Pyelonephritis is a common kidney disorder that occurs in both chronic and acute forms. The condition typically is the result of a bacterial infection and is characterized by inflammation of kidney tissue.

Most commonly, the infection is caused by fecal bacteria ascending upward through the urinary tract, but bacteria may also be introduced to the kidneys via the bloodstream, in which case it is referred to as hematogenous pyelonephritis. Acute pyelonephritis most often affects only a single section of the kidney, but the chronic disease, which develops after many years of repeated infections, usually involves more extensive regions of the organ, which generally has undergone substantial scarring.

Due to its bacterial origin, hematogenous pyelonephritis is typically highly responsive to antibiotics. When antibiotics are utilized, improvement in symptoms, which may include pain in the flanks, groin, or abdomen, discomfort or burning sensation during urination, fever, chills, nausea, vomiting, and cloudy urine, usually improve quickly. Patients should be careful to remember that antibiotics should always be taken as long as is prescribed even if symptoms have already disappeared.

Factors that increase the likelihood that both men and women will develop pyelonephritis include being a diabetic or having kidney stones, bladder tumors, bladder-related nerve problems, vesicoureteral reflux, or other urinary tract problems. Medical professionals generally recommend that individuals who are at high risk for pyelonephritis or who have recently recovered from an episode drink plenty of water and cranberry juice or take vitamin C tablets, all of which deter bacterial growth in the urinary tract.

Hematogenous Pyelonephritis at 10x Magnification - If pyelonephritis is left untreated, the acute form of the disease may eventually lead to chronic pyelonephritis and can cause permanent renal damage.

Hematogenous Pyelonephritis at 20x Magnification - Pyelonephritis is more common in women than men because of the greater ease with which E. coli can invade the female urinary tract due to its close proximity to the rectum.

Hematogenous Pyelonephritis at 4x Magnification - The risk of developing pyelonephritis increases significantly for men as they get older, when they are more likely to experience an enlargement of the prostate gland.