This paper examines the role of medical images in shaping reality, with a particular focus on obstetric ultrasound, which is viewed as a semiotic device that articulates visibility and belief. In a sociocultural context marked by the growing technoscientific orientation of medicine and the pervasive mediatization of experience, the visible dimension of reality — especially that of the gestating body and the fetus — is understood as the outcome of discursive practices, technical operations, and ideological models. From a materialdiscursive semiotic perspective, the article analyses ultrasound visualization as a form of visual enunciation that produces subjects, assigns value, and regulates access to symbolic and legal recognition. The paper is structured along three theoreticalanalytical axes: the modelling of regimes of meaning that shape the legibility of the image; the examination of iconization and referentialization processes through which the epistemic efficacy of medical visualization is established; and finally, an investigation into the systems of belief that consolidate around the ultrasound image, contributing to the definition of normative, affective, and social parameters of reproduction. The comparison with Karen Barad’s performative ontology highlights the specificity of the semiotic approach, particularly in its attention to the enunciative structure of the image. Beyond its diagnostic function, obstetric ultrasound operates as a cultural artefact that selects and organizes what can be made visible, generating significant symbolic and material effects. Through technical visualization, the ultrasound image renders a singular fetal figure visible, while the gestating body tends to be rendered opaque or peripheral. This visual and discursive reconfiguration redefines the ways in which pregnancy is perceived, known, and regulated. The analysis highlights the potential of semiotics to provide critical tools for examining the assumed transparency of clinical images, revealing their ideological underpinnings and political implications.