Andrew Siegel MD 11/23/19
First-line management of erectile dysfunction (ED) is lifestyle improvement– weight management, healthy eating, exercise that includes pelvic floor muscle training, tobacco cessation, alcohol use in moderation, etc. Second-line treatment is oral ED medications: Viagra, Cialis, Levitra, Stendra. If first and second-line managements do not help the situation, penile doppler studies are useful to evaluate the underlying cause of the ED and inform its best management.
An erection is a neuro-vascular (nerve-blood vessel) event. Erotic or touch stimulation releases nerve transmitters that dilate penile blood vessels, and with the blood surge into the penis, fullness and ultimately rigidity result. An erection depends upon:
- Muscle relaxation muscle within the penile arteries and erectile chambers to inflate the penis with blood
- Venous outflow constriction to maintain the erection.
- Engagement of the pelvic floor muscles for full rigidity and durability.
Penile doppler ultrasound is a functional test that evaluates arterial inflow, the ability of the erectile smooth muscle to relax, and the venous trapping. Based on the penile doppler findings, ED can be classified into arterial and venous types. Arterial ED is an impairment of arterial function with insufficient flow to induce an erection. Venous (veno-occlusive) ED is an impairment of the closure mechanism in which erections cannot be maintained because of venous leakage and subsequent deflation of the penis.
Penile imaging
Ultrasound uses high frequency sound waves to create images. Doppler ultrasound uses the Doppler effect to image the movement and velocity of body fluids, specifically the blood flow through arteries and veins in the body.
High school physics…The doppler effect is what causes the sudden change in pitch noticeable with a passing siren or an airplane. It is caused by an increase or decrease in the frequency of sound waves as the source and observer move toward or away from each other.
Because the penis is a protruding superficial organ with a great blood flow, it is ideal for doppler ultrasound testing. Penile doppler ultrasound images the movement and velocity of blood flow through the penile arteries and veins before and after the injection of a medication that induces an erection.
In addition to evaluating penile blood vessel functional issues, penile ultrasonography is also useful for evaluating penile structural problems including Peyronie’s disease, penile fractures, tumors, urethral scar tissue, urethral stones, and urethral out-pouchings (diverticula). Peyronie’s disease causes focal scarring of the outer sheath of the erectile chambers results in a penile lump, curvature, shortening, pain and ED. Penile ultrasound is ideal for imaging Peyronie’s disease, often demonstrating calcified nodules along the sheath of the erectile chambers and doppler studies typically revealing venous ED.
Penile blood supply map
ARTERIAL INFLOW: Internal iliac artery –> internal pudendal artery –> common penile artery –> 3 branches, the dorsal artery (responsible for engorgement of head of penis), the bulbourethral artery, and the cavernosal artery (responsible for engorgement of erectile chambers of the penis); cavernosal arteries –> helicine arteries
VENOUS OUTFLOW: sub-tunical venous plexus –> emissary veins –> circumflex veins –> deep dorsal veins –> peri-prostatic venous plexus
Attribution of image above: CFCF [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)%5D
Penile doppler ultrasound procedure
Penile doppler testing is relatively simple office procedure. A specialized ultrasound probe is used to scan the penis in longitudinal (orientation along the long axis of the penis) and transverse (cross section) views. The scanning is done with the penis flaccid and then repeated after an injection of a vasodilator medicine that induces an erection. The vasodilator Trimix is the medication that is typically used, starting at a dose of 0.1 ml and increasing to 0.4 ml as necessary, which is injected directly into the erectile chamber of the penis with a tiny needle.
By inducing an erection with the medication, the arterial inflow and venous outflow can be tested:
Peak systolic velocity (PSV) is the most reliable indicator of arterial disease. PSV is the maximal velocity of blood within the cavernosal artery at the time of the heart beating (systole). Arterial insufficiency is diagnosed on penile dopplers when the PSV < 25 cm/second and cavernosal artery dilation is sub-optimal.
End diastolic velocity (EDV) is the most reliable indicator of venous leak. EDV is the velocity of blood within the cavernosal artery at the time of the heart resting between beats (diastole). An EDV > 5 cc/sec is indicative of venous leak. Velocity measurements are taken at base of penis prior to and repeated at 5-10-minute intervals after the vasodilator injection, for at least 30 minutes. Cavernosal artery diameters and subjective determination of penile tumescence and rigidity are also recorded. Normal cavernosal artery diameter is 3-5 mm; after vasodilator injection it relaxes and opens up to a diameter of 6-10 mm.
Peak systolic velocity (PSV)
> 30 = normal
< 25 = arterial insufficiency ED
25-30 = equivocal
End diastolic velocity (EDV)
< 5 or reversal of blood flow rules out venous leak
> 5 = venous dysfunction, as veins are leaking
Phases of Erection
There are 5 phases that typically occur after penile vasodilator injection:
- Increased systolic (when the heart beats) and diastolic (time between heart beats) blood flow; no noticeable penile fullness
- Decreased diastolic flow as pressure rises within the erectile chambers; initial penile fullness
- Diastolic flow stops; penile fullness and near rigidity
- Diastolic flow reverses with maximal systolic flow velocity; penile rigidity occurs
- Decreased systolic flow with penile blood flow exit; penile softening
Another way to look at it:
Flaccid state: small diameter cavernous artery and PSV 2-15
Tumescent state: maximal diameter cavernous artery and PSV 15-35
Rigid erection state: smallest diameter cavernous artery (as artery gets compressed by inflated erectile chamber) and PSV less or equal to maximal response; reversal of blood flow in cavernosal artery because of tremendous pressure in erectile chamber
Bottom Line: The oral ED medications have revolutionized the management of ED. A quality erection with Viagra, Cialis, Levitra or Stendra confirms adequate arterial inflow and effective venous occlusive mechanisms. Penile dopplers play a vital role in the evaluation of non-responders to these medications, for those who cannot use these medications or those who experience significant side effects, as well as in the assessment of patients with ED following prostatectomy or other pelvic surgical procedures and in the evaluation of men with Peyronie’s disease. If full penile rigidity occurs after the injection of the vasodilator medication, a self-injection program becomes a viable potential option in the management of the ED. Penile prosthesis implantation is an option in men who fail the penile doppler study.
Wishing you the best of health,
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Dr. Andrew Siegel is a physician and urological surgeon who is board-certified in urology as well as in female pelvic medicine and reconstructive surgery. He is an Assistant Clinical Professor of Surgery at the Rutgers-New Jersey Medical School and is a Castle Connolly Top Doctor New York Metro Area, Inside Jersey Top Doctor and Inside Jersey Top Doctor for Women’s Health. His mission is to “bridge the gap” between the public and the medical community. He is a urologist at New Jersey Urology, the largest urology practice in the United States. Dr. Siegel is the author of Prostate Cancer 20/20: A Practical Guide to Understanding Management Options for Patients and Their Families. The first section of the book provides abundant information on the prostate and prostate cancer, while the second and third sections address male urinary and sexual concerns, respectively.
Video trailer for Prostate Cancer 20/20
Preview of Prostate Cancer 20/20
Andrew Siegel MD Amazon author page
Prostate Cancer 20/20 on Apple iBooks
PROSTATE CANCER 20/20: A Practical Guide to Understanding Management Options for Patients and Their Families is now on sale at Audible, iTunes and Amazon as an audiobook read by the author (just over 6 hours).
Dr. Siegel’s other books:
PROMISCUOUS EATING— Understanding and Ending Our Self-Destructive Relationship with Food
MALE PELVIC FITNESS: Optimizing Sexual and Urinary Health
THE KEGEL FIX: Recharging Female Pelvic, Sexual, and Urinary Health
Tags: Andrew Siegel MD, erectile dysfunction, penile arteries, penile doppler ultrasound, penile injection therapy, penile veins, penis, Peyronie's disease
Our Greatest Wealth Is Health 
February 6, 2021 at 6:17 AM |
[…] and damage of the erectile tissues. This can lead to permanent erectile dysfunction on the basis of venous leakage (veno-occlusive disease) in which the penile blood trapping mechanism fails to work properly, […]