STEPTRACKERREPRODUCTIVE | PATHOLOGY + EMBRYOLOGY + ANATOMY | HIGH-YIELD REVIEW

Penis & Urethra

Urethral openings in the wrong place, erections that bend or won't stop, HPV-driven penile cancer and its precursors, and urethral injuries.

FOCUS ON
Hypospadias: urethral folds fail to fuse → ventral opening (more common). Epispadias: misplaced genital tubercle → dorsal opening, bladder exstrophy. Peyronie: fibrous plaque → curved erection. Priapism: sickle cell, trazodone — urology emergency. Penile SCC: HPV-16, uncircumcised; in-situ precursors by site.
DISORDER
MECHANISM · CAUSE
FEATURES
CLUE
Hypospadias
Failure of the urethral folds to fuse
Opening on the ventral (under) side; chordee
With cryptorchidism, inguinal hernia · no circumcision before repair
Epispadias
Abnormal position of the genital tubercle
Opening on the dorsal (upper) side
Bladder exstrophy · "when you have epispadias, you hit your eye-spadias"
Phimosis & paraphimosis
Tight foreskin; paraphimosis = retracted foreskin can't return → venous congestion
Phimosis: ↑ infection, SCC · paraphimosis: painful swollen glans
Paraphimosis is an emergency
Balanitis
Glans inflammation: Candida (diabetes), poor hygiene, uncircumcised
Red, itchy glans with discharge
Check glucose
Peyronie disease
Fibrous plaque in the tunica albuginea (abnormal wound healing)
Painful, curved erection; palpable plaque; erectile dysfunction
Associated with Dupuytren contracture
Ischemic priapism
Venous outflow blocked → painful erection > 4 h → ischemia, fibrosis
Sickle cell disease, trazodone, PDE5 inhibitors, α-blockers, intracavernosal drugs, leukemia
Aspiration + phenylephrine
Erectile dysfunction
Vascular (atherosclerosis, Leriche), neurogenic (diabetes, spinal injury, prostatectomy), drugs, psychogenic
Drugs: β-blockers, thiazides, SSRIs, antiandrogens
Morning erections preserved → psychogenic · PDE5 inhibitors
Penile SCC
HPV-16; uncircumcised men, phimosis, smoking, lichen sclerosus
Glans or foreskin ulcer or mass; spreads to inguinal nodes
Neonatal circumcision protective
SCC in situ variants
HPV-related intraepithelial carcinoma
Bowen disease: gray-white plaque on the shaft · erythroplasia of Queyrat: red velvety glans · bowenoid papulosis: multiple reddish papules in young men
Bowenoid papulosis rarely invades
Urethritis
N gonorrhoeae (purulent), C trachomatis (watery), Mycoplasma genitalium, Trichomonas
Dysuria, discharge; sterile pyuria on routine culture
Reactive arthritis: urethritis + conjunctivitis + arthritis
Urethral injury
Pelvic fracture → posterior (membranous) urethra · straddle injury → anterior (bulbar) urethra
Blood at the meatus, high-riding prostate (posterior), inability to void
Retrograde urethrogram before a Foley

Mechanism — building the external genitalia

DHT5α-reductase
→
Genital tubercleGlans, corpora
Urethral foldsFuse ventrally → penile urethra
Labioscrotal swellingsScrotum
Folds fail to fuse
→
HypospadiasVentral
Tubercle misplaced
→
EpispadiasDorsal

Male and female homologs

PRIMORDIUM
MALE
FEMALE
Genital tubercle
Glans penis, corpora
Glans clitoris
Urethral folds
Ventral shaft (penile urethra)
Labia minora
Labioscrotal swellings
Scrotum
Labia majora
Urogenital sinus
Prostate, bulbourethral glands
Skene, Bartholin glands

How it's tested

COMMON CONFUSIONHypospadias (urethral folds, ventral) is common and tied to cryptorchidism. Epispadias (genital tubercle, dorsal) is rare and tied to bladder exstrophy.
THE TRAPBlood at the urethral meatus after pelvic trauma — don't place a urinary catheter until a retrograde urethrogram excludes urethral disruption.
YOUR APPROACHCongenital (which surface?) → acquired (curvature, prolonged erection, infection) → neoplastic (site of in-situ lesion, HPV, nodes) → trauma (anterior vs posterior urethra).

If you see… think…

Newborn with urethral opening on the underside of the penis → hypospadias
Urethral opening on the dorsal penis + exposed bladder → epispadias with exstrophy
Retracted foreskin stuck behind a swollen glans → paraphimosis
Curved painful erection and a palpable plaque → Peyronie disease
Sickle cell patient with a painful 6-hour erection → ischemic priapism
Antidepressant that causes priapism → trazodone
Uncircumcised man with a glans ulcer and inguinal nodes → penile SCC
Red velvety plaque on the glans → erythroplasia of Queyrat
Pelvic fracture, blood at meatus, high-riding prostate → posterior urethral injury
Fall astride a bar, perineal bruising, blood at meatus → anterior (bulbar) urethral injury