Vomiting After Coughing: Diagnosis and Management
Post-tussive vomiting (vomiting triggered by coughing) is highly suggestive of pertussis (whooping cough) and should prompt immediate clinical evaluation and treatment with macrolide antibiotics without waiting for laboratory confirmation. 1
Primary Diagnostic Consideration: Pertussis
Clinical Assessment Algorithm
In adults with cough and post-tussive vomiting, assess these four key characteristics to diagnose pertussis: 1
- Paroxysmal cough (recurrent prolonged coughing episodes with multiple bursts and inability to breathe during spells) 1
- Post-tussive vomiting (vomiting induced by coughing) 1
- Inspiratory whooping (continuous inspiratory airway sound with whooping quality) 1
- Absence of fever (temperature ≤98.6°F/37°C) 1
In children with acute cough (<4 weeks), assess for the three classical characteristics: paroxysmal cough, post-tussive vomiting, and inspiratory whooping. 1
Diagnostic Performance
Post-tussive vomiting has high specificity (77.7%) but low sensitivity (32.5%) in adults, meaning when present, it strongly suggests pertussis. 1, 2 The absence of paroxysmal cough or presence of fever makes pertussis unlikely. 1
In children, post-tussive vomiting is only moderately sensitive (60%) and specific (66%), making it less helpful as a standalone diagnostic test compared to adults. 1, 2
Common Pitfall to Avoid
Do not dismiss pertussis in vaccinated adolescents and adults, as the illness can be milder with absent whoop in previously vaccinated individuals. 3 The classic "whoop" is frequently absent in adults and previously vaccinated patients. 3
Immediate Management When Pertussis is Suspected
Antibiotic Treatment
Start a macrolide antibiotic immediately without waiting for culture results. 4 Azithromycin is the preferred agent. 4 Early treatment within the first few weeks will diminish coughing paroxysms and prevent disease spread. 1, 4
Isolation Precautions
Isolate the patient for 5 days from the start of antibiotic treatment, as patients are most infectious during the catarrhal stage and first 3 weeks after cough onset. 1, 3, 4
Diagnostic Confirmation
Order a nasopharyngeal aspirate or Dacron swab for culture, which is the only certain way to make the diagnosis (100% specific). 1, 4 PCR testing is available but not universally standardized for routine clinical use. 1, 4
Supportive Care Measures
Nutritional Management
Provide frequent small feedings immediately after coughing episodes to prevent aspiration and maintain nutrition, as post-tussive vomiting leads to substantial weight loss and feeding difficulties. 4, 5
Consider nasogastric or intravenous hydration if vomiting is severe enough to cause dehydration or significant weight loss. 5
Environmental Modifications
Maintain a calm, quiet environment to minimize coughing triggers, as paroxysms can be precipitated by stimulation. 4, 5
Reduce environmental irritants and tobacco smoke exposure. 5
Special Considerations for Infants
Infants under 12 months with suspected pertussis should be hospitalized for continuous cardiorespiratory monitoring due to high risk of apneic spells, bradycardia, cyanosis, and death. 5 Infants can present with apneic spells and minimal cough initially. 3, 5
Monitoring for Complications
Monitor closely for complications including pneumothorax, subconjunctival hemorrhage, subdural hematoma, seizures, and secondary bacterial pneumonia. 4, 5 These result from severe coughing pressure and can occur throughout the paroxysmal stage, which typically lasts 2-6 weeks. 5
Alternative Diagnoses to Consider
If pertussis is ruled out, consider asthma as a cause of post-tussive vomiting, particularly if coughing and wheezing are present. 6 Vomiting can be a dominant symptom of asthma where respiratory symptoms are overlooked. 6
For chronic symptoms (>8 weeks), consider diagnoses other than post-infectious cough, including upper airway cough syndrome, gastroesophageal reflux disease, or other chronic conditions. 1, 7, 8