Manager-Medical Records,
Aravind Eye Care System.

Medical records in most health care institutions are filed numerically according to patient’s medical record numbers. In the past, some hospitals have filed records according to patient’s names, discharge numbers, or diagnostic code numbers. Alphabetic filing by patient names is more cumbersome and subject to more error than numerical filing. Filing by discharge numbers and diagnostic code numbers is generally unsatisfactory because other important records or registers in the facility are concerned exclusively with medical record numbers

1. Numbering System
Three types of numbering systems are currently in use in health care facilities.
They are:

  • Serial Numbering System.

  • Unit Numbering System.

  • Serial Unit Numbering System.

1.1 Serial numbering:
In serial numbering the patient receives a new number each time he is registered or treated by the hospital. If he is registered five times, he acquires five different medical record numbers.

Patient, Ravi, gets registered in the hospital and receives a number 13650.When he returns for follow-up one week after treatment, he is registered under medical record number 14020. If he is visiting the hospital again the following year, he would receive yet another number such as 19560. Although all numbers assigned to this patient must be recorded in his Master patient index card, his medical records are filed in as many places as the number of times he has been treated in the facility.

1.2  Unit numbering:
Unlike the serial numbering systems, the unit numbering system provides a single record, which is composite of all data gathered on a given patient, whether as an outpatient, inpatient or emergency patient. The patient is assigned a medical record on his first visit, which is used for all subsequent visits and treatments. His entire medical record is thus in one folder under one medical record number.

With unit numbering, each time Ravi arrived at the hospital for treatment, he would receive the first number he had been assigned –13650.

1.3  Serial unit numbering:
This numbering system is a combination of the serial and unit numbering systems. Although each time the patient is registered he receives a new medical record number, his previous records are continually brought forward and filed under the latest issued number.

When patient Ravi returned for his follow-up one week after treatment, he would receive number 14020, but his out patient treatment data, filed under 13650, would also be brought forward to be filed with the notes made during his most recent visit. A unit record is thus created. When the older records are brought forward, some type of guide must be left in the file where the old record has been pulled, to indicate the new number under which the record is now filed. The empty chart folder marked with a referral to the new number is a satisfactory method for accomplishing this.

1.a  Annual numbering:
Serial numbering that includes the last two digits of the current calendar year, may be used by hospitals that primarily serve a transient population. In this system, the two digits for the year are added to the end of a serial number. The year designation serves as a control number in retiring inactive records. The serial numbers together with the calendar year also provide immediate data on the number of hospital admissions or visits that occurred during a specific year.

1.b  Family numbering:
Another adaptation of unit numbering is the family numbering system. Family numbering usually consists of placing extra pairs of digits, which signify placement of the individual in the household. These digits are usually placed immediately before the regularly assigned number. Prefix number pairs have a definite sequence and meaning, as follows:

01 = head of household (either mother or father)
02 = spouse
03 = children
04 = other family members
05 = housemaid.

An illustration of this is shown below

All patient information on one family is thus filed together by the family number.

File expansion:
Planning for file expansion is affected by the choice of a numbering system. It is necessary to leave 25% of the shelves open.

  • When using the unit numbering system, because additional room is needed to allow the expansion of the individual medical records.
  • With the serial numbering system the shelves remain constant, expanding only at one end of the file as new numbers are assigned to patients.

  • When using the serial-unit system, which requires a moving forward of medical records, gaps may occur on the shelves as records are pulled. This commonly happens when revisit rates are high.

Purging of files:
As inactive records are purged, gaps will appear in the active file area when using a serial numbering system.

Multiple-volume records also present a problem, which results from maintaining a unit system. Records of patients having had several occasions of treatment sometimes become so thick that additional folders are needed to house one complete medical record. In order to alert filing personnel and health care professionals that a medical record is contained in several folders, it is wise to mark each folder with both the volume number and the total number of volumes.

The first folder can be labeled as” Volume 1 of 2”, the second folder “Volume 2 of 2”, etc. It is important to that all folders on one patient are labeled whenever another volume is added to the set. The first folder labeled “ Volume 1 of 2” would change to “Volume 1 of 3” as a third folder is added.

Three types of numeric filing systems are commonly used for filing medical records- straight numeric, terminal digit, and middle digit.

2.1 Straight Numeric filing:
This refers to the filing of records in exact chronological order according to registration number. Thus, consecutively numbered records would be sequenced on the file shelves.

The following four medical records would be filed in consecutive order on a shelf: 65023, 65024, 65025, and 65026.

Obviously it is a simple matter to pull fifty consecutively numbered records from the file for study purposes or for inactive storage. Probably the greatest advantage of this type of filing system is the ease with which personnel are trained to work with it. This approach to filing has, however, certain inherent disadvantages. Because a staff must consider all digits of the record number at one time when filing a record, it is easy to misfile. The greater the number of digits that must be recalled when filing, the greater the chance for error. Transposition of numbers is common: record 65424 can be misfiled as record 56524. A more serious drawback to straight numerical filing is that the heaviest filing activity is concentrated in the area with the highest new numbers. Several staff filing records at the same time in such areas is bound to get in each other’s way.

Finally, quality control of filing is difficult with this system. Since staff are usually filing in the area of the most current records, it is not feasible to fix responsibility for a section of the file to one staff.

2.2  Terminal digit filing:
A six-digit number is usually used and divided with a hyphen into three parts, each part normally containing two digits. Within the number, the primary digits are the last two secondary digits, are the middle two and the tertiary digits are the first two digits.

In a terminal digit file, there are 100 primary sections, ranging from 00 to 99. When filing, staff must first consider the primary section within each primary section, groups of records are matched according to the secondary digit section, after locating the correct secondary digits section, the staff files in numerical order by the tertiary digits.

In the file, the second tertiary digits change with every record.

Note the following sequence in a terminal digit file

66-31-06 98-11-38 98-99-50
67-31-06 99-11-38 99-99-50
68-31-06 00-11-38 00-00-51
69-31-06 01-11-38 01-00-51

The terminal digit method of filing has been described using six numbers, but it can be adapted for using five, seven, or even nine digits. With a five-digit number, one could break it into three sections, as follows:

1-23-45 0-00-01

There are numerous advantages of terminal digit filing. As new records are added to the file, their terminal digit numbers are equally distributed throughout the 100 primary section of the file. Only every 100th new medical record will be filed in the same primary section of the file. The implications of this distribution are extensive. The congestion that results when several staff file active records in the same area is eliminated. Staff may be assigned responsibility for certain sections of the file (e.g. when four staff are filing, the first staff can be responsible for terminal digit sections 00-24, the second for 25-49, the third for 50-74, and the fourth for 75-99).

As registration numbers are still assigned in straight numerical order, the work is evenly distributed amongst each staff in each section. Numbers 463719, 463720, and 463721 are assigned in strict sequence, but the records would be filed in terminal digit section “19”, “20”, and “21” respectively. Inactive records may be pulled from each terminal digit section as new records are added. In this way the volume of records in each primary section is controlled, and large gaps in the file, which require back shifting of records is prevented. This volume control also simplifies planning of filing equipment.

2.3  Middle digit filing:
Here the staff files according to pairs of digits, as in terminal digit filing. However, the primary, secondary, and tertiary digits are in different positions. The middle pairs of digits in a six-digit number are the primary digits, the digits on the left are the secondary digits, and the digits on the right are the tertiary digits

76 68 96
Secondary Primary Tertiary

Shown below is a sample sequence in middle digit file

76-68-96 99-68-96 76-68-00 00-69-00
76-68-97 99-68-96 77-68-01 00-69-01
76-68-98 99-68-96      
76-68-99 99-68-96      

From the first example, one can see that blocks of 100 charts (e.g., 76-78-00 through 76-78-99) are in straight numerical order. This has several advantages: First, it is simple to pull up to 100 consecutively numbered charts for study purposes. Second, conversion from a straight numerical system to a middle digit system is much simpler than is conversion to a terminal digit system; third, blocks of 100 charts pulled from a straight numerical file are in exact order for middle digit filing. Middle digit filing provides a more even distribution of records that does straight numerical filing, although it does not equal the balance achieved by a terminal digit filing system.

Staff may be assigned responsibility for certain middle digit sections. As in terminal digit filing, the staff files by pairs of digits rather than by six or seven digits; therefore misfiles are reduced. There are certain disadvantages to middle digit filing. More training is involved than for straight numeric or terminal digit filing. Gaps result in the file when large groups of inactive records are pulled with more than six digits.

Guiding the files:
Guides should be placed throughout the files to expedite the filing and finding of records. The number of guides needed depends upon the thickness of the majority of the medical records in the file. For records of medium thickness, a guide for every fifty records is adequate. For very thick records, more guides are needed than inactive files.

When purchasing guides, durability and visibility should be the primary concern. The tab or projection on the guide should project far enough beyond the records to ensure complete exposure of the numbers on the guide.

To determine the total number of guides needed, the following formula may be used:

Total number of records                   = Total number of guides
Number of records between guides

If the total number of records is not known, an estimate may be made by multiplying the filing inches by the average number of records per inch. Several shelves of records should be counted to determine the average number of records per inch.

Missing records
Despite the extensive measures adopted to have good control of records, a certain percentage of records are not found where they are supposed to be. This could be due to not receiving the file, not filing in appropriate place, or misfiling. Under these circumstances, when a doctor insists on obtaining the original record for rendering care, the medical records technician must create a duplicate record with a similar number and with all previous ID data. The medical record technician should retain the duplicate record and immediately trace out the original records and incorporate the forms of the duplicate record into the original record. The record should then be filed.

Patient having multiple records
As a general rule, each patient should have one record and one number. Due to improper system or negligence of the MRD staff, the patients may have more than one record. In that situation, it becomes necessary to retain one record by canceling the others. The appropriate procedure is to retain the new record. The remaining records have to be cancelled and given cross-reference numbers. All the documents in the cancelled records need to be moved into the retained record. The cancelled empty folders with the cross-reference numbers should be placed in their respective area. Any cancelled record number should never be allocated to a new patient.