Pyelonephritis Flashcards
What is pyelonephritis?
- Inflammation of kidney parenchyma and renal pelvis
- Typically due to bacterial infection
Typical age for pyelonephritis
Female 15-29
Complicated vs uncomplicated pyelonephritis
Uncomplicated when:
* Structurally or functionally normal urinary tract
* Non-immunocompromised
Complicated is opposite, UTI in males complicated by definition as will be associated with abnormal tracts
Pathophys of pyelonephritis
- Bacterial infection of renal pelvis and parenchyma
- Either by ascending from lower urinary tract or directly from blood stream (septicaemia or infective endocarditis)
- Rare - spread from lymphatics in retroperitoneal abscess scenario
What happens when infection occurs at renal pelvis?
- Neutrophils infiltrate tubules and interstitium and cause suppurative inflammation
- Small renal cortical abscess and streaks of pus in medulla
Most common organism pyelonephritis
- Escherichia coli
- Others - Klebsiella, proteus
- Catheter - enterococcus faecalis, staphylococcus aureus, pseudomonas
- Staphylococcus saprophyticus is commensal and can cause
RF of pyelonephritis
Reduced antegrade flow of urine:
* obstructed tract eg BPH
* spinal cord injury –> neuropathic bladder
Factors promoting retrograde ascent of bacteria:
* female (short urethra)
* indwelling catheter
* Structural renal abnormalities eg vesico-ureteric reflux
Factors predisposing to infection:
* Diabetes
* Corticosteroid use
* HIV
Factors promiting bacterial colonisation:
* Renal calculi
* Sexual intercourse
* Oestrogen depletion (menopause)
Triad of pyelonephritis
- Fever
- Unilateral loin pain (or rarely bilateral)
- Nausea + vomitting
Typically develops over 24-48hrs
Other symptoms of pyelonephritis
Co-existing lower urinary tract infection:
* Frequency
* Urgency
* Dysuria
* Visible/non-visible haematuria
Examination findings pyelonephritis
- Pyrexial
- Features of sepsis
- Bilateral costovertebral angle tenderness +/- suprapubic tenderness
- Assess fluid status and measure post void residual volumes
Differentials for back pain and tachycardia
- AAA rupture
- Renal calculi
- Ectopic pregnancy etc
Investigations for pyelonephritis - bedside and bloods
- Urinalysis - nitrites and leukocytes
- Urinary beta-hCG if fertile age
- Urine MC&S
- Bloods - FBC, CRP, U&E - infection and renal function
Imaging for pyelonephritis
- Renal US scan - look for obstruction evidence - emergency if infected, obstructed system
- If obstruction suspected - non-contrast CT KUB
Management of pyelonephritis
- A-E approach
- Antibiotics based on guidelines (after urine culture specimen)
- IV fluids
- Analgesia
- Antiemetics
When to consider hospital admission for pyelonephritis?
Not all patients need to be hospitalised, most can be managed in community except:
* Clinically unstable
* Significant dehydration
* Co-morbids eg diabetes mellitus, renal transplant graft
* Immunocompromised
How to manage severe or non-responding cases to initial management?
- Cathterisation
- High dependency unit input
- Consider early CT imaging to check for complications eg obstruction, perinephric abscess, pyonephrosis
Males without a clear underlying cause or RF for pyelonephritis?
- Investigate and consider further imaging either US or CT KUB and flexible cystoscopy to rule out underlying causes
Complications pyelonephritis
- Severe sepsis
- Multi organ failure
- Renal scarring –> CKD
- Pyonephrosis
What is chronic pyelonephritis?
- Repeated infection can lead to this
- Repetitive inflammatory events than leads to fibrosis and destruction of kidney
- More common in obstructed systems –> urinary reflux
- Diagnosis made when small, scarred, shrunken kidney is seen on imaging
Chronic pyelonephritis in children and management of all cases
- More common in children
- Can present asymptomatic or with first presentation as CKD
- Management of all is to reverse underlying cause, optimise renal function and consider prophylactic abx
What is emphysematous pyelonephritis?
- Rare and severe form of acute pyelonephritis
- Caused by gas forming bacteria
- High mortality rate
How does emphysematous pyelonephritis differ from usual in presentation?
- Fail to respond to emperical IV abx
- CT imaging show evidence of gas within and around kidney
- Most common in diabetic patients as high glucose allows CO2 production from fermentation by enterobacteria
Treatment emphysematous pyelonephritis?
- Broad spectrum abx
- Severe cases –> nephrostomy insertion or percutaneous drainage of any collections
- Some cases nephrectomy may be required
