Updated on: May 12, 2020

Screening for COVID-19: When to use Z11.59

Original story posted on: May 11, 2020

Widespread testing for antibodies is not considered screening. Screening is for identifying the disease state.

People are really struggling with understanding when to apply Z11.59, Encounter for screening for other viral diseases, in relation to COVID-19. I think the issue is that we are trying to wrap our minds around this during a pandemic.

Let’s think about another condition for a moment to help us.

Tuberculosis is one of the top 10 causes of death in the world, and in 2018, an estimated 10 million people were ill with TB, globally. Worldwide, 1.5 million people died from tuberculosis in 2018, including a quarter of a million people with HIV.

In the United States, there are only approximately 9,000 tuberculosis cases per year, causing about 500 deaths annually. However, in the early 1800s, more than 25 percent of the deaths in New York City resulted from TB. Untreated tuberculosis has an R naught (R0) of approximately 10, which means one infected person can spread it to 10 people (COVID-19 has an R0 of ~2.3).

The decrease in deaths was multi-factorial, including better sanitation and an improved ability to diagnose the infection. But to this day, we still screen hospital personnel on a yearly basis for undetected tuberculosis infections. It is because healthcare workers are at a higher-than-average risk of encountering patients who can unwittingly transmit the bacillus. The code for this service is Z11.1, Encounter for screening for respiratory tuberculosis.

If an outbreak of TB was discovered in a particular homeless shelter, and all the individuals who might have been exposed were tested, this would not be a screening situation. This would be Z20.1, Contact with and (suspected) exposure to tuberculosis. If a homeless person were brought in for evaluation and it was eventually determined that they had never been to that affected shelter, their code would be Z03.818, Encounter for observation for suspected exposure to other biological agents ruled out.

During a pandemic, COVID-19 is, or has the potential to be, everywhere. If a patient is tested, it is either because they have symptoms, they are known to have been exposed, or we are concerned that they might have been exposed.

The World Health Organization (WHO) defines screening as “the presumptive identification of unrecognized disease in an apparently healthy, asymptomatic population by means of tests, examinations or other procedures that can be applied rapidly and easily to the target population.” It is the systematic application of a test to identify asymptomatic individuals at risk of a specific disorder to warrant further investigation or direct preventative action. There is a risk, but not an expectation, that a given person will have the condition. There is no known or potential exposure. Screening is a public health service in which members of a defined population who do not necessarily perceive themselves to be at risk or already affected by a condition are tested.

Back to 2020: elective procedures are now resuming. Part of the preprocedural work-up includes COVID-19 testing. At this time, it is because there is a significant chance the patient is infected due to the sheer prevalence of the virus. Years from now, when we are no longer in a pandemic situation, if we continue the practice of routinely testing for COVID-19 preoperatively to maintain surveillance and identify isolated infections to prevent dissemination, that will be screening, Z11.59.

Testing now is more diagnostic. It is to rule out COVID-19 in patients at risk. Testing in the future, when COVID-19 is a more contained infectious disease and exposure is not suspected, will be screening. It will be to rule in COVID-19 for a population with a low index of suspicion; there will be a lot to lose if we miss it.
Antibody testing is for identifying previous infection. You use Z01.84, Encounter for antibody response examination, as the code for this testing.

Keep in mind that your providers may use the word “screening” when it is not applicable, coding-wise. Just another coding-clinical disconnect to work through. Additionally, the coding guidelines constrain us in the use of Z03.818. Review the American Hospital Association/American Health Information Management Association (AHA/AHIMA) guidance (https://www.codingclinicadvisor.com/faqs-icd-10-cm-coding-covid-19) for their recommendations.

Regrettably, COVID-19 is going to be around for a long time. We are going to need to be facile using these codes. Be on the lookout for my COVID-19 coding flowcharts, coming soon to the ICD10monitor store. Perhaps they will help.


On May 1, 2020, the community of West Bloomfield, Mich., a suburb of Detroit, gets a stash of PCR tests and tests every inhabitant over 18 to identify COVID-19 cases.

Patients who test negative who are not believed to have COVID-19 would warrant Z20.828, Contact with and (suspected) exposure to other viral communicable diseases. The disease is known to be present in the Detroit community, and we suspect potential exposure. We are trying to identify the ill and asymptomatic patients. Remember, by definition, Z20.828 and Z03.818 are only for patients who are negative. If they were positive, the code would be U07.1, COVID-19.

On May 5, 2020, a patient comes in for outpatient preoperative clearance for an elective hip replacement scheduled for May 8. They have no known COVID-19 exposure. They get a PCR test and are told to isolate for the next three days. Their test returns negative, and the hip replacement is successful.

I would want to use Z03.818, Encounter for observation for suspected exposure to other biological agents ruled out, for the COVID-19 test. They stated there was no known COVID-19 exposure.

However, there is an Excludes1 note for Z01.81-, Encounter for preprocedural examination, and both Z01 and Z03 codes are mandatory principal/first-listed diagnoses, “except when there are multiple encounters on the same day and the medical records for the encounters are combined.” But Z01.81- isn’t going to justify a COVID-19 test. It is still pandemic time, so you can’t be sure there was no exposure.

I think you would have to use Z01.81- and Z20.828, until they change the guidelines to allow Z03.818 be a secondary code and eliminate the Excludes1. The guidance for Z20.828 is that it can be used when the disease is epidemic.

On May 6, 2020, an emergency appendectomy takes place in Chicago, Ill. No known or suspected COVID-19 exposure. Patient undergoes PCR testing to rule out COVID-19 infection to determine whether they need to be admitted to the COVID-19 unit. The test is negative.

Again, should be Z03.818, but it can’t be, because that would be a ridiculous principal diagnosis. It is pandemic time, so use Z20.828 as the justification for the PCR test.

It’s May 2025. All patients admitted to Happy Homes Assisted Living must get COVID-19 PCR testing, ever since 2020. Aunt Beulah goes to her PCP to get the test done to bring her results with her.

Z11.59, Encounter for screening for other viral diseases. This is a routine test done to a population (the population of people who want to live at Happy Homes) without concern for exposure.

On May 1, 2023, the community of West Bloomfield, Mich., a suburb of Detroit, PCR tests every inhabitant over 18 as scheduled public health surveillance.

Z11.59, Encounter for screening for other viral diseases. This is a routine test done to a population to identify unrecognized disease carrier state.

On May 2, 2022, John Smith returns home from a trip to a locale where COVID-19 is endemic. He didn’t get his COVID-19 vaccine, has a fever, and started to cough. He goes to his PCP for evaluation.

If the test is negative, and the provider doesn’t think he has COVID-19, Z20.828. He is considered to have had potential exposure. The provider could also have diagnoses COVID-19 clinically if they felt the clinical situation supported it. The PCR testing (currently) has a 30-percent false negative rate.

On May 2, 2022, John Smith returns home from a trip to a locale where COVID-19 is endemic. He was scheduled for his yearly check-up and is asymptomatic. His doctor thinks it would be prudent to check a COVID-19 PCR test. It returns negative.

Z20.828. There is suspected or potential exposure.

It’s May 2, 2022. John Smith goes to his doctor for his yearly check-up. They routinely do a COVID-19 PCR test once a year, so they swab him. It is negative.

Z11.59. THIS is a screening. No concern for exposure. Routine surveillance.

It’s May 2, 2022. John Smith goes to his doctor for his yearly check-up after having seen Contagion on Netflix. He remembers how awful COVID-19 was in 2020, and asks the doctor to be swabbed. There are sporadic cases in his community, but he has not had any concrete exposure. The doctor complies, and the test is negative.

Z03.818, Encounter for observation for suspected exposure to other biological agents ruled out. The provider thought it was reasonable to check, but there was no known or suspected exposure. The test was negative.

May 2, 2022. John Smith goes to his doctor after having seen Contagion on Netflix last night. He remembers how awful COVID-19 was in 2020, and asks the doctor to be swabbed. There have not been any cases in his community since 2020, there has been no known or suspected exposure, and John has had his COVID-19 vaccine. His doctor reassures him without performing a PCR test.

Z71.1, Person with feared health complaint in whom no diagnosis is made.

Programming Note: Listen to Dr. Erica Remer every Tuesday on Talk Ten Tuesdays, 10-10:30 a.m. EST.

Disclaimer: Every reasonable effort was made to ensure the accuracy of this information at the time it was published. However, due to the nature of industry changes over time we cannot guarantee its validity after the year it was published.
Erica E. Remer, MD, CCDS

Erica Remer, MD, CCDS has a unique perspective as a practicing emergency physician for 25 years, with extensive coding, CDI, and ICD-10 expertise. She was a physician advisor of a large multi-hospital system for four years before transitioning to independent consulting in July 2016. Her passion is educating CDI specialists, coders, and healthcare providers with engaging, case-based presentations on documentation, CDI, and denials management topics. She has written numerous articles and serves as the co-host of Talk Ten Tuesdays, a weekly national podcast. Dr. Remer is a member of the ICD10monitor editorial board, a former member of the ACDIS Advisory Board, and the board of directors of the American College of Physician Advisors.

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