Ultrasonography accurately evaluates the dimension and shape of the pilonidal sinus.

Purpose: To study the benefits of ultrasonography for detecting the borders of pilonidal sinus tissue. The correlation between physical and ultrasonographic examination was used for surgical planning.

Method: Between April and December 2004, 73 patients were recruited for this study. All patients were examined, and the borders of the sinus tissue were marked on the skin according to palpation before surgery. The surgeon also made a treatment plan considering the diseased tissue and marked a possible incision line. Patients were subsequently examined with ultrasonography. According to the ultrasonographic evaluation, the margins, extensions, and openings of pilonidal sinus tissue were determined and marked on the patient in a different color by a radiologist prior to surgery. The most suitable surgical treatment was decided according to the information obtained by ultrasonography.

Results: The average age was 23.03 +/- 3.05 (range 18-39) years. We found 81 lesions in 73 patients. Ultrasonographic borders of sinus tissue were similar to the borders marked by the surgeon in 56 patients (76.7%). In the remaining 17 patients (23.3%), ultrasonography detected branches or borders that distinctly exceeded the planned incision line. After ultrasonographic examination, the surgeon changed his incision line in 14 patients and the surgical intervention in 3 patients.

Conclusion: Palpation and methylene blue injection do not provide appropriate information in many patients. Our study revealed that pre-operative ultrasonography can improve the identification of the sinus tract and its branches when compared to palpation and methylene blue injection.