Revenue Cycle Insider

Don’t forget to test yourself at the end.

The most severe complications of diabetes are created by the damage the disease causes to the body’s blood vessels. The disease inflames, oxidizes, and damages them to the point where they can hemorrhage and, ultimately, fail.

This is especially true of the smaller blood vessels in the body, such as those in the body’s extremities, the kidneys, and the eyes, which is why neuropathy, kidney disease, and diabetic retinopathy are such common complications of the condition.

As an ophthalmology coder, this means you need to be familiar with all the nuances of diabetic retinopathy diagnosis coding. But following these four simple steps will help you keep everything straight.

Step 1: Understand Diabetes Types and Their ICD-10-CM Base Codes

To code diabetic retinopathy correctly, you first need to know the difference between the types of diabetes recognized by ICD-10-CM in its coding taxonomy:

• E08.- (Diabetes mellitus due to underlying condition) features codes used for conditions caused by underlying conditions, such as cystic fibrosis or diseases of the pancreas.
• E09.- (Drug or chemical induced diabetes mellitus) features codes used when the diabetes is brought on by drug or toxin poisoning.
• E10.- (Type 1 diabetes mellitus) features codes for diabetes caused by insulin dependence, where the body makes no insulin. This kind of diabetes is often referred to as juvenile diabetes, as the condition usually manifests before the patient reaches puberty.
• E11.- (Type 2 diabetes mellitus) features codes for diabetes caused by insulin resistance, where the body produces insulin, but of an insufficient quality or quantity.
• E13.- (Other specified diabetes mellitus) features codes used when genetic defects and pancreatectomy cause the diabetes.

For the most part, you’ll pretty much confine yourself to diagnoses in the E10.- and E11.- categories, as these are the most common forms of the disease. But regardless of the type of diabetes the patient has, all ophthalmic complications of diabetes are coded to 4^th character 3.

Reminder: ICD-10-CM guideline I.C.4.2 tells you that “If the type of diabetes mellitus is not documented in the medical record the default is E11.-, Type 2 diabetes mellitus.” However, defaulting to E11 if you don’t know the patient’s diabetes type is not a good idea, as the different types of diabetes require different treatment plans, and payers may or may not reimburse for treatments if the diabetes type is incorrectly documented. So, it is important you coordinate with your provider to pinpoint the exact diabetes diagnosis before billing for the patient’s treatment.

Step 2: Understand Differences Between Disease Stages

While your provider will ultimately determine the different stages of the patient’s diabetic retinopathy, for coding purposes, knowing how they will document the condition in the medical record will help you verify the code choice.

Diabetic retinopathy is classified as either nonproliferative (NPDR) or proliferative, which is the most severe form of the condition. NPDR is further classified by severity, and is either mild (characterized by a small number of microaneurysms or bulging blood vessels in the retina); moderate (a greater number of microaneurysms with the addition of hemorrhages in some of the blood vessels); or severe, which is characterized by severe hemorrhages and microaneurysms in all four quadrants of the retina, venous beading (irregularity) in at least two quadrants, and intraretinal microvascular abnormalities (IRMA) in at least one quadrant — a diagnosis based on what is known as the 4,2,1 rule.

If the condition progresses beyond severe NPDR, then it becomes proliferative, meaning new, but abnormal, blood vessels are formed in the retina while hemorrhages are occurring between the retina and the vitreous humor (the gel that fills the eyeball).

For each of the diabetes types, ICD-10-CM indicates the severity with 5^th characters:

2 = mild

3 = moderate

4 = severe

5 = proliferative

Step 3: Use a Combo Code for Macular Edema

At any nonproliferative stage, or when the condition progresses to proliferative, fluid can accumulate in the macular, the central part of the retina, creating a condition known as macular edema.

You indicate the presence of macular edema with a 6^th character 1, and if macular edema is not present, you use the 6^th character 9. If the provider diagnoses proliferative retinopathy, they then have the option of documenting whether traction retinal detachment, a condition where the macular is being pulled away from the retina, is present. If the retinal detachment involves the macular, then the condition is documented with 6^th character 2; if it does not, then you will use 6^th character 3. And if the retina is starting to detach from its underlying tissue as well, a condition known as rhegmatogenous retinal detachment, then you will use 6^th character 4. (ICD-10-CM reserves 6^th character 5 for proliferative diabetic retinopathy that is stable.)

Step 4: Don’t Forget Laterality

All the diabetic retinopathy codes require a 7^th character for laterality before they can become billable. Here are the 7^th character options:

1 = right eye

2 = left eye

3 = bilateral

9 = unspecified

Test yourself: A type 2 diabetic patient is diagnosed with severe bilateral NPDR with macular edema. You would report E11.3413 (Type 2 diabetes mellitus with severe nonproliferative diabetic retinopathy with macular edema, bilateral).

Bruce Pegg, BA, MA, CPC, CFPC, Managing Editor, AAPC