and 12 weeks postoperatively. Associations between preoperative and histological factors and AVF patency, maturation, and early complications were assessed using univariate and multivariate analyses.

RESULTS

The mean patient age was 51.6 ± 11.6 years, and 82.6% were men. Age > 60 years [odds ratio (OR): 5.25], alcohol use (OR: 13.75), and low high-density lipoprotein cholesterol (OR: 0.167) were independently associated with surgical site infection. Early postoperative bleeding was associated with elevated triglyceride levels, abnormal vessel morphology, smaller arterial diameter, and greater vessel depth. AVF maturation was adversely associated with smoking (OR: 2.76), elevated triglycerides (OR: 0.144), abnormal vessel wall histology (OR: 1.58), and suboptimal vascular characteristics.

CONCLUSION

Smaller and deeper vessels identified on preoperative Doppler ultrasonography, dyslipidemia, and histological vessel wall abnormalities were independently associated with poorer AVF outcomes. Routine lipid screening and selective use of intraoperative vessel wall biopsy may assist in identifying patients at higher risk of AVF failure and inform vascular access planning in chronic kidney disease.

Key Words: Arteriovenous fistula; Hemodialysis; Chronic kidney disease; Doppler ultrasonography; Vascular histopathology; Dyslipidemia

Core Tip: A prospective observational study is done to show preoperative parameters and histopathology of the vessels can also tell the outcome of arteriovenous fistula. This study will increase the horizon of readers of the journal to think in this direction, and will help to prognosticate end-stage renal disease patients post arteriovenous fistula.

INTRODUCTION

The number of patients requiring regular hemodialysis (HD) has substantially increased because of the rising prevalence of chronic kidney disease (CKD) and end-stage renal disease (ESRD)[1]. Adequate vascular access (VA) is essential for the delivery of maintenance HD. VA can be achieved through an arteriovenous fistula (AVF), an arteriovenous graft, or central venous catheters. Among these options, AVF is regarded as the most suitable form of VA because it is associated with lower infection and thrombosis rates and greater long-term safety compared with arteriovenous graft or central venous catheters[2]. Despite these advantages, reported AVF failure rates range from 15% to 50%[3-5]. AVF failure may occur because of early thrombosis, failure to mature, or late loss of patency. Histopathological studies of failed AVFs commonly demonstrate neointimal hyperplasia, impaired outward remodeling, and inadequate vessel wall thickening.

Although preoperative ultrasound mapping has been associated with improved AVF outcomes[6], access to these resources may be limited, and the findings do not always affect surgical decision-making[7,8]. In routine clinical practice, surgeons often rely on clinical characteristics, such as patient age and comorbid conditions that affect vascular structure, when selecting the most appropriate VA strategy. Several studies have identified clinical factors associated with AVF failure, including age[9], sex[10], comorbidities[11], vascular parameters[12], or combinations of these factors[5]. However, most investigations of AVF failure risk factors have been conducted in Western populations, which differ in health-care systems, patient characteristics, and disease profiles from those in Indian and Southeast Asian settings. This study identified clinical, biochemical, and vascular factors that reliably predict AVF functionality and complications at 1, 6, and 12 weeks after AVF creation.

MATERIALS AND METHODS

Study design

This prospective observational study was conducted at a single tertiary care hospital in India after approval was obtained from the Institutional Ethics Committee (approval No. FMIEC/CCM/428/2024). Written informed consent was obtained from all participants, and documentation will be provided on request. This study was conducted in accordance with the Strengthening the Reporting of Observational Studies in Epidemiology guidelines.

Study population

Adult patients (aged > 18 years) with CKD requiring AVF creation for HD were eligible for inclusion. Exclusion criteria included previous AVF creation, a history of cannulation, central venous stenosis, vasculitis, coagulopathy, pathological or obstructive proximal vessels, intravenous drug use, or recent trauma, cannulation, or vascular puncture at the intended operative site. To minimize confounding, only patients who completed 12 weeks of follow-up were included in the final analysis. Of the 76 patients screened, four were ineligible and three were lost to follow-up, resulting in a final study population of 69 patients. The recruitment and follow-up process is illustrated in Figure 1.

Figure 1 Study flow diagram showing patient screening, eligibility, and follow-up. Flow diagram illustrating patient recruitment, exclusions, losses to follow-up, and final study cohort included in the analysis. Of 76 patients screened, four were excluded based on predefined criteria and three were lost to follow-up, resulting in 69 patients completing 12-week follow-up and included in the final analysis. AVF: Arteriovenous fistula.

Preoperative evaluation

After written informed consent was obtained, baseline demographic, anthropometric, and clinical data were collected from medical records and patient interviews. Blood samples were obtained from the contralateral arm for laboratory evaluation. Preoperative Doppler ultrasonography was performed by an experienced sonographer to assess the diameter (mm) and depth from the skin (mm) of the target artery and vein in the intended operative limb. Measurements included arterial and venous luminal diameters as well as arterial and venous depth from the skin surface. Doppler flow parameters, including peak systolic velocity and end-diastolic velocity, were measured in both the artery and vein to evaluate arterial inflow and venous outflow, and resistance indices were calculated when feasible. Vessel wall characteristics, including calcification or evidence of stenosis, were also recorded. Magnetic resonance angiography was not performed as part of the study.

Surgical procedure

All participants received standard preoperative preparation, counseling, and medications. The surgical technique was not fully standardized across cases; however, procedures were performed by experienced surgeons to minimize operator-related variability, which may still have affected outcomes. Based on vascular anatomy identified on preoperative Doppler ultrasonography, a radiocephalic AVF, brachiocephalic AVF, or brachiobasilic fistula with transposition was created. Edge biopsy samples of both the artery and vein were obtained using an edge resection technique before anastomosis for histopathological evaluation. Although intraoperative vessel biopsy is not routinely performed due to its invasive nature, it provides direct insight into underlying vascular pathology that may influence fistula maturation. This exploratory approach was adopted to evaluate whether histological features could complement noninvasive predictors and improve mechanistic understanding of AVF failure. Biopsy specimens were stained with hematoxylin and eosin and assessed by a histopathologist blinded to clinical outcomes for the presence and severity of atherosclerosis, intimal hyperplasia, fibrosis, and calcification. Additional special stains, including Masson’s trichrome for fibrosis and von Kossa staining for calcification, were performed to improve visualization and confirm specific pathological features. All patients received standard intraoperative anticoagulation with intravenous heparin (5000 IU) to reduce the risk of thrombosis, followed by standard postoperative care and medications.

Follow-up evaluation

Postoperative outcomes were assessed at 1, 6, and 12 weeks after surgery. Early complications, including surgical site infection (SSI) and bleeding, were recorded at the 1-week follow-up. Outcomes evaluated at all follow-up visits included fistula functionality, maturation, and complications. Fistula functionality and patency were confirmed by clinical examination, defined by the presence of a palpable thrill and an audible bruit. Fistula maturation was determined using the “rule of sixes”, defined as a maturation time of 6 weeks, a flow rate of at least 600 mL/minute, a fistula depth of no more than 6 mm from the skin surface, and a minimum fistula diameter of 6 mm[4]. A flow rate below 100 mL/minute on Doppler ultrasonography was classified as a nonfunctional fistula.

Statistical analysis

Data were analyzed using SPSS Statistics version 20 (IBM, Armonk, NY, United States). Continuous variables are expressed as the mean ± SD and compared using the independent t test for normally distributed data or the Mann-Whitney U test for non-normally distributed data. Categorical variables were summarized as n (%) and compared using the χ² test or Fisher’s exact test, as appropriate. Risk factors for AVF dysfunction were evaluated using multivariate Cox regression analyses and then simplified to the understanding in binary format. Independent determinants of outcomes were identified by calculating odds ratios (ORs) with 95% confidence intervals (CIs). P < 0.05 was considered statistically significant.

RESULTS

A total of 69 eligible patients were enrolled in the study, with a mean age of 51.6 ± 11.6 years. Of these, 57 (82.6%) were men and 12 (17.4%) were women, yielding a male-to-female ratio of 4.75:1. The baseline characteristics of the study population are presented in Table 1. Of the 69 patients, 44 (66.67%) underwent radiocephalic AVF creation, 21 (30.43%) underwent brachiocephalic AVF creation, and 2 (2.9%) underwent brachiobasilic AVF creation.

Table 1 Baseline characteristics of study population, n (%)/mean ± SD.

Parameter	Value
Number of patients	69
Mean age, years	51.6 ± 11.6
Male:female ratio	4.75:1
Mean BMI	25.4 ± 2.7
Diabetes mellitus	25 (36.2)
Hypertension	35 (50.7)
Coronary artery disease	25 (36.2)
Smoking	11 (15.9)
Alcohol use	6 (8.7)
Mean hemoglobin, g/dL	8.8 ± 1.4
Raised triglycerides (> 200 mg/dL)	7 (10.1)
Abnormal vessel histology	34 (49.3)
Radio-cephalic AVF	46 (66.7)
Brachio-cephalic AVF	21 (30.4)
Brachio-basilic AVF	2 (2.9)

BMI: Body mass index; AVF: Arteriovenous fistula.

During the surgical procedure, vessel wall edge biopsy samples were obtained from all patients. Histopathological analysis revealed normal vessel morphology in 35 (50.7%) patients, whereas abnormalities were identified in 49.3% patients (Figure 2). Among the abnormal biopsies, atherosclerosis was observed in 35.3% patients and was characterized by lipid deposits, inflammatory cell infiltration, and smooth muscle cell proliferation within the intimal layer. Intimal hyperplasia, present in 38.2% of cases, was marked by excessive smooth muscle cell proliferation. Fibrosis was identified in 14.7% of cases and was characterized by excessive collagen deposition, whereas calcification, observed in 11.8% of cases, was characterized by prominent calcium deposits in the vessel wall.

Figure 2 Distribution of vessel wall histopathological findings from intraoperative edge biopsy samples. Bar chart showing the proportion of patients with normal vessel wall morphology and abnormal histopathological findings. Among abnormal biopsies, the predominant abnormalities included intimal hyperplasia, atherosclerosis, fibrosis, and calcification. Multiple pathological features were present in some specimens.

Among abnormal biopsies (Figure 3), atherosclerosis was observed in 12 cases (35.3%) and was characterized by lipid deposition, inflammatory cell infiltration, and smooth muscle cell proliferation within the intimal layer, often with focal calcification. Intimal hyperplasia was the most common abnormality, present in 13 cases (38.2%), and was marked by excessive smooth muscle cell proliferation and extracellular matrix deposition resulting in luminal narrowing. Fibrosis was identified in 5 cases (14.7%) and was characterized by excessive collagen deposition within the vessel wall, contributing to increased stiffness. Calcification was observed in 4 cases (11.8%), with calcium deposits located within the intima or media. These histological abnormalities were not mutually exclusive, and several biopsy specimens demonstrated overlapping pathological features.

Figure 3 Representative histopathological images of vessel wall biopsy specimens. Representative photomicrographs demonstrating major histopathological patterns observed in arterial and venous biopsy specimens. A: Atherosclerosis showing intimal lipid deposition with inflammatory cell infiltration (hematoxylin and eosin stain). Black arrows indicate lipid deposition within the intimal layer, while triangles indicate inflammatory cell infiltration; B: Intimal hyperplasia showing concentric smooth muscle cell proliferation and luminal narrowing (hematoxylin and eosin stain). Black arrows indicate smooth muscle cell proliferation and triangles indicate luminal narrowing due to intimal hyperplasia; C: Fibrosis highlighted by collagen deposition (Masson’s trichrome stain). Black arrows indicate collagen deposition within the vessel wall highlighted by Masson’s trichrome staining; D: Calcification demonstrating calcium deposition within the vessel wall (von Kossa stain). Black arrows indicate areas of calcium deposition within the vascular wall demonstrated by von Kossa staining.

Correlation of histopathology with outcomes

As shown in Tables 2 and 3, abnormal vessel histology on biopsy was significantly associated with loss of AVF patency at 6 weeks (OR: 1.652; P = 0.001) and delayed maturation at 6 weeks (P = 0.001 in univariate analysis; OR: 0.148; P = 0.002 in multivariate analysis). At 12 weeks, abnormal vessel wall histology remained an independent predictor of nonfunctional AVFs (P = 0.0001) and failure of maturation (P = 0.0001; OR: 1.583; P = 0.001). In addition, pathological changes in the vessel wall, particularly abnormal vessel morphology, were associated with an increased risk of early postoperative bleeding (P = 0.0001). Collectively, these findings demonstrated the substantial effect of preexisting vessel wall pathology on both early and late AVF outcomes.

Table 2 Factors associated with patency of arterio-venous fistula 6 weeks after surgery, on univariate and multivariate analysis, n (%)/mean ± SD.

		Univariate analysis			Multivariate analysis
Variables	AVF patency at 6 weeks	No	Yes	P value	Odds ratio	95%CI		P value
Triglycerides	< 200 mg/dL	4 (5.80)	3 (4.30)	0.036	0.162	0.032	0.828	0.029
	> 200 mg/dL	11 (15.90)	51 (73.90)
Vessel wall biopsy	Normal	0 (0.00)	31 (44.90)	< 0.0001	1.652	1.278	2.136	0.001
	Abnormal	15 (21.70)	23 (33.30)
Artery diameter (mm)		2.73 ± 0.97	3.52 ± 1.33	0.036	1.488	0.469	4.721	0.026
Vein diameter (mm)		2.75 ± 0.89	3.72 ± 1.12	0.003	1.677	0.431	2.457	0.041
Depth of artery from skin (mm)		4.81 ± 2.50	2.93 ± 2.05	0.01	2.633	1.254	4.379	0.015
Depth of vein from skin (mm)		2.82 ± 1.01	2.15 ± 0.95	0.02	1.869	0.852	2.736	0.026

AVF: Arteriovenous fistula; CI: Confidence interval.

Table 3 Factors associated with maturity of arterio-venous fistula 12 weeks after surgery, on univariate and multivariate analysis, n (%)/mean ± SD.

		Univariate analysis			Multivariate analysis
Variables	AVF patency at 6 weeks	No	Yes	P value	Odds ratio	95%CI		P value
Smoking	Yes	14 (20.30)	44 (63.80)	0.016	2.759	1.656	5.877	0.03
	No	0 (0.00)	11 (15.90)
Triglycerides	< 200 mg/dL	4 (5.80)	3 (4.30)	0.027	0.144	0.028	0.746	0.021
	> 200 mg/dL	10 (14.50)	52 (75.40)
Vessel wall biopsy	Normal	0 (0.00)	31 (44.90)	0.0001	1.583	1.242	2.019	0.001
	Abnormal	14 (20.30)	24 (34.80)
Artery diameter (mm)		2.57 ± 0.77	3.55 ± 1.33	0.011	1.751	0.536	5.712	0.031
Vein diameter (mm)		2.70 ± 0.90	3.71 ± 0.90	0.002	2.557	1.145	3.891	0.032
Depth of artery from skin (mm)		4.91 ± 0.51	2.43 ± 0.51	0.0001	0.532	0.11	1.967	0.001
Depth of vein from skin (mm)		2.87 ± 0.90	2.15 ± 0.94	0.014	0.856	0.214	1.95	0.036

AVF: Arteriovenous fistula; CI: Confidence interval.

Outcomes at 1 week

At the first follow-up, conducted 1 week after the procedure, 7 (10.1%) patients developed SSI, and 6 patients (8.7%) experienced significant AVF-related bleeding. No pseudoaneurysms were observed at this time point, and fistulas could not yet be classified as failed or matured. Nevertheless, 55 (79.7%) patients had a patent fistula at the 1-week follow-up. The incidence of early SSI after AVF creation was higher among patients older than 60 years and those with alcohol use (P = 0.009), diabetes (P = 0.024), and low high-density lipoprotein cholesterol levels (< 40 mg/dL; P = 0.0247). On multivariate regression analysis, age greater than 60 years (OR: 5.25; 95%CI: 1.413-19.505; P = 0.013), alcohol use (OR: 13.75; 95%CI: 2.157-87.651; P = 0.006), and low high-density lipoprotein cholesterol (OR: 0.167; 95%CI: 0.029-0.958; P = 0.045) were independently associated with SSI. Major bleeding within the first postoperative week was more frequent among patients with elevated triglyceride levels (> 200 mg/dL; P = 0.011), abnormal vessel morphology (P = 0.0001), smaller arterial diameter (P = 0.011), and greater vessel depth from the skin surface (P = 0.001). These factors were identified as independent predictors of major bleeding after AVF surgery (Table 4).

Table 4 Postoperative complications at 1 week.

Complication	Incidence (%)	Associated factors
Surgical site infection	10.1	Age > 60, Alcohol use, low high-density lipoprotein
Bleeding	8.7	High triglycerides, abnormal morphology, smaller artery, greater depth

Outcomes at 6 weeks

At 6 weeks, 54 (78.3%) patients had a functional AVF, whereas 15 (21.7%) patients had a nonfunctional AVF on clinical examination. Univariate and multivariate analyses indicated that elevated triglyceride levels (OR: 0.162; 95%CI: 0.032-0.828; P = 0.029) and abnormal vessel morphology (OR: 1.652; 95%CI: 1.278-2.136; P = 0.001) were independent predictors of loss of AVF patency. Larger vessel diameters and shallower vessel depth were associated with better outcomes, although the CIs indicated variability in these associations. At the same time point, 46 (66.7%) fistulas had matured, whereas 23 (33.3%) had not. On univariate analysis, smoking (P = 0.031), elevated total cholesterol (P < 0.0001), elevated low-density lipoprotein cholesterol (P < 0.0001), high-density lipoprotein cholesterol (P = 0.001), histological abnormalities (P = 0.001), and smaller arterial (P = 0.001) and venous diameters (P = 0.001) were associated with failure of maturation. On multivariate analysis, smoking (OR: 0.092; 95%CI: 0.029-0.297; P < 0.0001), elevated total cholesterol (OR: 6.111; 95%CI: 0.731-51.063; P = 0.045), elevated low-density lipoprotein cholesterol (OR: 0.138; 95%CI: 0.045-0.420; P = 0.001), histological abnormalities (OR: 0.148; 95%CI: 0.043-0.506; P = 0.002), smaller arterial diameter (OR: 0.569; 95%CI: 0.197-1.646; P = 0.029), and venous diameter (OR: 2.343; 95%CI: 1.068-4.717; P = 0.019) were independently associated with delayed AVF maturation (Table 2).

Outcomes at 12 weeks

At 12 weeks, 51 (73.9%) fistulas were patent, whereas 18 (26.1%) were nonfunctional. Nonfunctional AVFs were more frequent among patients with diabetes (P = 0.047), elevated triglyceride levels (P = 0.048), and abnormal vessel wall histology on biopsy (P = 0.0001). A normal vessel wall on biopsy independently predicted AVF patency at 12 weeks (OR: 1.9; 95%CI: 1.405-2.569; P = 0.0001). Of the 69 patients, 55 (79.7%) had AVFs that matured sufficiently for HD by 12 weeks. AVF maturation was associated with nonsmoking status (P = 0.016), triglyceride levels below 200 mg/dL (P = 0.027), and normal vessel wall histology (P = 0.0001). Mature AVFs were characterized by larger arterial and venous diameters and shallower vessel depth. On multivariate analysis, nonsmoking status (OR: 2.759; 95%CI: 1.656-5.877; P = 0.03), lower triglyceride levels (OR: 0.144; 95%CI: 0.028-0.746; P = 0.021), normal vessel wall histology (OR: 1.583; 95%CI: 1.242-2.019; P = 0.0001), greater arterial diameter (OR: 1.751; 95%CI: 0.536-5.712; P = 0.031), venous diameter (OR: 2.557; 95%CI: 1.145-3.891; P = 0.032), arterial depth (OR: 0.532; 95%CI: 0.11-1.967; P = 0.001), and venous depth (OR: 0.856; 95%CI: 0.214-1.95; P = 0.036), were independently associated with AVF maturation, although several CIs indicated variability in effect estimates (Table 3, Figures 4 and 5).

Figure 4 Patency and functional maturation of arteriovenous fistulas at 1, 6, and 12 weeks after surgery. Line/bar graph depicting the proportion of patients with patent and mature arteriovenous fistulas at each follow-up interval. Patency was defined by the presence of a palpable thrill and audible bruit, while maturation was defined according to the rule of sixes criteria. Trends illustrate progressive maturation over time with a gradual decline in nonfunctional fistulas.

Figure 5 Comparisons of blood vessel attributes determining arterio-venous fistula maturation. AV: Arteriovenous.

DISCUSSION

HD is a life-saving treatment option for individuals with ESRD, reducing morbidity and mortality and improving quality of life. Current clinical guidelines recommend the creation of a primary AVF as the preferred form of VA for most patients initiating long-term HD[13]. An ideal VA should deliver adequate blood flow for effective dialysis, allow reliable cannulation, be cost-effective, and maintain long-term patency with minimal complications. The most common complication of AVF creation is failure to mature because the fistula must remodel into a low-resistance conduit capable of sustaining the high flow rates required for HD sessions[14]. AVFs are generally expected to mature within 12 weeks after surgery, and fistulas that fail to mature within this period are considered unsuccessful.

In this study, clinical, biochemical, and vascular factors affecting AVF patency, maturation, and complications were evaluated. Arteriosclerotic changes, including intimal hyperplasia and atherosclerotic thickening, are common in patients with ESRD, and histopathological examination remains the most reliable method for identifying these vascular abnormalities. We observed that abnormal vessel wall histology on intraoperative biopsy was an independent predictor of delayed AVF maturation and loss of patency at both 6 weeks and 12 weeks after the procedure. In addition, pathological changes in the vessel wall were associated with an increased risk of major postoperative bleeding, contributing to early AVF failure within the first postoperative week.

AVF failure most commonly results from thrombosis secondary to venous stenosis[15,16]. After AVF creation, increased arterial pressure augments blood flow through the vein, leading to venous wall thickening and arterialization. Progressive vein expansion and increased blood flow contribute to adaptive arterial widening and venous remodeling. Wall stress is closely related to blood flow dynamics: High wall shear stress suppresses intimal hyperplasia and promotes outward remodeling, whereas reduced shear stress associated with low blood flow fails to inhibit intimal hyperplasia or support outward remodeling, resulting in progressive luminal narrowing[17]. Preexisting arterial pathological changes at the time of AVF creation may therefore limit blood flow required for successful maturation, leading to early AVF failure[18]. Although vessel wall biopsy provides direct information on underlying vascular pathology, its invasive nature limits routine clinical application. By contrast, noninvasive approaches such as Doppler ultrasonography and biochemical markers represent practical tools for preoperative risk assessment and prognostication. Preoperative Doppler ultrasonography mapping facilitates the identification of patients at increased risk of AVF failure. Previous evidence demonstrates higher failure rates when arterial diameter is < 2 mm and venous diameter is < 2.5 mm[19]. In the present study, larger arterial diameter independently predicted improved AVF maturation and patency, as well as a lower risk of postoperative bleeding. Venous diameter was also significantly associated with AVF failure risk. Farrington et al[20] similarly reported preoperative arterial diameter as an independent predictor of AVF failure, although venous diameter was not statistically significant in their analysis. Consistent with our approach, their study compared absolute vessel diameter measurements rather than predefined cutoff values. Current recommendations suggesting a minimum arterial diameter of ≥ 2.0 mm and venous diameter of ≥ 2.5 mm are not supported by high-quality evidence[19]. Although preoperative vascular measurements are widely implemented, they have not consistently improved AVF maturation rates. Allon et al[21] reported an increase in AVF creation rates (34%-64%) following routine preoperative mapping; however, maturation rates remained unchanged (46%-54%; P = 0.34). Similarly, a systematic analysis of four trials found no improvement in AVF maturation associated with preoperative mapping[22]. Collectively, these findings support re-evaluation of ultrasound-based selection criteria and provide the rationale for incorporating vessel wall histopathological assessment in the present study.

Arterial and venous depth were independent determinants of AVF maturation, patency, and early postoperative bleeding, with more superficial vessels associated with better functional outcomes but a higher risk of bleeding within the first postoperative week. Previous studies have reported superior AVF outcomes with superficial vessels[19], a finding that is consistent with our results. The role of serum lipid profiles in AVF maturation remains incompletely understood. In the present study, elevated triglyceride levels were associated with an increased risk of AVF nonmaturation at 12 weeks, loss of patency at 6 weeks, and early postoperative bleeding. In addition, dysregulated cholesterol levels were associated with the development of SSI within the first postoperative week. Although these findings suggest a potential role of lipid abnormalities in AVF outcomes, prior studies have reported inconsistent results regarding the association between serum lipids and AVF maturation[23]. Uremic dyslipidemia is classically characterized by elevated triglyceride levels and reduced high-density lipoprotein cholesterol, features that become more pronounced with advanced kidney failure and may be modified by renal replacement therapy and diabetes[24]. In patients with CKD, atherosclerosis progresses more rapidly and commonly manifests as calcified plaques within the arterial wall[25]. In a prospective study of 60 patients with autologous AVFs followed over 2 years, Righetti et al[26] reported significantly higher fistula patency rates among patients receiving folic acid and statin therapy compared with those not receiving statins (71.5% vs 39.1%)[27]. Tobacco smoking was identified as an independent risk factor for AVF failure in our study. Several investigations have similarly reported poorer AVF outcomes among current or former smokers[28-31]. However, the literature remains mixed because other studies, including those by Churchill et al[32] and Bashar et al[33], did not identify a definitive association between smoking history and VA outcomes.

Previous studies have reported a higher likelihood of AVF failure among patients with prolonged alcohol use compared with those who abstain[31,34]. Our findings differed because alcohol consumption was not associated with AVF failure at 12 weeks; however, patients without long-term alcohol use demonstrated a greater likelihood of early AVF maturation at 6 weeks. Arhuidese et al[34] reported that smoking was associated with reduced survival among patients undergoing HD but found no significant association between smoking and AVF maturation or SSI[35]. Endothelial dysfunction reflects an imbalance between vasodilatory and vasoconstrictive factors produced by the endothelium[36]. This dysregulation leads to decreased nitric oxide bioavailability, increased platelet aggregation, and impaired anticoagulant properties[37]. Environmental exposures, including air pollution and tobacco use, have been implicated in the development of endothelial dysfunction[38]. In the present study, age, body mass index, diabetes, hypertension, and serum calcium and phosphorus levels were not identified as independent predictors of AVF outcomes or postoperative complications.

In summary, our findings demonstrate that preoperative arterial diameter and vessel depth assessed by Doppler ultrasonography can effectively predict AVF outcomes. Screening for dyslipidemia before AVF creation and appropriate metabolic optimization may improve postoperative outcomes. Although intraoperative vessel wall biopsy provides valuable prognostic information, its invasive nature limits feasibility in routine clinical practice. Patients with histopathological vessel wall abnormalities should be considered at increased risk for AVF failure; however, widespread adoption of intraoperative biopsy is unlikely. Consequently, future efforts should focus on validating noninvasive predictors, including Doppler ultrasonography parameters and biochemical markers, for AVF risk stratification. Adjunctive strategies such as antiplatelet therapy and balloon-assisted maturation may represent potential avenues for improving AVF outcomes, but these interventions were not evaluated in the present study and should not be interpreted as endorsed recommendations. These preventive measures were neither performed nor analyzed in this cohort. Although attempts were made to minimize confounding, the study did not account for technical aspects of the surgical procedure, such as anastomotic technique or the use of loupe magnification, which may affect AVF outcomes. As the population of patients with ESRD requiring maintenance HD continues to increase, larger multicenter studies with longer follow-up are required to more precisely define determinants of AVF outcomes and strategies to reduce adverse events. Additional limitations include potential variability in Doppler ultrasonography interpretation and histopathological reporting, as interobserver reliability was not assessed. Furthermore, the lack of a detailed subgroup analysis based on AVF type (radiocephalic, brachiocephalic, or brachiobasilic) limits interpretation of access-specific outcome differences. Although the overall cohort yielded important insights, future studies with larger, stratified samples are needed to address these gaps. Finally, histopathologists were blinded to clinical outcomes, which may not have introduced assessment bias (Tables 5 and 6). The relatively small sample size (n = 69) limits the statistical power of multivariable models and increases the risk of overfitting. Therefore, these findings should be interpreted cautiously and considered hypothesis-generating rather than definitive.

Table 5 Arteriovenous fistula patency and maturation at follow-up.

Follow-up time	AVF patent (%)	AVF matured (%)	Independent predictors
1 week	79.7	N/A	Depth, triglycerides, histology
6 weeks	78.3	66.7	Triglycerides, smoking, histology, vessel size
12 weeks	73.9	79.7	Triglycerides, smoking, histology, vessel size

AVF: Arteriovenous fistula; N/A: Not applicable.

Table 6 Independent predictors of poor arteriovenous fistula outcomes.

Parameter	Odds ratio	P value
Raised triglycerides	0.144	0.021
Smoking	2.759	0.03
Abnormal vessel histology	1.583	0.0001
Arterial diameter (larger)	1.751	0.031
Venous diameter (larger)	2.557	0.032
Arterial depth (superficial)	0.532	0.001
Venous depth (superficial)	0.856	0.036

CONCLUSION

Thinner and deeper blood vessels identified on preoperative Doppler ultrasonography are associated with poorer outcomes following AVF creation. Screening for dyslipidemia and serum calcium abnormalities should be considered as part of preoperative evaluation, and intraoperative vessel wall biopsy may provide valuable prognostic insight, although its clinical applicability is limited. These findings are hypothesis-generating and warrant validation in larger prospective cohorts before routine clinical implementation. Pathological findings of the vessel enhance understanding of the mechanisms underlying AVF failure and indicate that patients with abnormal histopathological features are at substantially higher risk of adverse AVF outcomes. Recognition of these high-risk features may inform long-term VA planning and patient management in individuals with CKD. However, given the limited feasibility of routine intraoperative biopsy, validation of noninvasive alternatives for risk stratification is necessary. Perioperative parameters such as Doppler ultrasonography measurements and biochemical markers show promise for predicting postoperative AVF outcomes and warrant further investigation. Future research should prioritize the development and validation of preoperative, noninvasive predictors to improve AVF risk stratification and long-term access outcomes in patients with CKD.