What are the potential causes and recommended treatments for an adult or elderly patient with a history of a recent fall, presenting with progressive weakness, urinary retention, and ability to pass soft or watery stools?

Acute Spinal Cord Compression Until Proven Otherwise

This patient requires immediate MRI of the spine and urgent neurosurgical consultation—the combination of fall, progressive weakness, urinary retention, and preserved bowel function (soft/watery stools) is pathognomonic for cauda equina syndrome or acute spinal cord injury, which constitutes a surgical emergency. 1

Critical Diagnostic Framework

Red Flag Constellation

• Progressive weakness following trauma indicates evolving neurological injury requiring urgent imaging 1
• Urinary retention with preserved bowel function suggests sacral nerve root injury (S2-S4), which controls bladder function more than bowel function 1
• Sacral fractures from falls can cause bilateral traction of S2-S3 nerve roots, producing bladder paralysis (parasympathetic fibers) and incomplete sphincter paresis (somatic fibers) 1
• This pattern is particularly high-risk in elderly patients, as sacral fractures can result from simple falls 1

Immediate Evaluation Required

• Lateral sacral X-ray to identify fracture at S2-S3 level 1
• Complete neurological examination focusing on lower extremity strength, sensation in saddle distribution, anal tone, and bulbocavernosus reflex 1, 2
• Post-void residual measurement via bladder catheterization to confirm retention and decompress the bladder 3, 2
• Urodynamic studies (once stabilized) will show acontractile detrusor and neurogenic sphincter EMG in sacral nerve injury 1

Bladder Management Algorithm

Immediate Catheterization

• Prompt and complete bladder decompression is mandatory to prevent upper tract damage and relieve patient discomfort 3, 2
• Suprapubic catheterization is superior to urethral catheterization for short-term management in acute retention 3
• Assess renal function after catheterization to evaluate for upper tract damage from retention 4

Common Pitfall to Avoid

Do not attribute urinary retention to UTI without proper evaluation—the American Geriatrics Society warns against assuming urinary symptoms represent infection without systematic assessment 5. The presence of soft/watery stools makes fecal impaction (a common reversible cause of retention) unlikely 6.

Differential Considerations Beyond Spinal Injury

Medication Review

• Anticholinergic and alpha-adrenergic agonist medications are common pharmacologic causes of retention 3, 2
• The American Geriatrics Society emphasizes that polypharmacy creates high risk for drug-drug and drug-disease interactions in elderly patients 5

Neurogenic Bladder Assessment

• Diabetic autonomic neuropathy causes overflow retention rather than acute retention, but should be considered in diabetic patients 5
• Cortical, spinal, or peripheral nerve lesions can all cause retention and require neurologic consultation 3, 2

Disposition and Follow-Up

Admission Criteria

Admission is essential if the patient has 4:

• Abnormal renal function needing investigation and fluid monitoring
• Acute neurological problems (which this patient clearly has)
• Inability to manage catheter care

Recovery Timeline

• Patients with sacral nerve injury from fracture may gradually regain ability to urinate over weeks to months 1
• At 3 months post-injury, some patients still experience difficult urination despite normal neurological findings on examination 1
• Trial without catheter should be planned within 2-3 days only if neurological injury is excluded 4

Critical Action Items

1. Obtain spine imaging immediately—do not delay for urologic workup 1
2. Insert catheter for decompression while arranging imaging 3, 2
3. Neurosurgical consultation if imaging confirms spinal injury 1
4. Monitor renal function and assess for upper tract damage 4
5. Do not perform PSA testing in acute retention as it will be falsely elevated 4

The soft/watery stools in the context of urinary retention strongly suggest selective sacral nerve involvement rather than complete cauda equina syndrome, but this distinction requires urgent imaging confirmation 1.