Use of magnetic retrievers for endoscopic retrieval of swallowed magnets in children (literature review)

Introduction

Foreign bodies (FBs) of the gastrointestinal tract (GIT) are one of the most common emergency conditions in paediatric surgery [2, p. 26-30; 3, p. 127-130; 4, p. 124]. In children, due to age-related characteristics, the use of inedible objects is common and often due to limited language level, embarrassment or fear of repercussions, they do not inform their parents in time [7, p. 493-495; 9, p. 212-218; 11; 15, p. 171-174]. Therefore, there are often difficulties associated with untimely diagnosis and the occurrence of complications. FBs can be of various sizes and shapes, including acute FBs. Most of the FBs safely pass through the GIT, but magnetised structures, due to their peculiarities, pose a great danger to the child's organism [12, p. 117-119; 13, p. 718-720]. Magnet products are widely used in everyday life, from gaming to aerospace. The first symptoms of magnet ingestion may be non-specific, which complicates the diagnosis of the disease. In some cases, there may be no symptoms at all. Multiple swallowed magnets or swallowing a magnet with another metal object can pose a serious threat as it can lead to bowel perforation, fistulation, intestinal blockage, bowel obstruction and death. In most cases of FBs ingestion, the physician's tactic is to wait for the FBs to complete its passage through the digestive tract. However, in the case of ingestion of magnetised structures, this methodology is incorrect [5, p. 190-194; 8, p. 443-446]. The peak incidence of this pathology is between 6 months and 6 years of age [6, p. 325-329]. Even the most conscientious parents are not always able to prevent this problem. Based on the data on the increase in cases of FBs ingestion in children [9, p. 212-218; 16, p. 511-516], the question of the effectiveness of traditional methods of FBs extraction and the development of new ones, including those aimed at extracting magnetised FBs, remains relevant.

Aims and objectives of the study – to present the experience of treatment of patients with multiple foreign bodies (magnetic balls) in the lumen of the gastrointestinal tract.

Materials and methods, discussion:

We searched PubMed and Elibrary medical databases using the key words foreign bodies, children, gastrointestinal tract, magnets, children. A total of 112 full-text sources were identified. Of these, 17 sources most relevant to the aims of the study were selected by cut-off. Sources were culled when referring to the provision of care to adults, children with chronic diseases, children with other acute surgical pathology. Historically presented magnetic retrievers were used to remove metal objects from the stomach during endoscopy. They were formed from orogastric tubes, which consisted of a long flexible tube with a strong magnet at the end. This was found to be a basic and effective form of retrieval of swallowed metal objects, which was well tolerated in the awake state and did not require any risks of surgery or general anaesthesia. However, retrieval was performed under endoscopic control rather than endoscopic vision, and the potential risk of unhooking retrieved objects and the inability to assess mucosal damage were seen as disadvantages. With the recent advent of endoscopic retrieval instruments, stand-alone magnetic retrieval devices are no longer relevant. Extraction of ingested FBs from the stomach endoscopically has usually been performed using extraction forceps, traps, or stone extraction baskets. However, when magnets are swallowed, endoscopic extraction instruments may not perform optimally because the swallowed magnets may adhere to the metal rim of the instrument immediately after contact, preventing the extraction instrument from closing securely on the swallowed magnets. This can be a fiddly task involving many unsuccessful attempts to secure the magnet(s). Moreover, the weak force with which the swallowed magnets are attached to the metal rim of the retrieval instrument causes them to shift easily during retrieval of the endoscope. Contact with the upper and lower sphincters of the oesophagus is particularly dangerous. This leads to increased operative time, increased surgical frustration and the possibility of unhooking the swallowed magnets during retrieval and airway obstruction.

Retrieval of ingested magnets from the stomach is also traditionally performed endoscopically, but can be complicated by prolonged retrieval and fixation of magnetised FBs. However, conventional endoscopic instruments will be less effective than endoscopically assisted magnetic retrievers because of the mixed weak bonds that form between the metal retrieval device and the magnet. And preoperative testing and selection of an extraction tool that has the strongest interaction effect with the magnet may also be helpful. A simple magnet retriever with endoscopic support, may provide more efficient, time-saving and safe retrieval of ingested magnets under direct observation [17, p. 137-140].

If the FBs have passed through the ligament of Treitz and they do not advance within 3 days of swallowing and there is no possibility of endoscopic retrieval, a laparotomy is performed. If there are signs of intestinal perforation, intestinal obstruction, signs such as peritonitis or free air on imaging, or if FBs cannot be removed by less traumatic methods, emergency laparotomy is performed [10]. Thus, Averin V. I. and Golubitsky S. B. [1] cite a clinical case. The patient, 14 years old, was hospitalised with complaints of abdominal pain, absence of stools for 4 days. On admission and in the process of observation, the girl concealed the fact that a few days ago she swallowed metal magnets. Due to the appearance of intestinal obstruction of unclear etiology 2 days after admission, the patient underwent a review radiography of the abdominal cavity, which revealed FBs - magnets arranged in a chain. A midline laparotomy was performed. There was a moderate amount of serous effusion in the abdominal cavity. On revision, a small-togastrointestinal fistula was found, caused by magnets located in the jejunum at a distance of 30 cm from the ligament of Treitz and in the transverse colon. Entero- and colotomy with excision of necrotised areas of the intestine was performed. The FBs was extracted. The integrity of the small and large intestine was restored by double-row knotted sutures. The postoperative period proceeded well. On the 9th day after surgery, the child was discharged home in satisfactory condition [1].

Analysing scientific sources, it was observed that the success rate of endoscopic retrieval of ingested magnets located in the stomach is unclear from the literature [17, p. 137-140]. A success rate of 66% has been reported, but the process involves technical difficulties in extracting the magnets from the stomach. The size and configuration of ingested magnets have been described as one of the factors for unsuccessful endoscopic removal and the need for laparotomy. For example, Waters A. M. et al. [17, p. 137-140] found that by obtaining a sample of swallowed magnets and testing their adhesion strength to different endoscopic retrieval instruments before surgery, they could pre-select the most effective retrieval instrument. It is clear that different endoscopic retrieval instruments have different adhesion strengths to the magnets. In the swallowed ball chain experiment, the authors determined that biopsy forceps were more effective than endoscopic graspers in holding the swallowed magnets during retrieval, even though the biopsy forceps were smaller in size. This may be due to the iron density of the different instruments.

Several case reports have previously described various ways of creating and using a primitive magnetic retriever under endoscopic control. These were used to retrieve metallic or magnetic objects from the stomach. Two cases were found in adults: one included a large refrigerator magnet placed in a Roth mesh and tightened before insertion into the stomach, while the other involved a trap magnet that was pre-treated to have 2 linear slots to tighten the trap. Four other reports have been found in children, including a 12-inch magnetic head tube (Cook Co., Bloomfield, IL, USA) along with a thin paediatric endoscope (OD 3.5 mm), a magnet attached to the end of the endoscope, two magnetic discs connected by a steel spring and wire and a magnetised loop basket [14, p. 332-335].

In the course of their followings, Waters A. M et al. [17, p. 137-140] estimate that magnetic retrievers have the great advantage of having a strong magnetic field that binds to metallic objects or magnets, making them extremely difficult to detach during retrieval. The authors have developed a simple way to create a basic magnet extraction device that can be used in conjunction with a paediatric endoscope or through a working channel to remove magnets located in the stomach in children. The extraction process can be performed safely and efficiently under supervision.

Initially, the idea of magnetic retriever with endoscopic assistance in Waters A. M. et al. [17, p. 137-140] came up during an unsuccessful attempt at endoscopic retrieval of a long ball of 16 buckyball magnets with a total length of 9 cm located in the stomach and duodenum. Previous attempts using a variety of conventional extraction tools including extraction forceps, traps and extraction nets had failed because the ingested magnets repeatedly attached to the metal rim of the tool and failed to close securely on the ingested magnets. Moreover, it continued to detach during endoscope retrieval because it was only attached to the endoscope by a weak magnetic force. A basic magnet extraction device was created by placing a small magnet into the endoscopic extraction mesh. The retrieval mesh was then pulled over the small magnet to secure it and ensure that it remained closed inside the retrieval mesh. This device was inserted discreetly next to (rather than through) the paediatric endoscope into the child's stomach where the ingested magnets were located. Once the primitive magnetic retriever made contact with the swallowed magnets, they all combined into one strong magnet and were quickly and safely extracted in plain sight.

Thus, conventional endoscopic instruments are less effective due to the weak bonds that form between the metal extraction device and the magnet, which gives an advantage to magnetic retrievers performed in conjunction with endoscopy. Extraction of magnets from the stomach with the help of a magnetic retriever under endoscopic observation is the most effective, eliminates unnecessary traumatisation, reduces the time of the operation, because swallowed FBs are firmly and quickly attached to the magnetic retriever, which makes it difficult to detach them during extraction. In addition, it is possible to easily determine whether the extracted magnets have detached or whether there is any damage to the gastric mucosa or intestinal fistula [17, p. 137-140].

Conclusion

Considering the experience of the techniques outlined in the historical perspective, the technique of using magnetic retrievers for endoscopic retrieval of swallowed magnets in children is the most effective for FB ingestion in the GIT.