Penis Flashcards
Which virus is associated with penile SCC?
Equine papillomavirus 2
Which virus is associated with equine sarcoids?
Bovine palillomavirus type 1 and 2
Muscles of the penis
- Ischiocavernosus mm - short paired mm surrounding the crura of the penis from tuber ishii and sacrosciatic ligament inserting onto the crus and body of the penis
- Retractor penis - arises on the ventral surface of 2-3 coccygeal vertebrae passing over the sides of the rectum to meet the anus, below which fibres cross and run distally, loosly attached to the penile ventrum, attaching to tunica albuginea near the glans penis
- Urethralis muscle - surrounds the pelvic urethra and bulbourethral glands, continuous caudally with the…
- Bulbospongiousus muscle (formerly bulbocavernosus) - covers the CSP ventrally and extends nearly the entire length of the penis from the bulbourethral glands to the free portion of the glans
- Ischiourethral muscles extend from the ventral surface of the ischium and crura, pass around the ischial arch into the pelvic cavity, and end at the ventral layer of the urethralis muscle. Act to assist in erection
Surgical options for creating teaser bulls
- Epididectomy
- Vasectomy
- Phallectomy
- Preputial relocation (to the flank fold) or obliteration
What is this procedure
List the specific layers incised from superficial to deep
Perineal urethrostomy (permanent)
Skin/SQ
Retractor penis mm
Bulbospongiosus mm
CSP
Urethral mucosa
Label the sagittal section of the penis within the prepuce
a) CCP
b) Corpus spongiosum glandis
c) Urethra
d) Urethral process
e) Urethral fossa
f) External preputial orifice
g) Preputial cavity
h) Plica preputialis
i) Prepuce
What are the 2 erectile bodies in the penis? Describe their anatomical location and relations
Corpus cavernosum penis = CCP. Dorsally located. Originates below the ischial arch where the crura unite, & makes up the bulk of the shaft. It ends distally in 1 central and 2 blunt ventrolateral projections. Urethral groove runs along its ventral surface
Corpus spongiosum penis = CSP. ventrally located - lies in the urethral groove and surrounds the urethra. The bulb is the proximal enlargement. Distally the CSP expands into the glans penis capping the central projection of CCP
Label the cross section of the penis
a - dorsal veins of the penis
b - tunica albuginea
c - CCP
d - CSP
e - urethra
f - bulbospongiosus mm
g - retractor penis mm
Briefly outline the mechanisms of erection
- Parasympathetic stimulation rx in vascular engorgement via straightening of the helicene arteries and relaxation of sinusoidal smooth mm
- Contraction of the ischiocavernosus muscles (pudendal innervation) occludes arterial and venous flow by squashing against the ischium, making the CCP a closed system during peak erection (around 107mmHg during arousal and 6530mmHg during coitus)
- CSP is not a closed system but increased arterial flow and bulbospongiosus contraction lead to incr. pressure and distension of the glans (Pressure 76mmHg arroused & 994mmHg coitus)
Label the extended penis
a - glans penis
b - free part of the penis
c - attachment of inner lamina to the penis
d - inner lamina of preputial fold
e - preputial ring
f - outer lamina of preputial fold
g - internal part of external lamina of prepuce
h - fossa glandis
i - urethral process
j - corona glandis
k - collum glandis
Blood supply to the penis
External pudendal - supplies the cranial or dorsal artery of the penis - also supplies a branch to the scrotum and continues as the caudal superficial epigastric artery which provides branches to the prepuce
Obtrurator - The deep arteries of the penis originate from the obturator arteries and supply the CCP
Internal pudendal - supplies the pelvic portion of the urethra and terminates in the CSP as the artery of the bulb of the penis.
Blood exits by the venous plexus on the dorsum and sides of the penis - emptied by the external pudendal and obtrutator veins. Blood exits the penile root by the external pudendal
Penile innervation
Pudendal nerve primary nerve supply. Autonomic from pelvic plexus (sympathetic)
Pudendal nerves branch into the dorsal nerves of the penis, and the sympathetic fibers supply the smooth muscle of the vessels and the erectile tissue
Deep perineal and caudal rectal nerves supply the bulbospongiosus, ischiocavernosus, and retractor penis muscles.
Name the accessory sex glands and their urethral openings
- Paired seminal vesicles - each forms single excretory duct, which travels beneath the prostate and opens together with the ipsilateral ampulla on the colliculus seminalis via combined ejaculatory duct
- Paired ampullae of the ductus deferens - see above
- Prostate gland - located dorsal to the bladder neck. Secretions open through small slit like openings lateral to the colliculus seminalis
- Paired bulbourethral glands - located on the dorsolateral surface of the urethra at the ischial arch, 2-3 cm caudal to the prostate
Why might a foal be unable to fully extrude the penis at birth?
At birth the penis is not free in the preputial cavity as the epithelium of the internal lamina of the prepuce and the epithelium of the free part of the penis are fused into a single lamina, This is subsequently split into external and internal laminae in the first month of life under androgenic control
What nerve is being blocked? What are the landmarks and what structures are desensitised?
Pudendal nerve
The ischial arch is the main landmark; insert 1.5” needle at this level on the left and right of midline, aiming to the opposite side until the needle contacts bone
Penis and peri-anal skin are desensitised
Treatment principles for penile lacerations
- Debride and close fresh wounds. Catheterise to assist urethral anastomosis if disrupted.
- Penile amputation should be considered for complete urethral disruption in geldings
- Haematomas - immediate compression with tight bandage to limit haemorrhage. Ideally UGA from glans to preputial orifice (ie compressing free penis and internal lamina). Massage the penis once wrapped until wrap is loose from decrease in penile size, then repeat until maximal reduction in size is achieved. Then support the penis and internal lamina of the prepuce against the abdomen or within the preputial cavity to diminish haemorrhage and oedema.
- Cold therapy hastens vasoconstriction. If fails to respond, may need sx exploration to close potential rent in the tunica albuginea
- PO avoid sexual stimulation - increases chance of haemorrhage.
- Confine for 5-6d after haem stops, then light exercise to help with oedema along with hot packs to vasodilate and assist with resorption of the haematoma
What is meany by a ‘fractured penis’?
What is a potential sequalae of these injuries if left unsutured?
Rupture of the CCP
Rupture of the penile vessels or a caverous space causes extravasation of blood into the loose preputial fascia - swelling can be severe. Can even restrict urination in severe cases
Unsutured cavernous wounds may lead to impotence caused by creation of a shunt between the cavernous tissue and the superficial penile vasculature
What is this condition?
What are some potential causes?
List some treatment options.
Phimosis - inability to fully protrude the penis
Can be congenital (rare - NB not the normal fusion of the internal lamina to free portion of penis) or acquired dt trauma, inflamm or neoplasia rx in cicatrisation of the preputial orifice or preputial ring
Treatment: a) Constriction at external orifice; wedge resection of external lamina with base at orifice b) Constriction at preputial ring; wedge resection at the preputial ring - removal of a wedge of the internal preputial fold, and the inner lamina of the preputial fold can be sutured to the outer lamina of the preputial fold.
c) Segmental posthetomy (reefing) - remove constricted segment
Possible causes of paraphimosis
Preputial oedema - trauma/castration etc
Systemic dz - Dourine, purpura haemorrhagica
Damage to innervation - spinal trauma, EHV
Severe debillitation, starvation
Phenothiazines
Pathophysiology of paraphimosis
Oedema develops in loose connective tissue between the penis and internal lamina
Weight of the oedema causes muscular fatigue (retractor penis mm) & protrusion of penis & internal lamina from prepuce
Prolonged protrusion causes the pudendal nerves to become contused/stretched at ischial arch (this is also the mechanism with ACP rather than direct effect on penile innervation by tranquiliser
Blood within the CCP pools and clots within 2-5 hr, making the penis somewhat rigid (mistaken for priapism)
Protrusion itself produces oedema of the penis & prepuce(impaired venous & lymphatic drainage); as swelling increases, the preputial ring becomes a constricting cuff that compounds swelling distad
After several days fluid will seep through penile/pereputial epithelium. Increased fragility, skin breaks and balanoposthitis develops
Weight of the penis/prepuce eventually may damage pudendal nerves
The protruded penis becomes curved, with the glans penis pointing caudoventrad. urination is usually unimpeded
Erectile function usually lost but ejaculatory function may be preserved
Treatment of paraphimosis
- Medical: Penis should be preserved within the prepuce to preserve normal venous and lymphatic drainage and to protect against injury
- Retained temporarily w sutures or towel clamps across the preputial orifice or the preputial ring (not >3d as damage prepuce)
- Prolonged support can be provided by a nylon net or hosiery suspended at the preputial orifice by a crupper and surcingle
- If the protruded penis is too oedematous to enter prepuce, compress against abdo w bandage until oedema reduced
- Pneumatic bandage (or NIBP cuff as in case report) can be used directly on the penis. Also hydrophillic agents (glycerin, sulpha urea) may improve effectiveness of the compressive bandage. Massage between bandage changes may also help
- Topical ABs and systemic NSAIDs
- Topical 2% testosterone cream with udder cream.
- Light exercise
- Surgical: If the inelastic preputial ring is preventing/impeding penile retraction or impedes venous drainage - preputiotomy can be performed: Sever the preputial ring longitudinally - leave to heal by second intention
- Some salvage procedures (obv dont permit breeding) can be used to permanantly retain paralysed penis within prepuce; include the Bolz procedure, extensive posthetomy (Adam procedure) or partial phallectomy
Causes of priapism
Phenothiazine most common cause of low flow priapism (impaired venous drainage) - characterised by stasis of blood within the CCP. Failure of detumescence is caused by alpha receptor blockade
Other causes incl. GA, nematodiasis of the spinal cord, neoplasia of the pelvic canal
Incidence of penile dysfunction (paralysis or priapism) following phenothiazines
<1 in 10,000
Medical management options for priapism
- Physical therapy - penile massage, emollient dressings and compression against the body wall. May help return to prepuce but NO effect on restoration of penile bloodflow
- Benztropine mesylate 8mg slow IV: been used to reestablish venous drainage impaired by ∝blockade dt ACP; most successful if initiated soon after onset of CSs. Anticholinergic action so side effects similar to atropine
- (Terbutaline is a B2-adrenergic agonist has been used in humans. Clenbuterol also B2 agonist - may be effective)
- Intra-cavernosal ∝ adrenergics - 10mg phenylephrine in 10ml saline injected directly into the CCP of the erect equine penis is sometimes effective, provided it is initiated early in the course of dz (effect may be temp in chronic cases)
- Irrigation of the CCP w hep saline standing or GA: if there is no response to cholinergic blockade or >2 intra CCP injections of an ∝ adrenergic agent; removes sickled erythrocytes & improves acidotic environment in the CCP
- Insert 12-14g needle into the CCP just proximal to the glans penis which egresses 10 to 15 cm caudal to the scrotum, either through one or two large-bore needles inserted into the ccp or through a stab incision into the ccp.
- Irrigate until fresh blood appears in the egress. Can instill phenylephrine on completion
- Failure of appearance of fresh blood indicates permanent damage to the arterial supply
Surgical treatment options for priapism
Creation of a shunt between CCP and CSP - as the CSP does not act as a closed system thus restores venous drainage. Needs to be done before the cavernous tissue or the pudendal nerves become irreversibly damaged, (although this is difficult to determine when). Shunt best performed in the perineal region (more thorough evacuation and greater drainage of CCP, as well as less likely to penetrate urethra during spongiotomy)
- Technique: GA dorsal, urethral catheterisation, 15cm incision along the perineal raphe, 4-8cm caudal to the base of the scrotum to expose the penis & retract the right or left retractor penis mm to expose the bulbospongiosus mm covering ventral CSP
- Elevate one edge of bulbospongiosus mm from the edge of the urethral groove to expose 4-5cm of underlying tunica albuginea of the CSP
- Make a 3cm stab into tunica albuginea of CCP and evacuate stagnant blood
- Then stab 3cm into tunica albuginea of CSP (care re urethra), will bleed fresh blood.
- Suture the medial CSP incision to the medial CCP incision followed by lateral edges together with 2-0 or 3-0 absorbable material
- Bulbospongiosus is sutured to its origin on the tunica albuginea of the CCP at the edge of the urethral groove, and the subcutaneous tissue and skin are apposed.
- Minimal PO swelling/discomfort. Avoid sexual stimulation for at least one month PO
Complications/Px: Shunting doesn’t seem to negatively affect erectile and ejaculatory function, although obviously may be affected by the priapism itself
Stallions with decreased penile sensitivity dt pudendal nerve damage can be tx with the antidepressive imipramine before breeding, lowers ejaculatory threshold
Partial phallectomy: may be necessary if all other tx options fail. Remaining portion of the CCP may remain erect until it fibroses.
What is this condition?
What other penile abnormality often accompanies it? (also pictured)
Hypospadias - a rare congenital anomoly where the urethral opening is on the ventral aspect of the penis proximal to its normal location. Position is usually glandular, coronal, or subcoronal. Less commonly penile, penoscrotal, or perineal
Often seen with cordee - an abnormal ventral curvature of the penis
Treatment options for hypospadias
Only required if urine scalding is a problem
Affected horses should not be used for breeding
Tx depends on location; partial phallectomy most useful if coronal/subcoronal (although new stoma wiil also be on the ventral aspect of the penis, so scalding can still be a problem - may be better as removing curved portion of the penis if there is concurrent cordee)
Single stage urethroplasty has been successfully reported for correction of perineal hypospadias (Harrison et al EVE 2016) - penile skin circumcised at subcoronal level and the penis fully degloved. The urethral plate separated from the corpora & a plication was performed dorsally to correct the chordee of the corporal bodies, to straighten the penis. The urethral plate was tubularised in two layers with a continuous suture using 3/0 PDS. The urethral meatus was successfully relocated distally, opening at the tip of the glans. The urethroplasty was covered with dartos fascia and the penile shaft skin and prepuce were reconstructed
Give 3 differentials for the condition pictured
Which is the most likely dx and how can this be confirmed?
What additional diagnostics may be useful?
Penile squamous cell carcinoma (SCC) - most likely, by far the most common penile and preputial neoplasm
Other ddx incl sarcoids, melanomas, mastocytomas, and hemangiomas and cutaneous habronemiasis
Dx can be confirmed with histo, either retrospectively w excisional biopsy, or prospectively w incisional, although clincal appearance usually sufficient
May be useful to perform rectal exam to check for iliac LN enlargement - seen in approx 12% of affected cases
Management of cutaneous habronemiasis
Medical - aims to eliminate larvae and tx the hypersensitivity
Oral ivermectin (200ug/kg) or topical, oral or IV OPs combined with preds (1.5mg/kg PO BID 7-14d)
Surgical - elliptical or circumferential resection of fibrotic areas of internal lamina of the prepuce caused by chronic infestation ie segmental posthectomy
Amputation of an affected urethral process may be req. to restore normal urination and prevent haemospermia
What procedure is being performed?
What are the indications?
Outline the steps involved
a) Segmental posthectomy (syn posthioplasty, circumcision, and reefing); excision of circumferential segment internal preputial lamina
b) Indications are removal of preputial neoplasms, granulomas, or scars too extensive for simple excision (avoids penile amputation as long as underlying tunica albuginea not involved). Can also be used to maintain a paralysed penis within the prepuce by removing most of the internal lamina (latter = Adams procedure)
c) Technique:
- Standing with pudendal block or GA, urethral catheterisation and penile extension with gauze around collum glandis, tourniquet proximally.
- Parallel circumferential incisions through the preputial epithelium are created distal & proximal to lesion, & these incisions are connected by a longitudinal incision (care re large SQ br of external pudendal aa/vv superficial to tunica albuginea)
- The cuff of integument between the incisions is dissected from the penis, care re large vessels
- Release tourniquet and ligate any bleeding vessels
- Close loose adventitia then epithelium
- PO isolate from mares and wear stallion ring for 2-4weeks
What is an Adams procedure and how is it performed?
Modification of segmental posthectomy used to permanently maintain a paralysed penis within the preputial cavity
Same technique as for segmental posthectomy; the distal circumferential incision should be made through the penile epithelium where the internal preputial lamina inserts on the free portion of the penis. The proximal circumferential incision should be made close to the preputial orifice. Integument between the 2 removed, bleeding vessels ligated
Closure can be more challenging as prox incision wider than distal one; length of the proximal incision can be decreased by removing 2 triangles of epithelium on each side with the base being at the incision, 3cm wide and 4cm long
What is this procedure and what are the main indications?
Bollz technique of phallopexy
Indicated for permanent retractraction of a paralysed penis into the preputial cavity, while avoiding partial phallectomy
Can’t be used if the penis or internal lamina is badly damaged or if the horse is still capable of erection. Damaged bits of prepuce, can be removed by segmental posthetomy simultaneously
As for segmental posthetomy, not suitable if dz extends to underlying tunica albuginea
Describe the surgical steps in the Bollz technique of phallopexy
- GA dorsal with urethral catheter
- 10cm longitudinal incision on the perineal raphe, just caudal to the scrotum/scrotal scar.
- Penis bluntly separated from its surroundings - *care pudendal vessels
- Retract penis until the attachment of the internal preputial lamina onto the free body of the penis is visible at the cranial extent of the incision
- Anchor the penis in this position with 2 heavy, non-absorbable percutaneous sutures, 1 on each side of the penis, inserted through the attachment of the internal preputial lamina. penetrating the skin 2-4cm from the incision, avoiding entering the preputial cavity, urethra or cavernosal spaces
- Have a finger in the fornix of the preputial cavity during suture placement through the attachment of the internal preputial lamina onto the free body of the penis to ensure that the sutures do not penetrate the preputial epithelium.
- Tighten sutures until the glans penis is flush with the preputial orifice and tie over rolls of gauze or large buttons to prevent suture cutting through the skin
- Close SQ and skin in 2 layers. Remove percutaneous anchoring sutures in 10-12 days - adhesions have sufficient strength to maintain the penis in the retracted position
Name procedures A, B and C
List the advantages and disadvantages of each
A - Williams + decreased liklihood of stricture and contact dermatitis vs Vinsot
- more technically difficult
- Can’t leave stump unsutured
B - Vinsot + simple to perform
+ a modification w linear stoma can be performed standing
+ can leave stump to heal by 2° intention
- tendency for urethral stricture
-contact dermatitis may be an issue
C - Scott - req GA, can’t leave stump unsutured
Describe the steps for Vinsots technique of partial phallectomy
- W urethral cath & tourniquet in place, dissect a △ piece of epithelium, fascia, bulbospongiosus muscle, and CSP away from the VENTRUM of the penis; 2.5cm base directed prox and 4cm sides w apex directed distally (V-shaped for Vinsot). Apex of △ ideally 4-5cm above transection site. DON’T penetrate urethral lumen in this step.
- Incise the urethra on midline from base → apex & appose urethral mucosa to penile epithelium; sutures are to include CSP for compression/haemostasis. 2 lines of continuous suture (2-0 abs) better for haemostasis vs interrupted. Bites are closely spaced
- Stump transected w wedge-shaped incision
- Ligate large (ext pud) vessels dorsal and lateral to tunica albuginea
- Place large crushing sutures (horiz mattress) through the CCP and CSP (USP 0 abs) then close epithelium (everting or appositional)
- Can leave stump to heal by 2° intention; place large umbilical tape or bander castration ring around stump before transection.
Which technique of distal phallectomy has been performed?
Describe the steps
What are the main advantages of this technique?
a) Williams technique
b) Technique
- Remove △ of penile epithelium, fascia, bulbospongiosus mm, and CSP from the ventrum of the penis, with the 2.5cm wide base directed ventrally at the site of penile transection, and 4cm sides with the apex directed proximally (opposite way to Vinsot)
- Incise urethra on midline from base to apex and appose urethral mucosa to penile integument including/crushing CSP along each side of the △. 2-0/3-0 simple continuous pattern provides superior haemostasis vs interrupted. △ base not yet sutured
- Catheter removed and penis transected obliquely at a 30–45◦ angle, in a craniodorsal direction (NB GA), at the base of the △, so that the dorsal border of the penile stump is slightly longer than ventral
- Ligate large ext pudendal vasculature dorsally and laterally (2-0/0 absorbable)
- Stump closed w (0 or 1 abs or nonabs) sutures passing through urethral mucosa, tunica albuginea (TA) of urethral groove, TA of CCP & penile/preputial integument. Pre-placing sutures helps to place equidistant under even tension, then tightened and tied
- Final layer apposes urethral mucosa and penile/preputial integument
Main advantages are decreased incidence of PO stricture formation and urine scald
Which 4 tissue layers are involved in the closure of the penile stump with the Williams technique?
Urethra
Tunica albuginea of urethral groove
Tunica albuginea of CCP
Penile/preputial integument
What technique is being performed here?
Describe the steps
Scotts technique of distal phallectomy
- Circumferential incision at the intended site of transection at ∟ to the long axis of the penis
- Ligate dorsal/lateral branches of ext pudendal vessels
- Continue dissection down to catheterised urethra & separate 4-5cm length of urethra from the amputated penile stump and transect it
- Close the stump of CPP by apposing outer perimeter of its tunica albuginea to the tunica albuginea of the urethral groove with interrupted absorbable sutures pre-placed equidistantly
- Compress CSP by suturing its tunica albuginea to the urethral submucosa (3–0/2–0 abs); sutures are pre-placed
- Urethral stump can either be divided into 3 equal △ segments (with apices distally), interjoined with and apposed to 3 corresponding △ segments of penile/preputial integument w simple interrupted (3–0 or 2-0 abs or non-abs) sutures, including the underlying tunica albuginea
- OR stretched and folded back over the end of the penis, where it is sutured to the penile or preputial epithelium and underlying tunica albuginea
Describe the anatomy of the prepuce
Formed by a double fold of preputial skin, one inside the other
Prepuce proper consists of external (skin) and internal surfaces/laminae; the preputial orifice is where the 2 surfaces become confluent cranially
The internal lamina gives rise to the preputial fold (plica preputialis) who’s i cranial border forms the preputial ring. The preputial fold disappears in an extended penis; only the preputial ring remains identifiable by its smooth surface forming a ring-like elevation - useful surgical landmark
Folds are referred to external and internal laminae of the prepuce, and external and internal laminae of the preputial fold
Describe the surgical procedure for en bloc resection of the penis and prepuce with penile retroversion
- Fusiform incision around the preputial orifice from 6cm cranial - 10cm caudal (extend to include superficial ing LNs if involvement suspected/confirmed)
- Disssection continued to the penis, which is amputated 6-8cm caudal to the preputial orifice, leaving 4cm urethra protruding from the stump (similar to Scott technique). The amputated penis/prepuce removed en bloc
- 6cm subishial incision made (approx 20cm ventral to anus). Penile fascia bluntly separated & penis retroverted such that the stump points caudad
- Tunica albuginea of CCP and fascia of the penis are sutured to SQ of the subishial incision
- Dorsal aspect of the protruding urethral stump is incised longitudinally over its 4-cm length, & the edges of urethra are sutured to the edges of the subischial incision
- Close the cranial incision in 2 layers w deeply placed Penrose drains
Surgical procedure described by Wylie and Payne (2016 EVE) for penile amputation and preputial ablation.
- Site for urethrostomy marked in the standing horse; mark caudal limit of the bony pelvic floor/pubis and situate urethrostomy at least 10cm distal to this
- Subischial urethrostomy: GA dorsal, urethra identified by catheter & vertical skin incision made on midline overlying it at the pre-marked location. Urethra opened onto the catheter
- Over-sew the bulbospongiosus mm & CSP in a continuous, crushing layer with 2 metric polyglactin 910 (not incl urethral mucosa)
- Distal urethra is transected forming an opened spatulated flat structure which is apposed to the skin with a single suture proximally, distally and at left and right mid-points, then urethral mucosa is sutured to the skin w multiple SI 3-0 vicryll at 3mm intervals to form the urethrostomy
- Penis elevated vertically and fusiform skin incision made around prepuce
- Dissection continued to the penis, ligating branches of the caudal superficial epigastric aa (from ext pudendal) when encountered, & penis clamped and transected & closed w crushing sutures in the CCP and CSP (USP 1 pg910)- (MUST include TA for holding strength) as well as ligation of dorsal/lateral a
- Incision closed in 2 layers (SQ 2-0 PG910)
