“In my patient with abdominal pain, what physical exam finding can help differentiate abdominal wall from intra-abdominal sources of pain?”

Carnett’s sign (described by a surgeon, J.B. Carnett, in 1926) is a physical exam finding that helps differentiate abdominal wall or psychogenic pain from intra-abdominal sources of pain.

The test is considered positive when, upon locating the tender abdominal spot, the patient’s pain worsens on tensing of the abdominal wall muscles by lifting the head and shoulders from the bed or by raising both legs with straight knees. Conversely, if the pain decreases with this maneuver, an intra-abdominal source is more likely1,2. Sensitivity of 85%, specificity of 97%, positive likelihood ratio of 2.6 and negative likelihood ratio of 0.2 have been reported in various studies. 3,4

A positive Carnett’s sign should broaden the differential of abdominal pain to include: hernias, irritation of intercostal nerve roots, rectus sheath hematomas, myofascial pain, anterior cutaneous nerve entrapment (latter also discussed in another pearl) and psychogenic pain. In the appropriate clinical setting,  local corticosteroids or anesthetic injections, or the application of hot or cold packs may be therapeutic. 2,5

 References

  1. Carnett JB. Intercostal neuralgia as a cause of abdominal pain and tenderness. J Surg Gynecol Obstet 1926; 42:625-632.
  2. Bundrick JB, Litin SC. Clinical pearls in general internal medicine.  Mayo Clin Proceedings 2011;86: 70–74.  https://mayoclinic.pure.elsevier.com/en/publications/clinical-pearls-in-general-internal-medicine-2.
  3. Takada T, Ikusaka M, Ohira Y, et al. Diagnostic usefulness of Carnett’s test in psychogenic abdominal pain. Intern Med 2011;50:213-17. https://www.jstage.jst.go.jp/article/internalmedicine/50/3/50_3_213/_article
  4. Kamboj Ak, Hoverten P, Oxentenko AS. Chronic abdominal wall pain: a common yet overlooked etiology of chronic abdominal pain. Mayo Clin Proc 2019;94:139-44. https://www.mayoclinicproceedings.org/article/S0025-6196(18)30852-8/pdf
  5. Suleiman S , Johnston DE.  The abdominal wall: an overlooked source of pain. Am Fam Physician 2001; 64: 431-8. https://www.ncbi.nlm.nih.gov/pubmed/11515832

Contributed in part by Brad Lander MD, Mass General Hospital, Boston, MA.

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“In my patient with abdominal pain, what physical exam finding can help differentiate abdominal wall from intra-abdominal sources of pain?”

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