Inflammation of renal pelvis

Synonyms

Medical: pyelonephritis Upper UTI (urinary tract infection), pyonephrosis, urosepsis.

Definition

Inflammation of the renal pelvis (pyelonephritis) is an interstitial (i.e. between the actual renal tissue), bacterial, tissue-destroying (destructive) inflammation of the kidney and the renal pelvic caliceal system. Inflammation of the renal pelvis can occur on one or both sides.

Frequency

This is one of the most common kidney diseases. About 10 – 20 % of the population is affected. Chronic (recurrent) pyelonephritisPelvic inflammatory disease, if undetected, can lead to complete (terminal) renal failure in about 20% of cases. Women are affected about 2 – 3 times as often as men.

Causes

PyelonephritisPelvic inflammatory disease is mainly caused by bacteria like Escherichia coli, Enterococci, Proteus, Klebsiella, Pseudomonas aeruginosa or Staphylococcus. Due to the close “neighbourhood” of the urethra and anus, these germs are easily transferred into the urinary tract by smear infection (e.g. with toilet paper), especially in women, from where they ascend via the bladder to the renal pelvic caliceal system (NKBS). Very rarely the bacteria reach the renal pelvis via blood or lymph vessels.

The infection usually starts in the so-called papillae and then spreads in a wedge shape to the renal cortex. A pus cavity (abscess formation) within and around the kidney is possible, but very rare. Eventually, a wedge-shaped scar with retraction on the kidney surface may occur.

Risk factors

Various factors can promote inflammation of the renal pelvis:

  • Pregnancy (pyelonephritis gravidarum)
  • Estrogen deficiency (female sex hormone)
  • Metabolic diseases (diabetes mellitus, gout)
  • Medication (certain painkillers, antibiotics)
  • Enlargement of the prostate with urine retention, as well as any form of urinary flow disturbance
  • Paraplegia

Classification

One can distinguish between different forms of pyelonephritis-pelvic inflammatory disease according to its course (acute or chronic) and its origin (primary uncomplicated or secondary complicated), which will be discussed in more detail in the following. Forms:

  • Acute primary (uncomplicated) pyelonephritisPelvic inflammatory disease
  • Acute secondary (complicated) pyelonephritisPelvic inflammation