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Introduction Gastrointestinal involvement is among the most common and disabling manifestations of systemic sclerosis (SSc), and vascular dysfunction is considered a key pathogenic mechanism. Although Doppler ultrasound is increasingly used to investigate mesenteric circulation in SSc, data on mesenteric vascular reserve, defined as the postprandial vasodilatory response of the superior mesenteric artery (SMA), remain scarce. Previous studies have demonstrated reduced fasting SMA blood flow in SSc and correlations between Doppler indices and gastrointestinal symptoms, but the hemodynamic response to meal stimulation has not been systematically assessed. The aim of this pilot study was to evaluate mesenteric vascular reserve in SSc patients compared with matched healthy controls using Doppler ultrasound.Material and Methods We conducted a case–control pilot study including 10 SSc patients and 10 age-, sex- and BMI-matched healthy controls. Doppler ultrasound of the SMA was performed in the fasting state and 30 minutes after a standardized meal. Parameters assessed included SMA diameter, peak systolic velocity (PSV), end-diastolic velocity (EDV), mean velocity (VM), resistive index (RI), pulsatility index (PI), and blood flow (BF). Vascular reserve was defined as the postprandial delta of vessel caliber and BF.Results SMA hemodynamic characteristics in the fasting and postprandial state, as well as the corresponding deltas, are summarized in table 1. At baseline, SMA diameter and BF were comparable between groups (5.77±0.57 vs 5.66±0.65 mm, 1286±539 vs 1130±205 mL/min in SSc vs controls). After the meal, controls showed a marked increase in SMA caliber (10.8±8.6%) and BF (187.0±114.0%), whereas SSc patients displayed a blunted response (5.4±9.6% and 134.0±125.0%, respectively). Delta-PSV and Delta-EDV did not differ significantly between groups, suggesting that vascular reserve impairment was more evident when expressed in terms of structural dilation and BF augmentation rather than velocity parameters. No major adverse events were recorded.Conclusions This pilot study provides preliminary evidence of impaired mesenteric vascular reserve in SSc reflected by an attenuated postprandial increase in SMA caliber and blood flow. These findings highlight vessel caliber and BF as potentially more sensitive markers of altered vascular response compared to PSV. Given the crucial role of mesenteric perfusion in nutrient absorption and gastrointestinal function, our results may provide a pathophysiological link to malnutrition and digestive complications in SSc. These preliminary observations warrant validation in larger cohorts and longitudinal studies, which may clarify whether impaired mesenteric vascular reserve can serve as a biomarker for early gastrointestinal involvement in SSc.Abstract P.178 Table 1SMA hemodynamic characteristics in the fasting and postprandial state, as well as the corresponding deltas