Clinical data 1. Subjects: 1112 cases of children requiring fiberoptic endoscopy, including 689 males and 423 females, aged from 4 days to 15 years, with a mean age of 4 and 23 years, were collected from April 2005 to January 2007 in our department. They were divided into 0-3 years old group, 3-7 years old group, and 7-15 years old group according to their age groups. 2. Examination methods: Japanese-made Olympus pediatric-type fiberoptic endoscope, Olympus endoscopic camera system, Sony monitor. The fiberoptic endoscope was disinfected by glutaraldehyde immersion. Fasting and water fasting were not required before the examination. Each child was given 0 and 5% ephedrine for three times for bilateral nasal astringency and 1% bupivacaine for three times for bilateral nasal, pharyngeal and hypopharyngeal sprays. The child was placed in the supine position, the examiner was located at the head end of the child, and the fiberoptic laryngoscope was entered by the nasal cavity to observe the nasal cavity, nasopharynx, oropharynx, laryngopharynx, and larynx in turn. 3. Examination results: Among the children in the 0-3 years group, laryngeal diseases were predominant in 33 cases (58, 93% of the cases in this group), among which laryngitis and unilateral vocal cord paralysis with fixation were predominant (3 of them were postoperative congenital heart disease) in 18 cases (32, 14%) and 5 cases (8, 93%), respectively, followed by laryngeal cysts, laryngeal papilloma, laryngeal malformations, cysts at the root of the tongue, and Twenty-three cases (41,07%) had moderate to severe adenoid hypertrophy (see Table 1 for details). In the group of children aged 3-7 years, moderate-to-severe adenoid hypertrophy was predominant in 637 cases (73.64% of the cases in this group). There were 128 cases of laryngeal diseases, among which vocal cord nodules and laryngitis were predominant, followed by vocal cord polyps (see Table 2 for details). In the group of children aged 7-15 years, nasal and laryngeal diseases were predominant. There were only 42 cases of moderate-to-severe adenoid hypertrophy (21, 99%). Nasal diseases were dominated by sinusitis in 48 cases (25, 13%) and nasal polyps in only 5 cases (2, 62%). Laryngeal diseases were 96 cases, among which vocal cord nodules and laryngitis were also predominant, followed by vocal cord polyps (see Table 3 for details). 4, Discussion: Pediatric fiberoptic endoscopy has a small tube diameter, soft head, upper and lower bend up to about 1200, respectively, with strong brightness, large field of view and perspective 750, which allows comprehensive observation of the nose, pharynx and larynx [6]. It has been reported in the literature [7] that the children were given adequate local anesthesia before the examination, and with reasonable psychological intervention by the physician and skillful operation techniques, most of the children tolerated the examination well, and very few children who could not cooperate well could complete the examination with a certain degree of parental coercion and cooperation, and the use of fiberoptic laryngoscopy in children is safe. Among the 1112 children examined in this paper, only 3 cases had rhinorrhea after the examination, and none of them had laryngeal edema or laryngospasm. In recent years, obstructive sleep apnea hypoventilation syndrome (OSAHS) in children has received more and more attention from parents and otolaryngologists [2]. The main etiology of OSAHS in children is adenoid and/or tonsillar hypertrophy [3]. Previously, lateral nasopharyngeal radiographs were routinely used to examine the size of the adenoids and the degree of airway obstruction. In recent years, we have applied fiberoptic endoscopy in children to examine adenoids. Referring to the criteria for measuring the size of adenoids proposed by Zou Mingshun [4], combined with the results of fiberoptic endoscopy, we divided the size of adenoids examined by fiberoptic endoscopy into three degrees: mild: adenoids obstructing the posterior nostril by 1/3-1/2; moderate: adenoids obstructing the posterior nostril by 1/2-2/3 and protruding into the nasal cavity; severe: adenoids obstructing the posterior nostril by 2/3-4/5 and protruding into the nasal cavity significantly. For moderate to severe adenoid hypertrophy, surgical treatment may be considered in combination with clinical symptoms. In this paper, we found that moderate to severe adenoid hypertrophy with indication for surgery existed in children of all age groups, but the highest percentage was 73,64% in the 3-7 years group, 41,07% in the 0-3 years group, and 21,99% in the 7-15 years group. Due to the refusal of some parents to radiographs and financial considerations, the results of fiberoptic endoscopy in all children with moderate and severe OSAHS were not compared with the results of lateral nasopharyngeal films in this paper. However, 35 cases were found to have adenoid hypertrophy with obstruction of more than 2/3 of the airway on lateral nasopharyngeal radiographs, and moderate to severe hypertrophy of adenoids were also found on fiberoptic endoscopy. Another 19 cases were found to have mild to moderate hypertrophy of adenoids on lateral nasopharyngeal radiographs at outside hospitals or at our hospital, with no indication for surgery, and were found to have moderate to severe hypertrophy of adenoids on fiberoptic endoscopy after a period of conservative treatment in outpatient clinics with no significant relief of snoring and breath-holding symptoms The most hypertrophy was found and the site of obstruction was often in the posterior nostril, and all children confirmed the findings of fiberoptic endoscopy at subsequent surgery. Because lateral nasopharyngeal films are two-dimensional, they do not fully reveal the three-dimensional shape and size of the adenoids due to the body position at the time of the film [7]. In comparison, fiberoptic endoscopy is considered to have the following advantages: (1) It is a simple method that requires only surface anesthesia and is applicable to a wide range of ages. (2) It is basically a non-invasive examination method, causing only mild abrasions and bleeding of the nasal mucosa; (3) visual and three-dimensional observation of the degree and shape of adenoid hypertrophy, protrusion into the nasal cavity, and obstruction of the posterior nostril. Hoarseness is more common in school-age and preschool-age children, and they cannot cooperate with indirect laryngoscopy. Some infants also come to the clinic with laryngeal wheeze, and clinicians mostly diagnose them as congenital simple laryngeal wheeze by virtue of clinical manifestations, which can easily lead to misdiagnosis and delay the best time for treatment. In their study, Fu et al [5] found that the misdiagnosis rate of congenital simple laryngeal wheeze was as high as 50%, and suggested laryngoscopy as a screening method for it. The application of pediatric fiberoptic endoscopy can directly detect laryngeal malformations, masses and epiglottis movements. In this paper, the children who were seen with laryngeal wheeze were all in the 0-3 years group, and abnormalities were found in 7 cases, including 2 cases of laryngeal malformations, 3 cases of laryngeal cysts, and 2 cases of tongue root cysts. All of them had complete relief of laryngeal wheezing by surgery, which indicates that fiberoptic endoscopy is of great value in the differential diagnosis of laryngeal wheezing in infants. In our group, five children with congenital heart disease who presented with hoarseness (three who had not yet undergone cardiac surgery and two who were postoperative cardiac surgery) were found to have unilateral vocal cord paralysis and fixation in fiberoptic endoscopy, which provided auxiliary information for surgical procedures for congenital heart disease. According to the literature [1, 6], the main causes regarding hoarseness in children are laryngitis, vocal cord nodules, and the findings of the three groups of children in this paper are consistent with the literature. 18 cases of laryngitis in the 0-3 years group, accounting for 32, 14%, and no cases of vocal cord nodules or polyps were found; in the 3-7 years group, 56 cases of laryngitis, accounting for 6, 47%, 71 cases of vocal cord nodules, accounting for 8, 21%, and only 1 case of vocal cord polyps, accounting for 0 In the group of 7-15 years old, there were 28 cases of laryngitis, accounting for 14,66%, 61 cases of vocal cord nodules, accounting for 31,94%, and only 7 cases of vocal cord polyps, accounting for 3,66%. The use of fiberoptic endoscopy can clearly and distinctly show the lesions in the nasal cavity. In this paper, 5 cases of nasal polyps were found in the group of 7-15 years old (3 cases of posterior nostril polyps and 2 cases of small polyps in the middle tract), while none of these 5 cases were found to have nasal polyps during the outpatient anterior rhinoscopy. Some of the children were examined because of recurrent secretory otitis media and were also found to have adenoid hypertrophy to a large extent, suggesting a greater association between adenoid hypertrophy and secretory otitis media [2]. In conclusion, fiberoptic endoscopy applied to the examination of nasal cavity, nasopharynx, and larynx diseases in children is safe, rapid, intuitive, and less painful for the child, and has great value in outpatient diagnostic applications.