It is an infectious and inflammatory disease that effect the renal pelvis and parenchyma.
The most common infection agents are Eschericia coli, proteus and klebsiella species. Germs access the kidney by ascending (from down to up) path commonly and hematogenous (blood) path rarely. Lymphogenic and direct disseminations are very rare.
The kidney is large, tumorous and edematous. There are subcapsular and cortical mini abscess focuses. Collective system mucosa was covered by exudate.
Acute pyelonephritis is more common in women.
Predisposing factor include urinary system abnormalities, obstructions, urinary system stones, metabolic disorders such as diabetes and hyperuricemia, pregnancy, analgesic addiction and foreign bodies(catheter, stent i.e.) in the urinary system.
CLINICAL SYMPTOMS AND FINDINGS
Acute pyelonephritis is an inflammatous disease. There is an acute disease picture with fatigue. General status disorder may be seen. Body temperature exceeds 38°C with shivering. A continuous, blunt pain on costovertebral region and sensitivity is detected on palpation. Nausea and vomiting accompany to this picture. Abdominal distention, rebound sensitivity, decrease on bowel sounds and subileus symptoms may even be seen. The patients also have complaints with the urine and pyuria (plenty leukocytes in the urine test).
Leukocytosis and sedimentation increase are detected in the hemogram. Blood culture and urine culture should be sent for the test before the treatment.
Total kidney functions were not spoilt in non-complicated cases and blood urea nitrogen (BUN) and creatinine levels are normal.
Pyuria, leukocyte cylinders, becteriuria, hematuria with various grades and mild proteinuria are detected in complete urine test. Furthermore, large polymorphonucelar leukocytes (Glitter cell) with granular cytoplasm are detected. The infection agent may be reproduced in the urine culture.
Radiologic examinations are important for differential diagnosis and detection of complicating factors in particular.
It is seen in direct urinary system (DUS) radiography that kidney borders are wider than normal. If there are stones causing obstruction, they may be detected.
Intravenous pyelography (IVP) does not provide much information in the early stage and in non-complicated cases, however it is important for follow-up. Kidney borders are detected wide in IVP. Nephrogram may be poor and calyxes may not be filled in severe cases. Hydronephrosis is observed if obstruction is present.
Edema and stone and dilatation if present may be shown in ultrasonography.
Voiding cystouretrography, retrograde pyelography, cystoscopy may be performed for cases considered as complicated.
Differential Diagnosis :
It must be differentiated from renal abscess and peripheral abscess. Ultrasonography is very helpful for this differentiation. Beyond these, the diseases may be confused with pancreatitis, basal pneumonia, intraabdominal diseases, acute PID (Pelvic Inflammatory Disease), acute prostatitis, acute epididymoorchitis, cholecystitis, appendicitis, glomerulonephritis and ovarian diseases.
Complications are rare with early diagnosis and treatment. The most serious complication is septicemia and shock. It may transform into emphysematous pyelonephritis with bad prognosis in diabetic patients or patients with poor immunity. Complications also include pyonephrosis and kidney stone formation.
If acute pyelonephritis is treated insufficiently in infants and children, it may become chronic and cause chronic kidney failure by creating permanent renal scar.
The disease is serious in general, hospitalization and bedrest are required. Blood and urine samples are taken form the patient immediately. Parenteral fluid and empirical antibiotic treatment should be started as soon as possible. Antibiotics that will be given should create effective combinations for common pathogens. The classical combination is combination of aminoglycosides with penicillin or first or second generation cephalosporin (ampycillin + gentamycin, cefazolin + amycasine). The treatment response is evaluated after two or three days. Culture results have been obtained meanwhile. If there is a response to the treatment (clinical recovery, decrease on fever) and the microorganism reproduced in the culture is sensitive to the antibiotics used, the treatment started is continued for 1 week at least or until 3 days after fever reduction. Then oral antibiotic treatment should be given for 2 weeks more. If complicating factors are suspected during this period, they should be searched and treated.
These include bedrest until symptoms decrease, increase on fluid intake (oral or parenteral), analgesic for the pain, antiemetic agents for nausea and antipyretic agents for the fever if necessary.
NON-RESPONSELESS TO THE TREATMENT
If no response is present within 48 to 72 hours, the patient should be re-evaluated and complicating factors (such as obstruction) should be searched.
Clinical recovery does not show the sure of the infection. One third of the patients who have acute pyelonephritis recover in terms of symptoms even bacterial persistency. Therefore, urine culture should be performed by certain intervals within the 6 months period during, at the termination and after the treatment.
Chronic pyelonephritis is acquired during the childhood and carried to the adulthood. Immature and developing kidneys are effected. Scar occurs on polar (upper or lower pole) regions of the kidney in particular. The scar on the parenchyma damages the structure of the calyx by pulling and dilates it. The renal capsule is pale, parenchyma is deteriorated and the kidney is atrophic with various grades. Pelvic mucosa is pale and fibrotic.
The most common cause in the childhood is reflux; however, no scar develops within a kidney which has reflux and intact after 4 years. Reflux continues damaging with previously scarred kidneys.
Risk factors for chornic pyelonephritis development include metabolic diseases, analgesic aadiction, pregnancy, congenital abnormalities of the urinary system, stone and obstructions, vesicourethral reflux, foreign bodies within the urinary system, uro-intestinal fistulas and urinary diversions.
CLINICAL SYMPTOMS AND FINDINGS
It may progress with acute infection attacks. Fever and acute pyelonephritis like picture is seen on the acute phase.
If acute infection is present, it has less symptoms in general.
Feeling sick generally, fatigue, waist and side pains, weight loss, polyuria (much urinating) or olyguria (less urination), recurrent urinary system infections and fever may be observed. Hypertension, anemia, azotemia (urea elevation within the blood) occurs in advanced and nilateral cases.
Hemogram is normal except acute phase. Leukocytosis, sedimentation, CRP, blood urea nitrogen (BUN) and creatinine increase may be detected. Although pyruia (much leukocyte) and bacteriuria may be present in the urine test, they are not detected all the time. Significant proteinuria indicates advanced disease and glomerular involvement.
In direct urinary system (DUS) radiography, the sick kidney(s) are smaller than normal and their borders are irregular due to parenchymal scar and tractions. Chronic infection stones, tubular calcifications may be detected.
In intravenous pyelography (IVP), scar formation on the parenchyma on dilated calyxes level, atrophy and peranchymal irregularity, poor concentration on the kidney and if the event is bilateral, compensatory hypertrophy are observed. If the underlying cause is vesicoureteral reflux, ureter dilatation may be seen on IVP. VUR is definitely shown with voiding cystourethrography. It is possible to determine the presence of cystitis or abnormal orifice that causes the reflux with the cystoscopy.
Normal kidney on the left and atrophic kidney on the right
It may be confused with acute and chronic interstitial nephritis, paranephritis, paranephritic abscess, carbuncle of the kidney and renal tuberculosis.
- Acute pyelonephritis,
- Perinephritic abscess and pyonephrosis,
- Kidney stone (infection stone),
- Chronic Kidney Failure
Base line of the medical treatment includes eradication and prevention of the urinary system infections, long term suppressive antibiotic treatment if required.
Causes such as anatomical disorders, obstructions, stones, high grade reflux or reflux non-respondent to the medical treatment, hypertension (drug resistant, with unilateral atrophic pyelonephritis) require surgical treatment.
For surgical treatment, interventions to remove the pathology are selected primarily. If this is impossible, nephrectomy may be considered.
GENERAL PREVENTIONS: Close monitoring, control of urinary infections, early diagnosis and treatment of the complications are important. The patent should intake sufficient fluid.