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Urinary tract infection and VUR in children
In an infant with fever and no source, think of UTI; the diagnosis needs both an abnormal urinalysis and a properly collected culture, and after a first febrile UTI an ultrasound is done — and a VCUG only when there is a reason.
Why it matters in the exam
Questions test how urine is collected (catheter or suprapubic aspiration; a bag is suitable only for ruling out), what defines a positive culture, whether oral antibiotics are acceptable (yes, in a child who is not toxic) and which imaging is needed after the first episode. A common distractor is a routine VCUG after the first UTI — guidelines no longer recommend it.
The follow-on topic is VUR: it is graded I to V, most low-grade reflux resolves with age, and antibiotic prophylaxis reduces recurrent infections but has not been shown to prevent renal scarring, so it is used selectively. A common and missed cause of recurrent infections is bladder and bowel dysfunction (constipation, urine holding), and treating it is part of prevention.
Key points
- Diagnosis = abnormal urinalysis + positive culture from a clean sample.
- A urine bag is good only for ruling out.
- Oral in a child who is not toxic; intravenous under 2 months or when toxic.
- After a first febrile UTI: ultrasound; VCUG only when there is a reason.
- VUR: grades I–V; selective prophylaxis and treatment of bladder and bowel dysfunction.
Summary table
| Step | What to do | Details | Exam note |
|---|---|---|---|
| Urine collection | Catheter or suprapubic aspiration in an infant who is not toilet-trained | Bag — only to rule out; a positive bag result requires a catheter sample | Midstream urine in a toilet-trained child |
| Diagnosis | Abnormal urinalysis (pyuria or bacteriuria) and a positive culture | 50,000 CFU/mL or more of a single organism on a catheter sample (AAP) | E. coli is the common cause |
| Treatment | Oral in a child who is not toxic; intravenous in an infant under 2 months, a toxic child or with vomiting | 7–14 days for febrile infection; by local resistance | Oral is as effective as intravenous |
| Imaging | Renal and bladder ultrasound after a first febrile UTI at age 2–24 months | VCUG only if the ultrasound is abnormal, the infection is atypical, or a febrile UTI recurs | DMSA to detect scarring, not in the acute phase |
| VUR | Grades I–V | Selective antibiotic prophylaxis; surgery for high grades with recurrent infections | Treat constipation and urine holding |
A free exam question
על פי הנחיות קליניות . בישראל תינוקת בת 9 .חודשים אושפזה בשל חום בבדיקת שתן לויקוציטים מרובים וצמיחה של ECOLI 100000 מושבות למ"ל . טופלה ב gentamycin ובהמשך ב cephalexin ע לפי רגישות החיידק . התינוקת החלימה . מה תהיה ההמלצה בשלב זה ? (the question as examined, in Hebrew)
- א. התחלת טיפול אנטיביוטי מונע ב cephalexin עד ביצוע US כליות ודרכי שתן
- ב. החלפה תכופה של חיתול כדי למנוע מגע ממושך בין צואה לפתח השופכה
- ג. ביצוע US כליות ודרכי שתן; בדיקת שתן כללית ותרבית בכל חום מסיבה לא ברורה
- ד. ביצוע US כליות ודרכי שתן; .וטיפול אנטיביוטי מונע ברספרים למשך שנה
In the full version for subscribers
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Sources
- AAP Clinical Practice Guideline: Urinary Tract Infection — Diagnosis and Management of the Initial UTI in Febrile Infants and Children 2 to 24 Months, 2011, reaffirmed 2016 — Diagnosis, treatment and imaging
- NICE guideline NG224: Urinary tract infection in under 16s, 2022 — Diagnosis, management and imaging
- Nelson Textbook of Pediatrics, 22nd edition (2024) — Urinary Tract Infections; Vesicoureteral Reflux
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.