Medically reviewed by Dr. Edward Gheiler, MD, FACS — August 16, 2026
How Does a Penile Implant Work?
Squeeze the pump and watch the saline move. This interactive cutaway shows the same closed hydraulic loop your surgeon implants: a reservoir, a pump, and two cylinders, with nothing visible outside the body.
Sagittal cutaway · schematic · not to scale
Cylinder expansion behavior
Reservoir
Storage · holds the saline
A collapsible saline balloon lying flat against the inside of the lower abdominal wall, in front of the bladder (the space of Retzius), or in a high submuscular pocket when prior surgery has scarred that space. It empties as you pump and refills on deflation.
Tubing
Transit · connects all three parts
Kink-resistant tubing joins reservoir to pump and pump to both cylinders. It runs under the skin and is not felt. Because the loop is sealed, the same fluid simply shuttles back and forth for the life of the device.
Pump
Control · bulb below, deflation valve above
Sits loose in the scrotum between the testicles, found by feel through the skin. Squeezing the bulb sends its contents toward the cylinders; releasing draws a fresh charge from the reservoir. Pressing the valve on top opens the return path so the cylinders drain.
Cylinders
Rigidity · what you actually feel
A matched pair sized to your anatomy at surgery, seated inside the corpora cavernosa from the crura to just behind the glans. Input tubing enters at the tapered rear tip. As they fill, they push outward against the tunica albuginea and that resistance creates firmness.
Crura and rear tips
Anchor · why the device stays put
Each corpus cavernosum begins as a crus fixed to the ischial ramus of the pelvis. The cylinder rear tip, often lengthened with rear-tip extenders chosen at surgery, seats down inside the crus, so the inflated cylinder pushes against bone rather than sliding backward.
Corpora cavernosa
Host tissue · the two erectile chambers
Normally these fill with blood to produce an erection. The cylinders occupy them instead. The corpus spongiosum and urethra sit below and are left alone, which is why urination and sensation are unchanged.
Urethra
Untouched by the device
Runs from the bladder through the prostate, under the pubic bone, then along the underside of the shaft inside the corpus spongiosum. No implant component enters it. The glans is not implanted, which is why it stays softer than the shaft when inflated.
Prostate
Landmark · urethra passes through it
Sits just below the bladder neck, behind the pubic bone. It is not touched by the implant, though men who have had a prostatectomy are among the most common implant candidates.
Pubic bone
Landmark for reservoir placement
The pubis is the surgical landmark for reservoir placement. The reservoir is tucked behind the abdominal wall just above it, which keeps the device concealed and out of the way.
Bladder
Neighbor · defines the reservoir pocket
The space of Retzius lies in front of the bladder. Surgeons choose an alternate submuscular pocket when prior pelvic surgery, a transplant kidney, or mesh makes that space risky to enter.
Scrotum
Housing · holds the pump
The pump lives in a pocket in the scrotum, usually placed through the same small incision used to implant the whole device. Nothing is visible externally once healing is complete.
Saline ledger
Cylinder fill0%
Reservoir remaining100%
Rigidity
Moved this cycle 0.0 mL Per squeeze ~2.5 mL (teaching value) Loop total fixed: nothing enters or leaves
Part inspector—
Pick a part
Hover, tap, or use the list
Every labeled part has a real job in the loop. Choose one to read what it does.
Three parts, one closed loop
The implant is filled with sterile saline and sealed as a closed system during surgery. Inflating does not create fluid; it moves it from a soft reservoir into two firm cylinders, and deflating sends it back.
01 · STORAGE
Reservoir
A soft saline balloon tucked behind the lower abdominal wall, in front of the bladder (the space of Retzius), or in a high submuscular pocket. It empties as you pump and refills on deflation. It is not felt during normal activity.
02 · CONTROL
Pump and deflation valve
Sits loose in the scrotum between the testicles, reachable through the skin. The bulb drives fluid one way; the valve above it opens the return path. This is the only part you ever touch.
03 · RIGIDITY
Cylinders
A matched pair implanted inside the corpora cavernosa, the two chambers that would normally fill with blood. They expand against the tunica albuginea, and that resistance is what produces firmness.
What each squeeze actually does
Find the pump
The bulb sits in the scrotum and is located by feel. Nothing is visible from the outside; the whole device is under the skin.
Squeeze and release
Compressing the bulb pushes its contents toward the cylinders. Releasing it lets the bulb refill from the reservoir through an inlet valve, so the release stroke matters as much as the squeeze.
Repeat until firm
Each cycle transfers a small volume. Most men need roughly ten to twenty squeezes; the exact count depends on cylinder size and how full the system is.
Pressure holds it
The valves close and the cylinders stay pressurized with no further effort. Rigidity does not fade on its own and does not depend on arousal or blood flow.
Press the valve to deflate
Pressing the deflation valve lets tissue pressure push the saline back into the reservoir. The penis returns to a soft, concealed state within seconds.
The device does not touch the urethra. Sensation, orgasm, and the ability to urinate come from nerves and structures the implant leaves alone. It replaces rigidity, not feeling.
This model is a teaching schematic of one representative three-piece implant. Proportions, positions, and the squeeze counter are approximations, not device specifications; actual volumes, cylinder sizes, and squeeze counts vary by model and by patient. General education only, not medical advice. Discuss your case with a urologist.
