Case Study 2 – Answers

Answers – Complicated Urinary Tract infection – Acute Pyelonephritis in Pregnancy (hospital/acute care setting)

 
1) Likely diagnosis from Initial assessment & differentials

• Likely diagnosis: Acute pyelonephritis (fever, flank pain, urinary symptoms, systemic upset) in a pregnant patient.
• DDx: Renal colic, appendicitis, chorioamnionitis (if ROM/uterine tenderness), influenza/COVID, lower UTI, ovarian/adnexal pathology.
• Immediate priorities: Assess for sepsis, haemodynamic instability, hydration status; involve obstetrics early.

 
2) Investigations (before/alongside antibiotics)

• MSU for culture & susceptibilities before first dose (don’t delay treatment if very unwell).
• Bloods: FBC, U&Es, CRP; blood cultures if febrile/systemically unwell.
• Urinalysis; consider renal ultrasound if poor response/obstruction suspected; fetal assessment as per gestation/obstetric plan. NICE

 
3) The infection is considered complicated as the patient is pregnant.

 
4) Empirical antimicrobial therapy (pregnancy-safe)

• Give oral first line if can tolerate and not severe; IV if vomiting, unable to take PO, or systemically very unwell.
• NICE NG111 (pregnant ≥12 y):
  • First-choice oral: Cefalexin 500 mg BD–TDS (up to 1–1.5 g QDS if severe) for 7–10 days.
  • First-choice IV: Cefuroxime 750 mg–1.5 g TDS–QDS; review at 48 h and step down to oral when possible.
  • Total duration: typically 7–10 days, tailored to severity and culture.
  • Consult microbiology for alternatives/combination therapy if severe sepsis or resistance concerns. NICE
• Avoid/notes:
  • Nitrofurantoin, fosfomycin, pivmecillinam are not appropriate for pyelonephritis (poor renal tissue penetration). Summary of antimicrobial guidance: Urinary Tract Infection text summaries | RCGP Learning
  • Fluoroquinolones carry MHRA restrictions and are not first-line; in pregnancy they’re generally avoided. NICE
  • Trimethoprim generally avoided in 1st trimester unless benefits outweigh risks; use culture-guided therapy if considered (local policy).

 
5) Supportive management

• IV fluids to correct dehydration; paracetamol for analgesia/pyrexia; antiemetics as needed.
• Monitor vitals, urine output; consider VTE prophylaxis per local maternity protocol; foetal monitoring as indicated.
• Reassess at 48 h: clinical response + cultures → narrow therapy/switch IV→PO. NICE

 
6) Follow-up & prevention

Ensure culture-directed antibiotic completion.
• Safety-net: return urgently if worsening at any time or no improvement within 48 h of antibiotics. NICE
• Consider post-treatment test-of-cure MSU and prophylaxis if recurrent UTIs in pregnancy (local policy/obstetric team). (ACOG also supports 5–7-day targeted courses and acknowledges prophylaxis in recurrent cases.) Urinary Tract Infections in Pregnant Individuals | ACOG
• Liaison with obstetrics and provision of supportive care.

 
7) Counselling Provision of patient information leaflets regarding use of antibiotics in pregnancy and allow opportunity for questions, address any concerns.
Marking pointers (what an excellent answer shows)

• Recognises pregnancy = higher-risk → lower threshold for admission/IV therapy.
• Starts appropriate empiric therapy that penetrates renal tissue and is pregnancy-safe, then de-escalates to culture results.
• Documents antibiotic choice, dose, route, duration, and 48-h review with step-down plan.
• Addresses supportive care, obstetric liaison, and safety-netting.

 

Case Study 2 – Acute Pyelonephritis in Pregnancy – common pitfalls

 
1. Choosing antibiotics with poor renal tissue penetration

• Nitrofurantoin, fosfomycin, and pivmecillinam are fine for cystitis but not for pyelonephritis.

2. Prescribing teratogenic or unsafe drugs in pregnancy

• Fluoroquinolones, tetracyclines, and (in some trimesters) trimethoprim can be harmful — always check trimester safety.

3. Delaying antibiotics while awaiting culture results

• In pregnancy, pyelonephritis can progress rapidly; empiric therapy should start immediately after taking samples.

4. Inadequate total treatment duration

• Stopping at 3–5 days (cystitis duration) instead of 7–10 days increases recurrence risk.

5. Not liaising with obstetrics

• Pregnancy requires coordination with maternity services for foetal monitoring and follow-up.

6. Failure to reassess at 48 hours

• Missing the opportunity to step down to oral therapy, narrow spectrum, or escalate if not improving.

7. Insufficient safety-netting

• Not warning about recurrence signs, potential complications (preterm labour, sepsis), or the need for repeat cultures post-treatment.