Pyelonephritis 🔥
Guide to recognising and managing acute pyelonephritis / upper UTI in adults: HSE antibiotic pathways, MSU before antibiotics, referral criteria, and when nitrofurantoin is unsuitable.
📖 Definition & Presentation (HSE)
- Acute pyelonephritis / upper UTI: bacterial infection of the kidney and upper urinary tract.
- Consider when there is flank pain radiating to the iliac fossa and suprapubic area.
- Sudden onset systemic disturbance with fever, rigors, and vomiting is typical.
- Examination may show tenderness and guarding over the kidney, with nausea and/or vomiting.
- Lower UTI symptoms (dysuria, frequency, urgency) may coexist but are not required for the diagnosis.
- Usual pathogens are Enterobacterales (commonly E. coli).
🚨 Red Flags — Refer / Escalate
- Significantly dehydrated or unable to take oral fluids and medicines.
- Child or young person under 16 years with acute pyelonephritis.
- Aged 16 years and over with acute pyelonephritis and severe systemic infection (use HSE sepsis pathway).
- Pregnancy.
- Higher risk of complications: known or suspected structural or functional genitourinary abnormality, diabetes, or immunosuppression.
- No clinical response within 24 hours of starting antibiotics: consider hospital referral (per HSE).
- Inpatients: escalate for IV antibiotics, imaging, or urology if obstructed, septic, or not improving.
🔍 Assessment & Investigations
- Send MSU for culture and sensitivity in all cases before starting antibiotics (per HSE Expert Advisory Group).
- Tailor empirical antibiotic choice using previous culture results where available.
- Vitals, NEWS/MEWS, and sepsis screen if systemically unwell.
- Examine for loin tenderness, abdominal guarding, bladder fullness, and genital findings if relevant.
- Pregnancy test in people of childbearing potential.
- Bloods if unwell or admitted: FBC, U&E, CRP; lactate if sepsis suspected. Blood cultures if febrile/septic.
- Consider renal tract imaging (e.g. ultrasound) if obstruction, stones, abscess, or atypical course suspected; follow local protocol.
💊 Antibiotics — Acute pyelonephritis / upper UTI (HSE)
- Oral regimens below are from HSE Acute Pyelonephritis / Upper UTI v2.1.
- Nitrofurantoin is NOT a suitable antibiotic choice in pyelonephritis (inadequate tissue levels).
- If no response within 24 hours, consider referral to hospital.
- Review culture results and switch to a narrower agent when susceptibility is known.
- Severe infection, vomiting, or inability to take oral therapy: use local inpatient / IV antibiotic protocol and sepsis pathway.
🔁 Further Investigation & Follow-up
- Male patients: consider referral to secondary care for further investigation after a single episode of pyelonephritis without an obvious cause (per HSE).
- Female patients with recurrent pyelonephritis: consider referral to secondary care for further investigation.
- Address predisposing factors: stones, obstruction, incomplete emptying, catheter use, diabetes control.
- Document antibiotic start time, MSU sent, allergies, pregnancy status, and safety-net advice on discharge.
🩹 Supportive Care & Patient Advice
- Advise adequate oral fluids to avoid dehydration if able to drink.
- Paracetamol for pain and fever; avoid NSAIDs unless a clinician advises otherwise (kidney risk).
- Seek urgent review if unable to keep fluids down, worsening fever/rigors, confusion, or no improvement within 24 hours.
- Complete the full antibiotic course even if feeling better.
- Switch IV to oral when improving: see antibiotic IV-to-PO for inpatients.
Related NICE guidance
NICENICE NG111 — Pyelonephritis (acute): antimicrobial prescribing
Full guidance on nice.org.uk. BetterCall is not endorsed by NICE.
Note Template
Ready-to-use clinical note structure
🕒 04 / 11 / 2026 — 21:41 ATRP re: acute pyelonephritis / upper UTI Patient: [age] [sex] Admission Dx: [reason for admission] PMHx: [diabetes, structural/functional GU abnormality, immunosuppression, recurrent UTI, stones] 🧾 Hx: • Onset: flank/loin pain, fever, rigors, nausea/vomiting • Lower UTI symptoms: dysuria, frequency, urgency [Y/N] • Prior urine cultures / recent antibiotics • Catheter / obstruction risk / pregnancy: [Y/N] • Allergies: penicillin [Y/N — severity] fluoroquinolone [Y/N] 🩺 Exam: • Vitals: HR __ BP __ Temp __ NEWS __ • Loin tenderness / guarding: [side] • Hydration / able to take oral fluids and medicines: [Y/N] • Sepsis screen: [indicated / not] 🔬 Investigations: • MSU for C&S before antibiotics: [sent] • Bloods: FBC, U&E, CRP, lactate [if unwell] • Blood cultures: [if febrile/septic] • Pregnancy test: [result / N/A] • Imaging: [USS / CT / not indicated] 📋 Impression: Acute pyelonephritis / upper UTI — [community oral suitable / needs hospital / septic] 📌 Plan: • Antibiotics per HSE acute pyelonephritis v2.1: [cefalexin / ciprofloxacin / co-amoxiclav / trimethoprim if susceptible / local IV protocol] • Fluids, analgesia (paracetamol; avoid NSAIDs unless advised) • Review culture results; escalate if no response within 24 h • Referrals: [urology / microbiology / renal — or none] • Safety-netting: unable to drink, worsening systemic symptoms, pregnancy concerns 👤 [Your Name], [Role] IMC: _______
Educational reference only. Medical disclaimer