What Is the Renal Sinus?

In anatomical terms, sinus has the same meaning as a cavity, space, channel or “hollow.” There are many different sinus, or sinuses, throughout the body and they are generally named for their anatomical locations. The renal sinus is a cavity expansion inside the kidney that contains the renal pelvis, calices and the kidney’s vessels and nerves. In medicine, the term may commonly come up in relation to medical imaging tests as many things can be discerned pathologically from imaging of the renal sinus, including locating lesions and tumors.

Within the renal cavity or sinus, there are smaller arteries that lead to the renal arteries. The renal arteries enter the kidney at the hilum and branch into these smaller arteries, which is how blood flows to and from the kidneys. The glomerulus is the part of the kidney that acts as a filtration system and aids the kidneys in the production of urine. Urine is then collected in a cup-like system of collection tubes called calyces or calices, all of which lead to the renal pelvis. The renal pelvis is a basin-like collection area surrounded by the kidney in the center of the renal sinus area.

Imaging of the area, whether through ultrasound, computed tomography (CT), or magnetic resonance imaging (MRI), can help medical professionals determine specific information about types of lesions, complex renal diseases and also identifying and staging tumors. Though the renal cavity is comprised of major kidney vessels and the calices, there is also a great deal of tissue, fat and nerve channels, which can also be affected by a variety of pathologic states.

Examples of non-cancerous lesions affecting the renal sinus include cysts, aneurysms and inflammation. Renal cell carcinoma is cancer of the kidney and is often detected through CT imaging of the area. Many less complex diseases, such as diabetes, will show up in urine and blood analysis and do not require imaging. Most radiographers or imaging technicians are trained to obtain adequate visual record of the renal sinus as ordered. The medical specialty that deals directly with diagnosis and treatment of kidney diseases is nephrology. Similarly, a urologist is a medical doctor that specializes in diagnosis and treatment of the organs of the urinary tract in addition to male reproductive organs. At times, the roles of a nephrologist and urologist may overlap, but problems within the renal sinus are treated by a nephrologist.