There are two forms of the disorder: low-flow priapism and high-flow priapism.
Low-flow priapism
In this form of permanent erection, the penis becomes very hard and the glans takes on a pale bluish color. The blood cannot flow out of the erectile tissue as it is blocked. As a result, the blood remains in the tissue and puts pressure on the erectile tissue.
This can cause unpleasant pain and reduce the oxygen content in the blood. This can lead to a change in the tissue of the erectile tissue, which can result in a loss of potency. This form of permanent erection occurs in around 90 percent of all cases.

An Etruscan statue of the priapus
High-flow priapism
High-flow priapism occurs in around 10 percent of all cases. This is usually caused by injuries to the perineum or genital area. A large amount of blood flows uncontrollably through the arteries into the erectile tissue of the penis. In contrast to low-flow priapism, this makes the penis more elastic and pulsating.
The erection is only slightly painful or not painful at all. As the blood can flow freely, the oxygen content in the blood does not change, which is why the risk of loss of potency is much lower with this form of permanent erection.
Mixed forms of priapism
In addition to high-flow and low-flow priapism, mixed forms can also occur. These often occur as a result of treatment of impotence with medication.
A permanent erection can have many causes. These often remain unexplained. The factors that can trigger a permanent erection include
If the permanent erection lasts longer than two hours, a doctor should be consulted immediately.
The doctor will first ask about the patient's medical history. This includes, for example, whether the patient has had a permanent erection before, suffers from certain illnesses or is taking medication.
The doctor will also examine the penis externally and possibly examine the perineum and genital area for injuries. He may also take blood from the erectile tissue of the penis to perform a blood gas analysis. This enables a distinction to be made between low-flow and high-flow priapism.
In the case of low-flow priapism, the blood is dark in color and has a low pH value. If the patient suffers from high-flow priapism, the blood is bright red in color and has an almost normal pH value.
The doctor may also carry out an ultrasound examination. This examines the inflow and outflow of blood into the erectile tissue. In low-flow priapism, there is hardly any recognizable outflow of blood.
The permanent erection should be treated no later than four to six hours after the stiffening occurs in order to avoid consequential damage.
In the case of low-flow priapism, the treatment ensures that the blood can flow out of the erectile tissue again. To do this, the congested blood is aspirated by puncturing the penis with a syringe. The erectile tissue is also flushed with a saline solution. The doctor can also inject a substance into the penis that causes the muscles to contract and the blood to flow out again.
If these treatment methods do not lead to the desired result, the affected person's penis must be operated on. During the operation, a so-called shunt is placed between the blood-filled erectile tissue and the glans. The shunt is a short-circuit connection that ensures that the blood can flow out of the penis again.
The permanent erection in high-flow priapism usually subsides on its own.
In the rare cases in which this does not happen, the doctor can perform an angiography. After administering a contrast agent, he can see the blood vessels of the affected person. The damaged vessel is then closed by means of embolization (artificial vessel closure). However, this method itself can lead to erectile dysfunction (erectile dysfunction).
Another option is medication that helps to reduce the swelling of the permanent erection.