Introduction:

Primary failure includes early thrombosis and maturation failures.

Objectives:

To determine the risk factors associated with primary failure of native fistulas and their relationship with survival. To analyse the sonographic differences between mature fistulas and fistulas with maturation failure.

Material and Method:

Observational and retrospective study. Variables: sociodemographic, anthropometric, comorbidities, blood and ultrasound parameters. Statistical analysis: Descriptive. Logistic regression. Kaplan-Meier method.

Results:

Sample 65 native fistulas, 72.3% male. Age 69.7 years. 60% mature fistulas and 40% fistulas with primary failure (20% maturation failure and 20% early thrombosis). Risk factors for maturation failure: arterial diameters <2mm (OR:16.8; p=0.016). Risk factors for early thrombosis: age ≥65 years (OR:5.44; p=0.014), weight (OR:1.04;p=0.02) and body mass index (OR:1.17;p=0.027). Monocytes as a protective factor for early thrombosis (OR:0.0142; p=0.029).

People ≥ 65 years old, obese, and with arterial diameters <2mm had lower survival. Mature fistulas had a significantly higher vein diameter, peak systolic velocity, and vascular access flow (p<0.001).

Conclusions:

Fistulas performed with arterial diameters <2mm present a higher risk of maturation failure. The higher the age, weight, and body mass index, the higher the risk of early thrombosis. The fewer monocytes, the lower the risk of early thrombosis. Age, arterial diameter, and weight influence survival. There are ultrasound differences between mature fistulae and fistulae with maturation failure.