HL7 SCH Segment: Scheduling Activity
The HL7 SCH segment (Scheduling Activity Information) carries the core appointment details in SIU messages — appointment identifiers, event reason, timing, duration, and status. SCH is the defining segment of scheduling messages, analogous to how OBR defines orders and TXA defines documents.
SCH Field Reference
Section titled “SCH Field Reference”| Seq | Name | Type | Opt | Description |
|---|---|---|---|---|
★ SCH-1 | Placer Appointment ID | EI | O | Appointment ID from requesting system |
| Must be preserved across all SIU events for the same appointment. The requesting EHR uses this to correlate status updates. | ||||
★ SCH-2 | Filler Appointment ID | EI | O | Appointment ID from scheduling system |
| Assigned by the scheduling system when confirming a booking. Echoes SCH-1 and adds its own identifier. | ||||
SCH-3 | Occurrence Number | NM | O | Instance number for recurring appointments |
| Instance within a series (1, 2, 3...). Used with SCH-23/24 for recurring appointment tracking. | ||||
SCH-4 | Placer Group Number | EI | O | Groups related appointments together |
SCH-5 | Schedule ID | CE | O | Master schedule identifier |
★ SCH-6 | Event Reason | CE | R | Reason for the appointment |
★ SCH-7 | Appointment Reason | CE | O | Detailed reason/chief complaint |
★ SCH-8 | Appointment Type | CE | O | ROUTINE, FOLLOWUP, URGENT, WALKIN |
SCH-9 | Appointment Duration | NM | O | Duration amount |
SCH-10 | Appointment Duration Units | CE | O | MIN, HR, etc. |
★ SCH-11 | Appointment Timing Quantity | TQ | R | Start/end time, duration, frequency |
| TQ data type encodes start time, end time, and duration. For v2.5+, TQ1 segments may replace this field. | ||||
SCH-12 | Placer Contact Person | XCN | O | Person at requesting organization |
SCH-13 | Placer Contact Phone | XTN | O | Phone for requesting organization |
SCH-14 | Placer Contact Address | XAD | O | Address for requesting organization |
SCH-15 | Placer Contact Location | PL | O | Location of placer |
SCH-16 | Filler Contact Person | XCN | O | Person at scheduling organization |
SCH-17 | Filler Contact Phone | XTN | O | Phone for scheduling organization |
SCH-18 | Filler Contact Address | XAD | O | Address for scheduling organization |
SCH-19 | Filler Contact Location | PL | O | Location of filler |
SCH-20 | Entered By Person | XCN | O | Person who entered the appointment |
SCH-21 | Entered By Phone | XTN | O | Phone of person who entered |
SCH-22 | Entered By Location | PL | O | Location of person who entered |
SCH-23 | Parent Placer Appointment ID | EI | O | Parent appointment (recurring series) |
SCH-24 | Parent Filler Appointment ID | EI | O | Parent appointment from scheduling system |
★ SCH-25 | Filler Status Code | CE | O | Booked, Pending, Complete, Cancelled, etc. |
| Appointment lifecycle status. Each transition generates a corresponding SIU event (S12=New, S13=Rescheduled, S15=Cancelled, S26=No Show). | ||||
SCH-26 | Placer Order Number | EI | O | Associated order number |
SCH-27 | Filler Order Number | EI | O | Associated order number from filler |
★ SCH-1 O Appointment ID from requesting system
Must be preserved across all SIU events for the same appointment. The requesting EHR uses this to correlate status updates.
★ SCH-2 O Appointment ID from scheduling system
Assigned by the scheduling system when confirming a booking. Echoes SCH-1 and adds its own identifier.
SCH-3 O Instance number for recurring appointments
Instance within a series (1, 2, 3...). Used with SCH-23/24 for recurring appointment tracking.
★ SCH-11 R Start/end time, duration, frequency
TQ data type encodes start time, end time, and duration. For v2.5+, TQ1 segments may replace this field.
★ SCH-25 O Booked, Pending, Complete, Cancelled, etc.
Appointment lifecycle status. Each transition generates a corresponding SIU event (S12=New, S13=Rescheduled, S15=Cancelled, S26=No Show).
R = Required, O = Optional, C = Conditional, W = Withdrawn (backward compatibility only)
SCH-1 / SCH-2: Placer vs Filler Appointment IDs
Section titled “SCH-1 / SCH-2: Placer vs Filler Appointment IDs”The same placer/filler pattern used in orders (ORC-2/ORC-3) applies to appointments:
| Field | Assigned By | Example | Purpose |
|---|---|---|---|
| SCH-1 | Requesting system | APT78901^EPIC | Appointment ID in the requesting EHR |
| SCH-2 | Scheduling system | APT78901^SCHED_SYS | Appointment ID in the scheduling application |
Both IDs must be preserved across all SIU events for the same appointment. When the scheduling system confirms a booking, it echoes SCH-1 and adds its own SCH-2.
SCH-8: Appointment Type Codes
Section titled “SCH-8: Appointment Type Codes”| Code | Type | Description |
|---|---|---|
| ROUTINE | Routine | Standard scheduled appointment |
| FOLLOWUP | Follow-up | Follow-up to a previous visit |
| URGENT | Urgent | Needs to be seen soon (not emergency) |
| WALKIN | Walk-in | No prior appointment |
| CHECKUP | Checkup | Wellness/preventive visit |
| EMERGENCY | Emergency | Emergency scheduling |
SCH-11: Appointment Timing
Section titled “SCH-11: Appointment Timing”SCH-11 uses the TQ (Timing Quantity) data type to express the appointment schedule:
SCH|APT78901^SCHED_SYS|APT78901^EPIC|||||ROUTINE||30|MIN|^^30^202603101400^202603101430| TQ Component | Value | Meaning |
|---|---|---|
| TQ.3 | 30 | Duration: 30 units |
| TQ.4 | 202603101400 | Start: March 10, 2026 at 2:00 PM |
| TQ.5 | 202603101430 | End: March 10, 2026 at 2:30 PM |
For interfaces using HL7 v2.5+, TQ1 (Timing/Quantity) segments may replace SCH-11, providing more structured timing data.
SCH-25: Filler Status Codes
Section titled “SCH-25: Filler Status Codes”| Code | Status | Description |
|---|---|---|
| Booked | Confirmed | Appointment confirmed and scheduled |
| Pending | Pending | Requested but not yet confirmed |
| Waitlisted | Waitlisted | On waitlist for desired slot |
| Started | In Progress | Patient checked in, appointment started |
| Complete | Complete | Appointment finished |
| Cancelled | Cancelled | Appointment cancelled |
| Noshow | No Show | Patient did not arrive |
| Blocked | Blocked | Time slot blocked (not available) |
| Overbooked | Overbooked | Scheduled beyond normal capacity |
| Deleted | Deleted | Appointment record removed |
Status Lifecycle
Section titled “Status Lifecycle”Pending → Booked → Started → Complete ↘ Noshow ↘ Cancelled ↘ Waitlisted → BookedEach status transition generates a corresponding SIU event: S12 (New), S13 (Rescheduled), S14 (Modified), S15 (Cancelled), S26 (No Show).
SCH + Resource Segments
Section titled “SCH + Resource Segments”SCH defines the appointment; resource segments define what and who is needed:
| Segment | Resource Type | Example |
|---|---|---|
| RGS | Resource Group | Groups all resources for one appointment |
| AIS | Service/Activity | Office Visit, Physical Therapy, MRI |
| AIP | Personnel | Dr. Smith (Attending), Sarah (RN) |
| AIL | Location | Exam Room 3, Imaging Suite 2 |
| AIG | General Resource | Equipment, interpreter, wheelchair |
A complete scheduling message:
SCH|APT78901^SCHED_SYS|...|ROUTINE|OFFICE^Office Visit|30|MIN|...||BookedRGS|1|AAIS|1|A|OFFICE_VISIT^Office Visit^LOCAL|||202603101400|0|MIN|30|MINAIP|1|A|ATT1234^SMITH^JANE^^^MD|ATT^Attending^HL70443AIL|1|A|MAIN_CLINIC^EXAM3^01^MAIN_HOSP||202603101400|0|MIN|30|MINKey Implementation Considerations
Section titled “Key Implementation Considerations”Recurring Appointments
Section titled “Recurring Appointments”Recurring appointments (dialysis, chemotherapy, physical therapy) use:
- SCH-3 (Occurrence Number): Instance number within the series (1, 2, 3…)
- SCH-23/SCH-24 (Parent Appointment IDs): Link to the parent/template appointment
- TQ repeat pattern: Frequency encoded in SCH-11 (e.g., every Monday/Wednesday/Friday)
Each occurrence generates its own SIU^S12 (New Appointment) but carries the parent ID for series tracking. Cancelling one occurrence (SIU^S15) should not affect other instances unless the entire series is cancelled.
Appointment Conflict Detection
Section titled “Appointment Conflict Detection”When integrating scheduling systems, check for:
- Double-booking: Same provider or room at overlapping times
- Patient overlap: Same patient scheduled at two locations simultaneously
- Resource conflicts: Equipment or room already reserved
The scheduling system (filler) should reject conflicting appointments with an appropriate SIU^S26 or negative acknowledgment.
Bi-Directional Scheduling
Section titled “Bi-Directional Scheduling”Many implementations require two-way scheduling between EHR and departmental systems:
- EHR → Department: SIU^S12 books appointment in radiology, lab, or therapy system
- Department → EHR: SIU^S14/S15 pushes status updates (modified, cancelled, completed) back to the EHR
Both systems must maintain synchronized appointment states using SCH-1/SCH-2 as the correlation keys.