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(1) Background: Colorectal cancer is the second commonest cause of cancer deaths worldwide; recently, volatile organic compounds (VOCs) have been proposed as potential biomarkers of this disease. In this paper, we aim to identify and review the available literature on the influence of mechanical bowel preparation on VOC production and measurement. (2) Methods: A systematic search for studies was carried out for articles relevant to mechanical bowel preparation and its effects on volatile organic compounds. A total of 4 of 1349 papers initially derived from the search were selected. (3) Results: Two studies with a total of 134 patients found no difference in measured breath VOC profiles after bowel preparation; one other study found an increase in breath acetone in 61 patients after bowel preparation, but no other compounds were affected. Finally, the last study showed the alteration of urinary VOC profiles. (4) Conclusions: There is limited data on the effect of bowel preparation on VOC production in the body. As further studies of VOCs are conducted in patients with symptoms of gastrointestinal disease, the quantification of the effect of bowel preparation on their abundance is required.

BackgroundLateral flow tests (LFT) are point-of-care rapid antigen tests that allow isolation and control of disease outbreaks through convenient, practical testing. However, studies have shown significant variation in their diagnostic accuracy. We conducted a systematic review of the diagnostic accuracy of LFTs for the detection of severe acute respiratory syndromecoronavirus 2 (SARS-CoV-2) to identify potential factors affecting their performance. MethodsA systematic search of online databases was carried out to identify studies assessing the sensitivity and specificity of LFTs compared with polymerase chain reaction (PCR) tests. Data were extracted and used to calculate pooled sensitivity and specificity. Meta-regression analysis was conducted to identify covariates influencing diagnostic accuracy. ResultsIn total, 76 articles with 108,820 test results were identified for analysis. Pooled sensitivity and specificity were 72% (95% confidence interval (CI): 0.68-0.76) and 100% (95% CI: 0.99-1.00), respectively. Staff operation of the LFT showed a statistically significant increase in sensitivity (p=0.04) and specificity (p=0.001) compared with self-operation by the test subjects. The use of LFTs in symptomatic patient subgroups also resulted in higher test sensitivity. ConclusionLFTs display good sensitivity and extremely good specificity for SARS-CoV-2 antigen detection; they become more sensitive in patients with symptoms and when performed by trained professionals.

Achalasia is an idiopathic motility disorder of the oesophagus of increasing incidence. It is characterized by aperistalsis of the lower oesophagus and failure of relaxation of the lower oesophageal sphincter. Patients classically present with chronic symptoms of dysphagia, chest pain, weight loss and regurgitation, and they commonly suffer pulmonary complications such as recurrent microaspiration of static, retained food contents of the upper oesophagus. However, it has also been described, uncommonly, to present with megaoesophagus and secondary tracheal compression. We present a case of megaoesophagus secondary to achalasia which presented with stridor and signs of acute superior vena caval obstruction.

Aims Spontaneous pneumomediastinum (SPM) is usually a self-limiting condition in clinically stable patients with no obvious causative factor. SPM can be difficult to distinguish from important secondary causes such as tracheobronchial injury or oesophageal perforation. Therefore, thorough clinical history and examination is of paramount importance. We aim to highlight lessons learnt from our experience to improve rapid diagnosis and clinical management of these patients. Methods Patients were identified through hospital records between October 2019 – December 2021. Data was collected on clinical presentation, precipitating events, radiological confirmation of SPM and compared with current reported literature. Results 11 patients were identified, 8 males (72.7%), 3 females (27.3%) with a mean age of 29 ± 17 years. The most frequent symptom was retrosternal chest pain 27.3%; and vomiting the most common precipitating event (54.5%). Mean white cell count was 14×109/l on admission. All patients underwent plain film chest radiography, and subsequent computerised tomography of thorax, abdomen and pelvis. Patients underwent gastroscopy selectively, showing no acute pathology. Mean length of stay was 4.6 days. No patients required operative intervention or any other intervention beyond antibiotics. No complications or recurrence were found in patients at follow up. Conclusion SPM is a self-limiting condition with low morbidity and mortality. If life-threatening causes have been excluded, SPM can safely be managed expectantly at a local level, without the need of transfer to tertiary centres and prolonged hospital admission. We propose a structured approach to aid in the management of SPM and help address these challenges.