Hoover’s Sign (Pulmonary)

Hoover’s sign is one of two clinical signs described by Charles Franklin Hoover, the other being Hoover’s sign of paresis¹. This particular sign refers to the paradoxical inward movement of the lower lateral rib cage (costal margin) during inspiration, rather than the normal outward expansion².

Chronic obstructive pulmonary disease (COPD), particularly emphysema, leads to hyperinflation of the lungs due to air trapping². This hyperinflation flattens the diaphragm, which during inspiration contracts downward and paradoxically pulls the lower ribs inward instead of outward³ ⁴.

Prevalence

Hoover’s sign is a frequent observation in COPD:

• 77% of patients with airway obstruction demonstrated this sign in one study⁵.

• Another study reported the following prevalence⁶:

  • Mild COPD: 0%

  • Moderate COPD: 36%

  • Severe COPD: 43%

  • Very severe COPD: 76%

It can also be observed in other conditions⁷:

• Heart failure

• Asthma

• Severe pneumonia (especially in children)

• Bronchiolitis

• Unilateral diaphragmatic paresis

• Pleural effusion and pneumothorax

Risk factors

Previous studies have shown that Hoover’s sign is associated with⁶⁸⁹:

• Older age

• Higher BMI

• More severe airway obstruction

• Increased use of COPD medications

• Poorer pulmonary function test results (FVC and FEV1)

Clinical application

Observation

• Normally, the costal margin shows minimal movement during quiet breathing, and if movement occurs, it is directed outward and upward¹⁰.

• In COPD patients, paradoxical inward rib cage motion is more pronounced.

• Healthy individuals may show slight inward rib motion during maximal inspiration, but COPD patients exhibit marked paradoxical movement¹¹.

• Hoover’s sign can be observed both at rest and during physical activity¹¹.

• The paradoxical motion is most evident at the lower ribs¹¹.

• It is the most common and easily recognized sign of abnormal chest wall movement in COPD³.

• Not all COPD patients present with Hoover’s sign, and the reason for this variability remains unclear¹³.

Test execution

Examiner positionThe examiner places the index and middle fingers on the costal margin near the anterior axillary line¹⁰.

Patient instructionThe patient is asked to take a deep breath.

Interpretation

• Positive test: Costal margin moves inward during inspiration.

• Biphasic sign: Costal margin moves outward first, then inward, and outward again during expiration¹⁰.

Diagnostic validity and evidence

• High inter-rater reliability (observer agreement of 0.74 in one study)¹⁵.

• Sensitivity: 58%

• Specificity: 86%

• Strong diagnostic value for identifying obstructive lung disease, including COPD¹⁵.

Clinical implications

Hoover’s sign has been associated with:

• More frequent COPD exacerbations¹⁶.

• Increased dyspnea at rest, during daily activities, and after exercise – independent of FEV1 and BMI¹³.

• Greater number of hospitalizations and emergency visits – also independent of FEV1 and BMI¹³¹⁶.

Thus, Hoover’s sign can help identify COPD patients with more severe symptoms and higher healthcare utilization.

Hoover’s sign and diaphragmatic pathology

• Strong association between Hoover’s sign and impaired diaphragmatic function in severe COPD (GOLD stage 3 and 4)¹⁷.

• Can serve as a simple clinical method to evaluate diaphragmatic dysfunction.

Hoover’s sign and diaphragmatic paresis

• High specificity (84.6%), but low sensitivity (65.6%) for diaphragmatic paresis¹⁸.

• Helps differentiate unilateral diaphragmatic paresis (outward rib motion on the affected side, inward on the healthy side).

• In bilateral paresis, paradoxical respiration is observed.

Conclusion

Hoover’s sign is an important clinical indicator of severe COPD and diaphragmatic dysfunction.

• Sensitivity: 58% | Specificity: 86% – useful in diagnosing COPD.

• Strongly associated with dyspnea and increased healthcare utilization, identifying patients with greater treatment needs.

• Can also indicate diaphragmatic paresis, especially unilateral cases.

• A simple bedside test applicable in clinical practice for evaluating lung function and diaphragmatic status.

References

1. Hoover CF. THE DIAGNOSTIC SIGNIFICANCE OF INSPIRATORY MOVEMENTS OF THE COSTAL MARGINS. The American Journal of the Medical Sciences (1827-1924). 1920 May 1;159(5):633.

2. McKenzie DK, Butler JE, Gandevia SC. Respiratory muscle function and activation in chronic obstructive pulmonary disease. Journal of applied physiology. 2009 Aug;107(2):621-9.

3. Gilmartin JJ, Gibson GJ. Abnormalities of chest wall motion in patients with chronic airflow obstruction. Thorax. 1984 Apr 1;39(4):264-71.

4. Hoover CF. THE DIAGNOSTIC SIGNIFICANCE OF INSPIRATORY MOVEMENTS OF THE COSTAL MARGINS. The American Journal of the Medical Sciences (1827-1924). 1920 May 1;159(5):633.

5. Gilmartin JJ, Gibson GJ. Mechanisms of paradoxical rib cage motion in patients with chronic obstructive pulmonary disease. American Review of Respiratory Disease. 1986 Oct;134(4):683-7.

6. Garcia-Pachon E, Padilla-Navas I. Frequency of Hoover's sign in stable patients with chronic obstructive pulmonary disease. International journal of clinical practice (Esher). 2006;60(5):514–7.

7. Johnston CR 3rd, Krishnaswamy N, Krishnaswamy G. The Hoover's Sign of Pulmonary Disease: Molecular Basis and Clinical Relevance. Clin Mol Allergy. 2008 Sep 5;6:8. doi: 10.1186/1476-7961-6-8. PMID: 18775073; PMCID: PMC2546439.

8. Bruyneel M, Jacob V, Sanida C, Ameye L, Sergysels R, Ninane V. Hoover's sign is a predictor of airflow obstruction severity and is not related to hyperinflation in chronic obstructive pulmonary disease. European journal of internal medicine. 2011 Dec 1;22(6):e115-8.

9. Binazzi B, Bianchi R, Romagnoli I, Lanini B, Stendardi L, Gigliotti F, Scano G. Chest wall kinematics and Hoover's sign. Respiratory physiology & neurobiology. 2008 Feb 29;160(3):325-33.

10. Campbell EJ. Physical signs of diffuse airways obstruction and lung distension. Thorax. 1969 Jan 1;24(1):1-3.

11. Sarkar M, Bhardwaz R, Madabhavi I, Modi M. Physical signs in patients with chronic obstructive pulmonary disease. Lung India. 2019 Jan-Feb;36(1):38-47. doi: 10.4103/lungindia.lungindia_145_18. PMID: 30604704; PMCID: PMC6330798.

12. Maitre B, Similowski T, Derenne JP. Physical examination of the adult patient with respiratory diseases: inspection and palpation. European Respiratory Journal. 1995 Sep 1;8(9):1584-93.

13. Garcia-Pachon E, Padilla-Navas I. Clinical implications of Hoover's sign in chronic obstructive pulmonary disease. European Journal of Internal Medicine. 2004 Feb 1;15(1):50-3.

14. Medicine Textbooks Simplified. Hoover's Sign of COPD. Available from: http://www.youtube.com/watch?v=_36qvr_K-y8

15. Garcia-Pachon E. Paradoxical Movement of the Lateral Rib Margin (Hoover Sign) for Detecting Obstructive Airway Disease. Chest. 2002;122(2):651–5.

16. Aliverti A, Quaranta M, Chakrabarti B, Albuquerque AL, Calverley PM. Paradoxical movement of the lower ribcage at rest and during exercise in COPD patients. European respiratory journal. 2009 Jan 1;33(1):49-60.

17. Maloney TG, Anderson ZS, Vincent AB, Magiera AL, Slocum PC. Association of Hoover's Sign with Maximal Expiratory-to-Inspiratory Pressure Ratio in Patients with COPD. Chronic Obstr Pulm Dis. 2023 Jan 25;10(1):1-6. doi: 10.15326/jcopdf.2022.0341. PMID: 36394525; PMCID: PMC9995237.

18. Parmar D, Panchal J, Parmar N, Garg P, Mishra A, Surti J, Patel K. Early diagnosis of diaphragm palsy after pediatric cardiac surgery and outcome after diaphragm plication - A single-center experience. Ann Pediatr Cardiol. 2021 Apr-Jun;14(2):178-186. doi: 10.4103/apc.APC_171_19. Epub 2021 Feb 16. PMID: 34103857; PMCID: PMC8174623.