Chapter 7: Scheduling and Registration Processes
How to Understand the Master Patient Index
Understanding how a master patient index (MPI) works is essential to all clerical roles in the hospital. This is how they ensure that they do not create errors in the MPI database which can affect patient care and how they can view past patient admission information. The most serious clerical MPI errors include:
- a single patient being added multiple times resulting in multiple MRNs (known as an overlap)
- a patient being registered under another patient’s MRN, resulting in them sharing the same MRN and intermingling their health records (known as overlay) (Biddle, 2015).
Example: Master Patient Index
The table below represents what you will find in an MPI with headings, including
- name (will always be listed last name first in alphabetical order)
- ACCT/FIN#
- registration status (see below for definitions)
- date of visit
- location of visit
- MRN/HO# or hospital alias
| Name | Account Num | Status | Date | Location | Med Rec Num |
|---|---|---|---|---|---|
| EXAMPLE,KIM | OP000194/25 | REG CLI | 11/01/25 | DI | 0000396438 |
| EXAMPLE,KIM | IN000128/19 | DIS IN | 22/01/19 | 3W302-1 | 0000396438 |
| EXAMPLE,KIM | ER000213/23 | REG ER | 12/04/23 | ER | 0000541201 |
| EXEMPLAR,SIMRAM | SP000219/25 | PRE SDC | 17/08/25 | DS | 0000292165 |
| EXEMPLAR,SIMRAN | OP000193/16 | REG CLI | 11/04/16 | CAR | 0000292165 |
| TEST,JOHN | DS000219/24 | REG SDC | 22/12/24 | END | 0000459763 |
| TEST,JOHN | SP003287/25 | PRE CLI | 25/09/25 | PSC | 0000493431 |
| TEST,JOHN | SP003287/25 | PRE IN | 18/10/25 | SURG | 0000493431 |
Status Abbreviation Definitions
- ADM: currently admitted (will switch to DIS when discharged)
- CLI: clinic visit
- DEP: departed (has been discharged)
- DIS: discharged
- END: endoscopy visit
- ER: ER/ED visit
- IN: inpatient
- PRE: prescheduled (has not yet attended)
- REG: registered (has attended appointment)
- SDC: surgical day care
How to Interpret this MPI
First, note that patients are listed in alphabetical order by last name, with a patient’s most recent encounter listed first.
Next, review the MRN on the far-right side of the above table for EXAMPLE, KIM. You will see the MRN is the same for the first two EXAMPLE, KIM accounts but not the third. As you have just learned, each person is given their own unique MRN upon their first admission and they will continue to be registered under this number for every subsequent encounter. By checking the MRN number, you have now ascertained that there are two different patients with the name EXAMPLE, KIM.
Next, review the Account Numbers for the first EXAMPLE, KIM patient. These will be different, as each encounter has its own unique number for billing and administrative reasons. You can tell several things from looking at the Account Number and Status.
- Visit #1: in EXAMPLE, KIM’s most recent visit, the OP000194/25 indicates an outpatient visit in 2025, while the REG CLI means that she was registered for a clinic visit. Further information may be obtained in the location field, which indicates it was a DI (diagnostic imaging visit).
- Visit #2: in EXAMPLE, KIM’s prior visit, the IN000128/19 indicates an inpatient visit in 2019, while the DIS IN means that she was discharged from an inpatient visit. Further information may be obtained in the location field, which indicates which unit and bed number she was admitted to.
Source: Based on information from Alberta Health Services, 2016, pp. 10.
Practice Activity: Interpret the Master Patient Index
- Review the information for the EXEMPLAR, SIMRAN entries.
- How many patients do these represent?
- How many visits did the patient(s) have?
- Where and when were these visits?
- Review the information for the TEST, JOHN entries.
- How many patients do these represent?
- How many visits did the patient(s) have?
- Where and when were these visits?
References
Alberta Health Services. (2016, July). Meditech order entry (OE) user manual [PDF].
Biddle, M. (2015). Maintaining the master patient index: The impact of patient registration processes on data integrity. Applied Research Projects. 32.
a table or database that includes patient information used in registration and billing processes; each individual patient within the database has a unique identifier
