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General Business
Fundamentals of Diagnosis
Coding
© 2008, BSM Consulting
All Rights Reserved.
Fundamentals of Diagnosis Coding
General Business
Table of Contents
OVERVIEW.................................................................................................................................. 1
ICD-9 CM ORGANIZATION ........................................................................................................ 1
SELECTING THE APPROPRIATE CODE.................................................................................. 1
SUPPLEMENTAL CODES AND TABLES.................................................................................. 3
COVERAGE ISSUES .................................................................................................................. 3
CONCLUSION............................................................................................................................. 3
COURSE EXAMINATION ........................................................................................................... 4
© 2008, BSM Consulting
Fundamentals of Diagnosis Coding
General Business
OVERVIEW
In the current environment, physicians and staff are forced to learn seemingly more complicated and
time-consuming methods of coding and documenting medical records. This includes the selection of an
appropriate diagnosis code for the service provided.
The International Classification of Diseases (ICD) is the basis for the current diagnosis indexing system. It
is reviewed annually; the revisions are usually published every September. Officially, the system of
diagnosis codes is named International Classification of Diseases – 9th revision – Clinical Modification
(ICD-9-CM). Diseases and injuries are arranged into groups according to established criteria. Diagnostic
coding using ICD-9-CM became a mandatory Medicare claim requirement with the passage of the
Medicare Catastrophic Coverage Act of 1988. Since that time, it has become standard practice that
claims for reimbursement include an ICD-9 code.
The selection of an appropriate diagnosis code is oftentimes a complicated process. Individuals need to
be comfortable navigating the ICD-9-CM manual, familiar with medical terminology, and knowledgeable
with payer rules and regulations.
This discussion is meant to assist the reader to better understand the rules and regulations regarding
diagnosis coding; however, the responsibility for appropriate coding is always the physician’s.
ICD-9 CM ORGANIZATION
ICD-9-CM is separated into three volumes. Volume 1, the Tabular List, classifies groups of diseases
according to etiology and organ system in numeric order. Volume 2, the Alphabetic List, has diseases,
conditions and injuries. It is further separated into three sections: a) index to diseases, conditions, and
injuries; b) table of drugs and chemicals; and c) external causes of injuries and poisonings. Volume 3
contains procedure codes to identify facility services for hospitals. Additionally, some Medicaid payers
use ICD-9 procedure codes to categorize ambulatory surgery center facility services. Few practices find
use for Volume 3 and rarely purchase it.
Understanding the book’s organization, abbreviations, and instructional notations is useful to improve the
ease of its use. The entire ICD directory is arranged in a series of topics with indented categories and
sub-categories, much like a traditional outline where the indented sub-category is directly connected to
the more major category above and to the left of it. To find an appropriate ICD-9 code, it is easiest to first
look in the alphabetical listing (i.e., glaucoma) and secondarily in the tabular listing (i.e., 365.xx). The
tabular listing provides more detailed explanations and guidance. It further stratifies glaucoma disease to
various levels of specificity providing up to five digits (e.g., 365.11 – Primary open angle glaucoma). The
first three digits describe the location and category of disease; the fourth and fifth digits elaborate on the
description. Use of specific diagnoses (four to five digits) improve the quality of claims, may support
higher levels of service, and reduce claim denials.
SELECTING THE APPROPRIATE CODE
The diagnosis code should comport with the reason for the patient’s visit as described in the chief
complaint. For example, if the patient’s chief complaint is six-month follow-up of cataracts, the primary
diagnosis code should be 366.## (Cataract). If this patient’s past history also includes dry eye syndrome,
this added diagnosis is subordinated or omitted altogether. Without a complaint and finding to correlate
with dry eyes, this condition may not be particularly relevant to today’s encounter. The ICD-9 guidelines
support this approach.
“9. . . . Code all documented conditions that coexist at the time of the visit that require or affect patient
care, treatment, or management . . .”
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Fundamentals of Diagnosis Coding
General Business
If the patient had complained of dry eyes in addition to the cataract, then the dry eye diagnosis would be
an appropriate secondary diagnosis. You should list chronic conditions or secondary diagnoses only if
pertinent to the visit.
Many eye exams are associated with an ancillary service; this may be a diagnostic test(s) and/or minor
procedure. On the encounter form (or superbill), the provider will note one or more diagnoses (e.g.,
cataract, glaucoma, presbyopia, chalazion). Since the staffer at the check-out desk may not necessarily
know which diagnosis is associated with which service, the physician should match them up. One
approach is to draw a line between the CPT code and the ICD-9 code to make the association. Some
may choose to link them with numbers. Regardless of the approach, mismatched diagnosis codes result
in claim denials.
Sometimes patients present with a complaint or a symptom, but a conclusive diagnosis eludes the
physician. Physicians commonly document in the assessment “probable, suspect, rule out, or undefined
disorder.” Claims for reimbursement require a diagnosis code; however, no such codes exist to describe a
probable condition or rule out status.
The introduction to the ICD-9 manual addresses this issue by stating, “Diagnoses documented as
‘probable,’ ‘suspected,’ ‘questionable,’ or ‘rule out,’ should not be coded as if the diagnosis is confirmed…
code to the highest degree of certainty, such as describing symptoms, signs, abnormal test results, or
other reasons for the encounter.” It also states, “Codes that describe symptoms as opposed to diagnoses
are acceptable if this is the highest level of certainty documented by the physician.”
For example, a patient complains of vision loss that occurred suddenly and has not improved in the past
two days. Clinical exam reveals decreased visual acuity uncorrectable by refraction, yet no other
pathology is found to explain the vision loss. Further evaluation is indicated. Although this could be a
number of ocular or systemic diseases, you should use sudden visual loss (368.11) on the claim for
today’s encounter.
In another example, the patient presents with orbital pain and a bad headache for two days. Clinical exam
leads the physician to suspect temporal arteritis, and an ESR is ordered. The assessment in the patient’s
medical record states, “rule out temporal arteritis.” Without a conclusive diagnosis, it is inappropriate to
use temporal arteritis (446.5) to describe today’s exam. The correct choice is 379.91 – pain in or around
the eye and/or 784.0 – headache.
Be particularly mindful of not giving a patient a disease that you do not know for certain exists. Numerous
visual disturbance (368.xx) and unspecified disorder (379.xx) codes exist to cope with this diagnosiscoding quandary.
Patients return for follow-up exams so a physician can assess their progress for treated conditions.
During the course of treatment, diagnosis coding is straightforward. When the condition no longer exists,
what ICD-9 code is appropriate? The ICD-9 introduction states, “Do not include codes for conditions that
were previously treated and no longer exist.”
For example, a malignant lesion is removed from the patient’s eyelid. All margins are clear, and the
patient is informed that no further malignancy exists at this time. The patient returns six months post
excision with no problems or complaints for a follow-up check. The area remains clear with no signs of regrowth. Is it appropriate to code today’s visit with a malignant lesion diagnosis? No, the correct ICD-9 is
V10.83 – Personal history of malignant neoplasm, skin.
“V” codes cope with visits for circumstances other than disease or injury. “V” codes are almost always a
secondary diagnosis. Directions in the ICD-9 guide instruct whether or not a particular code is used only
as a secondary diagnosis. For example, V58.6x, Long-term current drug use, is listed as a secondary
diagnosis only.
There are patients who have a valid reason to be followed by an ophthalmologist or optometrist but may
not manifest any specific ophthalmic findings. Typically, these patients suffer from systemic disease which
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Fundamentals of Diagnosis Coding
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may include ocular manifestations. Diabetes, systemic lupus erythematosus, and rheumatoid arthritis are
three examples of systemic diseases that may be the basis of an ocular condition. In the absence of an
ocular manifestation, the primary diagnosis for the encounter is the systemic disease.
Particular attention should be paid to coding for diabetic disease. The ICD-9 guide provides detailed
instructions for coding the systemic disease and associated conditions.
Diabetes mellitus requires a five-digit diagnosis code beginning with 250.xx; the fifth digit describes the
type of diabetic disease and whether or not it is controlled or uncontrolled. The following are the fifth digits
for coding diabetic disease:
•
0, Type II or unspecified, NIDDM, not stated as uncontrolled
•
1, Type I, juvenile type, IDDM, not stated as uncontrolled
•
2, Type II, or unspecified, NIDDM, uncontrolled
•
3, Type I, juvenile type, IDDM, uncontrolled
If a diabetic patient presents with ocular manifestations, the ICD-9 guidelines instruct to code with the
systemic disease first and associated conditions second. For example, the patient is a type II diabetic with
uncontrolled diabetic disease and proliferative diabetic retinopathy. The ICD-9 selection for this patient
would be 250.52 (type II diabetic, uncontrolled with ocular manifestation) followed by 362.02 (PDR).
SUPPLEMENTAL CODES AND TABLES
Another set of supplemental codes is intended for external causes, such as injury or poison: E-codes.
The situation may require more than one E-code, but they are never used as primary diagnoses. These
are found in the E-code section. If the condition is due to medication or toxins, the Table of Drugs and
Chemicals will help define the situation. To identify an injury, there is an index to external causes at the
back of the ICD-9 manual.
ICD-9-CM also includes specified coding tables. Of particular interest to those in eye care is the
Neoplasm table. Appropriately, it is found in the “N” section of Volume 2. They are listed by location on
the body, organ, or tissue. The table is then expanded by whether the neoplasm is benign, malignant, etc.
There are occasions where the nature of the neoplasm is uncertain at the time of excision but looks
suspicious. It is a good habit to file the claim after receiving the pathology report so a definitive diagnosis
can be rendered along with an appropriate CPT code.
COVERAGE ISSUES
The purpose of a procedure drives the coverage policy of third-party payers and is described on the claim
for reimbursement as the diagnosis code. Limitations of coverage and reimbursement exist because
some ICD-9 codes are excluded from the policy. For example, Medicare doesn’t pay for exams for routine
vision care (V72.0) or to cope with refractive errors (367.xx). If a Medicare beneficiary’s chief complaint is
“wants new eyeglasses,” then this exam will be non-covered. Beneficiaries can become agitated and
confrontational when told that the coverage of their health plan doesn’t pay for some services. It might be
tempting to change the diagnosis on the claim form to prevent a denial, but don’t. Willfully and knowingly
filing a deceptive claim for reimbursement is fraud.
CONCLUSION
Selecting the diagnosis code demands the same time and attention as CPT code selection. Understand
the guidelines on how to select the most complete and accurate diagnosis, and never compromise your
practice by intentionally abusing diagnosis code selection to facilitate payment.
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Fundamentals of Diagnosis Coding
General Business
COURSE EXAMINATION
1. Diagnosis coding became mandatory because of this act:
a.
b.
c.
d.
Deficit Reduction Act
Medicare Catastrophic Coverage Act
Health Insurance Portability and Accountability Act
Medicare Modernization Act
2. Which volume of the ICD-9 CM contains facility procedure codes:
a.
b.
c.
d.
Volume 3
ICD-9 manuals do not contain procedure codes
Volume 1
Volume 2
3. Third-party payers will typically accept a diagnosis code with three digits (i.e., 364, disorders of
the iris and ciliary body).
a. True
b. False
4. A 59-year-old male presents for the first time with complaints of blurred vision at both distance
and near. The best-corrected and currently corrected vision is 20/30- in the right eye and 20/20 in
the left eye. The anterior and posterior exams are unremarkable. Refraction does not improve
vision in the right eye. Further workup is planned. The appropriate diagnosis code for the exam is:
a.
b.
c.
d.
366.12 (incipient cataract)
368.8 (blurred vision)
368.13 (visual discomfort)
V72.0 (routine examination of eyes and vision)
5. A 44-year-old female patient has rheumatoid arthritis and is being treated with chloroquine
(Plaquenil). Her primary care physician asks you to examine her to rule out maculopathy caused
by the use of this drug. She is found to have best corrected vision of 20/20 in each eye with a
myopic/astigmatic glasses prescription and a completely unremarkable posterior pole. Select an
appropriate ICD-9 code(s) for this exam:
a.
b.
c.
d.
367.1 (myopia), 367.21 (regular astigmatism)
362.55 (toxic maculopathy), E931.4 (adverse effect from chloroquine)
714.0 (rheumatoid arthritis), V65.5 (feared condition not demonstrated)
714.0 (rheumatoid arthritis), V58.69 (high risk drug)
6. It is a good idea to select an ICD-9 code that will get your claim paid, even if it isn’t entirely
accurate.
a. True
b. False
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Fundamentals of Diagnosis Coding
General Business
7. Your patient underwent a scleral buckle procedure to repair a retinal detachment 12 months ago.
He returns today at your request. He is doing well, and his vision has remained stable. You
examine him and find the healed horseshoe tear and healed laser sites, and the retina is
attached. Select an appropriate ICD-9 code(s) for this exam:
a.
b.
c.
d.
V45.69 (states following surgery of eye)
361.06 (old, partial detachment)
361.32 (horseshoe tear of retina without detachment)
V72.0 (routine examination of eyes and vision)
8. A patient is referred to your office for evaluation of a droopy eyelid. After obtaining a history and
doing an exam, you feel it would be prudent to check for myasthenia gravis. A tensilon test is
performed and is negative for MG. Select an appropriate ICD-9 code for this exam:
a.
b.
c.
d.
358.0 (myasthenia gravis – abnormality of nerve-muscle junction)
374.33 (mechanical ptosis – drooping not caused by nerve problem)
V41.1 (other eye problems)
V65.5 (feared condition not demonstrated)
9. Your established patient presents today for a follow-up of her AMD. During the course of the
exam, an increased intraocular pressure is noted and a visual field is performed. The assessment
includes diagnosis of AMD, stable and glaucoma suspect. To keep the claim simple, it is
appropriate to utilize glaucoma suspect (365.01) as the diagnosis on both the exam and the
visual field.
a. True
b. False
10. Your diabetic returns for a six-month evaluation. She has been insulin dependent for four years
and struggles to keep her glucose level under control. Her best-corrected vision has dropped to
20/60 in the right eye and is maintaining 20/25 in the left. Upon dilated exam, you note multiple
microaneurysms, dot hemorrhages and exudates in the right eye; left eye is normal. Fluorescein
angiography confirms BDR in the right eye. Select appropriate ICD-9 codes for this exam:
a.
b.
c.
d.
250.52 (uncontrolled type II DM), 362.01 (background diabetic retinopathy)
362.01 (background diabetic retinopathy), 250.53 (uncontrolled type I DM)
250.50 (controlled type II DM), 362.01, (background diabetic retinopathy)
362.02 (proliferative diabetic retinopathy), 250.52 (uncontrolled type II DM)
11. A child presents in the ASC with a corneal laceration caused by an injury to the eye while jumping
on a bed with a fork in hand. Select appropriate ICD-9 code for this procedure:
a.
b.
c.
d.
371.51 (Juvenile epithelial corneal dystrophy)
871.4 (Unspecified laceration of eye)
871.0 (Ocular laceration without prolapse of intraocular tissue)
E940.4 (Accident caused by cutting and piercing instruments or objects - includes fork)
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