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HIV Testing in Emergency Departments: A Practical Guide

Clinical Value of HIV Testing in the Emergency Department

By Richard Rothman, MD, PhD

The availability of rapid HIV testing in emergency departments provides a useful tool for clinicians that can inform treatment and disposition decision making for patients, as well as guide decision making in cases of occupational exposure and sexual assault. Although no formal studies have been done as of yet to evaluate the impact of rapid testing for practice, significant anecdotal experience is being gathered from sites around the United States that have been involved in screening, risk-targeted testing, or testing based on clinical suspicion. This section discusses the clinical course of HIV in relation to current CDC guidelines and should prove useful for the practicing emergency physician, as well as those involved in establishing HIV testing programs at their institution.

Stages of HIV Infection: Implications for Clinical Suspicion and Diagnostic Testing

The new CDC guidelines provide the following specific recommendations for diagnostic testing for HIV:

  • Clinicians should maintain a high level of suspicion for acute HIV infection in any patient who has a compatible clinical syndrome and who reports recent high-risk behavior. When acute retroviral syndrome is a possibility, a plasma RNA test should be used in conjunction with an HIV antibody test.
  • Any patient with signs or symptoms consistent with HIV infection or an opportunistic illness characteristic of AIDS should be tested for HIV.

Physicians practicing in emergency settings should thus be aware of the stages of HIV infection and the commonly associated clinical conditions.

Following initial infection, there is a brief period of rapid viral replication, resulting in a short interval of high viremic load and a drop in the patient's CD4 cell count (see fig. 1, below). Up to 80% of patients develop a viral syndrome (termed "acute seroconversion reaction"), characterized by fever (occurs in greater than 90% of cases), followed most commonly by fatigue (70%-90%), pharyngitis (>70%) rash (40%-80%), headache (30%-70%) lymphadenpathy (40%-70%), diarrhea and headaches (40%-50%). From a diagnostic testing standpoint, this stage of disease is termed the "window period" (e.g., the patient has not yet mounted a sufficient antibody response to detect disease by classical diagnostic testing (HIV antibody), but the disease can be identified instead by direct detection of the HIV virus (RNA assay).

Since the timing of the clinical syndrome and development of antibodies to HIV is not exact, the CDC advises performing both antibody and RNA testing in patients who present with a viral syndrome and who have a history of recent high-risk behavior (e.g., intravenous drug use or unprotected sex with a high-risk partner). Diagnosis at this stage is considered to be particularly important for the patient (since initiation of treatment may lower the viral set point and delay progression of disease) as well as the community (an "unaware" infected patient poses a particularly high risk for transmission due to high viral load). From a practical standpoint in the emergency department, diagnostic testing for those with acute seroconversion has been relatively low yield as of yet due to the highly nonspecific nature of the clinical syndrome. Further awareness of this entity, however, may improve detection.

Fig. 1 - Changes in CD4 cell counts and plasma viraemia during HIV infection (modified
from Fauci(5) with permission). During primary infection, CD4 cell counts drop while plasma
viraemia - measured by p24 antigen assay or polymerase chain reaction - is high, and in this early
period HIV antibody levels can still be undetectable. Jolles, S. et al. BMJ 1996;312:1243-1244

Most patients with unrecognized HIV who come to the emergency department are in the "clinically latent" phase of infection (which typically lasts from 8 to 10 years in untreated individuals). The early "asymptomatic period" (CD4 count > 500) occurs after resolution of the acute HIV seroconversion reaction. Although technically coined "latent," testing should be considered for patients who present to the ED with unrelated chief complaints, but are found on review of systems or physical examination to have persistent generalized lymphadenopathy. Other nonspecific complaints which may be recognized by the astute clinician to be associated with HIV include complaints of recurrent respiratory tract infections (e.g. sinusitis, pharyngitis, and otitis media), recurrent oral ulceration, herpes zoster, Bell's palsy and a variety of dermatologic conditions (most commonly papular pruritic eruptions, seborrhoeic dermatitis and fungal nail infections).

Patient with seborrhoeic dermatitis


Patient with onchomycosis


Patient with herpes zoster

herpes zoster


Symptomatic HIV infection develops when the immune system begins to fail, but prior to the occurrence of the classic conditions known to be associated with AIDS. At this stage, patients with underlying HIV may present to the ED with a primary complaint related to their being infected with HIV, but HIV may remain unrecognized since these conditions also occur in healthy non-immune-compromised populations. Strong evidence exists that the ED is one of the most common sites of interaction with the health care system prior to the diagnosis of AIDS (i.e., patients frequently present with clinical indicator conditions but are not diagnosed at the time of their ED presentation). Clinicians should thus strongly consider HIV testing in patients who present with any of following conditions, particularly those who endorse any of the recognized behavioral risk factors.

  • Pneumonia
  • Tuberculosis
  • Severe gingivitis or peridonitis
  • Persistent oral candidiasis
  • Unexplained chronic diarrhea (longer than one month)
  • Persistent fevers
  • Unexplained severe weight loss
  • Unexplained anemia, neutropenia, or thrombocytopenia

Patient with oral thrush

oral thrush

Even patients with typical lobar
should be tested for HIV

typical lobar

Patients with AIDS often present to emergency departments with complaints related to an AIDS-defining illness. At this point, it is critical to consider that HIV, as a missed diagnosis, may lead to significant morbidity and mortality due to inadequate treatment and/or inappropriate disposition. Examples include:

  • A patient with suspected "viral" pneumonia who has underlying PCP—here, failure to consider PCP in the differential diagnosis of a patient with dyspnea on exertion and nonspecific interstitial infiltrates may lead to inadequate antibiotic coverage and inappropriate disposition.
  • A patient who has headache, weakness, and low-grade fever with unrecognized risk factors and/or other sign of HIV (e.g., thrush or significant weight loss)—here, failure to consider serious CNS infections such as cryptococcal meningitis would likely lead to significant morbidity and mortality.

By definition, AIDS occurs when the patient's immune system becomes severely compromised (CD4 count less than 200). This table lists common AIDS-defining illnesses and associated common clinical presentation that should be considered in the ED.

Common Clinical Presentation of AIDS-defining Illnesses

Conditions to Consider Presenting Complaint Additional Comments
(see images below)
Dyspnea on exertion; fever, indolent cough CXR typically shows perihilar infiltrates.
Atypical CXR patterns common in later stage disease with 25% normal—look for hypoxemia
Recurrent bacterial pneumonia Cough, fever Routinely inquire about history of prior pneumonia
Cryptococcal meningitis Headaches, fever, change in mental status most common Serum and CSF crypotococcal antigen testing
(see image below)
Headache, fever, change in mental status most common; may see focal neurologic findings CT (with contrast): ring-enhancing lesion
Encephalitis Personality changes, headache, weakness CT shows diffuse atrophy
Lymphoma Headache, weakness, delta ms, may see focal neurologic findings CT shows single lesion
Candidiasis (esophogeal) Dysphagia; odonphagia; dehydration Direct examination of scraping: presence of pseudohyphal elements
Cryptosporidiosis; isosporiasis Prolonged diarrheal illness with dehydration Requires diagnostic testing of stool (culture, ova, and parasites)
Kaposi's sarcoma(c)
(see image below)
Darkly pigmented lesions Biopsy of lesion: proliferation of spindle cells and endothelial cells; hemosiderin-laden macrophages; extravasated RBCs
Salmonella septicemia (recurrent)
Prolonged or recurrent fevers, anorexia, fatigue, malaise; or local infection in bone, joints, pleura pericardium Culture: isolation of serotypes in blood, bone marrow, or site of infection
HIV wasting syndrome Weight loss >10% with fever, chronic diarrhea or fatigue > 1 month; severe muscle wasting Inquire about unintentional weight loss; look for temporal wasting
CMV retinitis
Painless progressive loss of vision; blurred vision; "floaters"; blind spots Fundoscopy (generally requires slit-lamp examination); findings include perivascular hemorrhage and exudate
Cervical cancer(d)
(see image below)
Genital warts or history of HPV
is a recognized risk. Consider early cervical CA in patients with genital warts and low-grade fever, fatigue, or weight loss
In women with history of genital warts or suspicious lesions, refer for Pap smear (squamous intraepithelial lesions). Cone biopsy advised in cases of serious cervical dysplasia

*Selected Images from Table

a. Two examples of diffuse interstitial infiltrates on chest x-ray in patients with PCP pneumonia
(the one on the left is more subtle)

Diffuse Interstitial Infiltrates

Diffuse Interstitial Infiltrates

b. Multiple toxoplasmosis enhancing
lesion on CT with contrast

Multiple Toxoplasmosis Enhancing Lesion

c. Patient with Kaposi's lesions on skin

Kaposi's Lesions

d. Human papillomavirus (HPV) lesions around perianal region

Human Papilloma Virus

Post-exposure Prophylaxis (PEP): The Clinical Value of Readily Available HIV Testing

The CDC provides detailed recommendations regarding PEP for both occupational and nonoccupational exposures. Critical elements of PEP that the emergency physician should be aware of include indications, timing, and procedures for referral in cases where ED treatment is initiated. The availability of ED-based rapid HIV testing is a crucial component of effective PEP because (1) decision making regarding treatment relies on rapid determination of the risk of the source patient, and (2) treatment may be rapidly initiated.

A detailed but easy-to-follow discussion of guidelines for PEP can be found on the CDC website for occupational exposure and nonoccupational exposure (PDF).

Occupational Exposure

Compelling data from retrospective case control studies found an 81% reduction of HIV infection in exposed health care workers (HCWs) who used PEP. Accordingly, PEP should be considered in all potential cases of HCW exposure. Because exposures often occur outside of weekday working hours, EDs serve as an important resource for HCWs in their own hospital, as well as those of nearby clinics and other health care facilities. The two fundamental considerations in determining need for PEP is information about the source (ideally, HIV serostatus) and the severity of exposure (e.g., mucus membrane or needle-stick exposure). Simple tables that guide treatment decisions can be found on the CDC Web site. In general, if the source patient can be tested immediately and is found to be HIV seronegative, PEP is considered unnecessary and not recommended. In those cases where the source is seropositive, treatment can be initiated almost immediately and in compliance with the recommended time frame for treatment initiation (within one hour if possible). Several ED-based programmatic studies have been conducted over the past several years demonstrating both the need and the effectiveness of HIV rapid testing services in EDs for health care workers who use PEP.

Nonoccupational Exposure

There are several routes of potential nonoccupational exposure to HIV for which the ED should (or may be asked to) consider PEP. These include victims of sexual assault and high-risk cases of unprotected sex and intravenous needle-sharing.

In 2005, CDC released new guidelines (PDF) regarding nonoccupational HIV PEP: For persons seeking care less than 72 hours after nonoccupational exposure to blood, genital secretions, or other potentially infectious bodily fluids of a person known to be HIV-infected (when that exposure represents a substantial risk for transmission), PEP is recommended and medications should be initiated as soon as possible after exposure. For those exposures that occur with persons of unknown HIV status, no recommendation is made.

The new recommendations are of limited utility for emergency physicians since in the vast majority of cases, the HIV status of the source will be unknown (reference 1). Further, since the source is generally unavailable, rapid testing rarely has direct utility for treatment decisions. In the vast majority of cases decision making will thus be on a case-by-case basis. General consideration regarding initiation of treatment should include the weighing of behavioral factors and the circumstances that led to HIV exposure, the patient's risk of HIV acquisition based on the type of exposure, and the possibility that the source is HIV-infected based on individual risks (if known) and/or risks of the local population (reference 2).

Emergency physicians have the most experience in nonoccupational PEP in the context of sexual assault victims. Here, PEP decision making should be initiated rapidly in conjunction with rape counselors. The few published studies describing PEP in victims of assault indicate that treatment is not routinely offered and is rarely completed for those seeking care in EDs, indicating a need for further education of both emergency physicians and patients. It remains unclear what the impact of the new CDC guidelines will have on the frequency of patient presentations to the ED, as well as ED physician practice. Again, further education and research are required.


  1. Merchant C, Mayer K. Perspectives on new recommendations for nonoccupational HIV postexposure prophylaxis JAMA. 2005;293(19):2407-2409.
  2. New York State Department of Health. HIV prophylaxis following nonoccupational exposure including sexual assault. National Guideline Clearinghouse [Accessed May 15, 2007.]


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