Urethral intercourse refers to the penetration of the female urethra

Urethra

In anatomy, the urethra is a tube that connects the urinary bladder to the genitals for the removal of fluids out of the body. In males, the urethra travels through the penis, and carries semen as well as urine...

 by an object such as a penis

Penis

The penis is a biological feature of male animals including both vertebrates and invertebrates...

 or finger

Finger

A finger is a limb of the human body and a type of digit, an organ of manipulation and sensation found in the hands of humans and other primates....

. It is not to be confused with urethral sounding

Urethral sounding

Sounding or urethral sounding is the medical use of probes called sounds to increase the inner diameter of the urethra and to locate obstructions in it...

, the act of inserting a specialized medical tool into the urethra as a form of sexual or fetishistic activity.

The untrained insertion

Urethral foreign body

Doctors have documented numerous cases of insertion of foreign bodies into the urethra, typically as the result of auto-erotic activities. This can result in serious medical problems....

 of foreign bodies into the urethra carries a significant risk that subsequent medical attention may be required. Documented cases of urethral intercourse appear to have occurred between heterosexual couples; a survey of the global medical literature available in 1965 reported accounts of thirteen separate cases. However, the stretching of the urethra required by this form of intercourse has also reportedly resulted in a complete and permanent loss of urethral sphincter

Urethral sphincter

The term urethral sphincter refers to one of two muscles used to control the exit of urine in the urinary bladder through the urethra. The two muscles are the external urethral sphincter and the internal urethral sphincter...

 control (urinary incontinence

Urinary incontinence

Urinary incontinence is any involuntary leakage of urine. It is a common and distressing problem, which may have a profound impact on quality of life. Urinary incontinence almost always results from an underlying treatable medical condition but is under-reported to medical practitioners...

); furthermore such intercourse would present a very high risk of bladder infection

Urinary tract infection

A urinary tract infection is a bacterial infection that affects any part of the urinary tract. Symptoms include frequent feeling and/or need to urinate, pain during urination, and cloudy urine. The main causal agent is Escherichia coli...

to the receptive partner.