How to Interpret a Urinalysis in a Febrile Infant

In Episode 36 of Med School Question of the Week for USMLE, Faustine Ramirez, MedSchoolCoach expert tutor, answers this medical school question: A 9-month-old boy presents to the emergency room with 2 days of fever, fussiness, irritability. His mother reports he has not been feeding well and has only had one wet diaper in the past 24 hours. He had one small non-bloody non-bilious emesis this morning after feeding, but otherwise has no other symptoms. He was born at term and has no other medical problems. He is uncircumcised. His temperature is 39.2 C, heart rate is 170/min, respiratory rate is 40, and blood pressure is 92/50. He is fussy but consolable, and the remainder of the examination is unremarkable. A catheterized urine specimen is collected and the urinalysis reveals: Specific gravity: 1.020 WBC: 10-15/hpf RBC: 0-1/hpf Leukocyte esterase: positive Nitrites: positive Protein: negative Ketones: negative Glucose: negative A urine culture is pending. What is the next best step?

• Observation until urine culture results
• Repeat urine specimen collection with a sterile collection bag
• Obtain abdominal X-Ray and stop feeds
• Obtain retrograde cystogram
• Start antibiotics and obtain renal/bladder ultrasound
• Start antibiotics and obtain voiding cystourethrogram