Introduction

Accidental foreign body ingestion is a common clinical problem especially in children. There are several reasons for the children's risky behavior, temperamental aspects, characteristics and level of development of the anatomical parts, physiological features such as immature swallowing coordination, poor chewing capacity and higher respiratory rates^[1]. Although complications are higher with sharp implements, reported rates of gastrointestinal perforation still remain rare at less than 1%^[2]. Mercury is a widespread heavy metal with potential severe impacts on human health. Mercury plays a significant role in foreign body ingestion in children, especially for the clinical thermometer. Children always swallow it unconsciously. Whether the toxicity is higher or not depends on the chemical forms of the mercury. Acute inhalation of metallic or inorganic mercury vapours mainly induces pulmonary diseases^[3], but elemental mercury in liquid is much safer than it. The form of mercury in clinical thermometer could not lead to the damage in liver, kidney or lung.

Case analysis

In the period of the year from 2010 to 2013, there were 8 patients admitted to The Department of Poisoning & Occupational Diseases, Qilu Hospital of Shandong University, Shandong, China, following got mercury foreign body in oral admission. In these patients, there were 5 male and 3 female; there were 3 patients under the age of 2 year-old, 2 patients from 3-year-old to 4-year-old and 3 patients from 12-year-old to 17- year-old. 8 patients of all had a certain contact history(Table 1) and all the patients got mercury foreign body trough oral admission by different ways(Figure 1).Most patients swallowing a clinical thermometer; one patient was palying a mercury bulb in hand but his grandmother couldn't find the mercury bulb when she realize her grandson was playing with it. And another boy was doing an experiment in his class and he just want to know how the mercury tasty so he swallow it. All the patients were health body[healthy] in past. Most of patients almost had no serious symptoms after swallow mercury in the inquiry of the process but one with sore throat and two with abdominal pain. 8 of the patients' X-ray (Figure 4) showed the circular high-density shadows which prompt the poisoning of mercury. They took the treatment of catharsis and the mercury was out of the body in one week.

Typical Case 1

A 14-year-old girl was admitted to The Department of Emergency, Qilu Hospital of Shandong University, Shandong, China, following attempted suicide by swallowing a nail clipper and mercury of a clinical thermometer(Figure 1) for the reason that her patients did not take her home from school. In the inquiry, the patient confirmed that the suicide attempt had occurred 7 hours prior to admission. On physical examination, the patient was conscious and the blood pressure was 122/78 mmHg, heart rate was 83 beats/min and O₂ saturation was 98%. The patient's eyes were neither anemic nor icteric and pupils of equal roundness and size (left, 2 mm; right, 2 mm). Cardiovascular, pulmonary, abdominal and neurological examinations showed no abnormalities. A series of X-ray scans(Figure 2) of the patient was performed and reviewed. A bar-type shadow of metal was observed on L3; a column shadow of metal was observed on L2 and scattered dot high-density shadows were observed between L3 and L5 in the first X-ray in local hospital. For the parts of the nail clipper were blunt, it was difficult to produce a perforation or the gastroscope could not pick them up which made the operation and gastrosope inapplicable, so the therapy of catharsis and other symptomatic treatment were given. At the 10 hours after the swallowing, a bar-type shadow of metal was observed on the middle of the pelvisand; a column shadow of metal was observed on hip bones, and scattered dot high-density shadow was on L4 on X-ray. Another round of catharsis was given, when it comes to the 30 hours after the swallowing, there was only a bar-type shadow of metal was showed beneath the pubic symphysis. On the next day, the X-ray showed no metal shadow in her body. The patient was fully cured.

Typical Case 2

A 6-year -old boy was admitted to The Department of Emergency, Qilu Hospital of Shandong University, Shandong, China with a two-day history of the thermometer mercury into his right hand. Two days ago, when playing the clinical thermometer, he broke the mercury bulb which made a wound and mercury into his right hand. There was an obvious wound in the boy's right hand which was also expanded by the operation in the local hospital for taking the mercury out. The x-ray scan(Figure 3) of the right hand showed seldom high-density circular shadows between the first metacarpal bone and the second metacarpal bone which promoted the mercury. Penicillamine as mercury displacemnt medicine was used to remove the mercury and debridement disinfection was given to keep the wound sterile and to promote healing once a day. A week after the admission, the wound of the patient's right hand was full cured.

Discussion

Foreign body ingestion is a common emergency situation in children with one or a few objects having been ingested^[4].? The kinds of foreign body are various. Children will often swallow what is readily available to them leading to common items such as coins, toy parts, jewelry, or batteries being swallowed^[5]. The clinical thermometer is also the common foreign body since the child especially the younger children have curiosity about it. For the kind of foreign body that the patient swallows are different, the clinical manifestations are also diversiform. These children can present with a variety of gastrointestinal (GI), respiratory, or nonspecific symptoms including choking, drooling, poor feeding, fever, wheezing, stridor, vomiting, dysphagia, odynophagia, chest, throat, or even neck pain^[6]. Diagnosis of the esophageal foreign body in infant and children can be easily made by a simple X-ray, and esophagogram. However, fish or chicken bones, wood, and thin metal objects are often not readily seen with plain radiography^[7]. And also, foreign body impaction may result in complications such as mucosal abrasions within the gastrointestinal tract, bleeding, gastric outlet obstruction, oesophageal or gastrointestinal perforation and secondary mediastinitis, peritonitis, abscess or fistula formation^[8].

For mercury, it is a silvery-white shiny heavy metal with unique chemical and physical properties. It has been used worldwide for many centuries for commercial and medicinal purposes^{[9, 10]}. One of the most common things is that it is the section of the clinical thermometer and for its easy access, it becomes the usual foreign body in children's accident in China. Mercury is a highly toxic element, there is no known safe level of exposure^[11]. Exposure conditions to mercury and profile of toxicity among humans depend on the chemical forms of the mercury: elemental or metallic mercury, inorganic or organic mercury compounds^[3]. Elemental mercury is liquid at room temperature, and in this form, is less toxic than inorganic or organic bound mercury. The mercury in clinical thermometer is elemental mercury so the toxicity is much less. But we should also realize that elemental mercury exposure can lead to Nephrotoxicity, Teratogenicity, Cardiovascular Toxicity, Carcinogenity, Genotoxicity, Mutagenesis, Reproductive Toxicity, Immunotoxicity and neurocognitive deficits and neuromotor disabilities^[11]. Symptoms of elemental mercury exposure may include headache, abdominal pain, and fever^[12], and may mimic the symptoms of a contagious infectious disease^[12]. Neuropsychiatric symptoms, which are the most significant findings, may include insomnia, irritability, memory loss, emotional lability, withdrawal, shyness and tremor^[13]. The kidney is the most common target organ in mercury poisoning. Kidney injury from mercury is known to cause dose-related tubular dysfunction and idiosyncratic nephrotic syndrome, and also, mercury exposure can lead to various glomerular lesion^[14].

In the first case, the patient took two different kinds of foreign bodies by oral admission. From the dynamic observation of the X-ray, we could find the fact that the excretion velocity of mercury was much faster than that of the nail clipper. And we could also find that the nail clipper was blunt so the patient's digestive tract had almost no injury, it was just too big to be expelled. When it was excreted, there were hardly complications. From the second case, the mercury in the boy's right hand was concentrated in the first place, but the operation made it separate. The boy made his right hand cowered in the treatment, so the X-ray of the last time we could find that the mercury was concentrated again. Except the wound, there was no visceral amage in the patient.

In our diagnosis and treatment of mercury foreign body, the younger children(under 10-year-old) ingested the mercury in clinical thermometer for fun or curiosity. They most took it unconsciously with no specific purpose, so the parents should pay attention to take care of their children. But for the elder children (above 10-year-old), they always ingested the mercury on purpose, for this part of children, the parents and teacher should not only take care of these children but also help them solve their problems. This part of children needs more mental concern to keep them from suicide. From this, we call on parents and teachers to give more attention to children to keep them safe.

From the cases in our diagnosis, we can come to the conclusion that the form of mercury in thermometer would not make an obvious symptom in children. The treatment of this situation is draining the foreign body out for major.

Another essential thing is that though the mercury in thermometer would not be damaged, the parents should take care of their children and keep the thermometer out of reach of children.

Conflict of Interest Statement

We certify that we have participated sufficiently in the work to take public responsibility for the appropriateness of the treatment, and declare that there are no conflicts of interest for his paper. This study was authorized by the Hospital's Ethics Committee and we have obtained the informed consent from the patients.

Acknowledgements: This study was supported by China National Key Clinical Speciality(Project number: 2012650) and China Taishan Scholar Program of Shandong Province?(Project number: ts20130911)