Barium Swallow

The barium swallow is a fluoroscopic examination of the pharynx and oesophagus after the patient swallows barium sulphate suspension, with spot films and recorded images taken during swallowing in several positions (upright, prone, oblique and supine). It shows the structure and the movement of the pharynx and oesophagus in real time.

A double contrast technique (effervescent granules to distend the oesophagus with gas, with high density barium) shows the mucosa in fine detail, and a single contrast technique with thin barium shows the lumen, strictures and motility. A tablet or marshmallow (12.5 mm barium tablet or bread bolus) tests for a stricture that only appears with solid food.

The effective dose is about 1.5 to 3 mSv, depending on the length of fluoroscopy. When a leak or perforation is suspected, or there is a risk of aspiration, a water soluble iso osmolar contrast agent replaces barium, and the study is called a water soluble contrast swallow.

Endoscopy is the first test for most dysphagia because it allows direct vision and biopsy. The barium swallow remains valuable for functional and anatomical assessment. It detects motility disorders (achalasia, spasm), pharyngeal and upper oesophageal problems (webs, Zenker diverticulum, cricopharyngeal bar), subtle rings and strictures, hiatus hernia, extrinsic compression and post-surgical anatomy. It also maps the anatomy before surgery or dilatation.

Dysphagia affects about 10 to 15% of people over 50.

Indications. Dysphagia (difficulty swallowing solids or liquids), odynophagia, food sticking, regurgitation, and recurrent aspiration. Suspected achalasia, oesophageal spasm and other motility disorders. Suspected stricture, ring, web, diverticulum or carcinoma (with endoscopy). Assessment of hiatus hernia and large paraoesophageal hernias before surgery.

Post-operative anatomy (anti-reflux surgery, gastric banding, oesophagectomy), when the surgeon needs a map. Suspected fistula (tracheo oesophageal fistula, H-type in infants, using small volumes). Vascular compression (dysphagia lusoria from an aberrant right subclavian artery) and mediastinal masses. Not for the routine diagnosis of reflux disease, because the test is insensitive for reflux.

Contraindications and precautions. Suspected perforation or anastomotic leak: use water soluble contrast, because barium in the mediastinum or pleura causes severe inflammation. High risk of aspiration (impaired swallow, reduced consciousness): use a speech and language therapy assessment, a small volume of a water soluble agent or a videofluoroscopic study.

Severe constipation or suspected large bowel obstruction: barium can cause impaction. Pregnancy: avoid unless essential. Allergy to contrast is rare with barium, but latex or flavouring components cause reactions. The patient fasts for 4 to 6 hours before, and any anticholinergic or antispasmodic agent is avoided if motility is the question.

Preparation and technique. Fasting for 4 to 6 hours. The patient swallows effervescent granules and high density barium in the erect position, then films are taken in prone right anterior oblique and other positions. For the pharynx, rapid images or video are recorded in the lateral and anteroposterior projections during swallows of thin barium, paste and a marshmallow or tablet.

The radiologist asks about symptoms, and the patient performs provocative manoeuvres (Valsalva, leg raising, water siphon) to show reflux or hernia.

Normal appearances. A smooth, tubular oesophagus about 20 to 25 cm long that distends to 2 cm or more. It has a smooth mucosal pattern of 3 to 4 thin longitudinal folds, an aortic arch indentation on the left, a left main bronchus and left atrial indentations. A normal peristaltic wave that clears barium from the upper to the lower oesophagus in 8 to 10 seconds.

The lower oesophageal sphincter opens briefly, and the gastro oesophageal junction lies under the diaphragm. In the pharynx, the soft palate closes the nasopharynx, the epiglottis tilts over the larynx, barium passes the cricopharyngeus without delay, and no barium enters the airway. A transient "ring" at the lower end (the A and B rings) and tertiary contractions are normal in older people.

Interpretation.

• Achalasia: a dilated oesophagus with absent peristalsis, a delay in emptying (barium column present at 1 and 5 minutes), and a smooth, tapered narrowing at the lower end ("bird's beak" or "rat tail"). Late disease shows a very dilated, sigmoid oesophagus (megaoesophagus).
• Pseudoachalasia from a cancer of the gastro oesophageal junction shows an irregular or nodular narrowing and needs endoscopy and CT.
• Diffuse oesophageal spasm: simultaneous, non-peristaltic contractions with a corkscrew or "rosary bead" appearance (nutcracker oesophagus and hypercontractile disorders are better evaluated by manometry).
• Oesophageal carcinoma: an irregular, shouldered stricture ("apple core"), an ulcerated mass, a rigid narrowed segment with abrupt edges and loss of normal mucosal pattern, and proximal dilatation; confirmation by endoscopy with biopsy and staging by CT.
• Benign peptic stricture: a smooth, concentric narrowing with tapering margins at the lower oesophagus (often with hiatus hernia and reflux); caustic strictures are long and smooth; radiation strictures involve the radiation field.
• Rings and webs: a lower oesophageal (Schatzki) ring, a thin, circumferential, symmetrical narrowing at the squamocolumnar junction, associated with intermittent dysphagia to solid food (best shown with a solid bolus). A cervical web is a thin anterior shelf at the level of the cricoid (associated with Plummer-Vinson syndrome).
• Diverticula: Zenker diverticulum (a posterior pouch just proximal to the cricopharyngeus with food retention and aspiration), mid-oesophageal traction diverticula (from mediastinal nodes), and epiphrenic diverticula (associated with motility disorders).
• Hiatus hernia: sliding hernia (the gastro oesophageal junction lying over the diaphragm in the chest with a gastric pouch, with reflux on provocation) and paraoesophageal hernia (part of the stomach in the chest with the junction in normal position, with risk of volvulus and obstruction).
• Varices: serpiginous mucosal filling defects in the lower oesophagus, seen on a thick barium coat in portal hypertension (endoscopy is more sensitive).
• Oesophagitis: granular or shaggy mucosa, ulcers, thickened folds and a stricture (reflux, Candida with a "shaggy" outline, viral ulcers in HIV, and drug induced ulceration).
• Extrinsic compression: a smooth external indentation by the aortic arch, an aberrant right subclavian artery (an oblique posterior indentation), enlarged left atrium, mediastinal masses and nodes, and thoracic spine osteophytes. In infants, a double aortic arch or pulmonary sling causes anterior or posterior indentation.
• Fistula: tracheo oesophageal fistula (barium in the airway, in a prone, cross-table study with a small volume), and oesophagobronchial fistula in cancer or tuberculosis.
• Post-operative: anti-reflux wrap (a smooth narrowing at the hiatus), gastric band position and slippage, oesophagectomy with a gastric conduit and anastomotic stricture, and leak (extravasation of contrast).
• Pharyngeal disorders: aspiration (contrast passing the vocal cords with or without cough), cricopharyngeal prominence (a posterior bar with impaired relaxation), vallecular residue, and nasal regurgitation (palatal insufficiency).

Critical values and findings needing immediate action.

• Extravasation of contrast (perforation, anastomotic leak): stop barium, give water soluble contrast, and call the surgical team immediately for antibiotics, nil by mouth and urgent CT.
• Aspiration of barium with respiratory compromise: suction, oxygen, chest physiotherapy and a chest film.
• Complete obstruction with food impaction: urgent endoscopy for removal.
• Mass, shouldered stricture or irregular ulceration suggesting carcinoma: urgent endoscopy with biopsy and staging.
• Achalasia with severe dysphagia or aspiration: specialist assessment for pneumatic dilatation, myotomy or peroral endoscopic myotomy.
• Large paraoesophageal hernia with obstruction or volvulus (chest pain, vomiting, inability to pass a nasogastric tube): emergency surgical review.
• Tracheo oesophageal fistula in an infant: nil by mouth, upright positioning, and surgery.

Limitations and artefacts.

• The test is insensitive for early mucosal disease (oesophagitis, small ulcers, Barrett oesophagus, early cancer), and cannot provide a tissue diagnosis; endoscopy and biopsy are needed for any stricture, ulcer or mass.
• Reflux is demonstrated inconsistently: a negative study does not exclude reflux, and a positive study is not specific, since reflux with provocative manoeuvres occurs in healthy people.
• Motility assessment is qualitative and limited by position, and manometry is the reference test for motility disorders.
• Poor coating, inadequate distension, air bubbles, food residue and saliva mimic lesions; tertiary contractions and normal rings mimic strictures.
• A narrowing in the lower oesophagus may be physiological (contraction of the sphincter) if the oesophagus is not distended.
• A thin barium swallow can miss strictures that only cause symptoms with solids, so a solid bolus or tablet is used.
• Barium that spills into the airway or mediastinum can cause complications. Water soluble contrast is less radio dense and may be missed in a small leak (a negative water soluble study should be followed by barium if the clinical suspicion is high and the patient is not at risk of aspiration).
• Radiation dose is moderate, so repeated studies are avoided.

Special groups.

• Infants and children: small volumes of non-ionic contrast for suspected tracheo oesophageal fistula and vascular rings, with feeding difficulty and recurrent chest infection; a videofluoroscopy with a speech therapist for swallowing disorders.
• Older adults: dysphagia from stroke, Parkinson disease, cricopharyngeal dysfunction, Zenker diverticulum and cancer; aspiration risk assessment.
• Post-surgical patients: contrast studies show leaks and strictures early after oesophagectomy and fundoplication.
• Patients with scleroderma: absent peristalsis in the lower two thirds with a patulous gastro oesophageal junction and reflux.
• Pregnancy: avoid.
• Regions: oesophageal squamous cell carcinoma is common in the east African corridor, southern Africa and parts of Asia, so a barium swallow is the first investigation where endoscopy is not available. Caustic ingestion strictures in children and Chagas megaoesophagus (in Latin America) are frequent causes of dysphagia. Achalasia is a common diagnosis in many regions.

Follow up tests. Upper gastrointestinal endoscopy with biopsy, CT chest and abdomen for staging, endoscopic ultrasound, high resolution oesophageal manometry for motility disorders, 24-hour pH or impedance monitoring for reflux, videofluoroscopic swallow study with a speech and language therapist for oropharyngeal dysphagia. Also arrange full blood count, iron studies, HIV test, and referral to gastroenterology, surgery or oncology.