Casalino_CH09

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CHAPTER 9

URETHRA


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9–1 Normal Urethra

David D. Casalino

PRESENTATIONDysuria.

FINDINGSCystogram shows a small lobulated collection of contrastextending cephalad from the right lateral aspect of thebulbous urethra.

DIFFERENTIAL DIAGNOSES• Anterior urethral injury : May be iatrogenic or may be

caused by blunt trauma or penetrating injury; clinicalhistory usually includes mechanism of injury; blood at themeatus is the cardinal sign of anterior urethral injury.

• Urethral stula : May result from infection, trauma, radi-

ation injury, surgery, or, rarely, neoplasm; irregular tractthat may be blind ending or communicate with a pelvicorgan or another segment of urethra.

• Urethral diverticulum : Can be congenital or acquired;acquired diverticula may be caused by trauma, instru-mentation, or infection and can involve any portion.

COMMENTS

MALE URETHRAThe male urethra has a length of 17.5 to 20 cm and con-sists of anterior and posterior portions. The posterior urethrais divided into the prostatic and membranous urethras. Theprostatic urethra is 3.5 cm long and extends from the inter-nal sphincter at the bladder neck and terminates at thedistal end of the verumontanum. The verumontanum is a1-cm long oval protuberance at the posterior wall of the pro-static urethra. Two ejaculatory ducts and prostatic glandsdrain into the verumontanum. The membranous urethra is1 to 1.5-cm long and extends from the distal end of the veru-montanum to the external sphincter at the urogenitaldiaphragm. It is the narrowest portion of the urethra.

The anterior urethra is divided into the bulbous, or bulbar,and penile, or pendulous, portions. The bulbous urethraextends from the external sphincter to the penoscrotal junc-

tion, where there is slight angulation of the urethra by thesuspensory ligament of the penis. The proximal bulbousurethra is dilated and has a conical shape at the bul-bomembranous junction. Contraction of the constrictornudae muscle may cause an anterior or circumferentialindentation of the proximal bulbous urethra and should notbe mistaken for a stricture. Cowper glands are paired glandsthat lie within the urogenital diaphragm and drain into eitherside of the dilated portion of the bulbous urethra via ducts

that are 2 to 4 cm long. There are also periurethral glands of Littré that drain into the anterior urethra and are morenumerous on the dorsal aspect. Contrast opacication of Cowper glands and ducts, glands of Littré, and prostaticducts during urethrography is often associated with urethralinammation or stricture, although not always. The penileurethra extends from the penoscrotal junction to the exter-nal meatus. The fossa navicularis is 1- to 1.5-cm long focaldilatation of the distal aspect of the penile urethra.

FEMALE URETHRAThe female urethra is 4 cm long and extends from the bladderneck obliquely in an anterior and inferior direction to the exter-nal orice situated between the labia minora. The urethra iswidest at its proximal aspect and tapers distally. Skene glandsare groups of periurethral glands found distally and emptythrough two small ducts to either side of the external meatus.

PEARLS

• The male urethra consists of anterior (prostatic andmembranous) and posterior (bulbous and penile) portions.

• Contrast opacication of Cowper glands and ducts,glands of Littré, and prostatic ducts during imaging isoften associated with urethral inammation or stricture,but not always.

• The female urethra is widest at its proximal aspect andtapers distally.

A. Cystogram shows a small lobulated collection of contrastextending cephalad via a smooth tract from the right lateral aspect

of the bulbous urethra. The appearance is characteristic of a normalCowper gland and duct.


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ADDITIONAL IMAGES (B-E)

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C. Retrograde urethrogram shows the verumontanum(arrow) and demarcation of prostatic (Pr), membranous(M), bulbar (B), and penile (Pe) portions of the urethra.

D. Retrograde urethrogram from a different malepatient shows the normal conical shape of the proxi-mal bulbar urethra with smooth focal indentation(arrow) caused by the constrictor nudae muscle.

E. Voiding cystourethrogram shows a normal femaleurethra.

F. Iatrogenic anterior urethral injury: Retrograde ure-throgram shows focal contrast leakage from the bul-bous urethra after abdominoperineal resection.

DIFFERENTIAL DIAGNOSES IMAGES (F-G)

B. Retrograde urethrogram, a composite image, showsa normal urethra.

G. Traumatic anterior urethral injury: Retrograde ure-throgram shows contrast leakage from the bulbous ure-thra with extension into the scrotum in a patient statuspost straddle injury.


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9–2 Female Urethral Carcinoma

David D. Casalino

PRESENTATIONUrethral mass associated with bleeding and dysuria.

FINDINGSCT shows a slightly heterogeneous soft-tissue mass of theurethra.

DIFFERENTIAL DIAGNOSES• Other malignancy involving urethra : Including bladder,

gynecologic, and rectal cancers; may have clinicalsigns and symptoms specic for a particular tumor;imaging may not be able to differentiate; tissue diag-nosis necessary.

• Infectious process : Including infected urethral diverticu-lum; signs and symptoms suggestive of infection.

COMMENTSCarcinoma of the urethra accounts for less than 0.01% of all female malignancies. Most of the patients are white and40 to 60 years old. Urethral carcinomas seem to develop inthe setting of chronic irritation or urinary tract infections.Squamous cell carcinoma (SCC) is the most commonhistopathologic type, accounting for 60% to 75% of cases,followed by transitional cell carcinoma (TCC) (15%-20%) andadenocarcinoma. The distal third of the urethra is the most

common site for SCC. Benign, synchronous lesions, such ascaruncles, papillomas, and polyps of the urethra, are oftenpresent. Presenting symptoms may include urethral bleed-ing, frequency, dysuria, urethral obstruction, and urethralmass. The diagnosis is usually made by clinical examination.

Voiding cystourethrography (VCUG) may demonstrate irreg-ular narrowing or a single or multiple irregular lling defects.CT and MR are helpful in assessing local invasion and nodalinvolvement. On CT, the tumor appears as a heterogeneous,soft-tissue attenuation mass. On MR, the tumor is typicallyhypointense on T1-weighted imaging, hyperintense onT2-weighted imaging, and enhances. Sagittal T2-weightedimaging is particularly useful for assessing tumor invasion of

the bladder, vagina, and pelvic oor. Tumors of the distalthird of the urethra, sometimes referred to as “anterior” ure-thral cancer, preferentially spread to the supercial anddeep inguinal nodes. More proximal tumors, sometimesreferred to as “entire” urethral cancer, spread to the internal

and external iliac and obturator nodes and not uncommonlyinvade adjacent organs. While anterior lesions can usually betreated with local surgical excision, entire urethral lesionsare often high-grade tumors, locally advanced, and maywarrant a combination therapy that includes surgery, radia-tion therapy, and chemotherapy.

A. Axial CECT shows a slightly heterogeneous soft-tissue mass ofthe urethra (arrow).

PEARLS

• Urethral carcinoma is the only epithelial malignancy ofthe urinary tract that is more common in women with a4:1 female-to-male ratio.

• SCC is the most common histopathologic type, followedby TCC and adenocarinoma.

• VCUG may demonstrate irregular narrowing or irregularlling defect(s).

• MR and CT are useful in the assessment of nodaldisease and local invasion.


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B. Sagittal CECT shows the urethral mass (arrow) with-out evidence of gross invasion into the surroundingstructures. Biopsy and subsequent surgery diagnosedurethral SCC with extensive inammatory change of

the urethra.

D. and E. Vaginal SCC involving the urethra: Sagittal T2-WI and contrast-enhanced T1-WI show a large, heteroge-neously enhancing mass arising from the anterior vaginal wall and invading the urethra and bladder.

ADDITIONAL IMAGE DIFFERENTIAL DIAGNOSES IMAGES (C-E)

C. Urethral diverticulum, infected: Axial contrast-enhanced T1-WI shows a heterogeneous lesion sur-rounding the urethra. The mass is predominantly low-signal intensity with peripheral enhancement and

septations.


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9–3 Male Urethral Carcinoma

David D. Casalino

PRESENTATIONHematuria, diminished urine stream, and palpable penile mass.

FINDINGSMR shows a heterogeneous, enhancing mass involving thecorpus spongiosum.

DIFFERENTIAL DIAGNOSES• Squamous cell carcinoma (SCC) of the penis : Rare in

the US, but accounts for 10% to 20% of all male malig-nancies in Asia, Africa, and South America; glans isinvolved in more than 50% of the cases; threefoldincreased risk in uncircumcised men.

• Penile sarcoma : Include epithelioid sarcoma, Kaposi,

leiomyosarcoma, and rhabdomyosarcoma; rare,accounting for less than 5% of penile malignancies;those arising from a corpus tend to metastasize early.

• Metastatic disease : Often a known primary, such asbladder urothelial carcinoma or prostate adenocarcinoma.

COMMENTSPrimary urethral carcinoma is rare. SCC is most common,accounting for 80% of the cases, and most often arises in thebulbous or membranous urethra but can occur in the moredistal urethra and, rarely, in the prostatic urethra. TCC is lesscommon, accounting for 15% of cases, and usually occurs inthe posterior urethra but can occur more distal.Adenocarcinoma is the least common and arises fromCowper glands or the glands of Littré. Urethral carcinomausually occurs in men that are more than 50 years of age.Chronic irritation, gonococcal urethritis, and urethral strictureare considered risk factors for the development of urethralcarcinoma. The most common presenting symptom is a pal-pable mass along the course of the urethra or in the per-ineum. Patients may also present with obstructive symptoms,hematuria, bloody discharge, pain, urethral stula, or peri-urethral abscess.

Urethrography typically demonstrates segmental, irregularnarrowing of the urethra. If there is a change in the appearanceof a chronic stricture or if the margins of a stricture are irregu-lar, carcinoma should be considered. Larger tumors may beseen as an inltrative mass on CT or MR. On MR, the tumor isusually isointense to low-signal intensity relative to the sur-rounding corpus spongiosum on T1- and T2-weighted images.MR is useful in assessing tumor size and location and in local

staging, which includes determination of invasion into thecorpora and other adjacent structures. Urethral carcinomamay also spread to regional lymph nodes and hematogenouslyto more distant sites. Posterior urethral carcinomas are moreoften associated with extensive local spread, distant metas-tases, and a worse prognosis. Surgical excision is the mostcommon treatment for urethral carcinoma.

PEARLS

• Carcinomas of the urethra are SCC in 80% of the cases andmost common in the bulbous and membranous portions.

• Patients with urethral carcinoma often have a history ofurethral stricture and a palpable mass.

• Urethral carcinoma should be considered when urethro-gram demonstrates a change in the appearance of achronic stricture or if the margins of a stricture areirregular.

• MR is particularly helpful in local staging.

• Primary tumor stages are I: invades subepithelial con-nective tissue; II: invades corpus spongiosum prostateor periurethral muscle; III: invades corpus cavernosumbeyond prostate capsule, anterior vagina, or bladderneck; and IV: invades other adjacent organs.

A. Axial contrast-enhanced T1-WI shows a heterogeneous,

enhancing mass involving the corpus spongiosum, extendingthrough its tunica into the intercavernous fascia.


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C. Retrograde urethrogram shows irregular narrowingof a long segment of anterior urethra caused by SCC.

D. Axial CECT shows an enhancing mass (arrow)involving the central region of the prostate. Biopsyshowed TCC of the prostatic urethra.

E. Squamous cell carcinoma of the penis: Sagittalcontrast-enhanced T1-WI shows a large mass withcentral necrosis involving the glans penis as well asthe ventral aspect of the corpus spongiosum andpenile urethra.

B. Sagittal contrast-enhanced T1-WI from the samepatient shows the mass that involves the penile ure-thra. The glans penis is normal. Biopsy showed SCC ofthe urethra.

ADDITIONAL IMAGES (B-D)

DIFFERENTIAL DIAGNOSES IMAGES (E-G)

F. Penile leiomyosarcoma: Axial contrast-enhancedT1-WI shows a heterogeneous, enhancing mass arisingfrom the corpus spongiosum with local invasion.

G. Metastatic disease: Sagittal contrast-enhancedT1-WI shows a heterogeneous, large enhancing massinvolving the prostate, proximal urethra, and base ofpenis. Biopsy showed synovial sarcoma.


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9–4 Urethral Stricture

David D. Casalino

PRESENTATIONDecrease urine ow, hematuria, and dysuria.

FINDINGSUrethrogram shows focal narrowing of the bulbous urethra.

DIFFERENTIAL DIAGNOSES• Iatrogenic stricture : History of instrumentation, catheter-

ization, or surgery.

• Traumatic stricture : History of trauma (blunt or penetrat-ing); focal stricture; straddle injury typically involves thebulbous urethra.

• Infectious or inammatory stricture : Relevant history of

infection or inammation; longer segment of urethraoften involved; gonococcus most often involves thebulbous urethra.

• Neoplasm : Stricture is rarely only manifestation of neo-plasm; elderly patient.

COMMENTSA urethral stricture is an abnormal narrowing of any part of the urethra caused by brous scarring. Urethral stricturesoccur primarily in men. The most common causes of ante-rior urethral strictures are iatrogenic and traumatic, fol-

lowed by infectious, inammatory, and neoplastic.Congenital strictures are rare. Iatrogenic strictures may bebecause of instrumentation, catheterization, or surgery andusually occur in the bulbomembranous and penoscrotal

junctions. They may be focal or long, solitary or multifocal.A straddle injury is the most common external trauma asso-ciated with anterior strictures. The bulbous urethra is usu-ally involved focally. The most common infectious etiology iscaused by Neisseria gonorrhoeae , which usually involvesthe bulbous urethra with multiple strictures. Strictures of the posterior urethra are usually the result of trauma orsurgery, such as radical prostatectomy or transurethralresection of the prostate (TURP), causing urethral distrac-tion or disruption. Patients with a urethral stricture may pre-sent with decreased urine ow, incomplete bladder empty-ing, dysuria, hematuria, or urinary tract infection.

The goals of imaging urethral strictures include assessmentof the number, location, length, and severity of the stricturesand detection of concomitant abnormalities, such as peri-urethral abscess, stula, false passages between different

portions of the urethra, and urine extravasation. This infor-mation is critical for determining appropriate treatment.

Retrograde urethrography is the primary imaging study forevaluating a urethral stricture. Proper patient positioning ina steep oblique orientation is necessary to avoid underesti-mating stricture length. Multiple projections may be com-plementary. Ultrasound and MR may be complementary inevaluating patients with strictures. Treatment options includedilatation, intraluminal stenting, cystoscopic urethrectomy,and open urethroplasty.

PEARLS

• Urethral strictures occur primarily in men and are mostoften iatrogenic or traumatic.

• Infectious strictures are typically secondary to gono-coccal urethritis.

•Retrograde urethrography is the primary imaging studyfor evaluating urethral strictures.

• Proper technique is critical in dening the extent andseverity of strictures and should include steep obliquepositioning of the patient and penis.

A. Retrograde urethrogram shows focal narrowing of the bulbousurethra because of a stricture related to prior straddle injury.


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B. Retrograde urethrogram from a different patientshows a very focal and tight stricture also secondary toa straddle injury.

D. Iatrogenic stricture: Retrograde urethrogram showsirregularity with focal stricture involving the anteriorurethra in a patient status post open urethral recon-struction using a buccal mucosal graft.

E. Infectious stricture: Retrograde urethrogram from apatient with gonococcal urethritis shows multiple stric-tures involving the bulbous urethra and penile urethra.There are glands of Littré abscesses (arrowheads) andinvolvement of Cowper ducts and glands (arrow).There is an air bubble at the penoscrotal junction.

C. Iatrogenic stricture: Retrograde urethrogram showsa 3.5-cm-long stricture at the penoscrotal junction.The stricture was because of prior catheterizations.Contrast partially lls a Cowper duct.

ADDITIONAL IMAGE DIFFERENTIAL DIAGNOSES IMAGES (C-G)

F. Infectious stricture: Retrograde urethrogram of a dif-ferent patient with gonococcal urethritis shows abeaded stricture of the bulbous urethra.

G.Neoplastic stricture: Retrograde urethrogram shows veryirregular, focal narrowing of the bulbous urethra causedby SCC of the urethra. (Figrures E-G courtesy of Neil F.Wasserman, MD, Veterans Administration Medical Center, Minneapolis, MN.)


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9–5 Gonococcal Urethritis

David D. Casalino

PRESENTATIONDecreased urine ow, incomplete bladder emptying, dysuriaand history of antibiotic treatment for urethral d ischarge.

FINDINGSUrethrogram shows focal narrowing of the bulbous urethra.

DIFFERENTIAL DIAGNOSES• Nongonococcal urethritis : Urethral discharge usually

scant; Chlamydia trachomatis accounts for up to 50% of the cases; complications, including stricture, are muchless common; less than 5% develop a stricture.

• Iatrogenic stricture : History of instrumentation or surgery.

• Trauma : History of trauma (blunt or penetrating); focalstricture; straddle injury typically involves the bulbous ure-thra.


COMMENTSGonococcal urethritis is due to infection by N gonorrhoeae ,a gram-negative diploccoccus, and is one of the most com-mon causes of urethral stricture. The infection starts in thedistal urethra and spreads proximally, though rarely proximal

to the external sphincter. Fifteen percent of patients willdevelop a stricture in the late stages of infection. Patientswith gonococcal urethritis usually present with a purulentdischarge. Dysuria and painful or swollen testicles may alsobe present. Diagnosis is usually made on the basis of clini-cal and laboratory ndings. Treatment involves antibioticswith coverage for C trachomatis , another common sexuallytransmitted disease often found in patients with gonorrhea.

No imaging is necessary for uncomplicated urethritis.Urethrography is usually performed to evaluate suspectedcomplications that may include stricture, periurethral s-tula, and periurethral abscess. Seventy percent of stricturesinvolve the bulbous urethra, but they can involve the penile

urethra. It is usually irregular or beaded and extends overseveral centimeters. Dilatation of Littré glands is not uncom-monly seen on urethrography. Filling of Cowper ducts mayalso be seen proximal to the stricture. Mucosal hyperpla-sia may occur and create nodular lling defects in the ure-thra. Periurethral abscess is thought to arise from a Littrégland that has become obstructed and infected. Theseabscesses may be life-threatening if not diagnosed andtreated quickly. The abscess may spread ventrally along

the corpus spongiosum. On occasion, the Buck fasciamay be penetrated and result in tissue necrosis and stulaformation between the urethra and perineum. “Wateringcan” or “watering pot” perineum refers to urination throughurethroperineal stulas, which are more commonly associ-ated with tuberculosis of the urethra. Urethrography maydemonstrate a periurethral abscess if it communicates with

the urethra or stula. Ultrasound may be helpful in the diag-nosis of periurethral abscess. CT and MR imaging maydemonstrate complications and the extent of the abscess.Treatment involves antibiotics, surgical debridement, andurinary drainage via suprapubic catheter.

PEARLS

• Uncomplicated gonococcal urethritis is usually diag-nosed on the basis of clinical and laboratory ndings.

• Fifteen percent of the patients with gonococcal urethri-tis develop a stricture, which involves the proximal bul-bous urethra in 70% of the cases.

• Periurethral abscesses and urethroperineal stulas maycomplicate gonococcal urethritis.

A. Retrograde urethrogram shows slightly irregular, focal narrow-ing (arrow) of the bulbous urethra and slight mucosal irregularityinvolving the penile urethra.


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B. Retrograde urethrogram from a different patientwith gonococcal urethritis shows a longer, beadedstricture of the bulbous urethra. (Courtesy of Neil F.Wasserman, MD, Veterans Administration Medical

Center, Minneapolis, MN.)

D. Retrograde urethrogram from a patient with gonococcalurethritis shows multiple strictures involving the bulbousurethra and penile urethra. There are glands of Littréabscesses (arrowheads) and involvement of Cowper ductsand glands (arrow). There is an air bubble at the penoscro-tal junction. (Courtesy of Neil F. Wasserman, MD, Veterans Administration Medical Center, Minneapolis, MN.)

E. Iatrogenic stricture: Retrograde urethrogram showsbeaded narrowing of a long segment of penile urethraand distal bulbous urethra. The stricture was presum-ably because of extended catheterization.

C. Retrograde urethrogram from a different patient showsa very long, smooth stricture of the bulbous and penileurethra. (Courtesy of Neil F. Wasserman, MD, Veterans Administration Medical Center, Minneapolis, MN.)


DIFFERENTIAL DIAGNOSES IMAGES (E-F)

F. Traumatic stricture: Retrograde urethrogram shows afocal stricture of the bulbous urethra in a young adultwho sustained a straddle injury when he was 9 years old.


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9–6 Balanitis Xerotica Obliterans, or Penile Lichen Sclerosus

David D. Casalino

PRESENTATIONDysuria and weak urine stream in patients with atrophicwhite patches on the glans penis.

FINDINGSUrethrogram shows smooth narrowing of the fossa navicu-laris and distal urethra.

DIFFERENTIAL DIAGNOSES• Infectious urethritis and stricture : Much more common;

relevant history of infection; discharge; more often multifo-cal; gonococcus most often involves the bulbous urethra.

• Iatrogenic stricture : History of instrumentation or surgery.

• Trauma : History of trauma (blunt or penetrating); focalstricture; straddle injury typically involves the bulbousurethra.


COMMENTSBalanitis xerotica obliterans (BXO) is a male genital variantof lichen sclerosus et atrophicus (LS), a skin disease of uncertain etiology that results in white, thickened plaquesinvolving the prepuce, glans, and/or urethral meatus. BXO is

a common cause of acquired phimosis and meatal steno-sis in schoolboys. Urethral involvement is uncommon,starts at the meatus, and spreads proximally in a conuentmanner. The involved segment typically shows smooth nar-rowing. In mild early BXO, patients may notice areas of grayish white coloration on the glans or inner layer of theforeskin. The involved areas may be itchy and are prone tossuring and hemorrhagic blistering during intercourse.Fibrous phimosis may develop. When more aggressive,BXO may cause the surface of the glans and inner prepuceto ulcerate, producing a purulent discharge. BXO is con-sidered premalignant and associated with SCC of thepenis, which may develop long after the BXO has beentreated.

Imaging is not necessary for the diagnosis of BXO, buturethrography may demonstrate urethral involvement,which typically appears as smooth narrowing of the fossa

navicularis and distal urethra. Treatment of urethral involve-ment often includes meatotomy and urethroplasty.

A Retrograde urethrogram shows smooth narrowing of the fossanavicularis and distal urethra.

PEARLS

• BXO is synonymous with penile lichen sclerosus andmale genital lichen sclerosus.

• BXO is associated with SCC of the penis.

• Urethral involvement is uncommon and spreads proxi-mally in a conuent manner from the meatus.

• Urethral involvement results in smooth narrowing of thedistal urethra.


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B. and C. Retrograde urethrogram from a different patient with BXO shows beaded narrowing of the distal urethra.

E. Iatrogenic stricture: Retrograde urethrogram showsbeaded narrowing of a long segment of penile urethraand distal bulbous urethra. The stricture was presum-ably caused by extended catheterization.

ADDITIONAL IMAGES (B-C)

D. Infectious stricture: Retrograde urethrogram frompatient with a history of gonococcus urethritis shows avery long, smooth stricture of the bulbous and penileurethra. (Courtesy of Neil F. Wasserman, MD, Veterans Administration Medical Center, Minneapolis, MN.)

DIFFERENTIAL DIAGNOSES IMAGES (D-E)


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9–7 Urethral Fistula

David D. Casalino

PRESENTATIONLeakage of urine from the ventral surface of penis duringmicturition.

FINDINGSUrethrogram shows a tract of contrast extending from theventral aspect of the penile urethra to the skin surface.

DIFFERENTIAL DIAGNOSES• Acute anterior urethral injury : May be iatrogenic or

caused by blunt or penetrating injury; clinical historyusually includes mechanism of injury; blood at the mea-tus is the cardinal sign of anterior urethral injury.

• Urethral diverticulum : Can be congenital or acquired;congenital diverticula usually involve the penile urethra;acquired diverticula may be caused by trauma, instru-mentation, or infection and can involve any portion.

• Cowper gland : Paired glands that lie within the urogeni-tal diaphragm and drain into either side of the dilatedportion of the bulbous urethra via ducts that are 2 to 4 cmlong.

• Opacication of penile veins : Typical anatomic distribu-tion; transient; urethral obstruction may be present.

• Ectopic insertion of ureter : Above the urogenitaldiaphragm; continuity with rest of the ureter.

COMMENTSA urethral stula may be congenital or result from infection,trauma, radiation injury, surgery, or, rarely, neoplasm. Fistulasmay communicate with the skin, a pelvic organ, such asbowel, vagina, or uterus, or another segment of urethra. A s-tula may be blind ending. Posttraumatic stulas may result if there is superinfection or a more distal obstruction causingincreased pressures within the urethra. Urethroperineal stu-las are often the result of a periurethral abscess in men withurethral strictures but may also result from surgery to correcta stricture or repair hypospadias. Presenting signs and symp-

toms vary, depending on the point of termination; for example,urethrocutaneous stulas to the perineum or scrotum mayresult in one or more openings that leak urine during micturi-tion, so-called “watering pot” perineum.

Urethral stulas are usually imaged with retrograde or void-ing urethrography; although stulography, uoroscopicstudies of the small bowel or colon/rectum, vaginography,or MR might be necessary for diagnosis. Imaging should

attempt to determine the location, number and size of s-tulas. During urethrography, lateral images of the lowerpelvis are particularly important. A stula typically appearsas an irregular tract that may be blind ending or communi-cating to another structure. The size and shape can bewidely variable. On MR, T2-WI in multiple planes is often

helpful for assessment of stulas, which are usually high-signal intensity and show enhancement.

PEARLS

• Urethral stulas may be blind ending or communicatewith the skin, a pelvic organ, or another segment ofurethra.

• Patient presentation depends on the point of termination.

• Imaging must be tailored to the type of stula that isclinically suspected.

• Urethrography is usually the imaging study of choice.

• Multiplanar T2-WI may be very helpful as well.

A. Retrograde urethrogram shows a stula extending from the ven-tral aspect of the penile urethra to the skin surface.


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B. Retrograde urethrogram from a different patientshows an irregular tract of contrast extending from theventral aspect of the penile urethra to a large roundcollection. The patient presented with postvoid drib-

bling and a history of prolonged catheterization.

C. Axial T2-WI shows a thin hyperintense stulabetween the right lateral wall of the anus and the ure-thra in a woman with Crohn disease.

D. Retrograde urethrogram shows a small stula(arrow) between the prostatic urethra and rectum in ayoung male with history of imperforate anus.

E. Anterior urethral injury: Retrograde urethrogramshows focal contrast leakage from the bulbous urethrawith extension into the scrotum in a patient afterstraddle injury.


DIFFERENTIAL DIAGNOSES IMAGES (E-G)

F. Cowper gland and duct: Cystogram shows a smallcollection of contrast (arrow) extending cephalad via asmooth tract from the right lateral aspect of the bul-bous urethra. The appearance is characteristic of anormal Cowper gland and duct.

G. Penile veins: Retrograde urethrogram shows con-trast opacication of multiple penile veins along thedorsal aspect of the penis in a patient with two largeurethral diverticula lled with calculi and a high-gradeproximal stricture.


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9–8 Urethral Diverticulum

Frank H. Miller

PRESENTATIONLower urinary tract symptoms; urinary frequency, dysuria,recurrent UTI; dyspareunia.

FINDINGSMR shows high-signal intensity lesion surrounding theurethra.

DIFFERENTIAL DIAGNOSES• Vaginal inclusion cyst : May be difcult to distinguish,

does not have connection to urethra; however, urethraldiverticulum may not show connection on MR.

• Endometrioma : Generally different symptoms, seenas high-signal intensity on T1-WI and T2-WI from

hemorrhage.• Ectopic ureterocele : Connection to ureter.

COMMENTSUrethra diverticula are saccular outpouchings from theurethra. They may be congenital or acquired. The majorityis acquired and is a result of recurrent infection andobstruction or trauma to the periurethral glands. Thesedilated glands, then, rupture into the urethral lumen. Theymay also develop after urethral stricture. Urethral divertic-ula are more common in females than males. Congenitaldiverticula are rare, more common in males in the mid-penile urethra.

Diverticuli are often difcult to diagnose because of non-specic symptoms and delay in diagnosis. Complicationsinclude infection, calculi, and rarely malignant degenera-tion. A tender periurethral mass may be palpated on phys-ical examination.

The most common site of involvement is posterior or pos-terolateral wall of the mid-urethra. The diverticula may beunilocular or multilocular.

MR has advantages because of its lack of invasiveness,reproducibility, and ability to show surrounding anatomywith high spatial and contrast resolution. Urethral diverticulaare typically seen as uid signal intensity and as low-signalintensity on T1-weighted images and well seen based ontheir high-signal intensity on T2-weighted sequences. The

multiplanar capability of MR helps localize the urethraldiverticulum accurately. In women, the diverticula maywrap around the urethra referred to as “saddle-shaped” or“horseshoe-shaped” diverticula. Gadolinium-enhancementcan be helpful to show the cystic nature and evaluate car-cinoma. Complications including infection, calculi, or neo-plasm can be detected on MR. Because of mass effectfrom the urethral diverticulum, the connection of a diver-ticulum to the urethra may not be seen. The distinctionmay require urethroscopy, biopsy, or surgical resection.

Urethroscopy may show the diverticulum and communica-tion with the urethra but the connection may not always beseen. Voiding cystography may show the diverticulum, butit may be difcult to see as well as MR and have the patient

void for the examination. Double-balloon catheter urethrog-raphy may show the diverticulum but is not performedeverywhere and is more invasive and uncomfortable.

PEARLS

• Urethral diverticula are often difcult to diagnosebecause of nonspecic symptoms and delay in diagnosis.

• Complications of urethral diverticula include infection,calculi, and rarely malignant degeneration.

• MR is least invasive method to show urethral diverticula.

A. Axial T2-WI shows high-signal intensity mass surrounding theurethra.B. Axial contrast-enhanced T1-WI shows the lesion is of uid densityand surrounds the urethra.


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CHAPTEUreth

CAUrethral Diverticul

IMAGE K

Comm

Ra

299

Typic

Unusu

C. Scout image from urethrogram in elderly male witha rm nodule and weak urinary stream shows large cal-cications projected over the urethra.

D. Retrograde urethrogram shows urethral diverticulumwith calcications in the urethra.

E. Endometriosis: Axial T1-WI shows high-signal intensitylesion from hemorrhage as a result of endometriosismimicking urethral diverticulum. The patient hadsymptoms of endometriosis.

F. Vaginal inclusion cyst containing clear cell carci-noma: Axial CECT in a different patient shows massnear urethra and vagina.

ADDITIONAL IMAGES (C-D)

DIFFERENTIAL DIAGNOSES IMAGES (E-H)

G. Vaginal inclusion cyst containing clear cell carci-noma: Sagittal CECT shows the mass is between thevagina and the urethra. It can be difcult to distin-guish vaginal inclusion cysts from urethral diverticula.

H. Vaginal inclusion cyst containing clear cell carci-noma: Longitudinal transvaginal sonogram shows themass has an associated nodule which had ow.Surgical resection showed the lesion was a vaginalinclusion cyst containing clear cell carcinoma.


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Casalino_CH09

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