Pyelonephritis Flashcards
What is pyelonephritis?
Inflammation of the kidney parenchyma and renal pelvis
What typically causes pyelonephritis?
Bacterial infection
Who can acute pyelonephritis affect?
Patients of all ages
Who has the highest incidence of pyelonephritis?
Women aged 15-29
What can pyelonephritis be classified as?
- Uncomplicated
- Complicated
What is uncomplicated pyelonephritis?
Present in structurally or functionally normal urinary tract in a non-immunocompromised host
Why are urinary tract infections in males complicated by definition?
Because they will be associated with abnormal urinary tracts
What does acute pyelonephritis result from?
Bacterial infection of the renal pelvis and parenchyma
How can bacteria reach the kidney?
- Ascending from lower urinary tract
- Directly from blood stream
- Lymphatics
When is pyelonephritis caused by lymphatic spread seen?
In cases of retroperitoneal abscess
What happens once bacteria have infected the kidney?
Neutrophils infiltrate the tubules and interstitial and cause suppurative inflammation. These are often small renal cortical abscesses and streaks of pus in renal medulla
What is the most common causative organism of pyelonephritis?
E. coli
What other organisms can cause pyelonephritis?
- Klebsiella
- Proteus
- Enteroccocus faecialis
- Staphylococcus saprophyticus
- Pseudomonas
Which of these bacteria cause pyelonephritis in catheterised patients?
- S. aureus
- E. faecalis
- Pseudomonas
What can cause pyelonephritis in immunocompromised patients?
- S. saprophytic
- Mycobacterium spp.
- Other fungi
What are the risk factors for pyelonephritis?
- Factors reducing antegrade flow of urine
- Factors promoting retrograde ascent of bacteria
- Factors predisposing to infection or immunocompromisation
- Factors promoting bacterial colonisation
What factors reduce the antegrade flow of urine?
- Obstructed urinary tract, including BPH
- Spinal cord injury, resulting in neuropathic bladder
What factors promote the retrograde ascent of bacteria?
- Female gender
- Indwelling catheter or ureteric stents/nephrostomy tubes
- Structural renal abnormalities, e.g. VUR
What factors predispose to infection or immunocompromise?
- Diabetes mellitus
- HIV
- Corticosteroid use
- Infection
What factors promote bacterial colonisation?
- Renal calculi
- Sexual intercourse
- Oestrogen depletion
What is the classical triad of pyelonephritis?
- Fever
- Unilateral loin pain (or rarely bilateral)
- Nausea and vomiting
Over what time frame does pyelonephritis develop?
24-48 hours
What other symptoms might be present in pyelonephritis?
Symptoms of co-existing lower urinary tract infection (frequency, urgency, dysuria), and haematuria
What may be found on examination with pyelonephritis?
Patients often look unwell, often pyrexial and features of sepsis.
Will have unilateral or bilateral costovertebral angle tenderness, with or without suprapubic tenderness
What should be assessed on examination in pyelonephritis?
- Fluid status
- Measure post-void residual volumes
- Evidence of AAA
What are the differentials for pyelonephritis?
- Ruptured AAA
- Renal calculi
- Acute cholecystitis
- Ectopic pregnancy
- Pelvic inflammatory disease
- Lower lobe pneumonia
- Diverticulitis
Who should ruptured AAA be considered in?
Any patient with back pain and tachycardia and/or hypotension, especially if elderly or with sufficient risk factors
What investigations are required in suspected pyelonephritis?
- Urine
- Bloods
- Imaging
What urine investigations are required in pyelonephritis?
- Urinalysis, assessing for nitrates and leucocytes
- Urinary beta-hCG (women of child-bearing age)
- Urine culture
What bloods should be done in pyelonephritis?
- FBC
- CRP
- U&Es
What imaging should be done in pyelonephritis?
Renal US scan
Why should a renal US be done in pyelonephritis?
Look for evidence of obstruction (infected obstructed system is urological emergency)
What should be done if an obstruction is suspected in pyelonephritis?
Non-contrast CT imaging of renal tract
What will patients who are systemically unwell with pyelonephritis require for management?
A-E approach and appropriate resuscitation
How should patients with pyelonephritis be initially managed?
Start empirical antibiotics based on local protocols and IV fluids as appropriate, also prescribing suitable analgesia and anti-emetics
What should be done once bacterial sensitivities are available?
Tailor antibiotic therapy
Where can many uncomplicated cases of pyelonephritis be treated?
In community
When should admission be considered for pyelonephritis?
- Clinically unstable
- Significant dehydration
- Co-morbidities such as diabetes mellitus, renal transplant graft, or immunocompromised
What may be warranted in the management of severe or non-responding cases?
Catheterisation and high-dependency unit monitoring
What should be considered in severe or non-responding cases of pyelonephritis?
Early CT imaging
Why should early CT imaging be considered in severe or non-responding cases of pyelonephritis?
To check for obstruction and complications of pyelonephritis
What are the complications of pyelonephritis?
- Severe sepsis and multi-organ failure
- Renal scarring leading to CKD
- Pyonephrosis
- Preterm labour in pregnant women
What can repeated infections of pyelonephritis lead to?
Chronic pyelonephritis
What can chronic pyelonephritis lead to?
Fibrosis and ultimately destruction of the kidney
When is chronic pyelonephritis more common?
In obstructed systems resulting in urinary reflux
What can cause urinary reflux?
- UTIs
- VUR
- Anatomical abnormalities
How is a diagnosis of chronic pyelonephritis made?
Radiologically, when evidence of small, scarred, shrunken kidney seen
Who is chronic pyelonephritis most commonly seen in?
Children
Why might chronic pyelonephritis be hard to diagnosis?
May be asymptomatic or first presentation of CKD
What is the mainstay of management of chronic pyelonephritis?
- Reverse underlying causes
- Optimise renal function
- Consider prophylactic antibiotics
What is emphysematous pyelonephritis?
A rare and severe form of acute pyelonephritis caused by gas forming bacteria
How does emphysematous pyelonephritis present?
Similar to acute, however typically fails to respond to empirical IV antibiotics
What will CT show in emphysematous pyelonephritis?
Evidence of gas within and around the kidney
Who is emphysematous pyelonephritis most common in?
Diabetic patients
Why is emphysematous pyelonephritis most common in diabetic patients?
High glucose allows CO2 production from fermentation by enterobacteria
How can mild cases of emphysematous pyelonephritis be treated?
Broad-spectrum anti-microbial cover
How might severe cases of emphysematous pyelonephritis be treated?
Nephrostomy insertion or percutaneous drainage of any collections present
