Pyelonephritis  is inflammation of the kidney, typically due to a bacterial infection. Symptoms most often include fever and flank tenderness. Other symptoms may include nausea, burning with urination, and frequent urination. Complications may include pus around the kidney, sepsis, or kidney failure.It is typically due to a bacterial infection, most commonly Escherichia coli. Risk factors include sexual intercourse, prior urinary tract infections, diabetes, structural problems of the urinary tract, and spermicide use. The mechanism of infection is usually spread up the urinary tract. Less often infection occurs through the bloodstream. Diagnosis is typically based on symptoms and supported by urinalysis. If there is no improvement with treatment, medical imaging may be recommended.Pyelonephritis may be preventable by urination after sex and drinking sufficient fluids. Once present it is generally treated with antibiotics, such as ciprofloxacin or ceftriaxone. Those with severe disease may require treatment in hospital. In those with certain structural problems of the urinary tract or kidney stones, surgery may be required.Pyelonephritis affects about 1 to 2 per 1,000 women each year and just under 0.5 per 1,000 males. Young adult females are most often affected, followed by the very young and old. With treatment, outcomes are generally good in young adults. Among people over the age of 65 the risk of death is about 40%. Signs and symptoms
Signs and symptoms of acute pyelonephritis generally develop rapidly over a few hours or a day. It can cause high fever, pain on passing urine, and abdominal pain that radiates along the flank towards the back.
Watchful waiting with serial imaging may be appropriate in rare circumstances. Follow-up
If no improvement is made in one to two days post therapy, inpatients should repeat an urine analysis and imaging. Outpatients should check again with their doctor. Epidemiology
There are roughly 12–13 cases annually per 10,000 population in women receiving outpatient treatment and 3–4 cases requiring admission. In men, 2–3 cases per 10,000 are treated as outpatients and 1– cases/10,000 require admission. Young women are most often affected. Infants and the elderly are also at increased risk, reflecting anatomical changes and hormonal status. Xanthogranulomatous pyelonephritis is most common in middle-aged women. It can present somewhat differently in children, in whom it may be mistaken for Wilms tumor. Research
According to a 2015 meta analysis, vitamin A has been shown to alleviate renal damage and/or prevent renal scarring. Terminology
The term is from Greek πύελο|ς pýelo|s, "basin" + νεφρ|ός nepʰrós, "kidney" + suffix -itis suggesting "inflammation".A similar term is "pyelitis", which means inflammation of the renal pelvis and calyces. In other words, pyelitis together with nephritis is collectively known as pyelonephritis. Etymology
The word pyelonephritis is formed by the Greek roots pyelo- from πύελος (púelos) renal pelvis and nephro- from νεφρός (nephrós) kidney together with the suffix -itis from -ῖτις (-itis) used in medicine to indicate diseases or inflammations. See also
Interstitial nephritis
Malakoplakia

References
External links

NIDDK
Atlas of Pathology