A case control study of the factors associated with occurrence of aerodigestive foreign bodies in children in a regional referral hospital in South Western Uganda

Worldwide, aerodigestive foreign bodies [ADFBs] are a common emergency in Ear, Nose and Throat [ENT] clinics and remain one of the main causes of morbidity and mortality especially in children under 3 years [1, 2]. Despite public awareness, and improvements in medical care, worldwide annual incidence of deaths from foreign body aspiration, is estimated to be between 500 and 2000 [3, 4].

The disease burden of ADFB is not known but varies according to geographic location. Anecdotal evidence suggests ADFB is one of the most common emergencies seen at the ENT Department at Mbarara Regional Referral Hospital [MRRH]. Little is documented regarding its prevalence and the characteristics of the children presenting with ADFBs. This lack of documentation may contribute to delays in diagnosis and inadequate management, and makes prevention through education of parents difficult. Determining these factors would aid timely diagnosis and management and provide data to inform health education and other primary prevention interventions for ADFB.

Therefore this study was undertaken to determine the proportion of ADFBs among all paediatric cases seen in the ENT clinic at MRRH, their clinical characteristics and factors associated with the condition.

In the review of records, there was a total of 64 cases of pediatric ADFB out of 971 pediatric cases treated in the ENT clinic between July 2011 and June 2012 yielding a prevalence of 6.6 %. Of the 64 cases, 36 [56.3 %] were male.

The socio-demographic characteristics of all study participants are illustrated in Fig. 1. Children under 5 years of age accounted for 75 % of the cases and of these cases, there were twice as many males as females [Male: Female ratio of 2:1].

The most frequent symptoms reported are shown in Table 1, and included sudden onset of cough [72 %] and difficulty in breathing [60 %] which are associated with aspiration of a foreign body into the airway and vomiting and retching [42.5 %] which are associated with swallowing of a foreign body. Only one parent/guardian attempted a Heimlich manoeuvre after witnessing the child swallowing a coin. Approximately 30 % of the children presented with fever , suggestive of possible secondary infection. Stridor [45 %], a hoarse voice [40 %], reduced chest movement and chest recessions [52.5 %] are common findings in foreign body aspiration and were common symptoms among the cases as shown in Table 2.

Out of the 26 X-rays that were received during the study, 73.1 % [n = 19] confirmed the presence of a radiopaque foreign body in the aerodigestive system (Fig. 2) while 23.1 % [n = 6] showed heterogeneous opacity or lung collapse which are both possible effects of a foreign body.

At least 60 % of the foreign bodies in the airway were removed from the right main bronchus and an example of such a foreign body is shown above in Fig. 2 on the right. In the oesophagus almost all of them [n = 14 or 92.8 %] were removed from the upper third at the level of the cricopharyngeal sphincter.

As shown in Table 3, equal numbers of organic and inorganic foreign bodies were removed or identified. Coins accounted for 55 % of all inorganic foreign bodies and seeds accounted for 80 % of the organic foreign bodies. 95 % of all foreign bodies were successfully removed by bronchosopy or oesophagoscopy. Two of the cases presented with airway foreign bodies [a ball bearing and cylindrical metallic casing of a pencil eraser] which were identified on radiography and by bronchoscopy but removal was unsuccessful via endoscopic methods; these children were referred for thoracotomy.

Foreign bodies in the aerodigestive tract are a major source of morbidity in developing countries, and understanding the features that predispose patients to the risk aspirating or swallowing a foreign body is critical to diagnosis, treatment, and prevention. As a first step toward improving overall management of this problem, we catalogued the prevalence of ADFB amongst pediatric patients at a tertiary care and academic medical center in Uganda, and identified potential risk factors.

The prevalence of ADFBs varies depending on the region and the hospital, and sometimes the two proportions are variable. For example, the University of Port Harcourt Teaching Hospital in Nigeria recorded a prevalence of laryngeal foreign bodies of 2.5 % without considering oesophageal foreign bodies [7]. In Mulago National Referral Hospital in Uganda, ingested foreign bodies are a common occurrence in the ENT department though the actual prevalence is unknown [8]. A retrospective review of records from the same hospital between 1993 and 1999, reported 240 bronchoscopies performed to remove aspirated foreign bodies which averages approximately 40 bronchoscopies per year [Awubwa, Unpublished observation]. Therefore, a prevalence of 6.6 % at MRRH is high, and may be explained by the fact that MRRH serves a much larger population than its catchment area as it is the only regional referral hospital in South Western Uganda providing ENT services. Some patients are referred from as far as the Democratic Republic of Congo, Tanzania, Rwanda and other in-country regions. In addition, MRRH is a government hospital providing free services, which contributes to the large numbers of patients seen.

When dealing with a patient presenting with an aerodigestive foreign body, a high index of suspicion is required to make a diagnosis. The children who had aspirated or swallowed foreign bodies presented with various but related symptoms and signs. The most common symptoms were sudden onset of cough [72.5 %] and dyspnea [60 %]. Noisy breathing also referred to as stridor was only seen in 40 % of the cases. These symptoms occur because on aspiration, the foreign body causes mucosal irritation in the airways prompting the cough reflex. The total or partial obstruction of the main airways from the aspirated object leads to increased velocity of the air as it passes  through a narrowed lumen during respiration, hence the noisy breathing. A swallowed foreign body in the oesophagus can at times be big enough to push against the trachea and cause stridor [9]; but this scenario was not encountered in this study. These findings are in agreement with others that noted that following foreign body aspiration in children, a high degree of suspicion was essential in arriving at the diagnosis and that the common symptoms were sudden onset of cough, dyspnea with noisy breathing in majority of the cases [10].

Radiography, though important, was much more useful when the foreign body was radiopaque so it could be identified on the film or if there was a suspected complication that could be identified on the film such as lung collapse. Digoy [11] also concluded that radiography in aerodigestive foreign bodies is much more important when dealing with esophageal foreign bodies than airway foreign bodies. In our study, there were only 2 radiopaque foreign bodies found in the airways- a ball bearing and a metallic casing of an eraser. However, as stated by Gilyowa [12], the absence of an identifiable foreign body on the radiograph does not rule out the presence of one in the system; therefore a high index of suspicion should always be maintained.

Our study demonstrated a high incidence of cervical esophageal foreign bodies as expected. This location [the cricopharyngeal sphincter] is the first of three anatomical narrowings of the oesophagus. Any large object is likely to fail to negotiate this section and instead get lodged causing the symptoms of drooling, retching and discomfort in the throat. For our aspirated foreign bodies, bronchoscopy usually revealed a foreign body in the right main bronchus, also similar to other literature reports. Studies done elsewhere also reported very similar results and explained this observation on the basis of the fact that the right main bronchus in children is more vertical and wider than the left [2, 13]. This anatomical feature makes it an easy target for a foreign body passing through the trachea. The most common foreign body removed from the esophagus was coins, particularly Sh. 100 coin. This is in agreement with the fact that worldwide, the most commonly swallowed foreign body is coins, which are a widely used legal tender [14].

During bronchoscopy for airway foreign body, seeds like groundnuts and beans were the most frequent foreign bodies removed. Similar to other areas in the world, they form a large part of the diet in the region so are easily accessible to children. This is comparable to studies by Ssewanyana [15] in Uganda, Black [16] in the United States and Mu [17] in China.

As in previous studies by Lima [18] and Ozdemir [19], in our study, foreign bodies were found to be much more common in children less than 5 years of age, peaking at about 3 years. This could be explained by the fact that in our community most mothers start weaning their babies at about 6 months of age by introducing solid foods. At this stage, the fact that the children’s dentition is not well developed to adequately chew the food and they cannot easily balance swallowing and breathing means that they are more prone to aspiration especially if food is not of the right consistency. The children also require more supervision as they eat and play especially when they are in the oral phase of development when they tend to place small objects in their mouths as also cited by a study conducted in Tanzania [12]. The risk of sustaining an ADFB reduces as the child gets older but is not completely eliminated.

In general, boys are considered more adventurous and curious compared to the girls as children grow. This may be the reason why a male: female ratio of 2:1 was found for the cases in our study. The regression model also showed this to be true and significant [p = 0.03]. This ratio is the same as that reported in other previous studies [12, 20, 21].

Looking at the socioeconomic status of the families from which all the children presented, majority of the controls were from the upper socioeconomic class while most cases were from the lower class. It was also observed that the higher the socioeconomic class of the family, the less the likelihood of the children sustaining an ADFB. This finding may be explained by the fact that families of middle or upper SES commonly have employed parents or guardians who can either afford to employ full time house help and child minders at home or to put their young children in professional day care facilities where there is always someone attending to them. Unlike parents from lower socioeconomic levels, these families rarely have more than 2 children under 5 years of age at the same time. This makes it easier to supervise and adequately care for the children. This is in agreement with the Turkish study by Ozdemir [19], which concluded that a higher social class is protective from ADFBs in children. In another study in from China, Mu [17] also found that there were slightly fewer foreign bodies among children from families living in urban areas [considered of a higher social class than those from the rural areas].

Significantly, we found that after adjusting for SES and the source of referral, the regression model showed that patients coming from other government health centres were more likely to have ADFBs when compared to those from private health facilities [p = <0.01]. The upper SES remained protective with the lowest risk of ADFB [OR = 0.29, p = 0.02]. This finding is likely because MRRH is the tertiary referral hospital for all other surrounding lower health centres and the only source of specialized health services in the region. The personnel at the lower level health centres are therefore more likely to refer to the tertiary centre any difficult cases.

Our findings suggest that male sex and poor socioeconomic status contribute to ADFB.

Educational initiatives designed to target these vulnerable populations may serve to decrease the incidence of ADFB in rural Uganda. Additionally, educating health workers to know the possible symptoms and signs of ADFBs will likely decrease morbidity and mortality from ADFB, by reducing delays in diagnosis.