Oxford Handbook of Clinical Examination and Practical Skills (2 edn)
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Notes
The procedures detailed in this chapter are for information only—to enable the reader to discuss it with their patients, to prepare the patients correctly, and to identify those patients who may or may not be suitable.
The reader is not expected to perform any of these investigations themselves and this chapter is not intended as a resource for those learning how to perform the investigations.
Computed tomography (CT)
Indications
Indications are manifold and too numerous to list. See ‘making best use of a department of clinical radiology’ via 
http://www.rcr.ac.uk
Contraindications
The standard radiation protection precautions apply.
The patient must be able to lie flat and still.
Examinations of the chest usually require the patient to hold their breath.
Technology
The CT scanner (Fig. 20.1) houses an x-ray tube and rows of detectors which spin at 2–3 revolutions per second, creating a force of up to 25g.
As the patient is moved slowly through the machine, spiral data is acquired which is then converted to ‘slices’ by the CT software and sent to PACS or a connected workstation for viewing.
A typical CT scanner. Note the presence of metal in the room (oxygen cylinder, etc.) indicating this is not an MRI scanner and the lead apron indicating that x-rays are being used. The CT scanner has a laser marker (shown) to help with patient positioning, an MRI scanner does not.
Procedure
This depends on the part of the body examined and the indications for the examination.
If indicated, the patient may be given oral contrast an hour or more before the examination.
The patient lies (usually supine) on the scanner table.
Head-first for head and neck; feet-first for almost everything else.
‘Scout’ views are acquired which are brief swipes across the area of interest. The resultant images are then used by the radiographer to set the parameters for the scan.
Most examinations involve intravenous iodinated contrast being given. Note that the contrast is not radioactive.
This is usually delivered via an intravenous cannula by an automatic pump-injection device, controlled remotely by the radiographer
Contrast may be hand-injected immediately before some scans.
Depending on the part of the body examined, the patient may be asked to hold their breath via speakers in the machine. Microphones within the scanner allow the staff in the control room to hear the patient.
The scan itself lasts no more than a couple of minutes.
Time taken to transfer the patient onto the scanner and set up the intravenous injections will vary.
Risks
Intravenous contrast reactions include anaphylaxis and nephrotoxicity.
Intravenous contrast should not be given to patients with renal impairment unless in special circumstances. Check local guidance.
Extravasation of intravenous contrast (pain, swelling, erythema).
Patient preparation
Fasting: not required for most examinations.
Magnetic resonance imaging (MRI)
Indications
Indications are manifold and too numerous to list. See ‘making best use of a department of clinical radiology’ via 
http://www.rcr.ac.uk
Contraindications
As there is no ionizing radiation, radiation precautions do not apply.
All ferromagnetic materials will be strongly attracted to the scanner creating missiles which may prove extremely dangerous. MRI-safe trolleys, resuscitation equipment and wheelchairs must be employed.
Implanted ferromagnetic devices, aneurysm clips, and retained foreign bodies (e.g. shrapnel or metallic fragments in the eyes) will also move towards the scanner potentially causing major injury.
Although electronic pacemakers are not made of ferromagnetic material, they may be ‘reset’ or stop altogether. The next generation of very new pacemakers is ‘MRI safe’ – check with the manufacturer.
A strict questionnaire is employed before anyone (staff or patient) is allowed near the magnet. If in doubt, access is denied.
Magnetic tape and credit cards may be ‘wiped’ by the magnet.
Many brands of mascara contain ferromagnetic filaments which may heat and cause burns to the eyelids.
Caution should also be taken with tattoos; some contain iron.
The patient must be able to lie flat and still for the duration of the scan.
Most scanners are relatively tight; larger patients may not fit—check the size and weight limits with your local department.
Technology
The MRI scanner (Fig. 20.2) houses a very large electromagnet which is always on.
Radiowaves are produced by the machine which interact with hydrogen atoms in the patient. Radiowaves are, in turn, produced by the interaction with the hydrogen atoms and are detected by the machine which converts the data into images. The scanner has no internal moving parts.
A typical MRI scanner. Note the absence of metal in the room (oxygen cylinder, etc.). A ‘coil’ is shown within the scanner.
Procedure
This depends on indications and the part of the body examined.
The patient lies on the scanner table. ‘Coils’ may be placed over the body part of interest.
Most examinations do not involve intravenous contrast being given. If this is given, contrast containing gadolinium (Gd) is usually used.
This is usually hand-injected immediately before the scan.
Depending on the part of the body examined, the patient may be asked to hold their breath via speakers in the machine.
The scan itself can last up to 40–50 minutes for some body parts.
Risks
Nephrogenic systemic fibrosis (NSF): linked to gadolinium exposure in 2006. Symptoms may begin up to 3 months from exposure and may include pain, swelling, erythema, fibrosis of internal organs, and death. Patients with renal impairment are at greatest risk (no cases recorded in those with GFR >60) and at least 9 hours of haemodialysis is required to remove it from the bloodstream. See latest guidance at http://www.rcr.ac.uk.
Metallic artefacts: twisting or movement of artefacts within the body.
Biological effects: the magnetic fields employed may induce voltages within the body. The most common effect is ‘magnetophosphenes’ or visual flashes seen by the patient as the optic nerve is stimulated. Stimulation of other nerves and muscles may occur.
Tissue burns: may occur if conducting loops (e.g. ECG leads) are in contact with skin.
Temperature: the oscillating voltages create tissue heating. Overall body temperature may rise by 0.3°C.
Noise: may reach up to 95dB. Headphones or earplugs are usually worn.
Claustrophobia: experienced by up to 10% of patients.
Barium swallow and meal
Barium swallows examine the oropharynx, oesophagus, and gastro-oesophageal junction; barium meals examine the stomach and first part of the duodenum. Swallows and meals are usually performed together as described here.
Indications
Investigation of oesophageal and gastric pathology. Indications include dysphagia, odynophagia, dyspepsia, weight loss, anaemia, epigastric mass, partial obstruction.
Always consider alternatives (e.g. OGD, MRI).
Contraindications
Absolute: lack of informed consent, complete bowel obstruction, suspected perforation (a water-soluble contrast may be used instead).
Relative: a large degree of patient cooperation is required so those unable to understand or follow instructions are unsuitable. Also, the patient must be able to stand for the duration of the examination and to lie supine if necessary.
Procedure
The patient drinks barium whilst the oesophagus and stomach are imaged fluoroscopically. Usually performed by a radiologist.
The patient stands in the fluoroscopy machine (Fig. 20.3).
A gas-producing agent is ingested (e.g. Carbex®) and the patient is asked not to belch.
Images are taken as the patient swallows mouthfuls of barium. The patient must be able to hold the liquid in their mouth and swallow on command.
Once views of the oesophagus have been obtained, the machine is tilted so the patient is supine. The patient is instructed to roll and tilt as images of the stomach are obtained from several angles.
This requires a certain degree of patient fitness.
The time taken depends to a degree on how easily the patient follows the commands, although usually lasts 15–20 minutes.
After the procedure, the patient may eat and drink as usual but is advised to open their bowel regularly to avoid barium impaction.
A typical fluoroscopy room set up for an upper gastrointestinal barium examination.
Risks
Leakage of barium through an unsuspected perforation.
Intraperitoneal and intramediastinal barium has a significant mortality rate.
Barium impaction (causing large bowel obstruction) or barium appendicitis.
Other information
A barium study will prevent a CT examination of the same area for a period of time as intestinal barium creates dense streak artefact.
Patient preparation
Fasting: nil by mouth for 6 hours before the examination.
Bowel preparation: none required.
Smoking: patients are asked not to smoke for 6 hours before the procedure as this increases gastric motility.
Water-soluble contrast examinations
In the case of recent surgery, suspected perforation, or investigation of a leak, water-based iodinated contrast is used instead of barium. Examples include Gastrograffin, Urograffin, Niopam, and Omnipaque.
A single-contrast examination is performed (i.e. the gas-producing agent is not given) and many of the ‘standard’ views are not included.
In contrast to the barium examinations, these studies can be carried out on patients who are frail and/or have recently had surgery.
Intraperitoneal or intramediastinal water-soluble contrast does not carry the risks of barium but aspiration of the contrast can result in pulmonary oedema and lung fibrosis. Hypersensitivity is also a risk.
Barium follow-through
Indications
Investigation of small bowel pathology, particularly suspected Crohn’s disease and strictures. Indications include pain, diarrhoea, malabsorption, partial obstruction, and anaemia.
Always consider alternatives (e.g. MRI, small bowel enema).
Contraindications
Absolute: lack of informed consent, complete small bowel obstruction, suspected perforation (a water-soluble contrast may be used instead).
Procedure
The patient drinks barium and the small bowel is intermittently imaged until the barium has reached the caecum. Usually performed by a radiologist or senior radiographer.
The patient is given a mixture of barium to drink.
The exact mixture given to the patient varies between centres and between radiologists. Some add Gastrograffin to the barium, which has been shown to reduce transit time. Many add 20mg of metoclopramide to the mixture which enhances gastric emptying.
Once the barium has been consumed, the patient is asked into the fluoroscopy room and images are taken of the small bowel with the patient lying supine (Fig. 20.4).
Real-time fluoroscopy is employed to assess small bowel motility.
Images are taken every 20–30 minutes until the barium has reached the colon.
The radiologist may use a plastic ‘spoon’ or similar radio-lucent device to press on the patient’s abdomen to separate loops of bowel.
Additional images of the terminal ileum are usually obtained, often with the patient supine, and many radiologists also acquire an ‘overcouch’ plain abdominal radiograph with compression applied to the lower abdomen.
The time taken depends on the small bowel transit time and, although usually an hour, patients are advised to allow up to 3 hours for the appointment.
After the procedure, the patient may eat and drink as usual but is advised to keep their bowel moving to avoid barium impaction.
A typical fluoroscopy room set up for an upper gastrointestinal barium examination.
Risks
Leakage of barium through an unsuspected perforation.
Intraperitoneal barium causes hypovolaemic shock and has a 50% mortality rate. Of those that survive, 30% have adhesions.
Barium impaction (causing large bowel obstruction) or barium appendicitis.
Medication effects (see ‘other information’).
Patient preparation
Fasting: nil by mouth for 12 hours before the examination.
Bowel preparation: laxative (usually Picolax® or similar) taken 12 hours before.
Other information
Metoclopramide aids gastric emptying. Extra-pyramidal side effects may occur, especially in young women, and there is a risk of acute dystonic reactions such as an oculogyric crisis. Contraindicated in patients with Parkinsonism/Parkinson’s disease.
A barium study will prevent a CT examination of the same area for a period of time as intestinal barium creates dense streak artefact.
Barium enema
The following refers to the standard ‘double contrast’ barium enema.
Indications
Investigation of colonic pathology. Indications include pain, melaena, anaemia, palpable mass, change in bowel habit, failed colonoscopy, and investigation of remaining colon in the case of a known colonic tumour.
Always consider alternatives (e.g. colonoscopy, CT colonography).
Contraindications
Absolute: lack of informed consent, possible perforation, pseudomembranous colitis, toxic megacolon, biopsy via rigid sigmoidoscope within 5 days, biopsy via flexible endoscope within 1 day.
Relative: barium meal within 7–14 days, patient frailty or immobility.
The procedure requires a large amount of patient cooperation. The patient must be able to lie flat and to turn over easily
The patient must be able to retain rectal barium and air.
Procedure
The colon is coated with barium, then inflated with air and images are taken from several different angles. Performed by a radiographer or radiologist.
The patient lies in the left lateral position on the fluoroscopy table (Fig. 20.5).
The operator may perform a digital rectal examination before starting.
A rectal tube is placed, attached to a bag of barium sulphate. The barium is run into the colon under x-ray guidance until it reaches the right colon.
The barium is drained.
Intravenous buscopan or, if contraindicated, glucagon is given.
The colon is inflated with air (or with CO2 in some centres).
The patient is instructed to roll and is tilted as images are acquired.
Once the images are obtained, the colon is deflated and the patient can go to the bathroom to empty their bowel and shower if necessary.
The examination may last 15–30 minutes.
The patient should be kept in the department until any medication side effects (e.g. blurred vision) have worn off.
A typical fluoroscopy room set up for a barium enema examination.
Risks
Perforation (increased risk in elderly, ulcerating lesions, systemic steroids, hypothyroidism, large bowel obstruction).
Intraperitoneal barium causes hypovolaemic shock and has a 50% mortality rate. Of those that survive, 30% have adhesions.
Cardiac arrhythmia (secondary to the large bowel distension).
Medication effects (see ‘other information’).
Patient preparation
Iron tablets: stop 5 days before.
Constipating agents: stop 2 days before.
Fasting: low residue diet 2 days before, fluids only on the day before.
Bowel preparation: laxative (usually Picolax®) taken at 08:00 and 18:00 on the day before.
Other information
Buscopan is given to inhibit intestinal motility. Side effects include blurred vision, dry mouth, and tachycardia.
Contraindicated in angina, untreated closed angle glaucoma, prostatic hypertrophy, myasthenia gravis, paralytic ileus, pyloric stenosis
Glucagon is given if buscopan cannot be given. Risk of hypersensitivity and is contraindicated in phaeochromocytoma, insulinoma and glucagonoma.
After the procedure, the patient may eat and drink as usual but is advised to keep their bowel moving to avoid barium impaction.
A barium study will prevent a CT examination of the same area for a period of time as intestinal barium creates dense streak artefact.
Water-soluble contrast examinations
In the case of recent surgery, suspected perforation, or investigation of a leak, water-based iodinated contrast is used instead of barium. Examples include Gastrograffin, Urograffin, Niopam, and Omnipaque.
A single-contrast examination is performed (i.e. the colon is not inflated with air) and many of the ‘standard’ views are not included.
No bowel preparation or fasting is needed.
Endoscopic retrograde cholangiopancreatography (ERCP)
Indications
Diagnostic: largely superseded by safer modalities such as endoscopic ultrasound and MRI/MRCP. Diagnostic indications include sphincter of Oddi dysfunction and primary sclerosing cholangitis.
Therapeutic: endoscopic sphincterotomy (biliary and pancreatic), removal of stones, dilation of strictures (e.g. PSC), stent placement.
Contraindications
Lack of informed consent, uncooperative patient, recent attack of pancreatitis, recent MI, history of contrast dye anaphylaxis, severe cardiopulmonary disease, futility (anticipated short-term survival with no features of sepsis).
Procedure
An ERCP involves the passage of an endoscope into the duodenum. The endoscopist injects contrast medium through the ampulla of Vater via a catheter. Real-time fluoroscopy is used to visualize the pancreas and biliary tree. Selected images are taken.
Dentures (if present) are removed.
Patient is given anaesthetic throat spray (lidocaine) and sometimes intravenous sedation/analgesia (e.g. midazolam, pethidine).
Patient lies on the couch in a modified left lateral (‘swimmers’) position with the left arm adducted and the right abducted. The endoscope is inserted as for OGD.
Under x-ray guidance, a polyethylene catheter is inserted into the biliary tree and contrast instilled to outline the pancreatic duct as well as the common bile duct and its tributaries.
Procedure time varies from 30–90 minutes.
Risks
Pancreatitis (2–9% of procedures of which 10% of cases are mild–moderate). Serum amylase is temporarily raised in 70%.
Infection (ascending cholangitis, acute cholecystitis, infected pancreatic pseudocyst, liver abscess, endocarditis).
Bleeding, perforation of the oesophagus, duodenum, bile ducts.
Failure of gallstone retrieval.
Prolonged pancreatic stenting associated with stent occlusion, pancreatic duct obstruction, pseudocyst formation.
Basket impaction around a large gallstone (may require surgery).
Patient preparation
Blood tests: Liver enzymes, platelets, and clotting are checked prior to the procedure.
Fasting: 4 hours except in the case of an emergency.
Antibiotic prophylaxis: recommended for:
Patients in whom biliary decompression is unlikely to be achieved at a single procedure (e.g. dilatation of dominant stricture in multifocal sclerosing cholangitis or hilar cholangiocarcinoma)
Consider also in patients with severe neutropenia (<0.5 x 109/L) and/or profound immunocompromise.
Other information
Intravenous sedation and analgesia is usually administered and the back of the throat is sprayed with local anaesthetic.
Hilar biliary obstruction demonstrated on MR or CT imaging may be more successfully stented using percutaneous transhepatic cholangiography (PTC) than ERCP.
Equipment allowing direct cholangioscopy (with the potential for sampling lesions) is becoming more widely available.
Ultrasound
Indications
Indications are manifold and too numerous to list. See ‘making best use of a department of clinical radiology’ via http://www.rcr.ac.uk
Contraindications
For some examinations, the patient must be able to cooperate with the operator and a degree of mobility is often required.
Ultrasound becomes increasingly less diagnostic at greater depths. Images of deeper structures in large individuals are often unobtainable and this should be borne in mind when considering who to refer.
Technology
The ultrasound probe houses a piezoelectric crystal which both projects and receives high-frequency sound waves. Much like radar, the ‘echoes’ are converted to images by the machine’s software.
Ultrasound cannot image through gas and requires a semi-liquid ‘gel’ between the probe and skin surface for optimum imaging.
A typical ultrasound machine is shown in Fig. 20.6.
A typical ultrasound room.
Procedure
This depends on the part of the body examined and the indications.
Time taken will vary depending on part of body examined, patient cooperation, and complexity of the findings. Most examinations last between 5–20 minutes.
Risks
There is no published evidence that ultrasound has ever directly caused harm to a patient.
The acoustic output of modern machines, however, is much greater than previously used.
Heating: some equipment can produce temperature rises of 4°C in bone. Most equipment in clinical use is unlikely to increase tissue temperature more than the 1.5°C which is considered ‘safe’.
Non-thermal hazard: ultrasound has been demonstrated to produce tiny gas pockets and bubbles in animal models. Neonatal lung is considered vulnerable to this but there is no evidence that diagnostic ultrasound can cause harm to other tissues.
Machines have a ‘mechanical index’ (MI) displayed on screen which acts as a guide to the operator.
Patient preparation
Depends on the indication and body part being examined.
Abdomen: patients are usually asked to fast for 6 hours prior to the examination. This ensures distension of the gallbladder and prevents the epigastric structures being obscured by overlying bowel gas.
Renal tract/pelvis: a full bladder is usually required. A full bladder creates an ‘acoustic window’, effectively pushing small bowel aside so that deeper structures (e.g. ovaries) may be seen.
Oesophagogastroduodenoscopy (OGD)
Indications
Diagnostic: haematemesis, dyspepsia (>55 years old), oesophageal and gastric biopsies (malignancy?), duodenal biopsies (coeliac?), surveillance (e.g. Barrett’s oesophagus), persistent nausea and vomiting, iron-deficiency anaemia, dysphagia.
Therapeutic: treatment of bleeding lesions, variceal banding and sclerotherapy, stricture dilatation, polypectomy, EMR, palliative intent (e.g. stent insertion, laser therapy), argon plasma coagulation for suspected vascular lesions.
Contraindications
Absolute: lack of informed consent, possible perforation, haemodynamic instability, hypoxaemia with respiratory distress, uncooperative patient.
Relative: pharyngeal diverticulum, recent myocardial infarction, or pulmonary embolus.
Procedure
Endoscopic examination of the mucosa of the oesophagus, stomach, and proximal duodenum. Allows direct visualization, mucosal biopsies, and other therapeutic procedures.
Dentures (if present) are removed.
Patient is given anaesthetic throat spray (lidocaine) +/– intravenous sedation (e.g. midazolam).
Patient lies on the couch in the left lateral position.
Hollow mouthpiece is inserted to protect the patient’s teeth and facilitate instrument passage.
Endoscope (9.5–12.5mm diameter, max 120cm long) is slowly advanced and ‘swallowed’ by the patient (Fig. 20.7 shows a typical scope).
Scope advanced and manipulated by the endoscopist to allow visualization of the target structures.
Procedure time varies but averages 5–15 minutes.
A typical gastroscope.
Risks
Minor throat and abdominal discomfort.
Cardiorespiratory: arrthythmias, MI, respiratory arrest, shock, death.
Infection (uncommon, e.g. aspiration pneumonia).
Perforation (around 0.03% with a mortality of 0.001% during diagnostic procedures, higher with therapeutic procedures).
Overall 2–3% perforation with oesophageal dilatation; mortality 1%.
Bleeding (caution with low platelet counts and high INR).
Medication effects including anaphylactic reactions and over-sedation.
Dental trauma.
Patient preparation
Fasting: 4 hours prior to the procedure unless in an emergency situation.
Antibiotic prophylaxis: none for OGD. See other topics for comparison.
Other information
Dosages of benzodiazepines and opiates should be kept to a minimum to achieve sedation, with lower doses being prescribed in elderly patients.
The pharynx is sprayed with local anaesthetic spray. There is some evidence that the combination use of local anaesthetic spray and intravenous sedation increases the risk of aspiration pneumonia.
Patients who have had intravenous sedation should not drive, operate heavy machinery, or drink alcohol for 24 hours afterwards.
Colonoscopy
Indications
Diagnostic: gastrointestinal bleeding, iron-deficiency anaemia, chronic diarrhoea, lower abdominal symptoms (chronic constipation, lower abdominal pain, bloating), evaluation of known IBD, surveillance for cancer (in IBD patients/after colonic polypectomy/after curative intent resection of colorectal cancer), screening for colorectal cancer.
Therapeutic: polypectomy (including endoscopic mucosal resection techniques: EMR), angiodysplasia treated with argon plasma coagulation (APC), decompression of volvulus or pseudo-obstruction, dilatation or stenting of strictures or malignant colonic obstruction.
Contraindications
Absolute: lack of informed consent, toxic megacolon, fulminant colitis, colonic perforation.
Relative: acute diverticulitis, symptomatic large abdominal aortic aneurysm, immediately post-op, recent myocardial infarction or pulmonary embolus, severe coagulopathies.
Colonoscopy can be performed safely in pregnancy but should be deferred in most instances unless requiring immediate resolution.
Procedure
Colonoscopy is an endoscopic examination of the mucosal surface from the anal canal to the terminal ileum.
Patient lies on the couch in the left lateral position with knees bent.
Endoscopist first performs a digital rectal examination.
Sedation (e.g. midazolam) may be given with monitoring of oxygen saturation. Intravenous analgesia (e.g. pethidine) is also given.
Increasing use of either no sedation (with improved techniques such as ‘Scopeguide®’) or inhaled nitric oxide.
Lubricated colonoscope (about 12mm wide and 185cm long) is passed rectally. Air is insufflated. Water-jet may also be used via the scope.
Figure 20.8 shows a typical scope.
Aim is to pass to the terminal ileum.
Duration varies but averages at about 20 minutes.
Risks
Perforation (0.2–0.4% diagnostic; higher with therapeutic procedures).
Bleeding (1 in 1000).
Abdominal distension, medication effects (allergic reactions, nausea, vomiting hypotension, respiratory depression).
Rarities: infection, post-polypectomy coagulation syndrome: pain, peritoneal irritation, leukocytosis and fever, splenic rupture, small bowel obstruction.
A typical colonoscope.
Patient preparation
Iron and constipating agents: discontinue iron tablets 7 days and constipating agents 4 days prior to the procedure.
Anticoagulant and antiplatelet therapy: in the case of a planned polypectomy or other therapeutic procedure, refer to BSG guidelines on the management of anticoagulant and antiplatelet therapy: http://www.bsg.org.uk.
Antibiotic prophylaxis: none for colonoscopy. See other topics for comparison.
Bowel preparation: the colon must be empty. Protocols vary but usually include prescribing 1 sachet of sodium picosulphate (Picolax®) for the morning and afternoon of the day before procedure.
Other information
The introduction of the bowel cancer screening programme has meant that endoscopists need to pass a ‘driving test’ to demonstrate high-level competency to perform safe screening colonoscopy.
Endoscopic mucosal resection (EMR) is used for larger or difficult flat polyps. The lesion is lifted by submucosal injection of gelofusin, adrenaline, and dye followed by snare resection. Polyps can then be retrieved by ‘Roth’ baskets for histological assessment.
Capsule endoscopy
Indications
Obscure gastrointestinal bleeding (in patients with negative gastroscopy and ileocolonoscopy), known or suspected small bowel Crohn’s disease, assessment of coeliac disease, screening and surveillance for polyps in familial polyposis syndromes.
Contraindications
Lack of informed consent, intestinal strictures, adhesions, obstruction.
Diverticula or fistulae that may block the passage of capsule endoscope.
Cardiac pacemakers or other implanted electronic devices.
Difficulty in swallowing tablets or known swallowing disorders.
Pregnancy (lack of available safety data).
Patients with obstructive symptoms or known or suspected inflammatory bowel disease should have either a small bowel follow through or a patency capsule (dissolves after 36 hours), with an abdominal radiograph taken 24 hours post ingestion to identify whether capsule is retained within small bowel.
If retained, capsule endoscopy is not appropriate
Capsule retention can occur even in the absence of strictures on barium or MR-enteroclysis study.
Procedure
The capsule (Fig. 20.9) consists of a disposable, wireless, miniature video camera which can be swallowed and passes through the intestine by peristalsis.
Images taken by the capsule are transmitted, via sensors secured to the abdominal wall, to a battery-powered data recorder worn on a belt.
The capsule leaves the stomach within 30 mins and the patient is allowed to drink after 2 hours and eat after 4 hours.
The external equipment (Fig. 20.10) is removed after 8 hours (approximate battery life) by which time the capsule has reached the caecum in 85% of patients.
The capsule is expelled naturally after 24–48 hours in the patient’s stool and does not need to be collected.
Data from the recorder is downloaded onto a computer workstation which allows approximately 50, 000 images to be viewed as a video.
Examples of a typical capsule endoscope. It is shaped to be easy to swallow and has its own light-source.
The external equipment which the patient will wear, consisting of a data-recorder and electrodes.
Risks
Capsule retention (may cause partial or complete intestinal obstruction; highest risk in patients with extensive small bowel Crohn’s disease, chronic usage of NSAIDs, abdominal radiation injury, previous major abdominal surgery, or small bowel resection).
Capsule endoscopy may also fail in patients with dysphagia, gastroparesis, and anatomical abnormalities of the gastrointestinal tract.
Patient preparation
Iron supplements: stop taking 1 week prior to procedure.
Constipating agents: stop 4 days before the procedure.
Fasting: patients are fasted for 8–12 hours prior to the procedure and may receive bowel prep (taken day before procedure).
Other information
Incomplete examination in 10–25% of cases.
Presence of dark intestinal contents in distal small bowel may impair visualization of mucosa
Delayed gastric emptying and small bowel transit can lead to exhaustion of battery life before capsule reaches ileocaecal valve.
Capsules are being developed to screen for oesophageal varices and may be more ‘guided’ in future as the technology develops.
Positive findings on capsule endoscopy may be reachable using either single- or double-balloon enteroscopy or spiral enteroscopy.
Exercise tolerance test (ETT)
Indications
Assessment of chest pain in those with known coronary artery disease (there is no longer a role for ETT in patients presenting with chest pain who do not have a history of coronary artery disease).
Assessment of haemodynamic response in those with known valvular disease who are asymptomatic.
Diagnosis of exertionally induced arrhythmias or syncope.
Contraindications
Any undiagnosed or previously unknown murmur (patient should undergo echocardiogram first).
Severe aortic stenosis (risk of syncope).
Hypertrophic cardiomyopathy with significant outflow obstruction (risk of syncope).
Severe hyper- or hypo-tension.
Unstable angina (should undergo coronary angiography).
Known severe left main stem disease.
Untreated congestive cardiac failure.
Complete heart block.
Aortic aneurysm.
Acute myocarditis or pericarditis.
Any recent pyrexial or ‘flu-like’ illness.
Procedure
ECG electrodes are put on the patient’s chest and a sphygmomanometer cuff on an arm.
The patient is asked to walk on a treadmill (see Fig. 20.11) connected to the computer whilst their ECG, BP, and heart rate are monitored. The speed and incline of the treadmill increase according to set protocols:
Bruce protocol: for assessment of physically fit and stable patients with suspected coronary artery disease. Seven stages starting at a 10% gradient at 1.7mph and increasing to 22% gradient and 6mph
Modified Bruce protocol: used in elderly patients or those who have been stabilized after a suspected episode of unstable angina. Starts at 1.7mph and 0% gradient and increases the gradient slowly to 10%.
Termination of the test depends on the results seen.
A typical ETT room.
Risks
Risks are those associated with exercise and include:
Arrhythmia, cardiac ischaemia, myocardial infarction, syncope.
Patient preparation
No specific preparation is required.
Patients are asked not to eat or drink for 3 hours prior to the test.
Comfortable clothing and shoes should be worn.
Indications for termination of procedure
Patient requests to stop.
Symptoms: fatigue, angina, dizziness, significant breathlessness.
Signs: drop in oxygen saturations <94%, target heart rate achieved, hypotension during exercise (e.g. BP <100mmHg), significant hypertension (e.g. BP >200mmHg).
ECG: any atrial or ventricular arrhythmia, frequent ventricular ectopics, new AV or bundle branch block, ST segment shift >1mm.
Causes of false positive results or low specificity
Often due to difficulty interpreting results as result of resting ST segment abnormalities:
Wolff–Parkinson–White syndrome, LBBB, atrial fibrillation, left ventricular hypertrophy, digoxin therapy, hyperventilation, biochemical electrolyte abnormalities (e.g. hypo- or hyperkalaemia), cardiomyopathies, LV outflow obstruction.
Beta-blocker therapy prevents the appropriate heart rate/blood pressure response during testing.
Echocardiography
Indications
Myocardial infarction: assess wall motion and left ventricular function.
Valvular heart disease: assess competency and examine prostheses.
Embolic stroke: to exclude a cardiac embolic source.
Infective endocarditis: look for valvular vegetations.
Cardiomyopathy: assess ventricular dilatation/hypertrophy and function.
Congenital heart disease.
Pericardial disease.
Pericardial effusion: distribution of fluid and suitability for drainage.
Aortic disease: severity and site of aneurysm, dissection, or coarctation.
Contraindications
The only contraindication is lack of patient consent or if the patient is unable to cooperate.
Technology
Echocardiography is an ultrasound examination and uses the same technology (and machines) as general ultrasound (Fig. 20.12).
Ultrasound becomes increasingly less diagnostic at greater depths and cannot see through lung. Images in large individuals are often suboptimal and the heart may not be seen at all in patients with hyperinflated lungs.
See Box 20.1 for other types.
A typical echocardiography room.
Along with 2-dimensional trans-thoracic echocardiography, the following methods exist:
3D: uses computer software to produce a 3-dimensional image. Useful in left-ventricular functional assessment especially post-infarction
4D: 3D imaging with real-time movement captured
TOE: trans-oesophageal echo is an invasive procedure. It requires written consent and is performed under sedation with local anaesthetic spray to the upper pharynx. The probe is covered, lubricated, and passed into the oesophagus behind the heart. It is used to visualize the posterior cardiac structures. The investigation of choice for infective endocarditis
Stress echo: Used to assess myocardial ischaemia at ‘rest’ and during ‘stress’. Stress is induced by exercise or (more commonly) by an intravenous infusion of dobutamine in a controlled environment
Bubble studies: Used to assess for intra-cardiac shunts such as atrial or ventricular septal defects or patent foramen ovale. Air bubbles are agitated in a syringe and injected into a peripheral vein. The Valsalva manoeuvre is performed and, if a shunt exists, bubbles will be seen moving from the right side of the heart to the left.
Procedure
Time taken will vary depending on examinations performed and complexity of the findings.
Most examinations last between 20–25 minutes.
With the patient lying on their left side, the operator uses a hand-held probe coated with gel to examine the heart usually via the anterior chest and epigastrium.
Risks
There is no published evidence that ultrasound has ever directly caused any harm to a patient.
Heating: some equipment can produce temperature rises of 4°C in bone. Most equipment in clinical use is unlikely to increase tissue temperature more than the 1.5°C which is considered ‘safe’.
Non-thermal hazard: ultrasound has been demonstrated to produce tiny gas pockets and bubbles in animal models but there is no evidence that diagnostic ultrasound can cause harm to tissues other than neonatal lung.
Patient preparation
No preparation is required.
Coronary angiography and angioplasty
Indications
Diagnostic: unstable or refractory angina, acute coronary syndrome, positive or inconclusive stress testing.
Emergency therapeutic: where possible, patients presenting with acute ST-elevation myocardial infarction should have primary coronary intervention rather than thrombolysis.
Elective therapeutic: suitable ‘target lesion’ identified on diagnostic coronary angiogram.
Contraindications
Absolute: refusal of patient consent.
Relative: acute renal failure, pulmonary oedema, known radiographic contrast allergy, uncontrolled hypertension, active GI haemorrhage, acute stroke, and untreated coagulopathy.
Procedure
A typical cardiac interventional suite is shown in Fig. 20.13.
Percutaneous access via a guide needle into a peripheral artery (most commonly the radial artery).
Guide catheter is introduced, the tip is placed at the coronary ostium, radio-opaque contrast is injected, and real-time x-ray is used to visualize the blood flow through the coronary arteries.
The coronary guidewire is inserted through the catheter into the coronary artery using x-ray guidance.
The guidewire tip is passed across the site of stenosis.
The balloon catheter is passed over the guidewire until the deflated balloon lies across the target lesion.
The balloon is then inflated and compresses the plaque and stretches the artery wall. A stent (wire mesh tube) can be inserted using a similar technique and be left in place maintaining the arterial lumen.
The guidewire, catheter, and sheath are carefully removed.
The patient should remain supine for 4 hours following the procedure unless an arterial closure device has been used.
A typical cardiac interventional suite.
Risks
Minor: contrast allergy, vasovagal reaction, haemorrhage and haematoma at puncture site, thrombosis formation, false aneurysm, arteriovenous fistulation, pulmonary oedema, and renal failure due to contrast nephropathy.
Major: limb ischaemia, coronary artery dissection, aortic dissection, ventricular perforation, air or atheroma embolism, ventricular arrhythmias, failure of procedure and need to proceed to CABG.
Death (<1 in 1000).
Patient preparation
Pre-procedure checklist: written consent, group and save, ECG, check FBC/clotting/urea and electrolytes.
Other information
Coronary angioplasty is associated with increased thrombus formation (balloon inflation disrupts the intima, revealing pro-thrombotic cores of plaques), therefore antiplatelet therapy is necessary.
Patients will need to have long-term antiplatelet therapy; usually lifelong aspirin 75mg od, but they will also need clopidogrel 75mg od (see local guidelines: usually 3 months for bare metal stents and 12 months for drug-eluting stents or angioplasty after acute coronary syndrome).
Patients with renal failure should be carefully considered. Iodinated contrast can be nephrotoxic and renal decompensation may occur following coronary angiography/plasty. The risk can be minimized by hydration before and after the procedure. Renal function should be carefully monitored. Check local guidelines.
Bronchoscopy
Indications
Diagnostic: histology/cytology in suspected lung malignancy, sample mediastinal lymphadenopathy, alveolar lavage (e.g. tuberculosis), transbronchial biopsy (e.g. diffuse lung disease).
Therapeutic: placement of guidewire for local radiotherapy, direct treatment (e.g. diathermy to strictures).
Placement of endobronchial stents and the removal of foreign bodies are usually accomplished at rigid bronchoscopy under GA.
Contraindications
Absolute: cardiovascular instability, life-threatening arrhythmia, severe hypoxaemia, respiratory failure with hypercapnia (unless intubated/ventilated).
Rigid bronchoscopy contraindications: unstable neck, severely ankylosed cervical spine, severely restricted temporomandibular joints.
Relative: uncooperative patient, recent myocardial infarction, tracheal obstruction, un-correctable coagulopathy.
Transbronchial biopsy with caution in uraemia, SVCO, pulmonary hypertension (risk of bleeding).
Procedure
Bronchoscopy is an endoscopic examination of the bronchial tree.
Patient sits on the couch, leaning back comfortably.
Sedation (e.g. midazolam) may be given with monitoring of oxygen saturation. Atropine may also be given to decrease secretions.
Pharynx is anaesthetized with aerosolized lidocaine.
Lubricated bronchoscope (about 6mm wide and 60cm long) is passed nasally or orally with use of a bite-block (Fig. 20.14).
Brushings, biopsy, or lavage (50–100ml saline) may be performed.
Duration varies but averages about 20–30 minutes.
A typical bronchoscope.
Risks
Bleeding from a biopsy site and transient fever (10–15%).
Medication effects: respiratory depression, hypotension, arrhythmias.
Topical anaesthesia: laryngospasm, bronchospasm, seizures, arrhythmias.
Minor laryngeal oedema or injury with hoarseness, hypoxaemia in patients with compromised gas exchange (1–10%).
Mortality is 1–4 in 10, 000 patients.
Transbronchial biopsy: pneumothorax (2–5%), significant haemorrhage (1%); death (12 in 10, 000).
Patient preparation
Anticoagulant and antiplatelet therapy: stop for 3 days. Clopidogrel should be stopped for 5 days.
Blood tests: check clotting and full blood count.
Spirometry: perform if underlying lung disease.
Fasting: nil by mouth 2 hours before the procedure, no solids 4–6 hours before procedure.
Post-procedure
Oxygen: supplemental oxygen for up to 1 hour.
Eating/drinking: drink after 1 hour. If no problems, can eat.
Chest radiography: only if dyspnoea or chest pain following biopsy (10% risk of pneumothorax).
Driving: if had midazolam or similar, not to drive or operate heavy machinery for the rest of the day.
