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Polysomnography and Sleep Apnea Coding Challenge (ICD-10-CM)

woman doing a sleep study
Woman is undergoing a sleep study (polysomnography).

**This post was reviewed and updated on January 19, 2024. **

The Coding Challenge

Question:

A 56-year-old morbidly obese female with a BMI of 50 and diabetes had a recent polysomnography. Her husband had witnessed loud snoring and pauses in her breathing during sleep. The sleep study showed an Apnea-Hypopnea Index (AHI) of 6. She is diagnosed with obstructive sleep apnea.  Which of the following ICD-10-CM codes should be assigned?

A. G47.33, E66.01, Z68.43, E10.9
B. G47.31, E66.01, Z68.42, E11.9
C. G47.33, E66.01, Z68.43, E11.9
D. G47.31, Z68.42, E66.09, E10.9  

Answer:

C. G47.33, E66.01, Z68.43, E11.9

Obstructive sleep apnea (OSA) is a common sleep disorder. A person with OSA experiences many complete or partial airway obstructions during sleep. They are referred to as apneas and hypopneas, respectively. Other symptoms may include loud snoring, gasping or choking, and daytime sleepiness.

A sleep specialist will perform a sleep study ( polysomnography) to monitor the brain waves, blood oxygen levels, heart rate, and breathing while you sleep. The Apnea-Hypopnea Index (AHI) is the primary measurement for indicating the severity of OSA.  According to the National Institutes of Health, risk factors for obstructive sleep apnea include obesity and type 2 diabetes.

ICD-10-CM Coding

In the ICD-10-CM codebook, codes for sleep apnea in adults and pediatrics are located in Chapter 6, Diseases of the Nervous System (G00 to G99), category G47. Codes from this range require four, five, or six characters to complete the code selection.

Locate and Verify

Looking in the Alphabetic Index under Apnea, apneic (of) (spells)/sleep/obstructive (adult)(pediatric) G47.33.  

In the Tabular, we can verify our correct code as:

G47.33 – Obstructive sleep apnea (adult) (pediatric)
Obstructive sleep apnea-hypopnea

There are also instructional notes at G47.3:

Code Also: any associated underlying condition

Excludes1:
apnea NOS (R06.81)
Cheyne-Stokes breathing (R06.3)
Pickwickian syndrome (E66.2)
sleep apnea of newborn (P28.3)

Excludes2:
nightmares (F51.5)
nonorganic sleep disorders (F51.-)
sleep terrors (F51.4)
sleepwalking (F51.3)

Obesity and type 2 diabetes are both risk factors of obstructive sleep apnea and should also be coded as indicated in the” Code Also” note. According to the documentation, the patient is morbidly obese and has a BMI of 50.

In the Index under Obesity/morbid/due to excess calories, it refers us to E66.01.  In the Tabular, we can verify our correct code as:

E66.01,  Morbid (severe) obesity due to excess calories

Excludes1: morbid (severe) obesity with alveolar hypoventilation (E66.2)

Before assigning this code, be sure to read all the other instructional notes. For example, a “Use additional” note at E66.01 tells us to assign a code to identify body mass index (BMI) if known (Z68.-).

When we go to the codes listed in the Tabular under Z68.-, we can verify our correct code as:

Z68.43, Body mass index [BMI] 50.0-59.9, adult

Note: This is the BMI for an adult 20 years of age or older — not to be confused with the BMI codes for pediatrics. 

BMI is categorized according to severity as follows:

  • Severe malnutrition: BMI < 16.0
  • Moderate malnutrition: BMI = 16.1-16.9
  • Mild malnutrition: BMI = 17.0-18.4
  • Normal: BMI = 18.5-24.9
  • Overweight: BMI = 25.0-29.9
  • Obese: BMI = 30.0-39.9
  • Morbidly obese: BMI = 40+

There is also a “Coding Note” at Z68 that states, “Use in conjunction with codes for any associated condition (i.e., E40-E46, E66.-, D68, R64).” That is our reminder to assign the appropriate code for morbid obesity, which we have already done (E66.01).

Now, for the diabetes. We know it is type 2 diabetes because the ICD-10-CM coding guidelines state, “If the type of diabetes mellitus is not documented in the medical record, the default is E11.-, Type 2 diabetes mellitus.”

We can find the code in the Index by looking up Diabetes, diabetic (mellitus) (sugar)/type 2 E11.9.

In the Tabular, we can verify our code as:

E11.9,  Type 2 diabetes mellitus without complications

Incorrect Answers

A, B, and D are incorrect. 

A. G47.33, E66.01, Z68.43, E10.9. E10.9, Type 1 diabetes mellitus without complications, is incorrect.

B. G47.31, E66.01, Z68.42, E11.9. G47.31, Primary central sleep apnea, is incorrect. Z68.42, Body mass index [BMI] 45.0-49.9, adult, is incorrect.

D. G47.31, Z68.42, E66.09, E10.9.  Again, G47.31, Primary central sleep apnea, is incorrect. Also, E66.09, Other obesity due to excess calories, and E10.9, Type 1 diabetes mellitus without complications, are incorrect.

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