What is the sequence of procedures for acne scar treatment using subcision, CO2 (carbon dioxide) laser, and TCA (trichloroacetic acid) chemical peel in one session?

Procedural Sequence for Combined Acne Scar Treatment

Recommended Order: Subcision → TCA Peel → CO2 Laser

When performing subcision, TCA chemical peel, and CO2 laser in a single session for acne scars, perform subcision first, followed by TCA peel, then conclude with CO2 laser resurfacing. This sequence is supported by multiple clinical studies demonstrating safety and efficacy with this specific order 1, 2, 3.

Step-by-Step Protocol

1. Begin with Subcision

• Perform subcision first to release fibrous tethering bands beneath rolling and boxcar scars 1, 2, 3
• Use tumescent anesthesia for patient comfort and to create a tissue plane that facilitates the procedure 1
• This mechanical release of dermal attachments must occur before ablative procedures to maximize scar elevation 2, 3

2. Apply TCA Chemical Peel Second

• After completing subcision, apply 20% TCA as a superficial chemical peel to the treatment area 1
• The TCA stimulates neocollagenesis and can be applied immediately following subcision in the same session 1
• This intermediate step prepares the skin surface before laser treatment 1

3. Perform CO2 Laser Resurfacing Last

• Complete the session with fractional CO2 laser as the final modality 1, 2, 3
• The laser provides additional collagen remodeling and surface texture improvement 2, 3
• Critically important: Any adjuvant platelet-rich plasma (PRP) must be applied AFTER the CO2 laser, not before 4, 5

Critical Rationale for This Sequence

Why Laser Must Be Last

• The American Academy of Periodontology explicitly states that laser treatment damages cells, so applying regenerative therapies like PRP before laser would negate their benefits 4, 5
• This principle extends to the overall sequence: ablative procedures should be performed last to avoid destroying the benefits of earlier interventions 4
• Laser-first approaches would potentially damage the tissue planes created by subcision 2

Evidence Supporting This Order

• A 2017 study of 114 patients demonstrated that the sequence of 20% TCA peel → subcision → fractional CO2 laser achieved a mean improvement of 2.9/4.0, with 90% patient satisfaction after a single treatment session 1
• Multiple studies confirm that subcision combined with CO2 laser (in this order) shows statistically significant superior results compared to laser alone (p<0.001) 2, 3
• The combination approach addresses different scar components: subcision releases tethering, TCA stimulates collagen, and laser provides surface remodeling 6, 1

Expected Outcomes and Side Effects

Efficacy

• Single-session treatment using this sequence achieves 54.7% average recovery rate versus 43.0% with laser alone 2
• Patient satisfaction scores are significantly higher with combination approaches (6.6 ± 1.2 vs. 5.2 ± 1.8 for laser alone, p<0.001) 2
• Results are particularly effective for rolling and grade 2-3 atrophic scars 1, 3

Common Side Effects by Modality

• Subcision: Bruising lasting 1-2 weeks in all patients when combined with other modalities 2
• TCA peel: Risk of postinflammatory hyperpigmentation, particularly in Fitzpatrick skin types III-IV 7
• CO2 laser: Erythema (expected in all patients), with significantly reduced duration when PRP is applied afterward 4, 5
• No persistent side effects beyond 6 months when proper technique is used 2

Post-Procedure Adjuvant Therapy

PRP Application (If Used)

• Apply PRP immediately after completing the CO2 laser as the final step 4, 5
• PRP can be applied topically, via microneedling, or intradermally 4
• Benefits include significantly shorter duration of erythema, edema, and crusting compared to laser alone 4, 5, 8
• PRP reduces downtime and accelerates healing without compromising scar improvement 4

Common Pitfalls to Avoid

• Never perform laser before subcision: This would damage the tissue planes needed for effective fibrous band release 4, 2
• Never apply PRP or other regenerative therapies before laser: The ablative laser will destroy cells and negate any regenerative benefits 4, 5
• Avoid 100% TCA CROSS technique in darker skin types: Higher concentrations show more pigmentary complications than subcision in Fitzpatrick III-IV skin 7
• Do not underestimate bruising duration: Inform patients that subcision causes 1-2 weeks of bruising when combined with other modalities 2