Infectious mononucleosis (IM) screen
IM is an acute herpes virus infection caused by the Epstein Barr Virus (EBV). It is a disease of variable severity, characterised by a range of symptoms that can include fever, lethargy, sore throat, lymphadenopathy, splenomegaly, hepatitis and jaundice. During the acute phase of illness, IM heterophile antibodies (primarily of the IgM class) appear in 80-90 % of IM cases. IM heterophile antibodies are usually demonstrable 1-12 weeks after the onset of the illness, but have been shown to persist for a year.
The test can be negative in the early stages of infection, but the presence of atypical mononuclear cells and a negative IM screen is more likely to be due to other viral infections, most notably CMV or to infection by Toxoplasma gondii.
General presentation can include sore throat, fever, fatigue, weight loss, malaise, pharyngeal inflammation, vomiting, petechiae and loss of appetite. Common signs also include lymphadenopathy, splenomegaly, hepatitis and haemolysis.
Older adults are less likely to have a sore throat or lymphadenopathy but are more likely to present with hepatomegaly and jaundice. Rarer signs and symptoms include thrombocytopenia, with or without pancytopenia, splenic rupture, splenic haemorrhage, upper airway obstruction, pericarditis and pneumonitis. A rare manifestation of mononucleosis is erythema multiforme.
Record last updated
August 21, 2025
Sample Container
4ml EDTA Vacutainers (Lavender top)
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Test Results
Yes, we have a Pathology User Guide
Yes. Please email your request to Imperial.nwlpcustomerservice@nhs.net
Results are communicated to clinical staff and are normally not communicated direct to patients either on telephone requests or in written report. If you need to contact us please click here to view the contact details page
Please contact the Customer Service Team Monday to Friday from 8:30am – 6:00pm on 0203 313 5353. Alternatively, see the Pathology User Guide for how to contact the relevant department. If advice is not urgent you can also email your query to Imperial.nwlpcustomerservice@nhs.net
Additional tests may be added by discussion with the relevant laboratory. The time limit for adding additional tests to a sample already received in the laboratory will depend on the type of sample and the department it was sent to.
Information on the repertoire of tests performed by pathology, including reference ranges, turnaround times and specimen requirements, can be found in the test directory.
Phlebotomy services are not managed by NWLP. For further information please see:
Imperial College Healthcare Trust Phlebotomy services
Chelsea and Westminster Hospital NHS Foundation Trust Phlebotomy services
NWLP operates UKAS accredited medical laboratories as per the references below. The current scope of accreditation for all NWLP’s laboratories can be found on the UKAS website.
See the following UKAS ref numbers:
- Clinical Biochemistry Ref: 8673
- Haematology and Blood Transfusion Ref: 8674
- Infection & Immunity Sciences (Including Immunology, Virology, Microbiology and Histocompatibility and Immunogenetics ) Ref: 8659
- Cellular Pathology (Including Histopathology, Cytology and Molecular Pathology) Ref: 9615
If you require copies of our certificate of accreditation and associated documentation please contact Imperial.nwlpcustomerservice@nhs.net.
UKAS requires the laboratories to be accredited for a particular repertoire/scope (ISO15189), any changes or additions to repertoire require assessment by UKAS (extension to scope).
The BD Hospital Tube Guide, BD GP Tube Guide and BD Paediatric Tube Guide provide visual references to the correct tube types and collection instructions.
Home testing
INSTRUCTION SHEET FOR BLOOD SAMPLE COLLECTION
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Our accreditations
Upholding excellence in diagnostic standards
Our laboratories are accredited by the UK Accreditation Service (UKAS) against the international standard ISO15189:2022. UKAS is the accreditation body for the UK that assesses medical laboratories.
Find out more about our accreditations on the UKAS website.
UKAS website