05 Νοέ Preoperative Imaging for Pilonidal Sinus Disease: Impact on Surgical Planning and Outcomes
Dr. Georgios Georgiou addressed which imaging modalities are available for pilonidal sinus disease (PSD), whether they are needed for diagnosis, operative planning and follow-up, whether they are needed in every case, and which modality is preferable. Sinography (fistulography) was technically demanding, and both sinography and CT fistulography expose a young patient population to radiation. In current practice, the armamentarium consists mainly of ultrasound (US) and MRI. US in the longitudinal and transverse axes shows the dimensions of the cyst, its proximity to the skin and to the tailbone, and sometimes trapped hair. MRI provides three-dimensional images and allows simultaneous assessment of the perianal region. PET-CT images are occasionally available but are not used in everyday practice.
According to the Italian, European and American guidelines, imaging is not required to establish the diagnosis, which rests on clinical examination by inspection and palpation, sometimes with intraoperative methylene blue.¹ ² Imaging should serve only as an adjunct in disease near the anal verge or to differentiate PSD from other conditions such as a painful coccyx, lipoma, subcutaneous cyst, anal fistula with a long tract at 6 o’clock, or hidradenitis suppurativa. Combined superficial and endoanal US can help to distinguish these entities,³ and MRI is particularly useful when a low PSD has to be distinguished from an anal fistula. Doppler US can also indicate an acute state, with increased blood flow in the periphery of an abscess.
For operative planning, imaging informs patient positioning, choice of anesthesia and selection of the surgical technique for simple or complicated disease. In one study, the surgeon changed the operative plan in 23.3% of cases after US, because palpation or methylene blue had left portions of pilonidal tissue unidentified.⁴ In a cohort of 72 patients, high-frequency US always provided valuable information,⁵ and instilling hydrogen peroxide into the cavity improves contrast.⁶ Preoperative MRI delineates extensions and branching with substantial agreement and is more reliable for deep extensions than for counting external openings, although expert consensus on MRI reporting is still needed.⁷ In a comparative study, side branches were detected in 22% of patients on US and in 40% on MRI, and the authors preferred MRI, especially for complex PSD.⁸
Intraoperative US, in contrast, identified previously undetected secondary tracts in 31.5% of patients, leading to a change in surgical approach.⁹ Dr. Georgiou showed how intraoperative US, here in a study by a Greek colleague, can reveal that what appears to be one cavity is in fact two, which changes the indicated technique.¹⁰ US also shows the fiber tip during SiLaC®, confirming that energy is delivered inside the cavity and not outside it, where it might create a seroma. In his view, this reduces the “blindness” for which SiLaC® is often criticized.
Dr. Georgiou noted that six to eight different classifications exist but none is used universally. Together with partners in ISoLP, he is working on a simple classification and treatment algorithm in which imaging would not be required for simple chronic disease, would be recommended for complex disease and would be strongly recommended in recurrent disease; this work is still unpublished. When comparing modalities, he described US as cheap, readily available, surgeon-performed, instant and repeatable, and therefore suitable for follow-up, but operator-dependent; MRI is expensive, not universally available and reported with delay by a radiologist, but provides more definitive imaging and information beyond PSD. The ISoLP position paper reports a sensitivity of 80–90% for high-frequency US, regards MRI as the cross-sectional modality of choice for extensive or multiloculated disease, notes that the fistuloscope often makes routine imaging unnecessary with EPSiT®, and supports selective
rather than routine preoperative imaging before SiLaC®/EPSiT® based on clinical complexity.¹¹
In two videos, Dr. Georgiou demonstrated bedside US with a sterile-covered portable probe in the operating room: transverse and longitudinal scanning to check whether pits communicate and whether a caudal extension is present before probing, to avoid false routes, followed by real-time visualization of the fiber during laser application in continuous or pulsed mode.
He concluded that surgeons should use every available tool to lower recurrence and complication rates.
REFERENCES
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2. Techniques in Coloproctology (2021) 25:1269–1280. doi:10.1007/s10151-021-02487-8 [Italian consensus, title and authors truncated on slide]
3. Youssef AT. The value of superficial [title truncated on slide] in evaluating pilonidal [disease]. J Ultrasound. 2015;18:237–243. doi:10.1007/s40477-015-0156-3
4. Mentes O, Oysul A, Harlak A, Zeybek N, Kozak O, Tufan T. Ultrasonography accurately evaluates the dimension and shape of the pilonidal sinus. Clinics. 2009;64(3):189-92. doi:10.1590/S1807-59322009000300007
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8. De Hous N, De Smet E, Bosmans F, Spinhoven M, Hendrickx T, Gaillard M, Van den Broeck S, Komen N. Efficacy of Ultrasound Compared to Magnetic Resonance Imaging for the Preoperative Mapping of Pilonidal Sinus Disease: A Proof of Concept Study. Surgical Innovation. 2025;0(0):1-8. doi:10.1177/15533506251387881
9. Gallo G, Goglia M, De Simone V, Gravante G, Sileri P, Crucitti A, La Torre M. Intra-operative ultrasound in the surgical treatment of complex and recurrent pilonidal disease: a retrospective, observational, single-center study. International Journal of Colorectal Disease. 2025;40:203. doi:10.1007/s00384-025-04961-3
10. Expert Review of Medical Devices. doi:10.1080/17434440.2021.1943362 [title and authors not visible on slide]
11. Ouali M, Martin-Martin GP, Avdicausevic S, Alam A, Istok P, Bruneikles I, Dobricanin V, de Parades V, Wu J, Ambe PC. International Society of Laser Proctology Position Paper on SiLaC and EPSiT/SiLaC in the Management of Pilonidal Sinus Disease. Lasers in Surgery and Medicine. [year/volume not visible on slide]
“ Intraoperative ultrasound reduces the blindness of SiLaC®: it shows the borders of the cavity, reveals hidden tracts and confirms that the fiber tip is delivering adequate energy inside the sinus.
