A renal venogram is a diagnostic procedure that provides information about the circulatory health of the kidneys. A renal venogram uses X-rays and intravenous (IV) contrast, also known as X-ray dye, to visualize the veins within the kidneys and the veins carrying blood away from the kidneys. Contrast causes the blood vessels to appear opaque on the X-ray image, allowing the doctor to visualize the blood vessels being evaluated.
Fluoroscopy is often used during a renal venogram. Fluoroscopy is a study of moving body structures similar to an X-ray movie. A continuous X-ray beam is passed through the body part being examined and is transmitted to a TV-like monitor so that the body part and its motion can be seen in detail.
In addition to evaluating the renal veins, hypertension (high-blood pressure) may be assessed during a renal venogram. A blood sample (renin assay) is obtained from each renal vein. The level of renin in the blood may help the doctor determine the cause of hypertension.
The veins in a healthy kidney are free from obstruction, clots, or high-blood pressure (hypertension). Some medical conditions may impede blood flow through the kidneys or cause increased blood pressure to the kidneys. If a problem with the veins of the kidney is suspected, the doctor may request a renal venogram to determine the cause of the problem.
A venogram can detect conditions stemming from the renal vein itself, as well as other problems that result from influences on the renal vein from other organs, such as the kidneys. Problems involving renal circulation include structural problems that can lead to a blockage of blood flow to or from the kidneys.
Problems involving the renal circulatory system may include, but are not limited to, the following:
- Renal vein thrombosis - An acute or chronic problem in which a blood clot forms in the renal vein. It can occur for various reasons including, but not limited to: postoperative complication after abdominal surgery, dehydration, congestive heart failure, kidney disease, pregnancy, and morbid obesity.
- Retroperitoneal fibrosis - A mass of fibrous tissue located towards the back of the abdomen near the kidneys. This mass may cause compression of the renal veins impeding normal blood flow.
- Renal tumors - Benign (noncancerous) or malignant (cancerous) tumors on or inside the kidneys.
- Renovascular hypertension - High-blood pressure, resulting from abnormal hormone levels that are produced or regulated in the kidneys.