Bladder Anatomy Uchendu

7/31/2019 Bladder Anatomy Uchendu

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Question:

Describe the radiological anatomy of the male urinary

bladder. Describe in detail the techniques fordemonstrating the organ.

Answer

- Introduction/Gross- Imaging Modalities:

* Cystogram* Pelvic scan

* CT scan* MRI* Plain radiography* Angiography

* RNI


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- Introduction/Gross

The urinary bladder is situated within the

pelvis. It is an extraperitoneal pyramidalmuscular organ when empty but as it fills,

it becomes ovoid and rises into the

abdomen stripping the loose peritoneumoff the anterior abdominal wall.


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It has a base/posterior surface, an apex, asuperior and two inferiolateral surfaces. The

ureters enter the posterolateral angles and theurethra leaves inferiorly at the narrow neckwhich is surrounded by the involuntary internal

urethral sphincter. The trigone is the triangularinner wall of the bladder between the uretericand the urethral orifices, this part of the wall is

smooth while the remainder of the bladder wallis coarsely trabeculated by crisis- cross musclefibres.


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The perivesical fat surrounds the bladder.

The bladder is relatively fixed inferiorly viacondensations of pelvic fascia, which attach it to

the back of the pubis, the lateral walls of the

pelvis and the rectum. The obturator internus

muscle is anterolateral and the levator ani

muscle is inferolateral to this.


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The vasa deferentia and seminal vesicle

are posterior to the bladder so also is

the cul-de-sac and rectum. Thebladder neck is fused with the prostate.


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Imaging Modalities

-

CystogramIt localises the bladder within the pelvis

cystogram is used to assess the integrity ofbladder following trauma or surgery or toinvestigate fistulas involving the bladder. Thebladder is filled with contrast which appear asrounded radio-opacity and demonstrates the

corrugation of the bladder wall especially whennot well distended.


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The bladder wall is seen as the soft tissue

density structure separating the perivesicalfat and the intravesical contrast

Irregular collection of contrast may be

trapped between muscles fibres aftermicturition the prostate may protrude up

into the bladder base to produce a prostatic

impression the full bladder outline shouldbe smooth and regular


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Pelvic US

Us is best for demonstrating the internal

anatomy. Routine examination of the bladderrequires it to be moderately full. The normalbladder has a triangle shape in the sagittal plane

and that of a square with the corners roundedoff in the transverse plane. The normal wallthickness is 2-3mm when the bladder ismoderately full. The bladder wall is slightly

echogenic which contrasts against the anechoicurine within it this beautifully demonstrating theinternal anatomy.


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It is also possible to visualize the lower ureter inyoung children and the use of colour Doppler

allows identification of ureteric jet

Relations, Anterior, Anterior abdominal wall(medium level echo), Pubic bone (posterior

acoustic shadow) Posterior: Rectum (poorly demonstrated)

Lateral: Obturator internus muscle (medium

level echo), levator on muscle (medium levelecho)


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Superior: Loops of bowel (not properly

demonstrated because of bowel gas;

evidence of peristalsis)

Inferior: Prostate (lobuted out line,

homogenous medium level echo)


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CTThe bladder is best appreciated when filled withurine or contrast and it is seen as a thin walledstructure between the urine and the periversicalfat the wall should not exceed 4-5mm fat. Theappearance of the urine depends on thepresence or absence of contrast, when present it

hyperdense but when absent it is hypodense


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The seminar vesicles which lie on the posteriorwall of the bladder appear as tubular structurerelated to the superior aspect of the prostateand posterior to the lower bladder but anteriorto the rectum. There is a fat plane between the

seminal vesicles and the bladder. In asuprapubic axial slice, the various structuresfrom anterior to posterior are


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i Anterior abdominal wall [(subcut. fat (hypodence);rectus abdominic (isodense)]

ii Urinary Bladderiii Seminal vesicle (isodense)

iv Rectum (gas + faeces + contrast => mixed density)

v Sacrum (hyperdense)vi Gluteus maximus (isodense)

vii Subcuit fat (hypodense)

Psoas muscles are demonstrated laterally at higher levelbut obturator internus muscle at lower levels


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MRI

MR is ideal to demonstrate the relationshipof the bladder in the coronal and sagittal plane.It is seen as a low/ intermediate signal line on t1W images, similar to urine hence poor contrast

between them but on T2 W1 the bladder wall isseen as a thin low signal intensity line adjacent tothe high signal of fat outside and urine inside the

bladder


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The bladder wall enhances intensity with IV

gadolinium.

On T2 W1 the seminal vesicle is hyperintense but

it has intermediate intensity on T1 W1.

NB- They low intensity bladder wall may beobscured by the chemical shift artifact that result

from the difference in resonance frequency

between fat and water proton


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Plain Radiograph.

The bladder may be identified on plain filmespecially when full. It is seen as a round softtissue density surrounded by lucent line ofperivesical fat. It should be smooth and

symmetrical.

Angiography

This demonstrates the superior and interiorvesical artery originating from the internal iliacartery as radio opaque lines


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RNI (Radionuclide Cystography)

AgentNon absorbable radiotracer e.g. 99M TC-MAG3 (Mercaptoacetylglycine)


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B. Describe in detail the technique fordemonstrating the urinary bladder.

- Outline

Indications

C.I

Patient preparation

Equipment/materials

Techniques proper description

After care

Complication


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(1) Cystogram

Indications(i) Abnormalities of the bladder e.g. fistula

mass

(ii) After bladder trauma(iii) After bladder surgery

(iv) Haematuria

(v) Difficulty in micturition


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C.I

Acute urinary tract infection Patient preparation

(a) The patient micturates prior to the exam

(b) Patient is fasted for about 6hrs prior toexam

Contrast medium

HOCM or LOCM


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Equipment/Materials

(1) Fluoroscopy unit with spot film device(2) Jaques or foley catheter. In small infants a fine

(5-7F) feeding tube.

(3)

Casettee and film(4) Emergency tray

(5) Sunctioning machine

Preliminary filmConed view of the bladder


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Technique

(a) The patient lies supine on the x-ray table.

Using aseptic technique a catheter, lubricatedwith Hibitane 0.05% in glycerine, is introducedinto the bladder. Residual urine is drained.Contrast medium is slowly dripped in a bladderfilling is observed by intermittent fluoroscopy.It is important that initial filling is monitoredby fluoroscopy in case the catheter is in the

distal ureter (Therapy mimicking vesicouretericreflux) or vagina.


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(b) Any reflux is recorded on spot films

(c) The catheter should not be removed untilthe radiologist is convinced that no more

contrast medium will drip into the

bladder.(d) Film are taken in AP, lateral and oblique.


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Aftercare

(A) No special aftercare is necessary, but patientsand parents of children should be warned thatdysuria, possibly leads to retention of urine,

may rarely be experienced. In such cases asimple analgesic is helpful and children may behelped by allowing to micturate in a warmboth.

(B) Antibiotics should be prescribed if reflux isdemonstrated.


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CX

(A) Due to the contrast medium Adverse rxn may result from absoprtion of

contrast medium by the bladder mucosa Contrast medium-induced cystitis

(B) Due to the technique

(a) Acute U.T.I

(b) Catheter trauma-may producedysuria, frequency, haematuria andurinary retention.


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(c) Complications of bladder filling e.g.perforation from overdistentionprevented

by using a non-retaining catheter e.g. Jaques.(d) Retention of a foley catheter

(2)

U/S* Indications(i) Haematuria(ii) Bladder outlet obstruction(iii) Bladder tumour and other pelvic masses(iv) Post trauma


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C.I

None Patient preparation

Full bladder

Equipment/material(a) 3.5SMHz transducer

(b) U/S machine

(c) Electrolyte/Ultrasound gel


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Technique

The patient lies supine and the bladder isscanned suprapublically in transverse and

longitudinal planes. Measurement taken of

three diameters before and aftermicturition enable an approx. volume to be

calculated.


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After Care

None Cx

None

3)Pelvic CT Indications

as already stated C.I

(i) rxn to contrast medium(ii) Pregnancy


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Patient preparation

- Bowel preparation

- Fast in the day of exam

- Give 500ml dilute contrast agent orally the eveningpreceding exam

Equipment/Materials

(a) CT Machine

(b) CT Printer

(c) Contrast agents(d) Mechanical injector

(e) Emergency tray

(f) Suctioning machine


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Technique

We give 500ml dilute contrast agent orallythe evening preceding the exam and repeat thedose 45 to 60min before the exam. The colonand the rectum can be distended by placing atube in the rectum and insufflating with 20 puffsof air, or the limit of patient comfort. Allpatients are asked to avoid micturition for 30 to

40min before the exam to allow bladder filling.IV


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contrast medium is routinely given bymechanical inject or at 2 to 3ml/sec for a total

dose of 150ml of 60% contrast agent. Lie patientsupine angulate your gantry. Scanning throughthe pelvis is performed with contiguous 2-5mm

thick slices. We routinely scan the abdomen aswell in patients with known or suspected pelvicmalign.

N.B: A contrast material enema (200ml)occasionally may be necessary to expediteopacification of Rectosigmoid


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After Care

None Cx

Rxn to contrast

4)MRI Indication

As previously stated

C.IMetallic prosthesis or metals in the bodye.g. bullet.


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Patient preparation

No special preparation

Equipment/Materials

(i) M.R. machine

(ii) Gadolinium

(iii) M.R. printer


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Technique

Patient are usually examined supine duringshallow respiration, with the urinary bladder atleast half full before the study is begun.

Both T1-W (TR=300-500msec, TE=15

35msec) and T2W (TR = 1,500

2,100 msec,TE = 90-120 msec) spin echo sequences arenecessary for complete examination of thepelvis. T2W1 provide clear delineation of thebladder wall, as well as internal morphology ofthe prostate gland and the uterus.


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Transaxial images are obtained in every case;

additional views are performed in either thecoronal or sagittal plane. Coronal images areuseful for evaluating the seminal vesicle andbladder neoplasms that involve the lateral wallwhile sagittal images are necessary is cases inwhich a bladder neoplasm is located along theanterior or posterior wall.


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After Care

None

Cx

None

Bladder Anatomy Uchendu

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