Medical Records Management Manual - Chapter 5

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Medical Records - Numbering and Filing Systems


Medical records in most health care institutions are filed numerically according to patients’ 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.

Medical Records Numbering System

Three types of numbering systems are currently in use in health care facilities-serial, unit, and serial unit.

Serial numbering

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

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

Unit numbering

Similar to the serial numbering system, 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 treatment is thus available in one folder under one medical record number. For example: With unit numbering, each time Ravi arrived at the hospital for treatment, he would receive the first number he had been assigned –13650.

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 record are continually brought forward and filed under the latest issued number. For example: When patient Ravi returned for his follow-up one month 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 old medical record made during his most recent visit. A unit record is thus created.

When the older records are brought forward, tracer card must be left in the shelf where the old record has been pulled, to indicate the new number under which the record is now filed. The tracer card marked with a referral note to the new number is a satisfactory method for accomplishing this.

Annual numbering

In annual numbering system, two digits indicating the year are added to the end of a serial number. The year designation serves as a control number in inactivating medical records. The serial numbers together with the calendar year also provide immediate data on the number of hospital registration or visits that occurred during a specific year.

Family numbering

Another version of unit numbering is the family numbering system. Family numbering usually consists of placing extra two digits, which indicates assigning number to each individual in the family.

These digits are usually placed instantaneously before the regularly assigned medical record number. Prefix number pairs have a definite order and meaning, as follows:

  • 01 = Head of Family (either mother or father)
  • 02 = spouse
  • 03 = children
  • 04 = any other family relatives
  • 05 = servant

Even though each patient of his family is assigned a separate medical record, the information pertaining to this family is thus filed together under one medical record number as “Family number”.

File Expansion

It is necessary to leave 25% of the shelves vacant when the unit numbering system is followed. This is because of expansion of the medical records when more forms are added to a record during frequent visits of the patient.

When serial-unit system is followed in a hospital, old medical records are forwarded to combine with the new medical records of the patient. Gaps may occur on the shelves as records are pulled and forwarded. This commonly happens when revisit rates are very high. In a serial numbering system since patients are assigned a medical record number during every visit, the shelves are filling only at one end as new numbers are assigned to patients every time.

Bulky Files

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.

For example, the first folder can be labeled as” Volume 1 of 2”, the second folder “Volume 2 of 2”, etc. If an extra folder is added the label should be changed to indicate the total number of folders. The first folder labeled “Volume 1 of 2” would change to “Volume 1 of 3” as a third folder is added.

Medical Records Filing Systems

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

Straight numeric filing

Straight numeric filing refers to the filing of records in exact ascending order according to medical records number. Thus, simultaneously all the numbered records would be in an ascending series on the filing shelves. For e.g., the following four medical records would be filed in the following order on a shelf: 65023, 65024, 65025, and 65026.

Clearly it is a simple matter to pull fifty continuous records from the filing area for study purpose or for inactive storage. Perhaps the greatest advantage of this type of filing system is the ease with which personnel are trained to work with it. However, this approach to filing has certain disadvantages. It is easy to misfile since a staff must consider all digits of the record number at one time when filing a record. The greater the number of digits that must be recalled when filing, the greater the chance for error. Alteration of numbers is common: medical record 65424 can be misfiled as record 56524.

A more serious problem to straight numerical filing is that the heaviest filing activity is concentrated in the area with the maximum number of new records. Several staff filing records at the same time in such areas is bound to get in each other’s way. Since staffs are usually filing in the area of the most current records, it is not possible to fix responsibility for a section of the file to one staff.

Terminal digit filing

A six-digit number or a seven-digit number can be 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 or three digits.

In a terminal digit filing, there are 100 primary sections, ranging from 00 to 99. A staff must first consider the primary section while filing the records. With each primary section, groups of records are matched according to the secondary digit, after locating the correct secondary digits section, the medical record staff files in numerical order by the tertiary digits. In medical records, the second tertiary digits changes with every record.

Note the following example 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 00-12-38 00-00-51
69-31-06 01-12-38 01-00-51

The terminal digit method of filing is described using six numbers, but as mentioned earlier 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:

7-65-43 0-00-01 etc.
With seven digits, the break up might be:
765-43-21 000-00-01 etc.

There are numerous advantages of terminal digit filing. When new records are added to the shelves, their terminal digit numbers are equally distributed throughout 100 primary sections of the shelves. Every 100th new medical record will be filed again in the same primary section of the shelves.

The obstruction that results while straight numeric filing is followed when several staff are filing in the same area is avoided. Staffs may be assigned responsibility for certain sections of the shelves. 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, 453720, 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 for filing equipment.

Advantages of terminal digit filing

Misfiling is considerably reduced with the use of terminal digit filing. Since the staff is concerned with only one pair of digits at a time, the transposition of numbers is less likely to occur. Even if the tertiary digits are increased to three, e.g., 245-68-90, recalling three digits is easier than recalling seven.

The training period for medical records assistant is usually a little longer for a terminal digit system than for a straight numeric filing, but most of the staff can learn it in a few days time.

Initial setting up of file shelves may be required from the starting stage, which may require more units of shelving since expansion capabilities must be planned for the total medical records area.

Middle digit filing

In this method the staff files according to pairs of digits, as in terminal digit filing. On the other hand, 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   
76-68-97   99-68-97  
76-68-98  99-68-98  
76-68-99  99-68-99  
77-68-00 00-69-00  
77-68-01 00-69-01  

From the example given, the staff can see that blocks of 100 records (e.g., 76-78-00 through 76-78-99) are in straight numerical order.

This has several advantages:

  • First, it is simple to pull out 100 consecutively numbered records for research purposes.
  • Second, conversion from a straight numerical system to a middle digit system is much simpler than converting to a terminal digit system.
  • Third, blocks of 100 records 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.

As in terminal digit filing, the staff is filing by pairs of digits rather than by six or seven digits; therefore wrong filing is reduced.

There are certain disadvantages to middle digit filing. More training may be necessary than the straight numeric or terminal digit filing.


Centralisation refers to the filing of outpatient, inpatient, and emergency patient’s records in one location. When continuous follow-up care is regularly provided by a hospital, a filing system which renders a unit record is most practical. Unit records are stored within the medical record department.


  • A decentralised file results when outpatient records are filed in the medical record department, but inpatient and emergency patient records are stored in their respective patient care areas.
  • A large medical complex consisting of several health care units which are physically separated from each other might need to adopt such a decentralised system for easy record retrieval and accessibility.
  • The decentralised file areas should remain, however, under the control of the medical record department.

Regardless of whether files are centralised or decentralised, there must be centralisation of authority over them. One person, logically the Manager of medical records department, should be authorised to establish and maintain control over all filing procedures and record usage.

Medical Record Request Form

Routine requests for medical records from Specialty clinics or doctors performing study or research, should be delivered to the medical record department by a specified time of day fixed by Hospital administrator or by medial records policy. The routine requests from the doctors or clinics are received through the medical record request form. The requisitions slip usually is a single form which contains necessary columns.

Fig. 5.1 - Medical Records request Form

- The minimum information to be included are, the patient’s name, medical records number, sign of person issuing medical records and the name of the person requesting with signature.

All routine requisitions for records should be received before 4 p.m. every day. The exact time set for the deadline is dependent on (1) the volume of requests received daily and (2) the number of medical records retrievers available to pull requisitioned records.

Usually maximum of 15 medical records may be issued to any doctor requesting for study. This is to minimize the delay in getting back from the concerned doctor the medical records of patients who may visit the hospital for consultation. If too many records are held by a doctor, the visiting patients may have to wait for a long time till their records are got back from the doctor.This will also reduce the work load of the concerned retriever thus, by controlling the huge number of medical records taken out from medical records filing area.

When the medical record is returned back, it is rechecked with the medical records request form and sent for filing. If the medical record is not returned within the established time, a note is sent to the person who has taken the medical records to return that immediately.


While the methods of numbering medical records and the system of filing have the same objective, that is, that is making available a continuous record of the patient at all times , the centralised unit or serial-unit system automatically attains this objective because all records of a patient are filed together in one folder and in one department. If a centralised unit system is coupled with terminal digit filing in hospitals where the activity of all records is very great, efficient and improved service for the patient, doctors, and other personnel should be the result. Unless the medical record is immediately available when and where needed all the time, labor and expenses in maintaining a medical record department is wasted.

Because the space required for the filing of medical records is growing rapidly, the medical record manager must face the problem of retention of records realistically. Therefore periodical surveys should be made by the departmental head which can greatly assist the administrative personnel responsible for making decisions regarding storage space and retention schedules.

Key points to remember

  • The unit numbering system provides a single record, which is a composite of all data gathered on a given patient.
  • The straight numeric filing system has a greatest advantage in training personnel within a limited span of time.
  • Alphabetic filing by patient names is more cumbersome and subject to more error than numerical filing
  • Periodical surveys should be made by the Medical Records Technician which can greatly assist the Hospital Administrator responsible for making decisions regarding storage space and retention schedules
  • Unless the medical record is immediately available when and where needed all the time, labor and expense in maintaining a medical record department is wasted

Student exercise

Answer the following

  1. Describe the following numbering system and list one advantage and disadvantage of each system.
    • Serial numbering
    • Serial-unit numbering
    • Unit numbering
  2. Define centralized and decentralized filing, and summarize the advantages of centralization for medial records.
  3. Arrange the following medical record numbers in a sequence according to each filing system: 213497, 213498, 213598, 213599, 313501, 313502, and 313503.
    • Straight numeric filing
    • Terminal digit filing
    • Middle digit filing
  4. What is Straight numeric filing system and explain the advantages and disadvantages of this filing system
  5. Method of issuing medical records to doctors or clinics on request. Explain?