The Grayhack shunt is established between:

The Grayhack shunt is established
between:
a) Corpora cavernosa and dorsal vein
b) Corpora cavernosa and saphenous vein
c) Corpora cavernosa and glans
d) Corpora cavernosa and corpora spongiosa
Correct Answer - B
Ans is ‘b’ i.e. Corpora cavernosa and saphenous vein
The Grayhack shunt is a surgical shunt between corpora cavernosa
and the saphenous vein done for the treatment of ischemic priapism.
Priapism is an uncommon condition of prolonged erection. It is
usually painful for the patient, and no sexual excitement or desire is
present.
Priapism may be classified into high- and low-flow types
(Nonischemic and ischemic).
Nonischemic (High flow) priapism:
Nonischemic priapism, also termed arterial or high-flow priapism,
features elevated vascular flow through the corpora cavernosa.
It usually occurs secondary to perineal trauma, which injures the
central penile arteries and results in loss of penile blood-flow
regulation.
Aspiration of penile blood for blood-gas determination demonstrates
high oxygen and normal carbondioxide levels.
Arteriography is useful to demonstrate aneurysms that will respond
to embolization.
Erectile function is usually preserved.
Ischemic (low-flow) priapism:
Ischemic priapism, also termed veno-occlusive or low-flow priapism,
features little or absent intracorporal blood flow. It represents a true
compartment syndrome involving the penis, needing emergency
management.
It is typically painful.
The corpora cavernosa is tense with congested blood and tender to
palpation. The glans penis and corpus spongiosum are soft and
uninvolved in the process.
The current theories regarding the mechanism of priapism remain in
debate, but most authorities believe the major abnormality to be
physiologic obstruction of the venous drainage. This obstruction
causes buildup of highly viscous, poorly oxygenated blood (low 02,
high CO2) within the corpora cavernosa.
If the process continues for several days, interstitial edema and
fibrosis of the corpora cavernosa will develop, causing impotence.
Treatment
Ischernic priapism is a urologic emergency.

  • First-line treatment consists of aspiration of blood and irrigation of
    the corpora cavernosa (via a needle put in the corpora cavernosa)
    along with intracavernous injection of an a-adrenergic
    sympathomimetic agent (phenylephrine) .(Sympathomimetic agents
    can be expected to exert contractile effects on the cavernous tissue
    and thus facilitate detumescence.)
  • Surgical shunting is needed when the intracavernous treatment
    fails.
    A surgical shunt has the objective of facilitating blood drainage from
    the corpora cavernosa, bypassing the venoocclusive mechanism of
    these structures. A variety of shunt procedures may be performed. A
    distal cavernoglanular (corporoglanular) shunt is the first choice.