Priapism Cavernous Blood Gas Classification
Classifies a priapism episode from the cavernous blood gas, which separates two conditions treated in opposite directions.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- pO2 in blood drawn from the corpus cavernosum
- 12 mmHg
- pCO2 in blood drawn from the corpus cavernosum
- 78 mmHg
- pH in blood drawn from the corpus cavernosum
- 7.05
- Hours since the erection began
- 30 hours
- Perineal or straddle trauma before onset
- Yes
- Sickle cell disease
- Yes
Result: ischemic, at 30 hours
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What the result means
- pO2 under 30, pCO2 over 60, pH under 7.25
- Ischemic priapism. A compartment syndrome of the erectile tissue, decompressed rather than observed.
- pO2 over 90, pCO2 under 40, pH near 7.40
- Non-ischemic priapism. An unregulated arterial inflow, usually painless and not an emergency; aspiration and a sympathomimetic treat the other type.
- A gas in between
- Color duplex decides: absent or minimal cavernosal arterial flow is ischemic, normal or high flow is non-ischemic.
- Nothing decisive
- Handled as ischemic until it is shown not to be, because that is the type where waiting costs erectile tissue.
- A trauma history
- Does not classify the episode. It is the classic story for the non-ischemic type and the classic reason an ischemic one is watched instead of decompressed.
- Under 4 hours
- Inside the window before an ischemic episode becomes a compartment syndrome.
- 4 to 24 hours
- A compartment syndrome. Necrosis of the cavernous smooth muscle begins around 24 hours.
- Past 36 hours
- Erectile function is rarely preserved. Intervention is for pain and detumescence rather than for potency.
- Sickle cell disease
- Does not change the acute treatment. Systemic care must not delay or replace the local intervention.
What you enter
- pO2 in blood drawn from the corpus cavernosum
- pCO2 in blood drawn from the corpus cavernosum
- pH in blood drawn from the corpus cavernosum
- Hours since the erection began
- Color duplex finding, if done
- Perineal or straddle trauma before onset
- Sickle cell disease
How this is calculated
Bivalacqua TJ, Allen BK, Brock GB, et al. The diagnosis and management of recurrent ischemic priapism, priapism in sickle cell patients, and non-ischemic priapism: an AUA/SMSNA guideline. J Urol. 2022;208(1):43-52. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.