An 80yo female with type II diabetes presents with 4 days of lower abdominal pain, associated with dysuria, haematuria and malaise.

She has a fever and elevated white cell count.

Describe and interpret the CT images


There is gas within the wall of the bladder.

The ureters and kidneys are normal in appearance.

Importantly, there is no free gas within the intraperitoneal or extraperitoneal space.

CT Case 015 Emphysematous cystitis 01
CT Case 015 Emphysematous cystitis 02


The CT findings demonstrate emphysematous cystitis.

Emphysematous cystitis, is one of the many ‘gas-in-the-wrong-place’ conditions (others being emphysematous cholecystitis / pancreatitis / aortitis/ appendicitis… the list goes on).

Emphysematous cystitis is a form of ‘complicated’ urinary tract infection. It is characterised by gas within the wall of the urinary bladder.

It is due to the presence of gas-forming bacteria and rarely fungi.

Other forms of emphysematous urinary tract infections include emphysematous pyelitis (gas in renal pelvis) and emphysematous pyelonephritis (gas in renal parenchyma).

As with emphysematous cholecystitis (CT case no. 10), emphysematous urinary tract infections are most often seen in diabetic patients. Other risk factors include immunocompromised state, neurogenic bladder, urinary tract outlet obstruction, chronic UTIs and long-term indwelling catheters.

Symptoms are similar to non-emphysematous cystitis. Additionally, patients will sometimes describe pneumaturia (frothy or foamy urine) due to gas in the urine.

Important complications to assess for on imaging are bladder rupture (free gas within the intra or extraperitoneal space) and extension of gas into the ureters and the renal parenchyma.

Unlike emphysematous pyelonephritis, which carries a high mortality rate and often requires surgical intervention, emphysematous cystitis normally doesn’t result in systemic illness and can be treated with antibiotics alone.




Dr Leon Lam FRANZCR MBBS BSci(Med). Clinical Radiologist and Senior Staff Specialist at Liverpool Hospital, Sydney

Emergency Medicine Education Fellow at Liverpool Hospital NSW. MBBS (Hons) Monash University. Interests in indigenous health and medical education. When not in the emergency department, can most likely be found running up some mountain training for the next ultramarathon.

Sydney-based Emergency Physician (MBBS, FACEM) working at Liverpool Hospital. Passionate about education, trainees and travel. Special interests include radiology, orthopaedics and trauma. Creator of the Sydney Emergency XRay interpretation day (SEXI).

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