Need help choosing the right code?
Ask CasePilot about procedures, modifiers, bundling, and coding guidance.
Try CasePilot© Copyright 2026 American Medical Association. All rights reserved.
A multiple sleep latency test (MSLT) or maintenance of wakefulness test is a specialized procedure designed to evaluate the presence and severity of daytime sleepiness, as well as to identify sleep abnormalities that may be associated with conditions such as narcolepsy. This test is typically conducted in a sleep study center, where the patient arrives in the morning after having completed a normal nighttime sleep period, usually about two hours prior to the start of the test. The procedure involves the attachment of various electrodes to the patient's body to monitor and record physiological measurements during multiple trials. These measurements include brain activity through electroencephalography (EEG), heart rate via electrocardiogram (ECG) electrodes, and muscle and eye movement through additional electrodes placed around the eyes and under the chin. Furthermore, an oxygen probe is affixed to the patient's finger to assess blood oxygen saturation, while airflow measurement devices are positioned at the nose and mouth to monitor respiratory function. The MSLT consists of a series of timed naps taken at two-hour intervals, interspersed with periods of wakefulness, during which the patient is observed by a sleep technologist through closed-circuit television. The environment is controlled, with the room darkened during nap periods to facilitate sleep. Throughout the test, the patient's ability to maintain wakefulness is assessed, and the collected data is meticulously analyzed by the physician, who then provides a comprehensive written interpretation of the physiological measurements obtained during the testing period.
© Copyright 2026 Coding Ahead. All rights reserved.
The multiple sleep latency test (MSLT) is indicated for the evaluation of various conditions related to excessive daytime sleepiness and sleep disorders. The following are the specific indications for performing this test:
The procedure for conducting a multiple sleep latency test (MSLT) involves several key steps that ensure accurate monitoring and assessment of the patient's sleep patterns and wakefulness. The following outlines the procedural steps:
Post-procedure care for patients who have undergone a multiple sleep latency test (MSLT) typically involves monitoring for any immediate effects of the test. Patients may resume their normal activities following the test, as there are generally no significant recovery requirements. However, it is important for the physician to review the results with the patient, discussing the findings and any potential implications for their health. The physician may recommend further evaluation or treatment based on the interpretation of the physiological measurements obtained during the MSLT.
| Short Descr | MULTIPLE SLEEP LATENCY TEST | Medium Descr | MLT SLEEP LATENCY/MAINT OF WAKEFULNESS TSTG | Long Descr | Multiple sleep latency or maintenance of wakefulness testing, recording, analysis and interpretation of physiological measurements of sleep during multiple trials to assess sleepiness | Status Code | Active Code | Global Days | XXX - Global Concept Does Not Apply | PC/TC Indicator (26, TC) | 1 - Diagnostic Tests for Radiology Services | Multiple Procedures (51) | 0 - No payment adjustment rules for multiple procedures apply. | Bilateral Surgery (50) | 0 - 150% payment adjustment for bilateral procedures does NOT apply. | Physician Supervisions | 09 - Concept does not apply. | Assistant Surgeon (80, 82) | 0 - Payment restriction for assistants at surgery applies to this procedure... | Co-Surgeons (62) | 0 - Co-surgeons not permitted for this procedure. | Team Surgery (66) | 0 - Team surgeons not permitted for this procedure. | Diagnostic Imaging Family | 99 - Concept Does Not Apply | APC Status Indicator | Procedure or Service, Not Discounted when Multiple | Type of Service (TOS) | 5 - Diagnostic Laboratory | Berenson-Eggers TOS (BETOS) | T2D - Other tests - other | MUE | 1 | CCS Clinical Classification | 227 - Other diagnostic procedures (interview, evaluation, consultation) |
| 26 | Professional component: certain procedures are a combination of a physician or other qualified health care professional component and a technical component. when the physician or other qualified health care professional component is reported separately, the service may be identified by adding modifier 26 to the usual procedure number. | TC | Technical component; under certain circumstances, a charge may be made for the technical component alone; under those circumstances the technical component charge is identified by adding modifier 'tc' to the usual procedure number; technical component charges are institutional charges and not billed separately by physicians; however, portable x-ray suppliers only bill for technical component and should utilize modifier tc; the charge data from portable x-ray suppliers will then be used to build customary and prevailing profiles | 52 | Reduced services: under certain circumstances a service or procedure is partially reduced or eliminated at the discretion of the physician or other qualified health care professional. under these circumstances the service provided can be identified by its usual procedure number and the addition of modifier 52, signifying that the service is reduced. this provides a means of reporting reduced services without disturbing the identification of the basic service. note: for hospital outpatient reporting of a previously scheduled procedure/service that is partially reduced or cancelled as a result of extenuating circumstances or those that threaten the well-being of the patient prior to or after administration of anesthesia, see modifiers 73 and 74 (see modifiers approved for asc hospital outpatient use). | 59 | Distinct procedural service: under certain circumstances, it may be necessary to indicate that a procedure or service was distinct or independent from other non-e/m services performed on the same day. modifier 59 is used to identify procedures/services, other than e/m services, that are not normally reported together, but are appropriate under the circumstances. documentation must support a different session, different procedure or surgery, different site or organ system, separate incision/excision, separate lesion, or separate injury (or area of injury in extensive injuries) not ordinarily encountered or performed on the same day by the same individual. however, when another already established modifier is appropriate it should be used rather than modifier 59. only if no more descriptive modifier is available, and the use of modifier 59 best explains the circumstances, should modifier 59 be used. note: modifier 59 should not be appended to an e/m service. to report a separate and distinct e/m service with a non-e/m service performed on the same date, see modifier 25. | 95 | Synchronous telemedicine service rendered via a real-time interactive audio and video telecommunications system: synchronous telemedicine service is defined as a real-time interaction between a physician or other qualified health care professional and a patient who is located at a distant site from the physician or other qualified health care professional. the totality of the communication of information exchanged between the physician or other qualified health care professional and the patient during the course of the synchronous telemedicine service must be of an amount and nature that would be sufficient to meet the key components and/or requirements of the same service when rendered via a face-to-face interaction. modifier 95 may only be appended to the services listed in appendix p. appendix p is the list of cpt codes for services that are typically performed face-to-face, but may be rendered via a real-time (synchronous) interactive audio and video telecommunications system. | CC | Procedure code change (use 'cc' when the procedure code submitted was changed either for administrative reasons or because an incorrect code was filed) | CR | Catastrophe/disaster related | GA | Waiver of liability statement issued as required by payer policy, individual case | GC | This service has been performed in part by a resident under the direction of a teaching physician | GZ | Item or service expected to be denied as not reasonable and necessary | PO | Excepted service provided at an off-campus, outpatient, provider-based department of a hospital | X5 | Diagnostic services requested by another clinician: for reporting services by a clinician who furnishes care to the patient only as requested by another clinician or subsequent and related services requested by another clinician; this modifier is reported for patient relationships that may not be adequately captured by the above alternative categories; reporting clinician service examples include but are not limited to, the radiologist's interpretation of an imaging study requested by another clinician | XE | Separate encounter, a service that is distinct because it occurred during a separate encounter | XS | Separate structure, a service that is distinct because it was performed on a separate organ/structure | XU | Unusual non-overlapping service, the use of a service that is distinct because it does not overlap usual components of the main service |
|
Date
|
Action
|
Notes
|
|---|---|---|
| 1991-01-01 | Added | First appearance in code book in 1991. |
Get instant expert-level medical coding assistance.