What are the key findings on physical examination for infectious mononucleosis (mono)?

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From the Guidelines

A thorough physical examination for mononucleosis (mono) should include checking for swollen lymph nodes, throat inflammation, tonsillar enlargement, splenomegaly, hepatomegaly, and a maculopapular rash, as these signs are crucial for establishing a clinical suspicion of the disease 1. The examination should prioritize identifying characteristic signs of this viral infection, such as swollen lymph nodes, particularly in the neck, armpits, and groin.

  • The physician will examine the throat for inflammation and tonsillar enlargement, often with a whitish-yellow coating.
  • Palpation of the abdomen is important to assess for splenomegaly (enlarged spleen), which occurs in about 50% of mono cases, and hepatomegaly (enlarged liver), which is less common but still significant.
  • The doctor may also check for a maculopapular rash, which can appear in some patients, especially those who have taken amoxicillin or ampicillin.
  • Fever is typically present and should be documented. These physical findings, combined with symptoms like fatigue, sore throat, and headache, help establish a clinical suspicion of mono. However, definitive diagnosis typically requires laboratory confirmation through tests like the monospot test or EBV-specific antibody testing, as described in the 2013 recommendations by the Infectious Diseases Society of America (IDSA) and the American Society for Microbiology (ASM) 1. The physical examination is crucial not only for diagnosis but also for monitoring complications, particularly splenomegaly, which carries a risk of splenic rupture and may necessitate activity restrictions during recovery.

From the Research

Physical Examination for Mono

  • The physical examination for mono, also known as infectious mononucleosis, typically includes checking for symptoms such as fever, lymphadenopathy, pharyngitis, and splenomegaly 2, 3, 4, 5.
  • Splenomegaly is common in patients with infectious mononucleosis, and splenic rupture is a rare but potentially life-threatening complication 2, 3, 4.
  • The physical examination may also include checking for other symptoms such as periorbital and/or palpebral edema, skin rash, and hepatomegaly 4.
  • Laboratory tests, such as the monospot test and serologic testing for antibodies to viral capsid antigens, may be used to confirm the diagnosis of infectious mononucleosis 4, 5.

Risk of Splenic Rupture

  • The risk of splenic rupture is higher in men under 30 years old, particularly within 4 weeks of symptom onset 2.
  • Splenic rupture can occur up to 8 weeks after the onset of illness, and patients should be advised to avoid contact sports or strenuous exercise for 8 weeks or while splenomegaly is still present 2, 4.
  • The majority of cases of splenic rupture occur without a preceding history of trauma, and patients should be warned about the symptoms of splenic rupture to ensure prompt presentation and minimize treatment delay 2.

Management and Treatment

  • Treatment for infectious mononucleosis is mainly supportive, and reduction of activity and bed rest as tolerated are recommended 4.
  • Patients should be advised to avoid contact sports or strenuous exercise for 8 weeks or while splenomegaly is still present 2, 4.
  • Prompt diagnosis is essential to avoid unnecessary investigations and treatments and to minimize complications, including splenic rupture 4, 5.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Infectious mononucleosis and the spleen.

Current sports medicine reports, 2002

Research

Infectious Mononucleosis: An Updated Review.

Current pediatric reviews, 2024

Research

Infectious Mononucleosis: diagnosis and clinical interpretation.

British journal of biomedical science, 2021

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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