Internal Medicine Coding Alert

Published on Sat May 01, 1999 PDF

Diagnosis coding for hypertension is a problematic issue for many internal medicine coders. Because physicians often write only hypertension in the patients chart, without specifying whether the condition is malignant or benign, coders often use the ICD-9 codes 401 (essential hypertension) or 401.9 (essential hypertension, unspecified) to report the condition.

Third-party payers often reject these code as a justifying reason for physical exams, diagnostic tests and procedures because it is non-specific. Other times, certain tests, procedures and exams are only covered if the diagnosis is malignant hypertension (401.0) and not benign (401.1).

Coders must report a diagnosis that is specific enough to get the claim paid, but can only code by the information available in the chart, states Beth Pysell, CPC, coding and reimbursement analyst for Mountain Management Services in Chattanooga, TN.

We can only code by the information weve been told, she states. There is no clear clinical definition of what is benign and what is malignant hypertension. And, even if we could tell the difference, we cant just change the physicians diagnosis of hypertension to benign or malignant. We end up getting unspecified codes a lot.

The key to correct coding for hypertension, however, is not in establishing a clear clinical definition of benign and malignant hypertension, but in educating the physicians thatfor reporting purposesthey must follow ICD-9-CMs definition of malignant and benign, regardless of the clinical definition that they adhere to, explains Jeri Leong, RN, CPC, a medical practice consultant and certified coding instructor based in Honolulu, HI.

The term unspecified in ICD-9 does not mean that the physician did not tell you which one it was, she begins. If you dont have more specific information, then you need to go back to your physician and ask him for the information.

ICD-9 Categories are Different from Physician Clinical Definitions

For coding purposes, practices should only consider the definitions for malignant and benign hypertension that are printed in ICD-9-CM, which basically differentiates between controlled and uncontrolled hypertension, she adds.

According to ICD-9, malignant hypertension is a severe form of hypertension, wherein the patients blood pressure reading is consistently higher than 120 diastolic and is difficult to treat. The definition for benign hypertension is listed as a mild and chronic form of hypertension that generally develops over an extended period of time. This is the most common form of hypertension.

Physicians should consider these definitions when reporting hypertension diagnoses for their patients, she says, and always rely on the information in the ICD-9 manual to determine the most specific code.

In the Index to Diseases section, under the heading hypertension, hypertensive is a list of all of the different complications of hypertension and the related codes, with separate codes for malignant, benign and unspecified.

Be Aware of Third-Party Payers Frequency Edits

Reporting the correct diagnosis code for hypertension is particularly important if you have payers who utilize frequency edits in their claims-processing software, emphasizes Leong.

For example, some payers have edits in their system that only allow three 99214 codes to be covered within a three-month period of time for patients who have controlled hypertension.

If a patients uncontrolled, malignant hypertension were incorrectly reported as 401.9 or just 401, then the payer might reject the claim. But, if it had been reported as malignant (401.0), it might have been covered by the payer as an acute condition.

Note: Sometimes, even when the diagnosis is reported correctly, the frequency edits cause the claim to be denied, Leong says. If practices believe they are correctly reporting the diagnoses for hypertension and still receive denials, check with the individual payer to find out why.

Do Not Report 401 Codes for Hypertension Complicating Pregnancy

Leong also notes that internists should not report 401 codes for hypertension that is complicating pregnancy.
Coders should use the 642 series (hypertension complicating pregnancy, childbirth, and the puerperium).

Fifth-digit classification is necessary with this series, adds Leong. The fourth digit denotes a specific-type of classification of hypertension complicating pregnancy, and the fifth digit is used to specify the episode of care involved.

The ICD-9 book lists the fifth-digit subclassification for these codes as:

0-unspecified as to episode of care or not applicable;

1-delivered, with or without mention of antepartum condition;

2-delivered with mention of postpartum complication;

3-antepartum condition or complication;

4-postpartum condition or complication.

For example, to report the diagnosis for a pregnant woman with elevated arterial blood pressure due to kidney disease before the baby is born, coders would report 642.13 (hypertension secondary to renal disease, complicating pregnancy, childbirth and the puerperium, antepartum condition or complication).