What is the possible diagnosis for a 35-year-old female presenting with lower back pain radiating down the posterior aspect of the leg, with a history of similar episode 4 years ago and daily activity of carrying a 37-lb baby?

Lumbar Radiculopathy (Sciatica)

The most likely diagnosis is lumbar radiculopathy (sciatica) secondary to lumbar disc herniation, most commonly at the L4/L5 or L5/S1 levels, given the classic presentation of lower back pain radiating down the posterior leg in a 35-year-old with repetitive mechanical stress from daily lifting and a prior similar episode. 1

Clinical Reasoning

This patient presents with the hallmark features of lumbar radiculopathy:

• Pain distribution: Lower back pain radiating down the posterior aspect of the leg is the defining characteristic of sciatica, indicating nerve root compression 1, 2
• Mechanical trigger: Daily carrying of a 37-lb baby represents repetitive axial loading and flexion stress on the lumbar spine, a known risk factor for disc herniation 1
• Recurrent pattern: The prior episode 4 years ago following sudden deceleration while driving suggests underlying disc pathology that has now recurred 1
• Duration: One week of symptoms places this in the acute phase (0-4 weeks), when most disc herniations are self-limited 1, 3

Key Diagnostic Features to Confirm

Perform a focused neurologic examination targeting the L5 and S1 nerve roots, as over 90% of symptomatic lumbar disc herniations occur at L4/L5 or L5/S1 levels 1:

• Straight-leg-raise test: Reproduction of her leg pain between 30-70 degrees of hip flexion has 91% sensitivity for herniated disc 1
• Crossed straight-leg-raise test: More specific (88%) but less sensitive (29%) for disc herniation 1
• L5 nerve root: Test great toe and foot dorsiflexion strength 1
• S1 nerve root: Test foot plantarflexion strength and ankle reflexes 1
• Sensory distribution: Map the dermatomal pattern of any numbness or paresthesias 1

Critical Red Flags to Exclude (All Absent in This Case)

The patient appropriately denies concerning features that would require urgent imaging or intervention 1:

• No urinary retention or incontinence (cauda equina syndrome has 90% sensitivity for urinary retention) 1
• No fecal incontinence 1
• No saddle anesthesia 1
• No progressive motor weakness 1
• No fever (vertebral infection) 1
• Age <50 years and no history of cancer (low pretest probability ~0.7% for malignancy) 1

Management Algorithm

Initial Conservative Management (First 4-6 Weeks)

Do NOT order imaging at this stage. Imaging in acute low back pain without red flags provides no clinical benefit and leads to increased healthcare utilization without improved outcomes 1:

1. Advise remaining active: This is more effective than bed rest for acute radiculopathy 1, 2
2. Apply heat: Heating pads provide short-term relief 2
3. NSAIDs: First-line pharmacologic therapy 3, 4
4. Reassurance: Inform her that 84-90% of disc herniations improve spontaneously within 4 weeks, with most showing reabsorption by 8 weeks 1, 3
5. Early progressive ambulation: Gradual return to activity as tolerated 3, 4

If Symptoms Persist Beyond 4-6 Weeks

Only then consider MRI (preferred over CT) if she becomes a candidate for epidural steroid injection or surgery 1:

• MRI provides superior soft-tissue visualization of discs and nerve roots without ionizing radiation 1, 2
• Imaging should only be obtained when results would change management decisions 1

Additional Therapies for Persistent Symptoms

If conservative management fails after 4-6 weeks 2, 4:

• Acupuncture 2
• Massage therapy 2
• Supervised exercise therapy 2
• Cognitive-behavioral therapy 2
• Epidural steroid injections for confirmed radiculopathy 1, 2

Surgical Referral Criteria

Consider discectomy only if ALL of the following are present 3:

• Definite disc herniation confirmed on MRI 3
• Corresponding syndrome of sciatic pain 3
• Corresponding neurologic deficit 3
• Failure of 6 weeks of conservative therapy 3

Critical Pitfalls to Avoid

• Do not order early imaging: 27.2% of patients inappropriately receive imaging within 4 weeks, leading to increased interventions without improved outcomes 1
• Do not recommend bed rest: Remaining active is superior to bed rest 1, 2
• Do not overlook psychosocial factors: Depression, job dissatisfaction, and passive coping strategies are stronger predictors of poor outcomes than physical findings 1
• Do not over-interpret imaging findings: Disc bulges and degenerative changes are present in 29-43% of asymptomatic individuals and correlate poorly with symptoms 1

Reassessment Timeline

Reevaluate in 4 weeks if symptoms persist or worsen, as most patients with acute radiculopathy experience substantial improvement within the first month 1