QuestionSBA
QuestionChoice
Renal calculi can present with back pain, which is typically "loin to groin". However, this patient has a fever, features of lower urinary tract infection (dysuria, frequency) and typical urine dipstick findings for urinary tract infection (leukocyte esterase and nitrites), which are not found in simple renal calculi. These features make an ascending urinary tract infection (pyelonephritis) more likely than renal calculus
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Renal calculi
QuestionChoice
Polycystic kidney disease is an autosomal dominant genetic disease leading to cyst formation on the kidneys, liver and pancreas. This can present with cyst rupture, which can cause back pain. However, this would usually be accompanied by haematuria. In addition, this would not explain the positive urine dipstick for nitrites and leukocyte esterase
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Polycystic kidney disease
QuestionChoice
There are some typical features of lower urinary tract infection in this question, including dysuria and urinary frequency. However, flank pain and fever are features that point towards a diagnosis of upper urinary tract infection, over a simple lower urinary tract infection
33644
b
Lower urinary tract infection
QuestionChoice
Renal cell carcinoma is an adenocarcinoma of the kidneys. Typical presenting features include haematuria, pain or mass in the flank and manifestations of metastatic disease. It is unlikely that a patient with renal cell carcinoma would develop symptoms this rapidly, combined with a clinical urinary tract infection
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Renal cell carcinoma
QuestionChoice
Pyelonephritis, also known as an upper urinary tract infection, is an ascending urinary tract infection that affects the kidneys. This is typically caused by E. coli and presents with fever, rigors and flank pain. They may also have signs of lower urinary tract infection (e.g. dysuria, frequency), but the presence of flank pain and/or fever are good differentiators between upper and lower urinary tract infection. Urine dipstick, bloods and midstream urine sample are typical investigations for pyelonephritis, with renal ultrasound scan considered if there is a risk of renal stones causing the infection (pyonephrosis). This condition is generally treated in an inpatient setting with broad-spectrum IV antibiotics
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Pyelonephritis
Concept
Chapter
# Summary 

Lower urinary tract infections (LUTIs), often manifesting as cystitis, typically involve the infection of the bladder. Primarily caused by transurethral ascent of colonic commensals like E. coli, symptoms include urinary frequency, dysuria, urgency, foul-smelling urine, and suprapubic pain. Investigations are generally limited to a urine dipstick test for leucocytes and nitrites, while management involves oral nitrofurantoin or trimethoprim, and conservative measures. A key differential diagnosis is pyelonephritis, a urinary tract infection affecting the kidneys. Pyelonephritis exhibits more severe symptoms like fever, malaise, loin pain, and vomiting, and requires hospital admission and intravenous antibiotics.

# Definition 

A lower urinary tract infection (LUTI) is generally defined as an infection of the bladder, often manifesting as cystitis.

# Aetiology 

LUTIs are caused by the transurethral ascent of colonic commensals, most commonly **E. coli**.

# Signs and symptoms

Patients with LUTIs generally present with:

- Urinary frequency
- Dysuria
- Urgency
- Foul-smelling urine
- Suprapubic pain
- Clinical examination may be normal or reveal suprapubic tenderness.

Red flag symptoms such as haematuria, loin pain, rigors, nausea, vomiting, and altered mental state may indicate more serious infection, and these patients may have/are at risk of developing pyelonephritis (see below) and likely need referral to A&E.


# Investigations

For LUTIs:

- Urine dipstick is positive for leucocytes and nitrites in most cases.
- In uncomplicated cases, no further investigations are required.
- In children, men, and pregnant women a mid-stream urine sample should be sent.

NB: Urine dipstick is unreliable in women aged older than 65 years and those who are catheterised.

If being managed in secondary care due to red flag symptoms consider:

- If there are signs of systemic upset consider routine blood tests such as FBC, U+E, and CRP.
- For uncomplicated UTIs, imaging is rarely required, but if there are concerns over antecedents/complications such as urinary retention/obstruction, an USS bladder/kidney scan would be the first port of call.

# Management 

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For LUTIs:

- First line management is with oral nitrofurantoin or trimethoprim. Antibiotic duration can vary (see below) however in women the standard course length is 3 days.
- The patient should be advised on conservative measures to reduce the risk of further infection e.g. regular fluid intake, post-coital voiding.

## Specific situations

**UTI in Men:**

- Empirical antibiotic drug treatment (if no cultures with sensitivities) with trimethoprim or nitrofurantoin for **7 days.**
- Refer to urology if there are ongoing symptoms despite treatment, if there is an underlying risk factor for UTIs (e.g. urinary calculi, suspected obstruction, previous GU surgery), or if there are recurrent episodes of UTI.

**UTI during Pregnancy (with no haematuria):**

- First-line antibiotics are nitrofurantoin (but *avoid at term),* for **7 days.**
- If nitrofurantoin is not suitable due to e.g. renal function, or there is no improvement in symptoms, consider second-choice antibiotics such as amoxicillin/cefalexin for 7 days.


# NICE Guidelines

[Click here for NICE CKS on urinary tract infection (lower) - women](https://cks.nice.org.uk/topics/urinary-tract-infection-lower-women/)

[Click here for NICE CKS on pyelonephritis - acute](https://cks.nice.org.uk/topics/pyelonephritis-acute/)

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A 33-year-old female presents to their GP with a one-day history of left-sided back pain. This was preceded by a five-day history of dysuria and urinary frequency. On examination, her temperature is 38.7ºC, and there is suprapubic and renal-angle tenderness. Urine dipstick is positive for leukocyte esterase and nitrites.

What is the most likely diagnosis?
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