Duplicated ureter is the most common renal abnormality, occurring in approximately 1% of the population.

Race: Duplicated ureter is more common in Caucasians than in African-Americans.

Sex: Duplicated ureter is more common in females. However, this may be due to the higher frequency of urinary tract infections in females, leading to a higher rate of diagnosis of duplicated ureter.

Definitive causes of ureterocele have not been found. While the abnormal growth occurs within the uterus, it has not been substantiated that genetics are to blame.

It has been estimated that VUR is present in more than 10% of the population. Younger children are more prone to VUR because of the relative shortness of the submucosal ureters. This susceptibility decreases with age as the length of the ureters increases as the children grow. In children under the age of 1 year with a urinary tract infection, 70% will have VUR. This number decreases to 15% by the age of 12. Although VUR is more common in males antenatally, in later life there is a definite female preponderance with 85% of cases being female.

Birth injuries that result in the formation of fistulas and urinary and fecal incontinence have been found to be strongly associated with economic and cultural factors. Teenagers and women who sustain injuries that develop into ureterovaginal fistulas during childbirth suffer significant social stigma. Ureterovaginal fistulas related to prolonged, obstructed labor are rare in developed nations but are more common in countries where access to emergent obstetrical care is limited.

Many other complications arise from ureteroceles. Redundant collection systems are usually smaller in diameter than single, and predispose the patient to impassable kidney stones. The effective "bladder within a bladder" compounds this problem by increasing the collision of uric acid particles, the process by which uric acid stones are formed. Ureterocele is also associated with poor kidney function. It can cause frequent blockage of the ureter leading to serious kidney damage. In other cases, a small, upper portion of the kidney is congenitally non-functional. Though often benign, this problem can necessitate the removal of non-functioning parts.

The American Urological Association recommends ongoing monitoring of children with VUR until the abnormality resolves or is no longer clinically significant. The recommendations are for annual evaluation of blood pressure, height, weight, analysis of the urine, and kidney ultrasound.

Duplicated ureter or Duplex Collecting System is a congenital condition in which the ureteric bud, the embryological origin of the ureter, splits (or arises twice), resulting in two ureters draining a single kidney. It is the most common renal abnormality, occurring in approximately 1% of the population. The additional ureter may result in a ureterocele, or an ectopic ureter.

Ectopic ureter (or ureteral ectopia) is a medical condition where the ureter, rather than terminating at the urinary bladder, terminates at a different site. In males this site is usually the urethra, in females this is usually the urethra or vagina. It can be associated with renal dysplasia, frequent urinary tract infections, and urinary incontinence (usually continuous drip incontinence). Ectopic ureters are found in 1 of every 2000–4000 patients, and can be difficult to diagnose, but are most often seen on CT scans.

Ectopic ureter is commonly a result of a duplicated renal collecting system, a duplex kidney with 2 ureters. In this case, usually one ureter drains correctly to the bladder, with the duplicated ureter presenting as ectopic.

A Gartner's duct cyst (sometimes incorrectly referred to as "vaginal inclusion cyst") is a benign vaginal cystic lesion that arises from the Gartner's duct, which is a vestigial remnant of the mesonephric duct (wolffian duct) in females. They are typically small asymptomatic cysts that occur along the lateral walls of the vagina, following the course of the duct. They can present in adolescence with painful menstruation (Dysmenorrhea) or difficulty inserting a tampon. They can also enlarge to substantial proportions and be mistaken for urethral diverticulum or other structures.

There is a small association between Gartner's duct cysts and metanephric urinary anomalies, such as ectopic ureter & ipsilateral renal hypoplasia. Because of this, imaging is recommended before excision.

Many women delay treatment for decades. Surgeons often will correct the fistula through major gynecological surgery. Newer treatments can include the placement of a stent and is usually successful. In 0.5-2.5% of major pelvic surgeries a ureterovaginal fistula will form, usually weeks later. If the fistula cannot be repaired, the clinician may create a permanent diversion of urine or urostomy. Risks associated with the repair of the fistula are also associated with most other surgical procedures and include the risk of adhesions, disorders of wound healing, infection, ileus, and immobilization. There is a recurrence rate of 5%–15% in the surgical operation done to correct the fistula.

Megaureter is a medical anomaly whereby the ureter is abnormally . Congenital megaureter is an uncommon condition which is more common in males, may be bilateral, and is often associated with other congenital anomalies. The cause is thought to be aperistalsis of the distal ureter, leading to dilatation.

The cutoff value for megaureter is when it is wider than 6 or 7 mm.

A functional obstruction at the lower end of the ureter leads to progressive dilatation and a tendency to infection. The ureteric orifice appears normal and a ureteric catheter passes easily.

Definitive surgical treatment involves refashioning the lower end of the affected ureter so that a tunnelled reimplantation into the bladder can be done to prevent reflux.

The prognosis of hydronephrosis is extremely variable, and depends on the condition leading to hydronephrosis, whether one (unilateral) or both (bilateral) kidneys are affected, the pre-existing kidney function, the duration of hydronephrosis (acute or chronic), and whether hydronephrosis occurred in developing or mature kidneys.

For example, unilateral hydronephrosis caused by an obstructing stone will likely resolve when the stone passes, and the likelihood of recovery is excellent. Alternately, severe bilateral prenatal hydronephrosis (such as occurs with posterior urethral valves) will likely carry a poor long-term prognosis, because obstruction while the kidneys are developing causes permanent kidney damage even if the obstruction is relieved postnatally.

Hydronephrosis can be a cause of pyonephrosis - which is a urological emergency.

Treatment of hydronephrosis focuses upon the removal of the obstruction and drainage of the urine that has accumulated behind the obstruction. Therefore, the specific treatment depends upon where the obstruction lies, and whether it is acute or chronic.

Acute obstruction of the upper urinary tract is usually treated by the insertion of a nephrostomy tube. Chronic upper urinary tract obstruction is treated by the insertion of a ureteric stent or a pyeloplasty.

Lower urinary tract obstruction (such as that caused by bladder outflow obstruction secondary to prostatic hypertrophy) is usually treated by insertion of a urinary catheter or a suprapubic catheter.Surgery is not required in all prenatally detected cases.

While most cases of horseshoe kidneys are asymptomatic and discovered upon autopsy, the condition may increase the risk for:

- Kidney obstruction – abnormal placement of ureter may lead to obstruction and dilation of the kidney.

- Kidney infections – associated with vesicoureteral reflux.

- Kidney stones – deviant orientation of kidneys combined with slow urine flow and kidney obstruction may lead to kidney stones.

- Kidney cancer – increased risk of renal cancer, especially Wilms' tumor, transitional cell carcinoma, and an occasional case report of carcinoid tumor. Despite increased risk, the overall risk is still relatively low.

The prevalence of horseshoe kidneys in females with Turner Syndrome is about 15%.

It can be associated with trisomy 18.

It can be associated with venous anomalies like left sided IVC 9.

Dipygus is caused by genetic, environmental, or teratogenic factors. It occurs early in intrauterine life.

Horseshoe kidney, also known as "ren arcuatus" (in Latin), renal fusion or super kidney, is a congenital disorder affecting about 1 in 600 people, more common in men.

In this disorder, the patient's kidneys fuse together to form a horseshoe-shape during development in the womb. The fused part is the isthmus of the horseshoe kidney.

Fusion abnormalities of the kidney can be categorized into two groups: horseshoe kidney and crossed fused ectopia. The 'horseshoe kidney' is the most common renal fusion anomaly.

Obstructive uropathy is a structural or functional hindrance of normal urine flow, sometimes leading to renal dysfunction (obstructive nephropathy).

It is a very broad term, and does not imply a location or cause.

Treatment consists of painkillers and surgical ablation of the dilated vein. This can be accomplished with open abdominal surgery (laparotomy) or keyhole surgery (laparoscopy). Recently, the first robot-assisted surgery was described.

Another approach to treatment involves catheter-based embolisation, often preceded by phlebography to visualise the vein on X-ray fluoroscopy.

Ovarian vein coil embolisation is an effective and safe treatment for pelvic congestion syndrome and lower limb varices of pelvic origin. Many patients with lower limb varices of pelvic origin respond to local treatment i.e. ultrasound guided sclerotherapy. In those cases, ovarian vein coil embolisation should be considered second line treatment to be used if veins recur in a short time period i.e. 1–3 years. This approach allows further pregnancies to proceed if desired. Coil embolisation is not appropriate if a future pregnancy is possible. This treatment has largely superseded operative options.

Coil embolisation requires exclusion of other pelvic pathology, expertise in endovascular surgery, correct placement of appropriate sized coils in the pelvis and also in the upper left ovarian vein, careful pre- and post-procedure specialist vascular ultrasound imaging, a full discussion of the procedure with the patient i.e. informed consent. Complications, such as coil migration, are rare but reported. Their sequelae are usually minor.

If a Nutcracker compression (see below) is discovered, stenting of the renal vein should be considered before embolization of the ovarian vein. Reducing outflow obstruction should always be the main objective.

It can be caused by a lesion at any point in the urinary tract.

Causes include urolithiasis, posterior urethral valves and ureteral herniation.

The evidence linking vitamin C supplements with an increased rate of kidney stones is inconclusive. The excess dietary intake of vitamin C might increase the risk of calcium oxalate stone formation, in practice this is rarely encountered. The link between vitamin D intake and kidney stones is also tenuous. Excessive vitamin D supplementation may increase the risk of stone formation by increasing the intestinal absorption of calcium; correction of a deficiency does not.

If left untreated, complications may arise including abscess formation, peritonitis, sepsis, and damage to the urinary tract by fibrosis and granuloma formation. It is recommended, as a first step, to drain the lesion with ultrasound or CT guidance. If a patient has an underlying obstructive problem it needs to be addressed according to its cause.

Diets in Western nations typically contain a large proportion of animal protein. Consumption of animal protein creates an acid load that increases urinary excretion of calcium and uric acid and reduced citrate. Urinary excretion of excess sulfurous amino acids (e.g., cysteine and methionine), uric acid, and other acidic metabolites from animal protein acidifies the urine, which promotes the formation of kidney stones. Low urinary citrate excretion is also commonly found in those with a high dietary intake of animal protein, whereas vegetarians tend to have higher levels of citrate excretion. Low urinary citrate, too, promotes stone formation.

A preureteric vena cava, also known as a retrocaval ureter, is a rare congenital malformation of the right human ureter, in which the ureter passes behind the inferior vena cava, causing compression possibly leading to hydronephrosis. The prevalence of this condition is approximately 1 per 1,000 persons, with males 2-3 times more likely than females to develop the condition. Symptoms often do not manifest until those with the condition are aged in their 20s or 30s.

In medicine, ovarian vein syndrome is a rare (possibly not uncommon, certainly under-diagnosed) condition in which a dilated ovarian vein compresses the ureter (the tube that brings the urine from the kidney to the bladder). This causes chronic or colicky abdominal pain, back pain and/or pelvic pain. The pain can worsen on lying down or between ovulation and menstruation. There can also be an increased tendency towards urinary tract infection or pyelonephritis (kidney infection). The right ovarian vein is most commonly involved, although the disease can be left-sided or affect both sides. It is currently classified as a form of pelvic congestion syndrome.

Tobacco smoking is associated with an increased risk of ureteral cancer.