What Is CPT 71271 for Low-Dose Lung Screening?

CPT 71271 is the medical billing code assigned to a low-dose computed tomography (LDCT) scan of the chest performed specifically for lung cancer screening. When your doctor orders this scan, the code tells your insurer that the purpose is to look for early-stage lung cancer in someone at high risk, not to diagnose symptoms you already have. The distinction matters because preventive screening and diagnostic imaging follow different coverage and reimbursement rules. Behind this five-digit code sits a body of evidence showing that annual LDCT screening saves lives in the right population, along with a set of eligibility rules, interpretation standards, and practical trade-offs that are worth understanding before you walk into the radiology suite.

How CPT 71271 Fits Into Lung Cancer Screening

Before CPT 71271 was introduced, providers used a patchwork of temporary and miscellaneous codes to bill for screening LDCT. The code 71271 was created to give a single, specific Category I CPT code for this purpose, replacing earlier codes like G0297 (a CMS-specific HCPCS code) and S8032 (a temporary code some private insurers recognized). Research tracking screening rates during the pandemic, for instance, identified all three codes together when measuring how many Medicare enrollees received lung screening LDCT.¹ In practice, 71271 is now the standard code you will see on your explanation of benefits if you undergo a screening LDCT.

The scan itself takes only a few seconds of breath-holding. You lie on a table that slides through a CT scanner, and the machine captures images of your entire chest in one pass. “Low-dose” means the radiation exposure is kept far lower than a standard diagnostic chest CT. Advances in image reconstruction technology have helped make this possible. Iterative reconstruction algorithms reduce the noise in images acquired at very low radiation doses, which means radiologists can read the scans confidently even though you are exposed to less radiation.² No IV contrast is needed, and the whole visit is typically in and out within 30 minutes.

Who Qualifies for Screening Under 71271

Not everyone can walk into a radiology center and get this scan covered as preventive screening. The U.S. Preventive Services Task Force (USPSTF) recommends annual LDCT for adults aged 50 to 80 who have a 20 pack-year smoking history and who currently smoke or quit within the past 15 years.³ A “pack-year” is one pack per day for one year, so someone who smoked two packs a day for ten years has 20 pack-years, and so does someone who smoked one pack a day for twenty.

These updated criteria, issued in 2021, expanded the eligible population considerably compared with earlier guidelines that required 30 pack-years and limited screening to ages 55 through 80. The lower threshold and younger starting age could nearly double the number of people eligible, potentially saving as many as 60,000 lives in the United States.⁴ Screening should stop once a person has not smoked for 15 years or develops a health problem that limits life expectancy or the willingness to pursue curative treatment.

Medicare has its own coverage determination that historically tracked more closely with the older, more restrictive criteria, covering people aged 55 through 77 with at least a 30 pack-year history. CMS has since moved to align more closely with the USPSTF update, but the details of age cutoffs and pack-year thresholds can lag behind the USPSTF recommendation depending on when final rules take effect. One firm Medicare requirement is that before your first screening LDCT is covered, you must have a shared decision-making visit with a qualified clinician who discusses the benefits, limitations, and potential harms of screening.⁵

The Evidence That LDCT Screening Reduces Deaths

The whole rationale for screening, and for CPT 71271 existing, rests on two landmark randomized trials. The National Lung Screening Trial (NLST) in the United States enrolled over 53,000 high-risk adults and found that three rounds of annual LDCT reduced lung cancer deaths by about 20% compared with standard chest X-rays.⁶ The Dutch-Belgian NELSON trial, the largest European trial, reported an even larger reduction: at ten years of follow-up, lung cancer mortality dropped by roughly 24% in the screening group.⁷

A systematic review synthesizing these and other trials for the USPSTF estimated that you would need to screen about 130 people over ten years to prevent one lung cancer death based on NELSON data, or about 323 people over roughly seven years based on NLST data.⁸ Those numbers are well within the range considered worthwhile for a population screening program. For context, the number of people you need to screen to prevent one death from breast cancer with mammography is in a similar ballpark.

What Happens After the Scan

Once the images are captured, a radiologist reads them and assigns a score using Lung-RADS, a standardized reporting system developed by the American College of Radiology. Lung-RADS categories range from 1 (negative, no lung nodules) through 4 (suspicious findings that warrant further workup), with subcategories in between for nodules that are probably benign but should be watched. The system was designed to bring consistency to how radiologists report findings and to reduce the number of false alarms.

Lung-RADS has substantially cut false-positive rates compared with the original NLST criteria. When Lung-RADS was applied retrospectively to NLST data, the false-positive rate after baseline dropped to about 5%, compared with roughly 22% under the original trial protocol.⁹ That improvement comes with a trade-off in sensitivity, meaning Lung-RADS catches somewhat fewer true cancers than the looser NLST criteria did, but the reduction in unnecessary follow-up procedures is considered worth it by most screening programs.

If your result is Lung-RADS 1 or 2, you simply return for your next annual screen. Lung-RADS 3 typically means a small nodule was found and a short-interval follow-up scan in six months is recommended. Lung-RADS 4 flags a nodule that may be cancer and usually leads to additional imaging, possibly a PET scan, and sometimes a biopsy.

False Positives, Follow-Up, and Overdiagnosis

False positives are the most commonly discussed downside of lung screening. Across multiple studies, the false-positive rate for LDCT has ranged from about 9% to 50%, with an average around 20% when using older interpretation criteria.¹⁰ With Lung-RADS now standard, real-world screening programs report false-positive rates closer to 13%.¹¹ Several factors push individual risk of a false positive up or down, including whether it is your first scan (higher false-positive rate) versus a repeat, whether you have emphysema or COPD, and even the experience level of the radiologist reading the images.

Most false positives resolve without invasive procedures. Among Medicare enrollees who had an LDCT screening, only about 3% underwent any follow-up procedure such as bronchoscopy, biopsy, or surgery within the following year, and the rate was lower for people on their second screening compared to their first.¹² Still, the anxiety and cost of follow-up imaging and the small risk from biopsies are real harms that the shared decision-making visit is supposed to address.

A related concern is overdiagnosis, the detection of a cancer that is real but so slow-growing it would never have caused symptoms or death. An analysis of the NLST estimated that about 18.5% of lung cancers detected by LDCT were overdiagnosed.¹³ A separate study using different modeling put the proportion of slow-growing or indolent cancers at around 25% of cases detected.¹⁴ This does not mean those cancers are harmless on a cell biology level, but it means some people end up treated for a cancer that was never going to threaten their life. Researchers are working on ways to identify indolent tumors earlier so that “active surveillance” can be offered instead of immediate surgery.

Insurance Coverage and Out-of-Pocket Costs

Under the Affordable Care Act, most private insurers must cover USPSTF-recommended preventive services with no cost sharing. Since LDCT lung screening carries a USPSTF “B” recommendation, that means the screening scan itself should be free to you if you meet the eligibility criteria. Medicare similarly covers the screening LDCT with no copay or deductible, provided you satisfy CMS-specific eligibility requirements and complete the shared decision-making visit.

Where costs can accumulate is in the follow-up. If your screening LDCT finds something that needs further investigation, the follow-up imaging and procedures shift from preventive to diagnostic billing, and normal cost-sharing kicks in. Among commercially insured patients who had follow-up procedures after a screening LDCT, the average out-of-pocket cost per episode was about $62, though the total insurer-plus-patient cost was substantially higher.¹⁵ That average is modest, but individual cases requiring biopsy or surgery can generate bills many times that figure.

Disparities in Who Gets Screened

Despite the expanded eligibility criteria, lung cancer screening remains underused, and the gaps are uneven across racial and socioeconomic lines. A systematic review found that Black and socioeconomically disadvantaged individuals face disparities at every stage: eligibility, actual utilization of screening, and follow-up care after a positive result.¹⁶

Part of the problem is the eligibility criteria themselves. Because the USPSTF criteria are built around pack-years of cigarette smoking, they inherently favor populations with higher rates of heavy cigarette use. Under both the old and updated guidelines, Black and Hispanic adults are significantly less likely to meet pack-year thresholds for eligibility, even though Black men have higher lung cancer incidence than white men. Compared with white respondents in national survey data, Black respondents were about 60% less likely and Hispanic respondents about 85% less likely to qualify for screening.¹⁷ This has prompted calls to incorporate individual risk prediction models rather than pack-year thresholds alone.

Incidental Findings on Screening LDCT

One consequence of scanning the entire chest that surprises many people is the high rate of incidental findings — things the radiologist sees that have nothing to do with lung cancer. In a large prospective study of screening participants in Australia and Canada, nearly three-quarters of people had at least one incidental finding on their baseline scan. The most common were coronary artery calcification (found in about 69% of people screened) and emphysema (about 54%).¹⁸ About 10% of participants had an incidental finding that required clinical follow-up outside the screening program.

A U.S. study cataloged similar patterns, finding that the most commonly reported incidental findings fell into pulmonary, cardiovascular, and gastrointestinal categories. About 15% of scans had an incidental finding that triggered further evaluation, with cardiovascular findings accounting for the largest share.¹⁹ Thyroid nodules, adrenal nodules, liver lesions, and kidney masses also turn up. Some of these findings are genuinely useful — early detection of significant coronary calcification, for instance, could prompt preventive cardiac care. Others generate additional testing and anxiety for conditions that turn out to be benign. This is another area the shared decision-making conversation should cover.

Smoking Cessation and the Screening Visit

Because everyone eligible for LDCT screening is either a current smoker or a recent former smoker, the screening visit is a natural moment to address tobacco cessation. In an Ontario pilot program that integrated smoking cessation counseling directly into the screening workflow, about 89% of current smokers attended the counseling session, and the one-year quit rate was 15.5%.²⁰ Those who did not quit still showed measurable reductions in the number of cigarettes smoked per day and in markers of nicotine dependence.

Despite this encouraging signal, a systematic review found insufficient data to recommend any single approach to cessation counseling within the screening setting. Whether the counseling should be brief or intensive, whether medications like nicotine replacement or varenicline should be offered proactively, and how follow-up should be structured are all open questions.²¹ What is clear is that quitting smoking delivers a larger mortality benefit than screening itself. The two are complementary, and some researchers argue that any screening program that does not incorporate cessation support is leaving the biggest potential benefit on the table.

Artificial Intelligence in LDCT Interpretation

Radiologists reading screening LDCTs may increasingly have AI assistance. Several computer-aided detection systems have been tested as “second reader” tools, and the results are promising. In a prospective randomized trial, radiologists who used an AI tool detected significantly more Lung-RADS-positive nodules (about 17% of scans flagged) compared with radiologists without AI assistance (about 10%), with no increase in reading time.²²

The benefit is especially pronounced for less experienced readers. In a study comparing radiologists at different career stages, residents using AI as a second reader saw their nodule detection rate jump from 64% to 77%, while senior radiologists, who were already catching most nodules, showed no meaningful improvement.²³ AI tools have also shown strong agreement with expert readers for coronary artery calcium scoring on screening LDCT images, which means a single scan could eventually serve double duty as both a lung cancer screen and a cardiovascular risk assessment.²⁴

Blood Biomarkers and the Future of Screening

One limitation of LDCT is that it finds plenty of nodules but cannot easily distinguish a dangerous cancer from a harmless lump of scar tissue. Researchers are exploring whether blood-based biomarkers can help. In the BioMILD trial, combining baseline LDCT results with a panel of circulating microRNAs in the blood predicted individual lung cancer risk and mortality better than imaging alone, which could eventually allow doctors to personalize how often each patient is rescanned.²⁵

Another approach involves looking at circulating tumor cells in people whose scans already show suspicious Lung-RADS 4 nodules. Early-stage work has shown that combining these cell-based blood tests with LDCT findings produced very high sensitivity and specificity for distinguishing cancer from non-cancer among patients with worrisome nodules.²⁶ More recently, researchers have tested combinations of immune and molecular blood markers and found that integrating these with imaging results produced a high negative predictive value, giving clinicians greater confidence in ruling out malignancy in LDCT-detected nodules and reducing the need for invasive follow-up.²⁷

None of these blood-based tools are part of standard clinical practice yet. But they point toward a future where the annual LDCT captured under CPT 71271 is one piece of a broader, more personalized screening strategy rather than a standalone test. If a simple blood draw before or after the scan could tell your doctor whether a nodule is worth worrying about, the false-positive problem that has dogged lung screening since the beginning could shrink considerably.