CAISS Extremity Injuries 4 — Questions and Answers
Question 1: A patient with a traumatic above-knee amputation (AKA) and no other injuries has an ISS of:
- 9
- 16
- 25 (Correct answer)
- 36
Correct answer: 25
Traumatic AKA is AIS 5; ISS = AIS² for the highest single region = 5² = 25 when it is the only injury.
Question 2: Which nerve injury modifier most significantly increases the AIS severity of a humeral shaft fracture?
- Radial nerve neurapraxia
- Median nerve contusion
- Brachial plexus avulsion (Correct answer)
- Ulnar nerve stretch
Correct answer: Brachial plexus avulsion
Brachial plexus avulsion associated with a humeral fracture represents severe neurological disruption and can raise AIS severity substantially.
Question 3: In the context of CAISS, why is it important to document the mechanism of injury for extremity trauma?
- It determines the AIS body region
- It affects the ISS calculation directly
- It helps select the most appropriate AIS descriptor when multiple codes apply (Correct answer)
- It replaces the need for imaging documentation
Correct answer: It helps select the most appropriate AIS descriptor when multiple codes apply
Mechanism of injury provides clinical context that helps the coder choose between similar AIS descriptors when injury specifics are ambiguous.
Question 4: Which of the following is an AIS 6 extremity injury?
- Bilateral femur fractures
- Traumatic hemipelvectomy (Correct answer)
- Open tibia fracture with arterial injury
- Crush injury to both feet
Correct answer: Traumatic hemipelvectomy
Traumatic hemipelvectomy (amputation through or above the pelvis) is incompatible with current life-saving treatment and is coded AIS 6.
Question 5: A patient has an isolated closed humeral shaft fracture. According to AIS, this is coded under which body region?
- Region 5 (Spine)
- Region 6 (Lower extremity)
- Region 7 (Upper extremity) (Correct answer)
- Region 8 (Unspecified)
Correct answer: Region 7 (Upper extremity)
Humeral shaft fractures are upper extremity injuries coded under AIS Region 7.
Question 6: When a patient sustains a pelvic ring fracture with significant hemorrhage, which body region is used for AIS coding?
- Abdomen (Correct answer)
- Lower extremity
- Spine
- External
Correct answer: Abdomen
Pelvic ring fractures are coded under the Abdomen (Region 4) in AIS, not the lower extremity region.
Question 7: A motorcyclist sustains a traumatic foot amputation through the mid-foot (Lisfranc level). Which AIS severity applies?
- AIS 2
- AIS 3
- AIS 4 (Correct answer)
- AIS 5
Correct answer: AIS 4
Partial foot amputation at or through Lisfranc joints is coded AIS 4 (severe) in the AIS lower extremity chapter.
CAISS Extremity Injuries 4
A patient with a traumatic above-knee amputation (AKA) and no other injuries has an ISS of: