Urinary Tract Infection & Pyelonephritis — SAQ

Stem

A 27-year-old at 12 weeks of pregnancy has a correctly collected screening urine culture growing Escherichia coli at 10^5 CFU/mL. She is well and has no dysuria, frequency, urgency, suprapubic pain, flank pain, fever or systemic features. Susceptibilities are pending. Her renal function is normal and no drug allergy is known.^[2]

Questions and reproducible marking guide

a) Give the diagnosis and explain why management differs in pregnancy. (2 marks)

Award exactly:^[2]

• 1 mark: Asymptomatic bacteriuria (ASB) in pregnancy — bacteriuria without symptoms attributable to UTI, irrespective of pyuria.^[1]
• 1 mark: Pregnancy is one of the few populations in which the IDSA 2019 ASB guideline and ACOG 2023 Clinical Consensus recommend screening and treatment because treatment reduces maternal pyelonephritis risk. Do not require the obsolete claim that every untreated patient has a 30% to 40% progression risk; that figure comes from older studies and is not a current universal absolute.^[1][2]

b) State two safeguards before selecting an antibiotic in this pregnancy. (2 marks)

Award exactly 1 mark for each of two different safeguards; maximum 2 marks. Each mark requires only one safeguard from this list:^[2]

• First 1 mark: award for any one of: confirm lower- versus upper-tract disease; use culture and susceptibility; check gestation; check allergy; check renal function; check G6PD status when relevant; check interactions; or verify the current product label/local obstetric policy.^[2]
• Second 1 mark: award for one different safeguard from the same list. Do not require a compound cluster for either mark, and do not award the same safeguard twice.^[2]

c) Outline treatment and follow-up once susceptibility is available. (3 marks)

Award exactly:^[2]

• 1 mark: Choose from the culture result, gestation, allergy, current renal function, interactions, current product label and local obstetric formulary; then use the locally specified dose and oral route for lower-tract disease.^[2]
• 1 mark: Under ACOG 2023, give a susceptibility-supported pregnancy-appropriate lower-tract agent for 5 to 7 days, with single-dose fosfomycin an exception when it is susceptibility-supported and appropriate. Nitrofurantoin and fosfomycin are lower-tract agents and must not be used for pyelonephritis.^[2]
• 1 mark: Explain that evidence is insufficient to mandate routine repeat culture after treated ASB. Distinguish this from cystitis, where repeat culture 1 to 2 weeks later may be considered or follow-up may be symptom-triggered.^[2]

d) Four weeks later she develops fever, rigors, right flank pain, vomiting and tachycardia. Give the diagnosis and immediate management. (3 marks)

Award exactly:^[2]

• 1 mark: Diagnose pyelonephritis/systemic UTI in pregnancy; admit, assess ABCDE and organ dysfunction, obtain urine culture and blood cultures before antibiotics when feasible, and involve obstetrics.^[2][3]
• 1 mark: Start a locally appropriate parenteral regimen with adequate renal-tissue exposure, selected from severity, prior isolate/exposure, allergy, pregnancy and renal function. Use prior susceptibility and a recent local antibiogram specifically when applying the IDSA 2025 septic-cUTI framework. Never use nitrofurantoin or oral fosfomycin for pyelonephritis. Under SSC 2021, shock or high-likelihood sepsis needs antimicrobials immediately, ideally within 1 hour; possible sepsis without shock needs rapid evaluation and treatment within 3 hours if concern persists. Give crystalloid and organ support with repeated individualized reassessment rather than an automatic unreviewed bolus.^[2][3]
• 1 mark: Monitor maternal response and fetal wellbeing appropriate to gestation. Follow a current imaging pathway such as the EAU Urological Infections guideline: image promptly for suspected obstruction, acute kidney injury or deterioration, and decompress an infected obstructed system urgently while antibiotics continue. Under ACOG 2023, step down to an active oral agent when clinically improving and able to absorb it, complete 14 days total, and obtain a urine culture after treatment.^[2]

Examiner consistency note

The four sections total 2 + 2 + 3 + 3 = 10 marks. Do not award extra marks for a fixed empirical drug table, a mandatory test-of-cure after ASB, a phenotype-independent pregnancy drug rule, routine imaging in every stable case, or antibiotics without culture narrowing and renal review.^[2]

References3ShowHide

1. [1]Nicolle LE, Gupta K, Bradley SF, et al. Clinical Practice Guideline for the Management of Asymptomatic Bacteriuria: 2019 Update by the Infectious Diseases Society of America Clin Infect Dis, 2019.PMID 30895288
2. [2]American College of Obstetricians and Gynecologists. Urinary Tract Infections in Pregnant Individuals Obstet Gynecol, 2023.PMID 37473414
3. [3]Evans L, Rhodes A, Alhazzani W, et al. Surviving Sepsis Campaign: International Guidelines for Management of Sepsis and Septic Shock 2021 Crit Care Med, 2021.PMID 34605781