Does a patient with a discharging pilonidal sinus need an MRI (Magnetic Resonance Imaging) before surgical intervention?

Pilonidal Sinus Pre-Surgical Imaging Requirements

No MRI or advanced imaging is required before surgical intervention for a discharging pilonidal sinus in most cases.

Rationale for No Advanced Imaging

Pilonidal sinus disease is a condition that primarily affects the subcutaneous tissue in the sacrococcygeal region, and its diagnosis is typically clinical. The evidence does not support routine pre-surgical advanced imaging for several reasons:

1. Clinical Diagnosis is Sufficient: Pilonidal sinus is diagnosed through physical examination, with visualization of the sinus tract opening(s) and assessment of discharge.

2. Superficial Nature: Unlike sinonasal disease (which the ACR guidelines discuss extensively), pilonidal disease is superficial and does not typically involve deep structures that would require advanced imaging 1.

3. No Evidence Supporting Routine MRI: None of the guidelines or research evidence provided supports the use of MRI before surgical intervention for uncomplicated pilonidal sinus disease 2, 3, 4.

When Imaging Might Be Considered

There are rare circumstances when imaging might be warranted:

• Suspected Complex Disease: In cases with extensive branching sinus tracts or recurrent disease after multiple surgeries
• Suspected Malignancy: When there is concern for malignant transformation (extremely rare at 0.1%, usually after 20-30 years of chronic disease) 5
• Suspected Deep Extension: If there is clinical suspicion of extension to deeper structures beyond the subcutaneous tissue

Surgical Planning Without Advanced Imaging

The surgical approach for pilonidal sinus can be determined without advanced imaging:

• Examination Under Anesthesia: Often provides all necessary information about tract extent
• Probing of Sinus Tracts: During surgery allows for identification of all branches
• Methylene Blue Injection: Can be used intraoperatively to identify all sinus tracts

Surgical Options

Several surgical approaches exist for pilonidal sinus:

• Open Healing: Lower recurrence rate (58% less likely to recur than primary closure) but longer healing time 2
• Primary Closure: Faster healing and earlier return to work (average 10.5 days sooner) 2
• Off-Midline Closure: Shows better outcomes than midline closure with lower infection rates and recurrence 2
• Asymmetric Excision: Can flatten the natal cleft and move the incision away from midline, reducing recurrence rates to as low as 0.9% 4

Potential Complications to Monitor

• Wound infection (1.8-13.6%)
• Failure to heal (13.6%)
• Recurrence (0.9-3.6%)
• Wound breakdown
• Fluid collections

Conclusion

For a patient with a discharging pilonidal sinus, proceed directly to appropriate surgical intervention without MRI or other advanced imaging. Focus should be on selecting the most appropriate surgical technique based on the extent of disease determined through clinical examination.