bluuebunny/crossref_metadata_2025_split huggingface dataset:
Colonoscopy and flexible sigmoidoscopy
Authors: East James E. , Saunders Brian P. 
Published: February 2020

Abstract
Colonoscopy involves full oral bowel preparation and planned examination of the whole large bowel, while flexible sigmoidoscopy is usually performed after a phosphate enema and visualizes only the rectum and left colon. In expert hands, after appropriate explanation to the patient (which increases the chances of the procedure being well tolerated), and (usually) some form of ‘conscious sedation’, total colonoscopy is possible in 98 to 99% of cases in the absence of obstruction, a severely ulcerated colon, or other contraindication. The indications for colonoscopy are wide and constantly expanding, and are likely to continue to do so until alternative less invasive techniques (‘virtual colonoscopy’ or genetic tests) are perfected. Common indications include patients with or requiring (1) bleeding, anaemia, or occult blood loss; (2) chronic diarrhoea or known inflammatory bowel disease, which is accurately and easily assessed by endoscopy and biopsy; (3) polyps that can be removed endoscopically; and (4) surveillance for cancer prevention. Therapeutic colonoscopy now allows resection of almost all benign colonic polyps and some very early cancers as well as dilatation of anastomotic or Crohn’s disease strictures and stenting of malignant strictures.
Diseases of the oesophagus
Authors: Fitzgerald Rebecca C. , di Pietro Massimiliano 
Published: February 2020

Abstract
Defective conduit function of the oesophagus readily induces clinical symptoms and may have serious effects on nutrition and the lungs, the latter resulting from aspiration of gastro-oesophageal contents. Oesophageal pain and dysphagia caused by diseases of the muscular layer or epithelium are often disabling. The oesophagus is exposed to numerous hostile environments including carcinogens in food or those derived from tobacco, betel nuts, and other ingested sources and hence carcinomas can occur. Chronic reflux disease from exposure to corrosive upper gastrointestinal secretions is also associated with malignant disease—adenocarcinoma—as well as benign stricture formation related to the action of pepsin.
Investigation and management of jaundice
Authors: Collier Jane 
Published: February 2020

Abstract
Haem molecules are degraded in macrophages to biliverdin and then to bilirubin, which is selectively removed by hepatocytes from sinusoidal blood and conjugated, chiefly with two glucuronic acid moieties. Conjugated bilirubin is excreted into the bile, but in many liver diseases it refluxes back into blood from which some is filtered into and darkens the urine (choluria). In the distal intestine, conjugated bilirubin is deconjugated and reduced to a series of uro- and stercobilinogens that give the normal colour to faeces. Jaundice is the clinical sign of hyperbilirubinaemia and usually indicates disease of the liver or biliary tree. Dark urine and pale stools indicate cholestasis. Stigmata of chronic liver disease do not define the cause of jaundice. Unconjugated hyperbilirubinaemia—presents with raised serum bilirubin levels and normal other liver-related blood tests. Causes include haemolysis and benign inherited unconjugated hyperbilirubinaemia (i.e. Gilbert’s syndrome). Conjugated hyperbilirubinaemia—routine liver-related blood tests cannot alone differentiate between intra- and extrahepatic causes of jaundice although high levels of transferases suggests hepatitis (e.g. viral, autoimmune) or hepatic necrosis (e.g. paracetamol). Alcohol and drug histories are needed in those with both elevated alkaline phosphatase and transferases. Extrahepatic cholestasis should be sought by abdominal ultrasonography to detect a dilated intra- and/or extrahepatic biliary tree (and often also to reveal its cause, e.g. gallstones, tumour). Further investigation depends on the clinical context: (1) likely large bile duct disease—endoscopic retrograde cholangiopancreatography, magnetic resonance cholangiography, and endoscopic ultrasonography; (2) likely intrahepatic cholestasis—autoantibodies, immunoglobulins, and liver biopsy.
Hepatic encephalopathy
Authors: Middleton Paul K. , Shawcross Debbie L. 
Published: February 2020

Abstract
Hepatic encephalopathy (HE) is a significant complication of both acute and chronic liver disease, causing much morbidity and mortality. It is a complex neuropsychological condition, associated with hyperammonaemia and systemic inflammation, with a wide spectrum of symptoms. The West Haven criteria describe grades of severity from 0 (subclinical) and I (changes in awareness, mood, attention, cognition, and sleep pattern) through to IV (coma). It is further classified by the underlying aetiology: type A, due to acute liver failure; type B, secondary to portosystemic shunting; and type C, occurring in chronic liver disease in association with precipitating factors including infections, gastrointestinal bleeding, and electrolyte disorders, particularly hyponatraemia. There is no definitive test or set of diagnostic criteria to establish a diagnosis of HE, which remains primarily a clinical diagnosis of exclusion in patients with a history or clinical evidence of liver disease. Management depends on the type of HE, but for type C (the commonest type) typically includes lactulose and rifaximin. Patients with cirrhosis with ongoing overt HE despite optimal medical management have a dismal outlook and should be considered promptly for liver transplantation.
Autoimmune hepatitis
Authors: Webb G.J. , Hirschfield Gideon M. 
Published: February 2020

Abstract
Autoimmune hepatitis is an idiopathic inflammation of the liver attributed to immune responses against self-antigens presumed to be of hepatocyte origin. It is typically a relapsing and remitting corticosteroid-responsive condition associated with hepatitic serum liver tests, elevated gammaglobulins, and positive immune serology. Histological features are not specific but often include expanded portal tracts with a lymphoplasmacytic infiltrate. Epidemiology: predominantly affects women, may occur throughout life, has some heritable component, and 60% of patients have other autoimmune diseases. Clinical features: many patients are asymptomatic and identified through investigation of abnormal serum liver tests. Presentation may be with anorexia, nausea, hepatic discomfort, and jaundice, but others may have nonspecific malaise or extrahepatic manifestations such as arthralgia, arthritis, or fever. Clinical signs vary greatly, ranging from none to jaundice and tender hepatomegaly to fulminant hepatic failure. One-third of patients present as cirrhotic. Diagnosis: characteristic laboratory findings include elevated serum transaminase activities, hypergammaglobulinaemia (as IgG), and circulating autoantibodies (e.g. antismooth muscle antibodies, anti-liver–kidney microsomal antibodies, and antinuclear antibodies). Diagnosis depends on the combination of clinical features and biochemical, immunological, and liver biopsy abnormalities, with exclusion of viral and other aetiologies. There may be overlap features with other autoimmune liver diseases (primary sclerosing cholangitis or primary biliary cholangitis). Treatment and prognosis: the condition tends to progress to hepatic fibrosis and cirrhosis. Most cases should be treated with an immunosuppressive regimen, typically prednisolone with azathioprine in the first instance, and most require long-term immunosuppression. Crude 10-year survival rate is 65% for those presenting with cirrhosis and greater than 95% for those presenting without. End-stage decompensated cirrhosis and acute nonresponsive autoimmune hepatitis with liver failure can be indications for liver transplantation.
Nonalcoholic fatty liver disease
Authors: Anstee Quentin M. , Day Christopher P. 
Published: February 2020

Abstract
Nonalcoholic fatty liver disease (NAFLD) is the most common liver disorder in the developed world, affecting 20 to 30% of Western adults. Nonalcoholic liver disease occurs with a range of severity from simple steatosis through nonalcoholic steatohepatitis (NASH) to fatty fibrosis and, ultimately, cirrhosis. The condition is a manifestation of the metabolic syndrome, strongly associated with obesity, insulin resistance, and dyslipidaemia. Dietary and genetic factors appear to determine susceptibility to the disease and its progression. In most patients, the condition is discovered incidentally when abnormal values of serum liver-related liver tests are reported. The diagnosis is usually one of exclusion. Liver biopsy is not always required but, in the absence of well-validated noninvasive biomarkers, remains the only way to detect steatohepatitis and accurately stage fibrosis of intermediate severity. However, biopsy is not practical in all cases and so a staged approach to patient assessment and risk stratification is advised. Treatment is directed at components of the metabolic syndrome: weight loss through diet and exercise has been shown to ameliorate disease. A range of novel pharmacological drug treatments are under evaluation.
Vascular disorders of the liver
Authors: Gimson Alexander 
Published: February 2020

Abstract
The liver’s complex blood supply and high metabolic activity may be affected in a number of clinical situations when there is reduced splanchnic inflow and impaired hepatic venous outflow. Budd–Chiari syndrome is caused by obstruction to hepatic venous outflow, usually by thrombosis within the hepatic veins. Causes include myeloproliferative disease, malignancy, and hypercoagulable states. Presentation may be acute, subacute, or chronic, and the diagnosis requires consideration in any patient presenting with acute liver failure, acute hepatitis, or chronic liver disease. Diagnosis is made by Doppler ultrasonography of the hepatic veins and confirmed with CT or MRI scanning. Management depends on the presentation, but involves anticoagulation in all cases, and thrombolysis, measures to decompress the liver, and liver transplantation in some. Survival is about 75% at 5 years. Other conditions discussed include congestive hepatopathy, ischaemic hepatopathy, hepatic artery aneurysm, and portal vein thrombosis.
Primary and secondary liver tumours
Authors: Alexander Graeme J.M. , Lomas David J. , Griffiths William J.H. , Rushbrook Simon M. , Allison Michael E.D. 
Published: February 2020

Abstract
A number of benign and malignant tumours arise in the liver. Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide. It is usually asymptomatic unless the cancer is advanced. Cross-sectional imaging with contrast with either CT or MRI is sufficient to make a firm diagnosis. Serum α-fetoprotein is elevated in most cases. Early diagnosis, perhaps through surveillance, increases the proportion of patients that can be considered for curative treatment, including surgical resection, radiofrequency ablation, or liver transplantation. The presence of symptoms denotes a poor prognosis, with less than 10% of patients surviving 3 years. Cholangiocarcinoma accounts for 7 to 10% of primary liver malignancies. The diagnosis of cholangiocarcinoma can be very difficult to make. Resection results in cure for only a few patients. Palliative approaches include photodynamic therapy, conventional radiotherapy, and high-dose local irradiation. Biliary stents relieve jaundice and may reduce the frequency of episodes of cholangitis. Haemangioma, usually an incidental finding, has a prevalence of 2 to 5% in the population. Focal nodular hyperplasia (prevalence 0.4–0.8%) is found predominantly in fertile women and is typically an incidental finding during abdominal imaging. Biopsy is required if there is diagnostic uncertainty and in particular to differentiate from hepatic adenomas. Interventions include surgery, radiofrequency ablation, transarterial embolization, or a combination of each according to location and patient fitness. Secondary tumours may be a presenting feature but more often are found during staging for primary malignancy or during follow-up. Symptoms include abdominal pain and hepatomegaly and later jaundice and ascites. For most patients with multiple metastases to the liver, the prognosis is poor and treatment palliative.
Liver and biliary diseases in infancy and childhood
Authors: Thompson Richard J. 
Published: February 2020

Abstract
Most liver diseases that occur in adults also occur in children, but some present almost exclusively in early childhood. Neonatal jaundice is common and usually short-lived. Onset before 24 h, or continuation beyond 2 weeks, strongly suggests an underlying pathology, when biliary atresia is the most common cause, with liver transplantation allowing some patients to survive to adolescence and adulthood. Some genetic causes of cholestasis (e.g. MDR3 deficiency) can present in adults. A long list of metabolic disorders present with evidence of liver involvement, with later manifesting diseases including those with accumulation of material in the liver. Liver transplantation is an excellent treatment for many of these disorders, and a growing number of metabolic disorders that do not cause liver disease per se are now being successfully managed through liver replacement, with patients surviving into adult life.
Electrocardiography
Authors: Houghton Andrew R. , Gray David 
Published: February 2020

Abstract
The electrocardiograph (ECG) has been recognized as a valuable diagnostic tool since the end of the 19th century. The normal ECG waveform consists of P, QRS, and T waves (and sometimes U waves)—P waves result from atrial depolarization, QRS complexes from ventricular depolarization, and T waves from ventricular repolarization. The standard 12-lead ECG utilizes four limb electrodes and six precordial electrodes to generate 12 leads or ‘views’ of the heart’s electrical activity. There are six limb leads (termed I, II, III, aVR, aVL, and aVF) and six precordial leads (termed V1, V2, V3, V4, V5, and V6). Supplementary ‘views’ can be obtained by using additional leads, such as V7, V8, and V9 to assess the posterior aspect of the heart and right-sided chest leads to look for a right ventricular myocardial infarction.
Cardiac arrhythmias
Authors: Ginks Matthew R. , Lane D.A. , McGavigan A.D. , Lip Gregory Y.H. 
Published: February 2020

Abstract
The term cardiac arrhythmia (or dysrhythmia) is used to describe any abnormality of cardiac rhythm. The spectrum of cardiac arrhythmias ranges from innocent extrasystoles to immediately life-threatening conditions such as asystole or ventricular fibrillation.
The key to the successful diagnosis of cardiac arrhythmias is the systematic analysis of an ECG of optimal quality obtained during the arrhythmia.
Continuous monitoring is necessary for identification when arrhythmias are intermittent. Ambulatory ECG recordings are of most value when they provide correlation between the patient’s symptoms and the cardiac rhythm at that moment. Alternative strategies for the detection of infrequent arrhythmias include the use of a patient-activated recorder, which is applied and activated during symptoms, or an external or implanted loop recorder.
Acute cardiac failure: Definitions, investigation, and management
Authors: Clark Andrew L. , Cleland John G.F. 
Published: February 2020

Abstract
Presentations of acute heart failure fall into three overlapping categories: acute breathlessness and pulmonary oedema; chronic fluid retention and peripheral oedema (anasarca); and cardiogenic shock. Features on examination include tachycardia, hypotension, a raised venous pressure, basal crackles, and peripheral oedema. Auscultation may reveal a third heart sound or features of valvular heart disease. Initial management focuses on confirming the diagnosis and identification of the immediate precipitant (e.g. arrhythmias, myocardial infarction, decompensating valvular heart disease). Initial investigations include a 12-lead electrocardiogram, chest radiograph, full blood count, biochemical screen, troponin, and thyroid function. Natriuretic peptides are useful in confirming the diagnosis where clinical features are present and a normal level of these is helpful in excluding the diagnosis. All patients should undergo echocardiographic assessment early in the course of a hospital admission to assess left ventricular function and to look for underlying valvular heart disease.
Percutaneous interventional cardiac procedures
Authors: Follan Edward D. 
Published: February 2020

Abstract
Percutaneous coronary intervention is the term applied to a variety of percutaneous, catheter-based procedures that accomplish revascularization by angioplasty (enlargement of a vessel lumen by modification of plaque structure), stenting (deployment of an internal armature or stent), atherectomy (removal or ablation of plaque), or thrombectomy (removal of thrombus). The most common single indication for percutaneous coronary intervention is acute coronary syndrome. Randomized trials have shown that direct intervention for ST-elevation myocardial infarction is superior to initial thrombolytic therapy when performed in appropriate centres, and it can be used as a salvage procedure after failed thrombolytic therapy. Balloon angioplasty is the traditional, basic technique of coronary intervention, but this is now uncommonly employed as a stand-alone treatment. A variety of percutaneous techniques can be used to remove atheroma or thrombus from coronary arteries as a prelude to angioplasty/stenting.
Acute aortic syndromes
Authors: Newton James D. , Mitchell Andrew R.J. , Banning Adrian P. 
Published: February 2020

Abstract
The acute aortic syndromes are acute dissection, intramural haematoma, and penetrating ulcer, and all involve disruption of the wall of the aorta with potentially devastating consequences. Although relatively uncommon, left unrecognized and untreated they can carry a mortality rate of up to 2% per hour and 50% within the first few weeks. Physical signs typically reflect the region of the aorta involved and effects of pressure on adjacent structures: evidence of new aortic regurgitation or development of pulse deficits should be actively sought. Abnormalities on the chest radiograph and ECG are common, but neither investigation is diagnostic and further imaging is always necessary by MRI, contrast-enhanced CT, or transoesophageal echocardiography, depending on local availability and the clinical condition of the patient. In the long term, strenuous efforts to control blood pressure are indicated for all patients who have survived aortic dissection, with repeat imaging at least once a year.
Structure and function of the pulmonary circulation
Authors: Morrell Nicholas W. 
Published: February 2020

Abstract
The normal pulmonary circulation distributes deoxygenated blood at low pressure and high flow to the pulmonary capillaries for the purposes of gas exchange. The structure of pulmonary blood vessels varies with their function—from large elastic conductance arteries, to small muscular arteries, to thin-walled vessels involved in gas exchange.
Pulmonary vascular resistance is about one-tenth of systemic vascular resistance, with the small muscular and partially muscular arteries of 50–150 µm diameter being the site of the greatest contribution to resistance. In the normal pulmonary circulation, a large increase in cardiac output causes only a small rise in mean pulmonary arterial pressure because pulmonary vascular resistance falls on exercise. Pulmonary blood flow is heterogeneous: gravity causes increased blood flow in the more dependent parts of the lung; within a horizontal region—or within an acinus—blood-flow heterogeneity is imposed by the branching pattern of the vessels.
Hypertensive urgencies and emergencies
Authors: Lip Gregory Y.H. , Shantsila Alena 
Published: February 2020

Abstract
Hypertensive urgencies and emergencies occur most commonly in patients with previous hypertension, especially if inadequately managed. About 40% of cases have an underlying cause, most commonly renovascular disease, primary renal diseases, phaeochromocytoma, and connective tissue disorders. Hypertensive emergencies occur when severely elevated or sudden marked increase in blood pressure is associated with acute end-organ damage. Malignant phase hypertension is a rare condition characterized by very high blood pressure, with bilateral retinal haemorrhages and/or exudates or cotton wool spots, with or without papilloedema. Presentation is typically with visual disturbance, with or without headaches. Urinalysis may demonstrate proteinuria and haematuria, even in the absence of primary renal disease. Some patients with mild renal impairment at first presentation may improve, or even regain normal renal function, but this is unlikely to occur in those with more severe renal impairment at presentation.
Bronchoscopy, thoracoscopy, and tissue biopsy
Authors: Shah Pallav L. 
Published: February 2020

Abstract
Direct visualization of the airways by bronchoscopy has become an important tool in the diagnosis of respiratory disease since its introduction in Japan in 1966. The ability to visualize specific areas significantly improves diagnostic yield in comparison to blind procedures. Similarly, the diagnosis and treatment of pleural disease has improved significantly with the introduction of thoracoscopy, which allows the direct inspection of the pleural cavity. Tissue biopsy has also evolved, with more procedures now being performed with some form of image guidance. Bronchoscopy, thoracoscopy, and radiologically guided biopsy techniques provide different methods for visualizing and sampling thoracic lesions, the approach chosen in any particular case being based on several factors, including the anatomical location of abnormal areas, presence of coexisting pulmonary disease, presence of comorbidities, and local expertise. CT is useful in both selection and planning of the most appropriate sampling method.
Upper respiratory tract infections
Authors: Little P. 
Published: February 2020

Abstract
Acute upper respiratory tract infections include acute pharyngitis/tonsillitis and acute rhinitis. Acute sinusitis, acute otitis media, and influenza also come under the umbrella of infections of the upper respiratory tract. Otitis media and influenza will be discussed elsewhere: this chapter concentrates on acute pharyngitis/tonsillitis, acute rhinitis, and acute sinusitis. Acute upper respiratory tract infections are one of the commonest reason for patients to seek medical advice in the United Kingdom, and nearly all cases are managed in primary care. Respiratory tract infections are also the commonest reason for antibiotics to be prescribed, leading to serious concern that the inappropriate use of antibiotics for predominantly self-limiting conditions will foster the development of antibiotic resistance, with the danger that serious infections will become untreatable. Thus it is currently an international priority to discourage the use of antibiotics where there is poor evidence of their efficacy.
Pneumonia in the normal host
Authors: Lim Wei Shen 
Published: February 2020

Abstract
Pneumonia is an acute or chronic infection involving the pulmonary parenchyma.
Most cases are caused by microbial pathogens, the commonest being Streptococcus pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae, Chlamydia pneumoniae, legionella, anaerobic bacteria, and viruses (influenza, parainfluenza, and respiratory syncytial virus). Staphylococcus aureus is an important superinfecting pathogen in influenza, and the most common form of embolic pulmonary infection with injected drug use and tricuspid valve endocarditis. The main preventive measures are smoking cessation, and vaccination against influenza and S. pneumoniae. Its classic presentation is with cough and fever, with variable sputum production, dyspnoea, and pleurisy. Most patients have constitutional symptoms and many also have gastrointestinal symptoms. Clinical examination may reveal features indicative of the severity of respiratory compromise and (in some cases) of consolidation.