Gas On Abdominal X-ray DDx • LITFL • CCC Differential Diagnosis

Overview

Location of gas on the abdominal x-ray may suggest the the underlying cause

Intraluminal gas — bowel gas pattern
Free intraperitoneal air — pneumoperitoneum
Other gas collections — biliary, intramural, etc.

Bowel gas patterns may point to an underlying cause — bowel gas patterns include:

Normal
Nonspecific
Adynamic ileus
Mild — localized ileus or “sentinel loop”
Severe — “colonic pseudo-obstruction”
Small bowel obstruction; central, valvulae conniventes, pliable (“bent finger”)
Large bowel obstruction – peripheral, haustra, contains feces

Causes

Pneumoperitoneum

Causes

Perforated peptic ulcer (usually duodenal)
Gastric ulcer perforation (benign or malignant)
Intestinal perforation (e.g. large bowel obstruction causing cecal perforation, inflammatory bowel disease)
Cecal or sigmoid volvulus
Perforated appendicitis or diverticulitis (infrequent)
Colonoscopy and biopsy
Residual postoperative gas
Post-laparoscopy
Post-dialysis
Penetrating trauma
Breakdown of surgical anastomosis
Ruptured pneumatosis cystoides intestinalis (e.g. ischemic gut, necrotizing enterocolitis)
Gas-forming intra-abdominal infection
Extension from the chest (e.g. pneumomediastinum, bronchopleural fistula)
Air via uterine tubes (e.g. post-sexual activity, spa bath, water ski-ing)

Mimics of pneumoperitoneum

Hepatodiaphragmantic interposition of the colon
Idiopathic (Chilaiditi syndrome)
Secondary to colonic distention (obstruction or ileus)
Rib margin that parallels diaphragm
Perihepatic fat

Right upper quadrant gas

Gallstone ileus (biliary-enteric fistula) [Rigler triad; Bouveret syndrome]
Sphincterotomy or surgical anastomosis
Emphysematous cholecystitis
Hepatic portal venous gas (bowel infarction)
Hepatic or subdiaphragmatic abscess
Pneumoperitoneum (overlying liver)
Hydrogen peroxide ingestion (or other gas forming substance)

CCC Differential Diagnosis Series
NEURO	Anosmia, Ataxia, Blepharospasm, Bulbar and Pseudobulbar palsy, Central Pontine Myelinosis, Cerebellar Disease, Chorea, Cranial nerve lesions, Dementia, Dystonia, Exophthalmos, Eye trauma, Facial twitches, Fixed dilated pupil, Horner syndrome, Loss of vision, Meningism, Movement disorders, Optic disc abnormality, Parkinsonism, Peripheral neuropathy, Radiculopathy, Red eye, Retinal Haemorrhage, Seizures, Sudden severe headache, Tremor, Tunnel vision
RESP	Bronchial breath sounds, Bronchiectasis, High airway pressures, Massive haemoptysis, Sore throat, Tracheal displacement
CVS	Atrial Fibrillation, Bradycardia, Cardiac Failure, Chest Pain, Murmurs, Post-resuscitation syndrome, Pulseless Electrical Activity (PEA), Pulsus Paradoxus, Shock, Supraventricular tachycardia (SVT), Tachycardia, VT and VF, SVC Obstruction
GIT	Abdominal distension, Abdominal mass, Abdominal pain, Asterixis, Dysphagia, Hepatomegaly, Hepatosplenomegaly, Large bowel obstruction, Liver palpation abnormalities, Lower GI haemorrhage, Malabsorption, Medical causes of abdominal pain, Rectal mass, Small bowel obstruction, Upper GI Haemorrhage
GUT	Genital ulcers, Groin lump, Scrotal mass, Urine colour, Urine Odour, Urine transparency,
MSK	Arthritis, Shoulder pain, Wasting of the small muscles of the hand
DERM	Palmar erythema, Serious skin signs in sick patients, Thickened Tethered Skin, Leg ulcers, Skin Tumour, Acanthosis Nigricans
ENDO	Diabetes Insipidus, Diffuse Goitre, Gynaecomastia, Hirsutism, Hypoglycaemia, SIADH, Weight Loss
HAEM	Splenomegaly
PAEDS	Floppy infant
MISC	Anaphylaxis, Autoimmune associated diseases, Clubbing, Parotid Swelling, Splinter haemorrhages, Toxic agents and abnormal vitals, Toxicological causes of cardiac arrest
IMAGING	CHEST: Atelectasis, Hilar adenopathy, Hilar enlargement on CXR, Honeycomb lung, Increased interstitial markings, Mediastinal widening on mobile CXR, Pulmonary fibrosis, Pseudoinfiltrates on CXR, Pulmonary opacities on CXR, ABDO: Gas on abdominal X-ray, Kidney mass, BRAIN: Intracranial calcification, Intracranial structures with contrast, Ventriculomegaly, OTHER: Pseudofracture on X-Ray,
LABS	LOW: Anaemia, Hypocalcaemia, hypochloraemia, Hypomagnesaemia, HIGH: Bilirubin and Jaundice, Hyperammonaemia, Hypercalcaemia, Hyperchloraemia, Hyperkalaemia, Hypermagnesaemia, ACID BASE: Acid base disorders, Resp. acidosis, Resp. alkalosis, Creatinine, CRP, Dipstick Urinalysis, Laboratory Urinalysis, Liver function tests (LFTs), Pleural fluid analysis, Urea, Urea Creatinine Ratio, Uric acid, Urinalysis, Urine Electrolytes

Cite this article as: Chris Nickson, "Gas On Abdominal X-ray DDx," In: LITFL - Life in the FastLane, Accessed on March 21, 2023, https://litfl.com/gas-on-abdominal-x-ray-ddx/.

Critical Care

Compendium

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Chris Nickson

Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also a Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.

After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.

He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE. He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.

His one great achievement is being the father of three amazing children.

On Twitter, he is @precordialthump.

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