A group of urologists took ultrasounds of more than 250 men before and after their penis became erect to conclude that an erection is mainly of two types - either it is a ‘grower' or 'shower.’

The findings of the study were presented over the weekend at the European Association of Urology (EAU) Congress in Milan.

The ultrasound scans of the multiple penises before and after they became erect showed that there was a standard distribution curve to the growth.

On one extreme are "growers," whose flaccid penises grew by more than 56%. On the other side are the "showers," whose penises grew less than 31% during erection. Most men, surprisingly, fall between the two categories, while only about 25% of men belong to the two extremes, according to The Guardian.

The study might seem frivolous but researchers believe the findings can prove important in treating people requiring penile surgery.

“It is important to be able to predict if a patient is a grower or a shower as when we see them, they are usually in a flaccid state,” Dr. Manuel Alonso-Isa, a urologist at the University Hospital HM Puerta del Sur in Madrid, Spain, said in a statement. “If they grow a lot when they get an erection, it might mean they need a different surgical approach compared to someone who doesn’t grow much.”

In the study, researchers could not establish a relation between a patient’s medical history and the type of penis, indicating there was no correlation between added length of the penis and age, weight, smoking status, or other health conditions of the individual.

Interestingly, showers seemed to have larger flaccid penises- 4.4 inches compared to 3.5 inches. Growers, in comparison, showed to have a thinner tunica albuginea - a thick fiber that envelops the spongy penile tissue.

“This makes sense as the tissue is being stretched further,” Dr. Alonso-Isa added. “So it could be that this tissue has more elastic fibers in men who are growers than those who are showers. But we need to do more research to prove this hypothesis.”

Researchers believe there may be other factors that would have played a role in the erection, but they didn’t investigate further.

“In the meantime, we have defined what constitutes a ‘grower’ or a ‘shower’ in a scientific way, which will be important for the future,” said Dr. Alonso-Isa.

“This is a frequent area of concern for our patients and the emphasis should be on normalizing baseline and erectile length for all,” Professor Maarten Albersen, a urologist at the University of Leuven, Belgium, commented on behalf of the European Association of Urology.

It is worth noting that this is a preliminary study that is yet to be formally peer-reviewed. So, the findings should be considered with a pinch of salt. Furthermore, the participants were men who had visited hospitals and clinics in Spain, and as a result, may not be representative of an average man.