骨盆固定螺釘延遲性移位導致大陰唇膿瘍：病例報告

黃國倫¹、吳俊賢^1、2、林嘉祥^1、2

¹義大醫療財團法人義大醫院 泌尿科；

²義守大學 醫學系

Delayed Migration of a Pelvic Fixation Screw Causing Labia Majora Abscess: A Case Report
Guo-Lun Huang¹, Chun-Hsien Wu^1,2, Victor C. Lin^1,2

¹Department of Urology, E-Da Hospital, Kaohsiung, Taiwan;

²School of Medicine, College of Medicine, I-Shou University, Kaohsiung, Taiwan

Introduction: Delayed migration of pelvic fixation hardware is rare, particularly into the female external genitalia. The dartos muliebris, homologous to the scrotal dartos in male, lies beneath the subcutaneous tissue of the labia majora. Together with the continuous fascial planes of Scarpa’s and Colles’ fasciae, it may provide a potential subcutaneous route for screw migration from the pelvic region to the vulvar tissue. We report a rare case in which a displaced pelvic screw migrated along these planes, resulting in a labia majora foreign body with abscess formaton.

Case report: A 62-year-old woman with a medical history of diabetes mellitus and an open book pelvic fracture that had been surgically repaired with internal fixed metallic implant over superior pubic rami seven years earlier, presented with progressive swelling over the left labia majora for one month. On physical examination, the area was tender, erythematous, and warm to touch, suggesting local infection. A soft tissue ultrasound of external genitalia showed the presence of a foreign metallic object located just beneath the subcutaneous layer of left labia majora, raising suspicion of a migrated fixation screw (Fig. 1A). Pelvic X-ray revealed a metallic screw dislodged from the previous fixation site (Fig. 1B). Computed tomography (CT) of the pelvis demonstrated a displaced screw extending into the left vulvar region, accompanied by abscess formation within the surrounding soft tissue (Fig. 1C). After multidisciplinary consultation, the patient underwent incision and drainage of the left labia majora abscess. A vertical incision was made over the affected area, revealing a 2.5-cm dislodged screw embedded within the subcutaneous layer, superficial to the dartos muliebris, and surrounded by purulent material (Fig. 1D). The screw was carefully removed, the abscess cavity was thoroughly irrigated, and a Jackson-Pratt drain was placed for postoperative drainage. The drain tube was removed on postoperative day 5, and she was discharged in stable condition. However, approximately six weeks later, she developed recurrent abscess formation at the same site. Subsequent surgical management included repeat incision and drainage with excision of necrotic tissue, followed by delayed wound closure five days later. At present, the patient remains under regular outpatient follow-up, with complete wound healing and no further recurrence.

Conclusion: This case highlights a rare instance of pelvic fixation screw migration into the labia majora, leading to abscess formation. Understanding the anatomic homology between the scrotum and the labia majora is essential to explain this rare phenomenon. The dartos muliebris and the continuous fascial planes of Scarpa’s and Colles’ fasciae may account for the unusual route of screw migration. Awareness of these pathways is essential for surgeons and radiologists when evaluating unexplained vulvar foreign body in patients with a history of pelvic fixation.