The Emergency Department does not stand alone — it is the hub of a wheel whose spokes reach into diagnostic imaging, the laboratory, the operating room, critical care, and the inpatient bed tower. How tightly those spokes are drawn, and how cleanly a patient and their information move along them, determines whether the ED runs at the pace its acuity demands or silts up because the next destination is too far, too slow, or too contested. This article addresses the planning of ED adjacencies and the vertical and horizontal transport that connects them, with emphasis on the time-critical service lines (stroke, STEMI, trauma, sepsis) and on the chronic bottleneck that defines ED throughput in most U.S. hospitals: the inpatient hand-up.

Why adjacency planning is a throughput decision, not a wayfinding one

Adjacency is often treated as an architectural nicety — a bubble diagram exercise resolved before the program is fixed. In the ED it is a clinical and operational decision with measurable consequences for door-to-needle time, door-to-balloon time, trauma survival, and overall length of stay. Every minute a stroke or STEMI patient spends in transit to CT or the cath lab is a minute of ischemic tissue lost; every avoidable transport handoff is a fresh opportunity for a fall, a dislodged line, a missed deterioration, or a communication gap.

The governing constraint is that the ED is a 24/7, surge-on-demand environment that cannot defer demand the way an elective service line can. When a downstream destination is unavailable, the patient does not leave — they hold in the ED, consuming a treatment bay, a monitor, and a nurse. Adjacency planning is therefore the discipline of minimizing both the distance and the dependency between the ED and the destinations its patients most need, so that the department can clear its bays and absorb the next arrival.

Three principles frame the work:

• Co-locate by frequency and acuity. The destinations a patient reaches most often, and most urgently, belong closest. Imaging (especially CT) and the inpatient route lead this list; the OR and ICU follow for the smaller but highest-stakes cohort.
• Plan for the information path, not just the patient path. Lab results, imaging studies, and clinical context must arrive at the destination as fast as the patient does. A pneumatic tube, a PACS network, and a warm verbal handoff are as much "adjacency" as a corridor.
• Design the route, not just the endpoints. Two departments can be programmatically adjacent yet operationally distant if the corridor between them is shared with the public, the elevator is undersized, or the path crosses a fire/smoke barrier with a non-hold-open door.

Imaging: keep CT inside the ED footprint

Diagnostic imaging is the ED's most frequent and most time-sensitive adjacency. The defining decision is the location of computed tomography.

CT belongs in or immediately adjacent to the ED. In any ED above the smallest rural scale, a dedicated ED CT scanner within the department footprint is now the standard of care for moderate-to-high volume facilities, and it is effectively mandatory for stroke- and trauma-designated centers where door-to-CT time is a tracked, reported metric. Sharing the main radiology department's scanner forces ED patients to compete with scheduled outpatients and inpatients, introduces transport across departmental boundaries, and makes the ED's most critical timeline hostage to another department's queue. A scanner sited so it is accessible from both the ED resuscitation zone and the imaging corridor (a "swing" or shared-access bay) can serve both populations while preserving ED priority, but the priority must be unambiguous.

Planning considerations for ED imaging:

• Adjacency hierarchy: CT closest, then general radiography (often distributed — a room within the ED plus portable units for the resuscitation bays), then ultrasound. MRI is typically reached via the main imaging suite, but stroke programs increasingly want rapid MRI access; where a stroke center commits to MRI-based protocols, plan the route and the screening/safety zoning accordingly.
• The resuscitation–CT axis is the single most important imaging adjacency. A trauma or stroke patient should reach CT from the resuscitation room without traversing public space or making a vertical move. The ideal is a straight, wide, dedicated corridor — gurney-width with clearance for the patient plus accompanying staff, IV poles, monitors, and a portable ventilator.
• Point-of-care ultrasound (POCUS) lives at the bedside and is an equipment/IT provision rather than a room, but the imaging program should account for it (storage, charging, image archiving to PACS).
• MRI safety zoning (the four-zone model with controlled access to Zone IV) governs any MRI sited near the ED; ferromagnetic-object control and screening are life-safety issues, and the route from the ED must not allow uncontrolled gurney/equipment entry into the magnet room.
• Shielding and structural loads for CT and any fixed imaging are coordinated with a qualified medical physicist and the structural engineer; these drive slab thickness, lead-lined partitions, and door specifications early in design.

The decisive enabler behind the imaging adjacency is PACS (picture archiving and communication system). With images instantly available on any workstation, the radiologist's reading location is decoupled from the scanner — but the patient's path to the scanner is not. Network and IT density at the scanner, in the resuscitation rooms, and at every reading and provider station is part of the imaging adjacency program.

Laboratory: bring the lab to the ED, virtually

For the ED, the laboratory adjacency is overwhelmingly an information and specimen-transport relationship rather than a physical-proximity one. The clinical question is almost never "how far is the lab?" but "how fast does the result return?"