Penetrative anal intercourse may require high axial loading forces

Despite increases in the lifetime prevalence of anal intercourse, little is known about the safety of inflatable penile prosthesis use during anal intercourse or the forces required for anal penetration.

We sought to determine the force required for anal penetration.

A digital force gauge device was secured to a silicone phallus with a length and girth representative of the average male phallus in the United States and inserted into the anal canal of 6 male participants for a total of 5 measurements per participant. The maximum axial forces on insertion were recorded. Participants then completed a survey eliciting demographic information and past experience with receptive anal intercourse.

The outcome measure was the force recorded during insertion of a force gauge device into the anal canal.

The median maximal force recorded on anal penetration was 26.5 N (2.7 kg; range: 16.1-51.7 N or 1.64-5.27 kg). Participants who engaged in receptive anal intercourse more than once per month tended to use lesser median maximal forces (25.7 N or 2.62 kg) than participants who engaged less frequently in receptive anal intercourse (41.6 N or 4.24 kg).

Compared with the forces required for vaginal penetration, anal penetration forces may cause additional mechanical stress to the phallus.

While the study is limited primarily in its small sample size and in the use of a single device for anal penetration with a set size and rigidity, the resulting findings presented here are to our knowledge the first reported data pertaining the force required for anal penetration.

As the forces required for anal penetration exceeded those for vaginal penetration, clinicians may need to carefully counsel patients on the safe use of an inflatable penile prosthesis for anal intercourse.