The aim of the study is to report a case of a rare congenital anomaly of the venous system and to emphasize its clinical importance. We describe a case of aplasia of the right common and external iliac veins in a healthy seven-year-old boy who was referred for Doppler ultrasound examination for further evaluation of an abnormal varicosity in the suprapubic region. Colour Doppler ultrasound revealed a dilated, arch-shaped vein. Contrast-enhanced magnetic resonance angiography showed the absence of the right common iliac vein and external iliac vein. It also clearly demonstrated the aberrant venous structure, originating from the right common femoral vein and draining to the left common femoral vein. In conclusion, in our case, the patient's life was threatened because the aberrant venous connection crossing within subcutaneous fatty tissue was not protected from external trauma and possible abdominal surgical interventions. Additional attention should be given to avoid such injuries, which can cause significant haemorrhage.