Is the unlisted procedure code 22899 for retroperitoneal access to the spine (anterior retroperitoneal exposure of spine L4-L5) medically necessary for a patient with spinal stenosis (M48.061), spondylolisthesis (M43.16), and other spondylosis with radiculopathy (M47.26)?

Medical Necessity Assessment for Anterior Retroperitoneal Exposure (Code 22899)

Direct Answer

The anterior retroperitoneal exposure (code 22899) is medically necessary for this elderly patient with grade 2 spondylolisthesis at L4-L5, as the operative plan includes anterior lumbar interbody fusion (ALIF) which requires vascular access and mobilization that only a specialized vascular/access surgeon can safely provide. 1

Clinical Justification for Fusion in This Case

The presence of grade 2 spondylolisthesis with severe stenosis at L4-L5 represents clear biomechanical instability that mandates fusion in addition to decompression. 1, 2

• Grade 2 anterolisthesis constitutes documented spinal instability, which is a Grade B indication for surgical decompression with fusion according to the American Association of Neurological Surgeons 1, 2
• Preoperative spondylolisthesis is a documented risk factor for 5-year clinical and radiographic failure after decompression alone, with up to 73% risk of progressive slippage 1
• Class II evidence demonstrates that 96% of patients with spondylolisthesis and stenosis treated with decompression plus fusion reported excellent or good outcomes, compared to only 44% with decompression alone 1, 2

Why Anterior Approach Requires Separate Vascular Access Code

The anterior retroperitoneal exposure is a distinct and necessary component performed by a vascular/access surgeon, separate from the spinal fusion procedure itself. 1

• The operative note clearly documents that a separate surgeon performed "anterior spinal exposure at the L4-L5 disc space with medial immobilization of the peritoneal sac and left ureter, isolation and immobilization of the aorta and vena cava, left common iliac artery and vein with ligation of the segmental vessels" 1
• This vascular access procedure requires specialized expertise in retroperitoneal anatomy, vascular mobilization, and management of major vessels that is distinct from the orthopedic/neurosurgical fusion procedure 1
• The documentation explicitly states the access surgeon's "unique risks and benefits of anterior spinal access" were discussed separately with the patient 1

Evidence Supporting Anterior Interbody Fusion Approach

Circumferential fusion (360-degree) with anterior interbody support demonstrates higher fusion rates compared to posterolateral fusion alone in patients with severe stenosis and spondylolisthesis. 1

• Interbody fusion devices provide anterior column support, restore disc height, and improve foraminal dimensions, which is particularly important in grade 2 spondylolisthesis 1
• The anterior approach allows for direct visualization and complete discectomy, optimal cage placement with lordotic correction (20-degree lordosis cage used in this case), and avoids posterior scar tissue from potential future posterior surgery 1

Two-Stage Surgical Plan Rationale

The planned two-stage approach (anterior fusion followed by posterior decompression and instrumentation) is appropriate for grade 2 spondylolisthesis with severe stenosis. 1, 3

• The first stage (anterior interbody fusion) provides anterior column support and restores disc height 1
• The second stage will address posterior decompression of neural elements and provide posterior instrumentation for additional stability 1, 3
• This staged approach allows for optimal biomechanical reconstruction while managing surgical complexity and patient tolerance 3

Critical Distinction from Standard Decompression-Only Cases

This case fundamentally differs from isolated stenosis cases where fusion is not indicated. 4, 1

• The American Association of Neurological Surgeons recommends decompression alone for stenosis without instability 4, 1
• However, fusion is specifically recommended when decompression coincides with any degree of spondylolisthesis, which this patient clearly has (grade 2) 1, 2
• The presence of spondylolisthesis changes the treatment algorithm from decompression alone to decompression with fusion 1, 2

Common Pitfall to Avoid

Do not deny the anterior access code (22899) based on the misconception that it is included in the fusion code. 1

• The anterior retroperitoneal exposure is performed by a separate surgeon with distinct training and expertise 1
• The vascular mobilization, vessel ligation, and ureter management are not performed by the spinal surgeon and represent separate procedural work 1
• Code 22899 is appropriately used when there is no specific CPT code for the anterior access procedure 1

Documentation Supports Medical Necessity

The clinical documentation demonstrates:

• Failed conservative management since 2016 with progressive symptoms 1
• Objective radiographic findings of grade 2 anterolisthesis with severe stenosis on MRI and CT myelogram 1
• Neurological symptoms including radiculopathy with numbness and tingling 1
• Clear surgical indication for fusion based on documented instability 1, 2
• Appropriate two-stage surgical planning for complex spinal reconstruction 1, 3

The anterior retroperitoneal exposure (code 22899) should be certified as medically necessary for this patient's anterior lumbar interbody fusion procedure. 1, 2