In humans, the kidneys are two reddish-brown bean-shaped blood-filtering organs that are a multilobar, multipapillary form of mammalian kidneys, usually without signs of external lobulation. They are located on the left and right in the retroperitoneal space, and in adult humans are about 12 centimetres in length. They receive blood from the paired renal arteries; blood exits into the paired renal veins. Each kidney is attached to a ureter, a tube that carries excreted urine to the bladder.
The human urinary system, also known as the urinary tract or renal system, consists of the kidneys, ureters, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and blood pressure, control levels of electrolytes and metabolites, and regulate blood pH. The urinary tract is the body's drainage system for the eventual removal of urine. The kidneys have an extensive blood supply via the renal arteries which leave the kidneys via the renal vein. Each kidney consists of functional units called nephrons. Following filtration of blood and further processing, wastes exit the kidney via the ureters, tubes made of smooth muscle fibres that propel urine towards the urinary bladder, where it is stored and subsequently expelled through the urethra during urination. The female and male urinary system are very similar, differing only in the length of the urethra.
Prune belly syndrome is a rare, genetic birth defect affecting about 1 in 40,000 births. About 97% of those affected are male. Prune belly syndrome is a congenital disorder of the urinary system, characterized by a triad of symptoms. The syndrome is named for the mass of wrinkled skin that is often present on the abdomen of those with the disorder.
The ureters are tubes composed of smooth muscle that transport urine from the kidneys to the urinary bladder. In an adult human, the ureters typically measure 20 to 30 centimeters in length and about 3 to 4 millimeters in diameter. They are lined with urothelial cells, a form of transitional epithelium, and feature an extra layer of smooth muscle in the lower third to aid in peristalsis. The ureters can be affected by a number of diseases, including urinary tract infections and kidney stone. Stenosis is when a ureter is narrowed, due to for example chronic inflammation. Congenital abnormalities that affect the ureters can include the development of two ureters on the same side or abnormally placed ureters. Additionally, reflux of urine from the bladder back up the ureters is a condition commonly seen in children.
A urethral stricture is a narrowing of the urethra, the tube connected to the bladder that allows the passing of urine. The narrowing reduces the flow of urine and makes it more difficult or even painful to empty the bladder.
Urinary tract obstruction is a urologic disease consisting of a decrease in the free passage of urine through one or both ureters and/or the urethra. It is a cause of urinary retention. Complete obstruction of the urinary tract requires prompt treatment for renal preservation. Any sign of infection, such as fever and chills, in the context of obstruction to urine flow constitutes a urologic emergency.
Hydronephrosis describes hydrostatic dilation of the renal pelvis and calyces as a result of obstruction to urine flow downstream. Alternatively, hydroureter describes the dilation of the ureter, and hydronephroureter describes the dilation of the entire upper urinary tract.
Horseshoe kidney, also known as ren arcuatus, renal fusion or super kidney, is a congenital disorder affecting about 1 in 500 people that is more common in men, often asymptomatic, and usually diagnosed incidentally. In this disorder, the patient's kidneys fuse to form a horseshoe-shape during development in the womb. The fused part is the isthmus of the horseshoe kidney. The abnormal anatomy can affect kidney drainage resulting in increased frequency of kidney stones and urinary tract infections as well as increase risk of certain renal cancers.
A nephrostomy or percutaneous nephrostomy is an artificial opening created between the kidney and the skin which allows for the urinary diversion directly from the upper part of the urinary system. It is an interventional radiology/surgical procedure in which the renal pelvis is punctured whilst using imaging as guidance. Images are obtained once an antegrade pyelogram, with a fine needle, has been performed. A nephrostomy tube may then be placed to allow drainage.
Feline lower urinary tract disease (FLUTD) is a generic category term to describe any disorder affecting the bladder or urethra of cats.
Vesicoureteral reflux (VUR), also known as vesicoureteric reflux, is a condition in which urine flows retrograde, or backward, from the bladder into one or both ureters and then to the renal calyx or kidneys. Urine normally travels in one direction from the kidneys to the bladder via the ureters, with a one-way valve at the vesicoureteral (ureteral-bladder) junction preventing backflow. The valve is formed by oblique tunneling of the distal ureter through the wall of the bladder, creating a short length of ureter (1–2 cm) that can be compressed as the bladder fills. Reflux occurs if the ureter enters the bladder without sufficient tunneling, i.e., too "end-on".
Posterior urethral valve (PUV) disorder is an obstructive developmental anomaly in the urethra and genitourinary system of male newborns. A posterior urethral valve is an obstructing membrane in the posterior male urethra as a result of abnormal in utero development. It is the most common cause of bladder outlet obstruction in male newborns. The disorder varies in degree, with mild cases presenting late due to milder symptoms. More severe cases can have renal and respiratory failure from lung underdevelopment as result of low amniotic fluid volumes, requiring intensive care and close monitoring. It occurs in about one in 8,000 babies.
In urology, voiding cystourethrography (VCUG) is a frequently performed technique for visualizing a person's urethra and urinary bladder while the person urinates (voids). It is used in the diagnosis of vesicoureteral reflux, among other disorders. The technique consists of catheterizing the person in order to fill the bladder with a radiocontrast agent, typically diatrizoic acid. Under fluoroscopy the radiologist watches the contrast enter the bladder and looks at the anatomy of the patient. If the contrast moves into the ureters and back into the kidneys, the radiologist makes the diagnosis of vesicoureteral reflux, and gives the degree of severity a score. The exam ends when the person voids while the radiologist is watching under fluoroscopy. Consumption of fluid promotes excretion of contrast media after the procedure. It is important to watch the contrast during voiding, because this is when the bladder has the most pressure, and it is most likely this is when reflux will occur. Despite this detailed description of the procedure, at least as of 2016 the technique had not been standardized across practices.
A ureteral stent, or ureteric stent, is a thin tube inserted into the ureter to prevent or treat obstruction of the urine flow from the kidney. The length of the stents used in adult patients varies between 24 and 30 cm. Additionally, stents come in differing diameters or gauges, to fit different size ureters. The stent is usually inserted with the aid of a cystoscope. One or both ends of the stent may be coiled to prevent it from moving out of place; this is called a JJ stent, double J stent or pig-tail stent.
Pyelogram is a form of imaging of the renal pelvis and ureter.
Urologic diseases or conditions include urinary tract infections, kidney stones, bladder control problems, and prostate problems, among others. Some urologic conditions do not affect a person for that long and some are lifetime conditions. Kidney diseases are normally investigated and treated by nephrologists, while the specialty of urology deals with problems in the other organs. Gynecologists may deal with problems of incontinence in women.
Duplicated ureter or duplex collecting system is a congenital condition in which the ureteric bud, the embryological origin of the ureter, splits, resulting in two ureters draining a single kidney. It is the most common renal abnormality, occurring in approximately 1% of the population.
Ureteral cancer is cancer of the ureters, muscular tubes that propel urine from the kidneys to the urinary bladder. It is also known as ureter cancer, renal pelvic cancer, and rarely ureteric cancer or uretal cancer. Cancer in this location is rare. Ureteral cancer becomes more likely in older adults, usually ages 70–80, who have previously been diagnosed with bladder cancer.
Renal ultrasonography is the examination of one or both kidneys using medical ultrasound.
