Gas On Abdominal X-ray DDx

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 contrastVentriculomegaly,
OTHER: Pseudofracture on X-Ray

LABS

LOW: Anaemia, Hypocalcaemia, hypochloraemia, Hypomagnesaemia

HIGH: Bilirubin and Jaundice, HyperammonaemiaHypercalcaemia, 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


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CCC 700 6

Critical Care

Compendium

Chris is an Intensivist and ECMO specialist at The Alfred ICU, where he is Deputy Director (Education). He is a Clinical Adjunct Associate Professor at Monash University, the Lead for the  Clinician Educator Incubator programme, and a CICM First Part Examiner.

He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives. He was one of the founders of the FOAM movement (Free Open-Access Medical education) has been recognised for his contributions to education with awards from ANZICS, ANZAHPE, and ACEM.

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

On Bluesky, he is @precordialthump.bsky.social and on the site that Elon has screwed up, he is @precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

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