Background

The incidence of tubal clip migration is reportedly 25%. However, less than 1% of those who experience clip migration will present with symptoms such as pain, an abscess, or spontaneous extrusion [1]. As we report in this article, clip migration is unpredictable, rare, and the exact mechanisms are not well understood. Here, we present a rare case of sterilisation clip migration through the entire pelvic floor, as well as a literature review of reported sterilisation clip migration.

Case

A 66-year-old female was referred from the community to the Surgical Emergency Unit with a possible metallic foreign body under the skin following an attempted routine gluteal cyst excision. The patient first noticed a lump under the skin 2 years ago which gradually became more apparent and tender over the past 2 months. The patient denied recent trauma or procedures in the gluteal region and inflammatory markers were normal. Examination revealed a non-mobile solid pin-like structure just beneath the skin 5 cm laterally from the anal verge (Fig. 1). An ultrasound confirmed a 15 × 7 mm foreign body in the subcutaneous tissue of the posteromedial aspect of the upper thigh (Fig. 2). The foreign body was excised easily under local anaesthesia, revealing a closed Filshie sterilisation clip. The wound was closed primarily, and recovery was uncomplicated. Apart from a laparoscopic sterilisation procedure 24 years prior, the patient was fit and well, with a normal body mass index (BMI).

Fig. 1
figure 1

Illustration of location of foreign body palpated during examination, marked with a cross, on an image adapted from https://theodora.com/anatomy/surface_anatomy_of_the_lower_extremity.html

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Fig. 2
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Admission ultrasound image showing foreign body in the subcutaneous tissue of the posteromedial left thigh

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Discussion

The overall number of sterilisation procedures in NHS hospitals is falling. The latest NHS Digital data suggest a 26% decrease in annual sterilisation procedures over a 10-year period. In the 2018/2019 year, there were 12,918 procedures performed, down from 17,562 in 2008/2009 [2]. However, there is a paucity of population-wide data on the specific type of female sterilisation method used. There have been advances in sterilisation methodology over the last two decades, namely the introduction of transcervical hysteroscopic devices. However, laparoscopic and laparotomic approaches are still utilised particularly in developing countries to achieve the common goal of uterine tubal occlusion [3]. As with all surgical procedures, this operation carries risks. Specific risks include a failed procedure, migration of the clip to other structures, and damage to surrounding anatomy. The latest NICE guidance corroborates a 1 in 200 failure rate of this procedure in achieving sterilisation [4], as reported in a 2001 publication by Mr Marcus Filshie, inventor of the Filshie clip [5]. With regard to clip migration, it appears that slow peritonealisation of the clip(s) results in a higher likelihood of migration. Faster peritonealisation of the clips renders them more likely to remain in situ [5]. Furthermore, while allergic reactions have been reported to cause Hulka clip sterile abscess formation [6], the titanium-silicone basis of Filshie clips makes this less likely, since these materials are commonly implanted elsewhere in the body and are not generally associated with sterile abscess formation [7]. The exact mechanism of migration through the pelvic floor however remains poorly understood. Given the rarity of this pathology, there is limited information on the pathophysiology of this migratory behaviour. Principles of acute and chronic inflammation in Crohn’s disease may help to explain how an abscess from the fallopian tubes could form a fistulous tract through the pelvic floor through neutrophil, macrophage, and fibroblast action, however this is unproven and requires further investigation [8].

We performed a literature review (Table 1) to determine whether this was a unique migration location, as well as to ascertain the incidence of sterilisation clip migration. In June 2023, we searched PubMed from June 1950 to June 2023 with the search terms [(sterilisation) OR (tubal ligation)] AND (clip) AND (migration) to identify other cases of sterilisation clip migration. We also searched the references of each of these papers to further widen our capture. This revealed 34 case reports of sterilisation clip migration, mostly to the bladder and anterior abdominal wall (Fig. 3). Despite an extensive literature search, no similar cases to this were identified. Locations such as the bladder, pelvic peritoneum, inguinal region, femoral region, anterior abdominal wall, spontaneous expulsion through the vagina, and even the liver have all been reported, however none to the gluteal area through the pelvic floor. Interestingly, this complication of tubal sterilisation does not appear to be either an early (< 5 years) or late (> 10 years) event. Figure 4 illustrates how there is a range of when these patients have presented in the acute setting for treatment. However, when exactly the migration occurs is not yet known, as a proportion of these cases may well show migration prior to acute illness presentation; for example, those with asymptomatic migration presenting later with acute sepsis. Furthermore, not all cases of clip migration will have been published in the literature, and there may be further cases not captured by our search strategy, therefore the true prevalence of these instances may be underestimated. Clips placed elsewhere in the body may also migrate. Surgical clip migration after laparoscopic cholecystectomy is another documented occurrence of a different type of clip migration [9]. A case report described a patient who developed cholangitis due to clip migration 10 years after initial laparoscopic cholecystectomy. CT imaging revealed hyperdense material in the dilated common bile duct, retrieved by endoscopic retrograde cholangiopancreatography via balloon trawl.

Table 1 Literature review of sterilisation clip migration
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Fig. 3
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Proportion of reports of migration by anatomical location

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Fig. 4
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Variation in time to acutely presenting with clip migration symptoms following sterilisation procedure

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Patients with a previous sterilisation procedure and suspected subcutaneous foreign body without trauma should elicit a high index of suspicion for migrated sterilisation clips. We show that these clips can migrate through multiple layers of muscle and fascia, including the pelvic floor. Clinicians should be aware of the possibility of clip migration especially when patients present with recurrent abscesses of unknown cause, and thorough history taking may help to guide the working diagnosis. The role of plain film X-radiography is yet to be elucidated, however this may be a simple screening investigation if a radiopaque foreign body is thought to be the underlying cause. Ultimately, the majority of the cases of sterilisation clips were diagnosed on surgical exploration, rather than prior imaging. However, in cases of recurrent abscesses, pre-operative imaging may help reduce the incidence of recurrent abscess formation especially in cases where the sterilisation clip is not excised during the index operation.

Conclusions

Patients with a previous sterilisation procedure and suspected subcutaneous foreign body without trauma should elicit a high index of suspicion for migrated sterilisation clips. These clips can migrate through multiple layers of muscle and fascia, including the pelvic floor.