Diagnostic Approach for Young Women with Urinary and Systemic Symptoms

Initial Assessment and History

The presence of fever or chills suggests pyelonephritis or systemic infection, and distinguishing between flank pain and lower back pain is crucial to identify pyelonephritis or mechanical back pain 1
Assessing the duration and progression of symptoms is essential in determining the appropriate course of action 2
Red flag assessment for back pain includes evaluating for urinary retention or fecal incontinence, saddle anesthesia or motor deficits, unexplained weight loss, recent infection or IV drug use, and progressive neurologic symptoms 1, 3

Vital signs, including temperature, should be taken to identify fever 1
A neurologic examination, including motor strength, sensory testing, and reflexes in lower extremities, is necessary 2, 4
Laboratory tests such as complete blood count (CBC) and erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) may be ordered if systemic infection or red flags are present 1

Routine imaging for back pain is not recommended initially unless red flags are present 4, 3, 5
Urgent MRI with and without contrast may be necessary if red flags such as fever with back pain, progressive neurologic deficits, or urinary retention are present 3, 1
The American College of Physicians recommends against routine lumbar spine imaging in young women without red flags due to radiation exposure concerns 3, 5

If urinary symptoms predominate, obtaining urinalysis immediately and treating infection if present is crucial 3
If red flags are present for back pain, urgent MRI and laboratory studies such as CBC, ESR, and CRP should be ordered 1
The American College of Physicians recommends against delaying imaging if red flags are present and against empirically treating with antibiotics without urinalysis 1, 3, 5