Case of Isolated Absence of the Right Renal Vein with Drainage via an Enlarged Cortical Vein into the Ipsilateral Gonadal Vein

Background: Right-renal-vein agenesis is an exceptionally rare congenital anomaly. Absent the orthotopic vein, renal blood diverts through collaterals and, in rare cases, a single hypertrophied cortical vein draining into the ipsilateral gonadal vein. Unrecognised, it can mimic thrombosis or tumour and, if the solitary channel is injured, cause catastrophic haemorrhage. Objective: To detail the presentation and multimodality imaging cues of right-renal-vein agenesis with exclusive cortical-to-gonadal drainage. Case Presentation: A 43-year-old expatriate man in Dubai reported vague right-flank discomfort and occasional tea-coloured urine. Examination and renal biochemistry were normal; urinalysis showed microscopic haematuria. Multiphase contrast-enhanced CT revealed no right renal vein entering the inferior vena cava; perirenal channels merged into a hypertrophied cortical vein descending to a dilated right gonadal vein. Colour and spectral Doppler demonstrated low-velocity monophasic venous flow, excluding shunt or arteriovenous malformation. The contralateral renal vein and both renal arteries were unremarkable. With preserved renal function and mild symptoms, conservative management was adopted; at one-year review the patient remained asymptomatic and imaging findings were unchanged. Conclusion: Identifying an absent orthotopic vein, dominant cortical collateral, preserved enhancement and venous Doppler waveform prevents misdiagnosis and averts inadvertent ligation during surgery. When blood pressure and renal function are stable, periodic imaging alone ensures a favourable prognosis.