Pyelonephritis

Question 1

What is pyelonephritis?

Answer 1

• Inflammation of kidney parenchyma and renal pelvis
• Typically due to bacterial infection

Question 2

Typical age for pyelonephritis

Answer 2

Female 15-29

Question 3

Complicated vs uncomplicated pyelonephritis

Answer 3

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

Question 4

Pathophys of pyelonephritis

Answer 4

• 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

Question 5

What happens when infection occurs at renal pelvis?

Answer 5

• Neutrophils infiltrate tubules and interstitium and cause suppurative inflammation
• Small renal cortical abscess and streaks of pus in medulla

Question 6

Most common organism pyelonephritis

Answer 6

• Escherichia coli
• Others - Klebsiella, proteus
• Catheter - enterococcus faecalis, staphylococcus aureus, pseudomonas
• Staphylococcus saprophyticus is commensal and can cause

Question 7

RF of pyelonephritis

Answer 7

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)

Question 8

Triad of pyelonephritis

Answer 8

• Fever
• Unilateral loin pain (or rarely bilateral)
• Nausea + vomitting

Typically develops over 24-48hrs

Question 9

Other symptoms of pyelonephritis

Answer 9

Co-existing lower urinary tract infection:
* Frequency
* Urgency
* Dysuria
* Visible/non-visible haematuria

Question 10

Examination findings pyelonephritis

Answer 10

• Pyrexial
• Features of sepsis
• Bilateral costovertebral angle tenderness +/- suprapubic tenderness
• Assess fluid status and measure post void residual volumes

Question 11

Differentials for back pain and tachycardia

Answer 11

• AAA rupture
• Renal calculi
• Ectopic pregnancy etc

Question 12

Investigations for pyelonephritis - bedside and bloods

Answer 12

• Urinalysis - nitrites and leukocytes
• Urinary beta-hCG if fertile age
• Urine MC&S
• Bloods - FBC, CRP, U&E - infection and renal function

Question 13

Imaging for pyelonephritis

Answer 13

• Renal US scan - look for obstruction evidence - emergency if infected, obstructed system
• If obstruction suspected - non-contrast CT KUB

Question 14

Management of pyelonephritis

Answer 14

• A-E approach
• Antibiotics based on guidelines (after urine culture specimen)
• IV fluids
• Analgesia
• Antiemetics

Question 15

When to consider hospital admission for pyelonephritis?

Answer 15

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

Question 16

How to manage severe or non-responding cases to initial management?

Answer 16

• Cathterisation
• High dependency unit input
• Consider early CT imaging to check for complications eg obstruction, perinephric abscess, pyonephrosis

Question 17

Males without a clear underlying cause or RF for pyelonephritis?

Answer 17

• Investigate and consider further imaging either US or CT KUB and flexible cystoscopy to rule out underlying causes

Question 18

Complications pyelonephritis

Answer 18

• Severe sepsis
• Multi organ failure
• Renal scarring –> CKD
• Pyonephrosis

Question 19

What is chronic pyelonephritis?

Answer 19

• 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

Question 20

Chronic pyelonephritis in children and management of all cases

Answer 20

• 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

Question 21

What is emphysematous pyelonephritis?

Answer 21

• Rare and severe form of acute pyelonephritis
• Caused by gas forming bacteria
• High mortality rate

Question 22

How does emphysematous pyelonephritis differ from usual in presentation?

Answer 22

• 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

Question 23

Treatment emphysematous pyelonephritis?

Answer 23

• Broad spectrum abx
• Severe cases –> nephrostomy insertion or percutaneous drainage of any collections
• Some cases nephrectomy may be required