What criteria should I use to decide whether to refer a patient with p

Guideline-aligned answer with reasoning, red flags and references. Clinically reviewed by Dr Kola Tytler MBBS CertHE MBA MRCGP.

Refer a patient with pyelonephritis to secondary care if they:

Are significantly dehydrated or unable to take oral fluids and medicines .
Are pregnant .
Have a higher risk of developing complications, such as known or suspected structural or functional abnormality of the genitourinary tract, underlying disease (e.g., diabetes mellitus or immunosuppression), or if symptoms persist or worsen despite antibiotic treatment .
Have reduced kidney function due to acute kidney injury or chronic kidney disease .
Experience severe flank or abdominal pain or a high fever (>39.4°C) .
Have recurrent pyelonephritis (two or more episodes in 6 months or three or more in 12 months) .
Do not improve within 48 hours of starting antibiotics, unless the infecting pathogen is resistant to the initial antibiotic and an alternative is available, and the patient remains clinically well enough for community care ,,.
Show signs of sepsis, such as significant tachycardia, hypotension, breathlessness, impaired consciousness, perfuse sweating, rigors, pallor, or significantly reduced mobility .

Additional considerations include:

People with known or suspected structural or functional abnormalities of the genitourinary tract or underlying disease, such as diabetes or immunosuppression, should be considered for referral .
People with reduced kidney function due to acute kidney injury or chronic kidney disease, severe pain, or high fever should be referred .

What criteria should I use to decide whether to refer a patient with pyelonephritis to secondary care?