Diphallia is a rare genetic condition that occurs when a male baby is born with duplication of the penis.

There are different types of diphallia, ranging from partial to complete penile duplication. Having two completely developed penises, or true diphallia, is very rare.

Ever since the first description of diphallia in 1609, researchers have only reported 100 additional cases worldwide. It may occur in 1 in every 5–6 million live births.

This article takes a closer look at diphallia, including its symptoms, causes, effects on a male’s life, and the possibilities for treatment.

What is diphallia?

A person with diphallia may have a partial to complete penile duplication.

Every case of diphallia is unique, and the amount of duplication varies with each. Most males with this condition will have two penises of about the same size, located side by side.

Some males will have a larger penis located above a second, smaller penis. For others, the duplication will only affect the head of the penis.

Earlier classification described three types of diphallia:

• a duplication of only the tip of the penis, or the glans
• bifid phallus, wherein each penis has only one column of soft tissue (the corpus cavernosum) instead of two, as is normally the case with true diphallia
• complete diphallia, wherein there is a complete duplication of the penis

However, current classifications claim that there are only two types of diphallia: true diphallia and bifid phallus.

Diphallia usually occurs alongside other birth irregularities. These can include:

• a cleft scrotum
• hypospadias, wherein the opening to the urethra is on the underside of the penis, instead of the tip
• duplication of the urethra in both penises
• no urethras in either penis
• abnormal heart muscles
• two bladders
• a missing anus
• atypical muscles attached to the bones
• irregular positioning of the scrotum
• irregularities affecting the public bone
• misshapen, rotated, or extra kidneys
• complications of the kidney and colorectal systems

Males with diphallia are at greater risk of spina bifida. They are also more likely to be sterile.

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