How to Know If Blood Is Trapped in Your Penis (Priapism)
If you have a painful, fully rigid erection lasting more than 4 hours that is unrelated to sexual stimulation, you likely have acute ischemic priapism—a medical emergency requiring immediate evaluation. 1
Key Warning Signs
Physical Examination Findings
- The shaft of your penis (corpora cavernosa) will be completely rigid and tender
- The head of your penis (glans) and the underside channel (corpus spongiosum) remain soft 1
- This pattern is the hallmark of ischemic priapism where blood is truly "trapped"
Critical Time Threshold
- Any erection lasting >4 hours requires emergency medical evaluation 1
- Pain is common but not always present, so don't rely on pain alone 2
- The longer you wait, the higher your risk of permanent erectile dysfunction 1
Important Distinctions
Partial vs. Full Rigidity
Not all prolonged erections are emergencies:
- Partial tumescence (not fully rigid): Less likely to be true ischemic priapism and may be observed 2
- Fully rigid shaft with soft glans: This is ischemic priapism—seek immediate care 1
Non-Ischemic (High-Flow) Priapism
Some men have a different type where blood flows too much rather than being trapped:
- The penis is partially erect, not fully rigid
- Usually painless
- Often follows trauma to the groin or perineum 3, 4
- This is not an emergency but still needs evaluation
What Medical Evaluation Involves
When you present to the emergency department, clinicians will:
Take a detailed history looking for: 1
- Duration of erection
- Any medications (especially erectile dysfunction injections, psychiatric medications)
- History of sickle cell disease or blood disorders
- Recent trauma to the groin
- Previous episodes
Perform a blood gas test from the penis (corporal blood gas): 1
- This is the definitive test to confirm trapped blood
- In ischemic priapism: oxygen level <30 mm Hg, CO2 >60 mm Hg, pH <7.25
- This confirms the blood is stagnant and oxygen-deprived
May use Doppler ultrasound if the diagnosis is unclear 1
- Shows absent or minimal blood flow in ischemic priapism
- Shows normal or increased flow in non-ischemic priapism
Critical Pitfalls to Avoid
- Don't wait to see if it resolves on its own if you're fully rigid for >4 hours—permanent damage begins early 1
- Don't assume pain means it's more serious—some ischemic priapism can be relatively painless initially 2
- Don't confuse prolonged erections from ED injections with true priapism if it's been <4 hours and not fully rigid 2
When to Seek Immediate Care
Go to the emergency department immediately if: 1
- Erection lasting >4 hours
- Fully rigid shaft (even if the head is soft)
- Especially if you have sickle cell disease
- Especially if you recently used erectile dysfunction injections
The natural course of untreated ischemic priapism is permanent erectile dysfunction due to tissue death from lack of oxygen 1. Early treatment (within 4-6 hours) has the best chance of preserving your erectile function.