A penile implant, also known as a penile prosthesis, is a medical device surgically placed within the penis to treat severe erectile dysfunction (ED) that has not responded to other medical therapies. These devices restore the ability to achieve and maintain an erection firm enough for sexual intercourse. Penile implants are highly customized, meaning “size options” involve a precise, individualized process performed by the surgeon, not a selection from a shelf. Accurate sizing is paramount to the procedure’s success, ensuring optimal function and high patient satisfaction.
Types of Implants and Their Components
The devices available fall into two primary categories, and their structure dictates how sizing is approached. The first type is the Malleable, or semi-rigid, implant, which consists of a pair of flexible rods implanted within the corpora cavernosa. These rods are always firm and can be manually bent into an upward position for intercourse or a downward position for concealment. Malleable implants offer size options primarily in fixed length and diameter.
The second and most common type is the Inflatable Penile Prosthesis (IPP), which typically uses a three-piece system. This system includes two cylinders placed inside the penis, a fluid-filled reservoir implanted in the lower abdomen, and a pump positioned in the scrotum. The cylinders determine the length and girth of the erection, filling with saline fluid transferred from the reservoir via the pump. Size options for an IPP are a combination of the cylinder dimensions and the selection of the non-penile components.
Determining Optimal Dimensions
The determination of the implant’s dimensions is not a preoperative decision but a meticulous process that occurs intraoperatively, during the surgical procedure itself. The surgeon first accesses and dilates the corpora cavernosa to create the space for the prosthetic cylinders. Specialized measuring tools, often called sizing rods or calibrated dilators, are then inserted into the dilated chambers.
These instruments precisely measure the available internal space, spanning from the most proximal point (the crura) to the distal end near the glans. The goal is to maximize the longitudinal length of the cylinders while ensuring they fit entirely within the natural anatomical boundaries. Implants must be sized appropriately to avoid complications. An undersized implant can lead to “floppy glans syndrome,” where the tip of the penis remains soft, while an oversized implant can cause chronic pain or tissue erosion.
Surgeons select a cylinder length based on this precise intraoperative measurement, often using a Rear Tip Extender (RTE) to fine-tune the overall length in increments of 0.5 to 1.5 centimeters. The cylinder diameter, which relates to the girth, is also determined at this stage by selecting the widest cylinder that the tunica albuginea, the fibrous sheath surrounding the corpora, can comfortably accommodate. Some advanced cylinder designs are available that allow for expansion in both length and girth when inflated, maximizing post-operative dimensions. The range of cylinder lengths generally available from manufacturers is wide, often spanning from approximately 12 to 27 centimeters, depending on the model.
Customization Beyond the Cylinders
For inflatable implants, sizing options extend beyond the cylinders to the hydraulic control mechanism, which includes the pump and the reservoir. The fluid reservoir, which holds the sterile saline solution, is typically placed beneath the abdominal muscles in the retropubic space. While capacity is often standardized, some manufacturers offer different sizes (such as 75cc or 125cc options) to ensure proper fit within the abdominal cavity. The reservoir’s placement is a customization point, as alternative locations may be necessary for patients who have had prior abdominal surgery.
The scrotal pump, which serves as the control unit for inflation and deflation, is selected and positioned based on the patient’s anatomical features and dexterity. Manufacturers offer various pump profiles and designs, some featuring simplified, one-touch deflation mechanisms. This selection is important for patients who may have limited hand strength or coordination due to conditions like arthritis or neurological issues. Careful placement within the dependent part of the scrotum ensures the pump is concealed yet easily accessible for the patient to operate.
Patient Expectations Regarding Post-Operative Size
A primary concern for patients considering a penile implant is the final post-operative size. The surgical goal is to restore the patient to their natural, pre-disease size, not to lengthen the penis beyond its natural capacity. The surgeon’s measurement of the stretched penile length before surgery provides the most reliable estimate for the achievable post-operative inflated length.
In many cases, the implant cylinder selection aims to match this pre-ED length. The procedure often results in a girth increase because the cylinders are designed to fill the available space entirely. Patients frequently report a subjective feeling of decreased length after the procedure, even when objective measurements show length preservation. This perception is managed with proper preoperative counseling that sets realistic expectations about the outcome.
The implant also prevents the complete retraction of the penis that may have occurred due to chronic ED, often resulting in a flaccid appearance that is longer and wider than before the surgery. To ensure the best size outcome, patients are instructed to begin inflating and deflating the device early in the post-operative period. This “cycling” helps stretch the surrounding tissues and prevents the penis from healing in a foreshortened state, which maintains the achieved dimensions.