What could be causing coughing, vomiting, and severe left back pain, and what is the appropriate course of action?

Immediate Evaluation for Coughing with Vomiting and Severe Left Back Pain

This presentation requires urgent evaluation to rule out serious visceral or infectious causes, particularly given the combination of respiratory symptoms with severe unilateral back pain, which may indicate referred pain from an intra-abdominal or retroperitoneal process rather than a primary respiratory condition.

Critical Red Flags to Assess Immediately

• Fever, tachycardia, or hemodynamic instability suggest serious infection such as pyelonephritis, pneumonia with pleural involvement, or epidural abscess 1, 2
• Severe unilateral back pain with cough and vomiting can indicate referred visceral pain from gastrointestinal pathology (duodenal ulcer, pancreatitis), renal pathology (pyelonephritis, nephrolithiasis), or even abdominal aortic aneurysm 3, 1
• Constitutional symptoms (weight loss, night sweats) raise concern for malignancy or tuberculosis 4, 2
• Neurological deficits (leg weakness, saddle anesthesia, bowel/bladder dysfunction) indicate possible cauda equina syndrome or epidural compression requiring emergency imaging 2, 5

Diagnostic Approach

History Focus

• Duration of cough: If ≥2 weeks with paroxysmal episodes and post-tussive vomiting, consider pertussis until proven otherwise 4, 6
• Back pain characteristics: Unilateral left-sided pain with cough suggests either musculoskeletal strain from coughing paroxysms OR referred visceral pain from kidney, spleen, pancreas, or posterior gastric/duodenal pathology 3, 1
• Medication review: ACE inhibitors cause dry cough but would not explain severe back pain 6, 7
• Smoking status and risk factors for serious disease 4, 8

Physical Examination Priorities

• Vital signs including temperature and oxygen saturation 6, 1
• Costovertebral angle tenderness (suggests pyelonephritis) 1
• Abdominal examination for peritoneal signs, masses, or pulsatile mass 1, 3
• Respiratory examination for consolidation, pleural rub, or decreased breath sounds 4
• Neurological examination including lower extremity strength, sensation, and reflexes 2, 5

Initial Diagnostic Testing

• Chest radiograph to rule out pneumonia, pleural effusion, or structural abnormalities 8, 4
• Urinalysis and urine culture if costovertebral angle tenderness present 1
• Complete blood count to assess for leukocytosis suggesting infection 1
• Renal function and lipase if visceral pathology suspected 3
• CT abdomen/pelvis with contrast if red flags present and initial workup unrevealing, to evaluate for retroperitoneal pathology, renal stones, or occult abscess 1, 2

Treatment Algorithm

If Pertussis Suspected (≥2 weeks cough with paroxysms and post-tussive vomiting)

• Start azithromycin 500 mg once daily for 3-5 days immediately without waiting for laboratory confirmation 6, 4
• Isolate patient for 5 days from start of antibiotic treatment 6, 4
• Obtain nasopharyngeal aspirate or Dacron swab for culture confirmation, but do not delay treatment 6, 4
• Early treatment within first 2 weeks decreases paroxysms and prevents transmission 6, 4

If Visceral Pathology Suspected (severe unilateral back pain predominates)

• Urgent imaging and specialist consultation based on clinical suspicion 1, 2
• Pyelonephritis requires IV antibiotics 1
• Duodenal ulcer requires proton pump inhibitor therapy and possible endoscopy 3
• Epidural abscess or compression requires emergency neurosurgical evaluation 2, 5

Symptomatic Management for Cough

• Ipratropium inhalation as first-line cough suppressant 6, 8
• Dextromethorphan 60 mg (not over-the-counter subtherapeutic doses) when other measures fail 6, 7
• Prednisone 30-40 mg daily for short period if severe paroxysms and common causes ruled out 6, 4

Critical Pitfalls to Avoid

• Do not assume this is simple musculoskeletal back pain from coughing without ruling out visceral referred pain, as duodenal ulcers and other intra-abdominal pathology commonly present as back pain 3
• Do not delay pertussis treatment waiting for laboratory confirmation if clinical picture fits, as effectiveness decreases after 2 weeks 6, 4
• Do not miss epidural abscess or compression syndrome, which require emergency intervention to prevent permanent neurological damage 2, 5
• Do not use antibiotics indiscriminately for viral post-infectious cough, but do treat if pertussis suspected 6, 4
• Do not overlook serious causes like pulmonary embolism, which presents with cough in nearly half of cases 4