Pyelonephritis

Pyelonephritis is a clinical diagnosis of upper urinary tract infection and is managed primarily under the care of general medicine.

Aetiology:

1. Usually stem from an ascending infection (from the bladder)

2. Hematogenous spread

3. The usual culprits: Escherichia coli, Klebsiella, Proteus, Enterococcus

4. Less common organisms: Mycobacteria, fungi and opportunistic pathogens

Risk factors:

1. Women are more prone to infection.

2. Vesicoureteric reflux (VUR).

3. Calculi - obstruction and urinary stasis within the renal pelvis.

4. Indwelling catheter, ureteric stent and nephrostomy.

5. Diabetes and immunocompromised patients are more prone to serious/atypical infections and perinephric abscesses or emphysematous pyelonephritis.

6. Neuropathic bladder - Urinary stasis.

7. Prostate enlargement - Urinary stasis and backpressure.

Presentation:

• Unwell adult or child with fever, nausea, vomiting, flank pain or suprapubic pain and discomfort.

• Chills and rigors are common.

• Sometimes patients may complain of preceding dysuria, frequency and urgency as well as ongoing LUTS which started acutely and were succeeded only by features of systemic illness.
  
  

When you need to worry:

1. Ongoing pain

2. Systemically unwell or septic

3. Diabetics

4. Pregnant patients - Preterm labour secondary to infection is an established complication

5. Significantly deranged blood tests - Full blood counts, renal function and CRP

6. Imaging shows obstruction requiring decompression

7. Unsafe discharge (social circumstances)

Management:

1. Urine dipstick (useful only in the context of patients who do not have a long-term catheter)

2. Urine for M/C/S

3. Routine blood tests, including a CRP

4. Blood cultures

5. Procalcitonin - a useful inflammatory marker in the case of children

6. Imaging - Ultrasound KUB, CTU, MRI

7. IV antibiotics - start as per trust guidelines and alter once cultures are available. Co-amoxiclav is the first-line antibiotic (Ciprofloxacin if penicillin allergic) for a total of 7 days.

8. IV fluids, IV paracetamol and antiemetics with supporting analgesics such as codeine or morphine.

9. Regular observations, input/output charting and daily or alternate day blood tests.

10. Decompression - Nephrostomy or ureteric stent insertion. Decompression is mandatory in obstructive pyelonephritis and should be considered in emphysematous pyelonephritis.

11. Deferred surgical management - Ureteroscopy and stone fragmentation.

Imaging in pyelonephritis:

Indicated in recurrent episodes of acute pyelonephritis to visualise the kidney, rule out stones and assess for obstruction.

1. An ultrasound KUB is the first line of imaging

2. DMSA scans have a role in recurrent infections and decreased renal function. Useful for assessing renal scarring and parenchymal health

3. CT urinary tract - Indicated in an uncertain diagnosis, poor progress after commencement of treatment or clinical deterioration. CT scans usually show fat stranding and detect any gross abnormalities of the renal tract that could be contributing to infection. Additionally, they are useful in picking up emphysematous pyelonephritis (Gas in the collecting system/parenchyma/adjacent to the kidney)

Complications:

1. Chronic pyelonephritis, destruction and scarring of renal tissue

2. AKI and CKD

3. Renal and perinephric abscess formation

4. Emphysematous pyelonephritis

5. Septic shock
   
   

https://patient.info/doctor/pyelonephritis