Considerable improvements have been made to the original small bowel capsules. Optical enhancements include the use of multi-element lenses, which allow a wider angle of view and adaptive illumination , an automatic internal analysis of the average illumination of each frame leading to response by the internal LED. Superior quality lenses also contribute to improved picture clarity, and in the future , it is likely pictures will be available in high definition. Power management strategies have increased the duration and performance of capsule endoscopes and are imperative to facilitate other capsule technological advancements.

One of the major drawbacks of CE is the time-consuming process of CE reporting, and therefore, great efforts have been devoted to streamlining this process without jeopardising diagnostic accuracy . The suspected blood indicator highlights frames containing multiple red pixels as an indicator of bleeding or vascular abnormalities but in practice results have been inconsistent, and currently, it can only be recommended as a supportive tool [1, 2]. Quick view aims to reduce CE reading time by selecting 1 frame every X frames (as set by the reader), producing a condensed video for review. This has shown promising potential, especially when coupled with other image enhancing software systems [3, 4]. Fujinon intelligent chromoendoscopy (FICE) enhances surface contrast in three specific wavelengths (red, green and blue) and appears to improve image quality and visualisation of small bowel lesions; however, its clinical utility remains unclear [5, 6].

3D reconstruction of the gastrointestinal (GI) tract seems to assist diagnosis at conventional endoscopy by enhancing mucosal textural features and abnormalities [7–9]. A version for CE has been trialled and improved visualisation of a significant proportion of vascular lesions but was less beneficial for inflammatory and protruding lesions [10]. Encouraging results have been reported by investigators using automated tumour recognition software, where the computer aided system achieved a tumour recognition accuracy of 92.4 % [11]. Still in the early stages of development , the future of such field-enhancement techniques remains uncertain.

Upper GI haemorrhage is a common cause of Emergency Department (ED) attendance and early therapeutic upper GI endoscopy (OGD), within 24 h, has established benefits [12]. When OGD is performed in ED, up to 46 % of patients can be safely discharged compared to 14 % when OGD is not available [13, 14]. Despite recommendation in UK guidelines [15], many hospitals are unable to meet this demand with one study indicating only 50 % of patients had an OGD within 24 h [16]. Validated scoring systems [17, 18] exist to enable risk stratification of patients in ED but due to increasing patient age and co-morbidities may ultimately require admission for OGD. Promising results have been achieved using oesophageal CE to risk-stratify patients presenting to the ED with upper GI bleeding in the hope of allowing early discharge. CE detected dyspeptic/inflammatory lesions comparable to OGD in one study [19], while a further reported 88 % sensitivity and 65 % specificity for CE ability to detect fresh blood in the upper GI tract. 25 % of patients with normal OGD in this study had a positive CE suggesting lesions can be overlooked with both techniques [20]. CE appears to be at least as accurate as our traditional scoring systems for upper GI bleeding; however, larger studies are needed to confirm these findings [21]. Poor visualisation of the duodenum due to the lapsed battery life of PillCam Eso was a major factor in lack of concordance between CE and OGD findings; this could potentially be addressed in newer generation capsules. ED physicians appeared to be competent to use the system after a brief training period [22]. Initial cost analyses appear favourable although further studies are required to validate this [20].

CE could be regarded as a more accurate physiologic representation of the stomach than seen with conventional endoscopy where air insufflation can compress vasculature leading to diminished blood flow. This has been recognised in GAVE, a recognised cause of OGIB that can be successfully treated with APC. Small bowel CE seems to be a useful tool for identifying the condition where standard OGD often fails [23, 24].

Due to its acceptability, CE has been considered as an alternative to conventional OGD in order to improve compliance with investigation of the upper GI tract. This is particularly pertinent to countries with high gastric cancer incidence where screening programmes are under consideration. Small bowel CE is unable to examine all areas of the capacious stomach, even with patient positional change strategies. Certain areas are often obscured by large mucosal folds making it of limited use as a sole diagnostic or screening examination for gastric cancer [25]. The first step in order to examine the large volume stomach will be for capsules to have some element of manoeuvrability and work is already underway to this effect.

The first case report of this novel technology, published by Paul Swain et al. in 2010, used a modified Pillcam Colon with one of the cameras replaced by magnetic material. The magnetically manoeuvrable capsule appeared to be easily manipulated in the oesophagus and stomach using a handheld external magnet [26]. This was followed by a series focussing on gastric visualisation and safety of the technique. No adverse event s were experienced, and >75 % of the gastric mucosa was visualised in 7 out of 10 patients undergoing the procedure [27].

Further studies have been undertaken using a specially developed magnetically steerable capsule with a magnetic guidance system similar to standard magnetic resonance imagers. In this case, the capsule is manipulated using a joystick rather than a hand-held paddle. Promising results were also achieved with all major areas of the stomach identified in >85 % of examinations. Comparison with conventional upper GI endoscopy was also encouraging with 58.3 % of gastric lesions detected by both modalities, while 14 lesions were missed by magnetically steerable capsule endoscopy (MSCE) and 31 lesions missed by OGD (that were seen on MSCE) [28]. The relative high cost of installing such a system is a major drawback to this technique.

Impaired visualisation due to gastric mucous and debris remained a challenge for both techniques since there is no suction facility. Changing patient position appeared to facilitate movement of these pools allowing better images to be achieved. Ingestion of water, sodium bicarbonate and simethicone have also been used. More studies are required to determine the optimum preparation protocol for patient tolerability, stomach distention and mucosal visualisation. Learning curves were demonstrated with both techniques and not only in terms of manoeuvring the capsule with the associated equipment but also in familiarising oneself with the altered appearance of a more collapsed stomach, particularly the cardia and fundus.

These devices can also be applied to broadening the clinical utility of small bowel, oesophageal and colon CE. If the capsule can be manoeuvred to stop and look more closely at an area of interest, it may improve diagnostic yield or allow targeted biopsy or therapy. Preliminary studies on ex vivo models show promising results but further work in human populations is necessary [29, 30]. Other techniques to manipulate capsules remotely have been trialled but there is limited published data. Capsule with legs [31], paddles [32] and propellers [33] have been tried with some element of success; however, extensive work is required for these to become clinical reality. Work is also underway to enable a two-way interaction with the capsule so it can be commanded to execute certain functions at a time deemed appropriate by the operator [34].