Introduction

Transnasal gastrointestinal endoscopy (TNE) was first reported in 1994 by Shaker et al. as T‐EGD with the advent of ultrathin (UT) endoscopes [1]. Since then, use in adult has been increasing worldwide by both gastroenterologists (esophagogastroduodenoscopy [EGD] and esophagoscopy) and otolaryngologists (esophagoscopy) [2,3]. Implementation has occurred mainly in Far Eastern countries such as Japan, but also in Western countries though uptake has been lower (mostly in France and Canada). It is now reported that TNE makes up 9% of hospital practice in Japan compared to 1% in endoscopy units worldwide [4–8]. Pediatric use is limited to a single report in 2016 by Friedlander et al. corresponding to 21 cases in children aged 8–17 [9]. The technique was well tolerated. Per unpublished reports from the same center, TNE usage has increased to as many as 100–140/year (4–5% of practice) in children aged 5–21 years of age.

Ultrathin endoscopes used for adult TNE/EGD and pediatric oral EGD are much narrower, 4.9–5.9 mm (depending on manufacturer and tip maneuverability/optic capability), in comparison to a minimum of 8.6 mm for conventional gastroscopes (Table 43.1) [3,10]. It is important to note that as a result of the narrower scope, the instrument and suction channel are much smaller (2.0–2.4 mm), limiting the flow rate when suctioning and restricting its therapeutic use. However, in recent years several devices have been made to accommodate such channels. These devices include grasping forceps (i.e., Olympus, Boston Scientific), APC probes (i.e., ERBE), and nets (i.e., US Endoscopy). Owing to the smaller channel, the biopsy forceps have a diameter of 1.8 mm, resulting in smaller samples being obtained. Despite this, a large study involving over 1000 samples obtained using UT scopes showed that its biopsy specimens are comparable in diagnostic yield to samples obtained using conventional gastroscopes and biopsy forceps [11]. There have been more recent studies in pediatrics and adults also demonstrating adequacy of samples in specific conditions such as eosinophilic esophagitis and Barrett’s esophagus [9,11–13]. The deeper areas of tissues such as lamina propria seemed to vary between standard biopsies and the smaller samples [12]. There have been other small cohort studies suggesting tissue samples may not be adequate, but larger studies seem to contradict this [11,14].

The pediatric TNE study did not use adult UT endoscopes as they cannot be passed through most children’s narrow nasal passages [9]. The Aerodigestive Program, a multidisciplinary airway and digestive disorder clinic responsible for the study, used pulmonary bronchoscopes (2.8–4.0 mm outer diameter) that had channels of 1.2 mm or 2 mm respectively. They used the associated forceps designed for the channels. This study demonstrated that TNE in younger children with movie goggles distraction was also possible with adequate samples obtained [9]. However, in this study TNE was unable to access the duodenum due to the shorter length of the bronchoscope.

Available adult UT endoscopes and pediatric bronchoscopes used in the pediatric studies are listed in Table 43.1 and range in outer diameter (OD) from 2.8 to 4.2 mm with channels of 1.2–2 mm with two‐way tip deflection.

The main advantage that TNE offers is the ability to carry out endoscopy without the use of sedation, which carries risks, complications, high cost, and added time for the patient and caregivers. In one adult study, sedation‐related cardiopulmonary risk in all forms of endoscopy was 0.6%, while pediatric studies also demonstrate similar events [15–17]. Additionally, in pediatrics there is a further potential risk of anesthesia for the developing brain [18]. Endoscopy in children commonly involves general anesthesia compared to the more common procedural sedation used in adults. The concerns regarding general anesthesia in children continue to be addressed in the literature [18,19].

Additionally, the route of insertion results in less pharyngeal stimulation and gag reflex than unsedated oral endoscopy as the endoscope does not touch the tongue, thereby making it more comfortable for patients [20].

At present, there are no guidelines stipulating indications or contraindications for TNE over and above those for standard oral endoscopy. However, there are relative contraindications for adult or pediatric patients with significant coagulopathy or recurrent and significant epistaxis (especially if related to hereditary haemorrhagic telangiectasia [HHT] – a contraindication for TNE); standard EGD (sEGD) is usually carried out over TNE [3].

Preendoscopy preparation

In pediatrics, preparation for TNE is of the utmost importance because success depends on a cooperative child. The authors recommend a precounseling visit and preparatory video viewing by the family discussing TNE and demonstrating the technique. This could be done by phone or in person per provider preference. Anxiety is not a contraindication as unpublished data demonstrate that children with treated anxiety commonly do well. If a child were to become nervous or would not tolerate the procedure due to a panic attack/anxiety flare, a previsit with a counselor who specializes in anxiety commonly will enable the child to undergo unsedated TNE easily and without complication. For the average child undergoing their first TNE, a child‐life expert or a physician with expertise in child distraction and coping is recommended to review techniques with the child.

The above group also reported success with the use of video goggles of various forms. This same group notes that children may also be able to cope with the technique without goggles, similar to adults, in certain cases. Demonstration of the technique in pediatrics can be seen at www.pediatricendoscopy.com. Following a precounseling visit and consent with the family, the procedure can begin (Figure 43.1).

Nasal preparation is aimed at providing nasal and pharyngeal anesthesia, and improving ease of endoscope insertion via turbinate shrinkage with topical decongestants. In a randomized study, 55.8% patients who underwent unsedated TNE found that the most painful area during endoscope insertion was the nasal cavity, emphasizing the need for adequate preparation [21]. A more recent study reported this to be less than 20% [6]. Various methods of nasal preparation have been described, including pledgetting the nasal cavity with cotton tip and gauze coated in lidocaine, aerosolized spray containing local anesthesia and decongestant (e.g., 5% lidocaine and 0.5% phenylephrine hydrochloride), a combination of these, or none [10]. Most centers performing TNE would advocate the use of aerosolized spray with topical pharyngeal anesthesia and decongestant. The pediatric group performing TNE currently uses 4% aerosolized lidocaine after blowing the nose, using three sprays to each nostril and one spray orally (total dose 0.3–0.4 mL) per patient. Nasal decongestion was not found helpful nor reported by the pediatric group. The best route for nasal traverse is seen in Figure 43.2, avoiding the inferior turbinate, and then central insertion into the esophagus is as for standard endoscopy (Figure 43.3).

Views and image quality

There were concerns about the quality of images obtained from the first‐generation UT scopes, but the more recent models have a brighter light source and improved objective optical system, thereby improving views. A randomized control trial involving one experienced endoscopist comparing TNE (Fujinon EG‐530N) and conventional gastroscopes found no difference in views obtained in the esophagus, stomach, and duodenum [22]. As expected, the view proximal to the esophagus including the hypopharynx and cricopharyngeal area was better with TNE [22]. The authors also found no difficulty with pyloric intubation with TNE [22]. Crews et al. also evaluated the quality of views obtained from TNE (TNE‐5000, Vision Sciences) and conventional gastroscopes and found no statistical difference between the quality of videos created with either [23].

Paediatric TNE using bronchoscopes had varying image quality based on generation of scope (video graphics array [VGA] vs high definition [HD]) and usage of air insufflation. UT bronchoscopes are designed without continuous air flow, which if used creates more gagging in the esophagus. When air insufflation is used intermittently, the viewing was optimal barring operator technique, but with air let out the tissues would collapse. The newest UT bronchscopes used for GI TNE have similar HD optics to standard gastroscopes.

Duration

A UK randomized trial compared TNE and sEGD and found that mean preparation time was longer in TNE (5.5 min vs 4.6 min, p < 0.001) [24]. In terms of procedure time, some studies reported that the duration of unsedated TNE was significantly longer compared to sEGD, but one did not [21,22,25]. However, in reality the difference between the two was around a minute; one study reported that the duration for TNE and sEGD was 8.4 ± 3.2 min and 7.7 ± 3.4 min (p = 0.02) respectively [22]. In this same study, patients were observed for an hour post procedure, but 80% of patients from both groups would be happy with a shorter duration of observation post procedure (20 minutes). More importantly, the recovery time for TNE was significantly shorter than sEGD (5.0 min vs 10.0 min, p <0.001) [24].

In the single‐center report by Friedlander et al., the average time of TNE was 8.6 minutes with total office time of 60–90 minutes [9]. From newer unpublished data, this center reports average duration of a first‐time TNE of 60 minutes in office and 45 minutes for follow‐up TNE, and average TNE time has decreased to under six minutes for esophagoscopy/gastroscopy compared to EGD.

Success rates

The success rates for adult unsedated TNE are high. One metaanalysis reports this at 94% (95% confidence interval [CI] 91.6–95.8) in comparison to 97.8% in unsedated UT transoral EGD, but when TNE was compared to unsedated sEGD it performed slightly poorer (RD −2.0%, CI −4.0 to −1.0) [26]. When UT scopes of <5.9 mm was used, similar success rates to sEGD were obtained [26]. Unsuccessful attempts have been attributed to nasal pain, narrow nasal passages or altered anatomy [27].

Success rates in pediatric TNE are also high. As of this publication, the reporting group using TNE has performed 264 TNE that had not been stopped once started. There were six children who came in for TNE but due to motion or anxiety were not able to sit still to start the procedure (97.8% success rate if those children were included).

Patient comfort and preference

A metaanalysis reported that when patients were offered a choice of TNE or sEGD for future endoscopies, a significant proportion of patients opted for unsedated TNE (RD 63%, CI 49–76), and 85.2% of patients were willing to undergo unsedated TNE again in the future [26]. Patients who have undergone unsedated TNE found it more comfortable compared to unsedated EGD (comfort score TNE: 7 ± 2.3 vs EGD: 5.4 ± 2.78, p <0.001) [22]. In the same study, the number of patients who reported gagging was significantly lower in the TNE group (77% vs 26%, p <0.001) [22].

The single‐center pediatric study reports that of families of children between 8 and 17 years who had undergone previous EGD, 100% would undergo TNE again while 74% of children would undergo TNE again [9]; 84% of families and 53% of children preferred TNE to sEGD [9].

Complications and safety profile

Esophagogastroduodenoscopy is associated with cardiopulmonary stress with increased heart rate and systolic blood pressure [22,28]. TNE, on the other hand, does not have this effect, and patients undergoing TNE are noted to have a consistent heart rate and systolic blood pressure [22,29]. Furthermore, it is not associated with episodes of desaturation [21,22].

A recent metaanalysis evaluated adverse events associated with TNE; epistaxis was the only event consistenly note, comprising 2% of all cases [26]. These are largely self‐limiting events [21]. In patients with chronic liver disease or liver cirrhosis, TNE has been found to be safe, with a low rate of self‐limiting epistaxis (4–6%) [30,31]. There was only one case of reported esophageal perforation [32]. Reports of presyncopal episodes associated with TNE have also been published (two out of 95 patients in one study) [33].

Using unpublished data from the pediatric TNE center doing esophagoscopy rather than EGD, 5.2% of subjects undergo an episode of spit up or emesis that is brief and limited, 2.6% had nasal irritation without epistaxis, 0.9% presynscope, 0.5% anxiety attack, and 0.4% nausea.

Therapeutic use

The main common therapeutic use would be insertion of nasoenteric tubes. TNE‐assisted insertion (either via guidewire assistance or pull‐through method with biopsy forceps) was shown to be safe and comparable to fluoroscopic insertion [34,35]. It was found to be safe in critically unwell patients [35]. Overall, the therapeutic use of a TNE scope is limited.

Future considerations

Training in TNE may be a limiting factor as to why its use is not as widespread as one might expect. Further consideration of formalized training for TNE for independent and trainee endoscopists should be undertaken. Some literature exists documenting self‐training in operators who are experienced endoscopists [36].

The pediatric center reporting unsedated TNE has implemented a training program for TNE endosocopists. They have reported use of 3D printed models and a curriculum. To date, they have completed a single fellow training and are in the process with two other attending gastroenterologists. Multiple other centers have visited for basic, but not hands‐on training due to medical legal US licensing and malpractice issues.

An additional facet with TNE is its potential use in the clinic setting, much like laryngoscopy by ENT specialists. This is currently performed in Japan and was done by the pediatric center in their study [6,9]. Most endoscopy services are set up to be done in procedural units. Perhaps with further training, implementation of TNE, and improvement of endoscopic technology for diagnostic adult and pediatric TNE, bringing diagnostic TNE into the clinic setting may be a possibility.

Such technology has significant potential to transform the practice of pediatric gastroenterology from a method to avoid endoscopy due to risks to a highly valuable tool to make more informed decisions about therapies. With such a tool, careful thought should be given to who truly needs an endoscopy to prevent overuse. Although TNE is safe, effective, and well tolerated, it still carries a cost, discomfort, and potential risk.

Conclusion

In pediatrics, transnasal esophagoscopy using bronchoscopes has been reported to be safe and effective. In both adults and pediatrics, it is well tolerated and is preferred by most patients. With currently available technology, pediatric transnasal EGD is limited to subjects who can tolerate the longer and wider adult UT scopes. As it can be used without sedation, TNE reduces the potential of sedation‐related risks. However, due to its smaller diameter and lack of anesthesia, its therapeutic use is limited. With improvement in technology, the quality of UT scope views and imaging is continuing to improve, making TNE an attractive alternative for adult and pediatric patients undergoing upper gastrointestinal tract examination.