Prior authorization for a CT scan

CT requests are often reviewed with one question in mind: why this test, and why now, rather than a cheaper or radiation-free option. A good request answers that before it is asked, and it shows the reviewer the prior imaging and the clinical change that prompted the scan.

What CT reviewers check

Unlike MRI requests, where the argument is often about how long conservative care lasted, CT reviews focus on test selection and on repetition. Reviewers want to see that ultrasound or plain radiography was considered or has already been done, that the scan is not a repeat of a recent study without a new reason, and that contrast is justified and safe.

• The clinical question the scan will answer, in one sentence.
• Why CT rather than ultrasound, x-ray or MRI for that question, including patient factors such as body habitus or an implanted device.
• Prior imaging of the same area: date, modality and the finding that needs follow-up or clarification.
• For follow-up of a finding, its size or character and the interval since it was last seen.
• Risk factors that raise pre-test probability, such as smoking history for a lung nodule.
• Kidney function and allergy history when contrast is requested.

The order to write it in

Begin with the exact study, since CT codes differ by region and by contrast phase. CT chest without contrast is 71250. Follow with the indication and its diagnosis code, then the prior imaging, then the risk factors, and finish with how the result will be used. Reviewers reading dozens of CT requests a day look for the prior study and the interval first, so put them near the top.

Example

Request: CT chest without contrast (71250).
Diagnoses: Solitary pulmonary nodule (R91.1); personal history of nicotine dependence (Z87.891).

An 8 mm solid nodule in the right upper lobe was reported on a CT pulmonary angiogram performed for chest pain three months ago. The same report recommended interval CT follow-up. No prior chest imaging is available for comparison.

[Patient initials], 61, is a former smoker with a 30 pack-year history who stopped four years ago. There is no haemoptysis or weight loss.

Given the nodule size and risk profile, follow-up CT at three months is requested to assess for growth. The result will determine whether the patient is discharged from surveillance, continues interval imaging or is referred for further assessment.

Why CT requests come back

1. Test choice not explained. An abdominal CT for right upper quadrant pain without a prior ultrasound is a frequent refusal. If ultrasound was done or was unsuitable, say so with the date or the reason.
2. Repeat scan without a new indication. Give the date of the last study and the clinical change since then, or the follow-up interval the original report recommended.
3. Contrast not supported. State why the phase is needed and include a recent kidney function result.
4. Symptom code too vague. Abdominal pain has site-specific codes, for example R10.31 for right lower quadrant pain. Use the one that matches the examination.

Where ClearPass fits

You can photograph the earlier radiology report and have its findings read into the note, after removing identifiers from the image. From that note ClearPass drafts the CT justification in the length you choose, with ICD-10 and procedure codes. Outside the one country where it holds a rules pack, the letter argues clinical necessity and does not quote a payer's imaging criteria. It never states that the scan will be approved, and you check every line before filing. For MRI, the reasoning differs; see MRI prior authorization.

What ClearPass does not do

• It does not replace your judgement. Every note is an AI draft that you review and correct before it is used.
• It is not a medical device and does not make clinical decisions. It is a documentation aid.
• It does not connect to your EMR. The note is copy-ready text that pastes into any system.

Privacy

Clinical note content is not stored on ClearPass servers: it is processed to write the note, then discarded. Consultation audio is transcribed and discarded, never stored. Your note history stays in your browser, on your device, and you choose how long it is kept. Common identifiers are removed from typed and transcribed text before it reaches the AI; that is a best-effort safeguard, so leave names, ID numbers and file numbers out where you can. Processing goes through the AI providers named in our Privacy Policy, which sets out exactly what each one receives and how long it keeps it. ClearPass does not sign HIPAA business associate agreements today.

Questions

Related

• Prior authorization for MRI: what the request needs
• ICD-10 codes that support a prior authorization request
• Prior authorization letters written from the visit itself
• An AI medical scribe for pulmonology