Neoplastic and Nonneoplastic Disease of the Bladder

Fig. 35.1

Historical image of transurethral US of the bladder. The picture demonstrates two small intraluminal bladder masses. Bladder wall is easily identified, showing that one of the bladder mass involves a small diverticulum

Fig. 35.2

Another “antique” image of transurethral US. Note the integrity of the echostructural pattern of bladder wall at tumor’s base

Fig. 35.3

A deep infiltrating bladder mass seen at transurethral US. The echostructural pattern of anterior bladder wall is easily seen, and it demonstrates a diffuse interruption

The patient is usually examined in the supine position with a sufficiently full bladder (200–300 ml). Bladder US requires careful and complete scanning with transverse and longitudinal sections.

The fine regulation of light is essential to obtain a significantly improved image quality and to correctly visualize the anterior wall (superficial compared to the skin) and posterior wall (deep). The use of high-frequency probing or the use of a second tissue harmonic imaging tool improves the quality of the imaging by reducing some reverberation artifacts. Effectively, abdominal ultrasound is limited in the evaluation of the anterior bladder wall due to reverberation artifacts, such as the rain effect.

Echo-Doppler may be useful to assess the ureteral jet and make a differential diagnosis of a bladder lesion.

Table 35.1 briefly resumes the quality of images obtained by different approaches and probes.

Table 35.1

Synthetic overview of imaging quality according to different probes and approaches to the bladder

	Abdominal	Transrectal or transvaginal	Transurethral
Instrument	Convex 3.5–5-MHz probe	Linear biplanar 7.5-MHz probe	Endoscopicprobe 5–7.5 MHz
Overall view	+++	+	++
Bladder wall appearance	+	+	+++
Trigone	++	+++	−
Anterior wall	+−	−	+
Lateral wall	++	−	+
Bladder dome	+	−	+
Surrounding organ	++	++	−

35.3 Report

The findings report should [9]:

Include the name of the physician examiner, place, and date.
Include the patient’s name, surname, and date of birth.
Briefly include all clinical information and the indications for the specific investigation.
Describe type of current ultrasound examination and the probe.
Use standard anatomical and ultrasound terminology.
Describe all abnormal findings, including number, side, shape, dimension, and characteristics.
Try to obviate to any difficulties or limits encountered while performing the investigation; underline the diagnostic accuracy of current test.
Suggest types of studies for further investigation; in case of serious findings, inform the patient and contact the patient’s doctor.

Example: Bladder Ultrasound Examination

Dr. Samuel Smith; Urology Department, NY City Hospital; June 26th, 2015

Patient: Richard Doyle; October 23th, 1947

Queries: asymptomatic hematuria

Abdominal bladder ultrasound by convex 5-MHz probe

Ultrasound findings:

Bladder filling volume is sufficient for exhaustive examination. The bladder wall thickness is normal. The right and left ureteral jets are present. Presence of a polypoid hypoechoic mass in the right bladder wall, 1.5 × 5 mm; the hyperechoic line of inner mucosa is not interrupted. Power Doppler images show considerable vascularity of the mass. The post-micturition volume is 20 ml.

Urologist consultation and cystoscopy are strongly suggested since these ultrasound and power Doppler images are suggestive of carcinoma of the urinary bladder.

The exams included:

1.

Two pictures of the bladder in transverse and longitudinal scan
2.

Two pictures of the mass in transverse and longitudinal scan (Fig. 35.4)

Fig. 35.4

An example of exhaustive US report in case of bladder cancer. The two images describe in detail the bladder mass with a transverse and longitudinal scan

35.4 Diagnosis

In the diagnosis of luminal defects of the bladder, it is of paramount importance to remember the normal bladder wall anatomy, which consists of mucosa, detrusor smooth muscle, and adventitia. This anatomical distinction is easily visualized by US, as the ultrasound appearance of the bladder wall is as a sandwich structure with a hypoechogenic muscular wall between the mucosa and adventitial layers, which are slightly hyperechogenic.

The possibility of distinguishing each component of the bladder wall depends upon bladder wall thickness, which varies with the state of urine filling; the upper limits are 3 and 5 mm for a full bladder and empty bladder, respectively. The trigone represents an important landmark: it is the triangular area which lies between the two ureteral orifices and the internal urethral orifice; in this region, the musculature of the bladder floor is dense and usually hypertrophied, forming the interureteric ridge.

All these concepts explain why a bladder ultrasound scan requires adequate bladder filling and the limits of US evaluation in cases of detrusor hypertrophy or small lesions.

35.4.1 Neoplastic Bladder Disease

Most bladder tumors are transitional cell carcinomas, accounting for approximately 90 % of all primary malignant lesions. They are usually found in the region of the trigone or bladder base or on the lateral walls as unique or multiple lesions. According to their intrinsic characteristics, they show different patterns in growth, with papillary, sessile (or infiltrative), and mixed papillary and sessile shape.

On ultrasound [10], they appear as a papillary (polypoid) or sessile (plaque with large base) lesions projecting into the lumen, usually quite echogenic and fixed with changes in the patient’s position. Ultrasound must describe the presence of wall alterations (assessment of lesions >3 mm), number, size, shape, and tumor staging.

In cases of superficial lesions, the bladder wall shows no echostructural alterations with a normal ultrasound appearance of the sandwich pattern (Figs. 35.5, 35.6, 35.7, and 35.8). Endophytic tumors appear as hypoechogenic, fixed proliferative lesions; however, they are sometimes hyperechogenic due to the presence of superficial calcifications.

Fig. 35.5

A small exophytic tumor at bladder neck

Fig. 35.6

A small, diffuse hyperechoic exophytic tumor at bladder wall. The normal hyperechoic internal layer is continued at tumor’s base. This is a typical pattern of superficial bladder cancer

Fig. 35.7

Another small exophytic bladder mass at bladder base

Fig. 35.8

Bladder scan by means of transrectal US. Abdominal US is negative

In cases of infiltrating lesions, the bladder wall shows an interruption [11] or deformation, and sometimes the bladder tumor extends beyond the bladder wall. The hyperechoic layer of bladder mucosa is interrupted (Figs. 35.9, 35.10, and 35.11).

Fig. 35.9

Small bladder tumor at bladder neck. Despite small size, US shows partial interruption of the hyperechoic mucosa layer. This is a histologically confirmed case of infiltrating bladder cancer

Fig. 35.10

A transrectal US showing an infiltrating bladder cancer. The entire bladder wall is diffusely interrupted, and the mass seems to reach the plane of seminal vesicle

Fig. 35.11

A transverse and longitudinal picture of an infiltrating bladder cancer. The mass is partially exophytic with a large base, and the echostructural pattern of bladder wall is diffusely interrupted

The diagnostic accuracy of US for bladder tumor diagnosis and staging [12] is generally considered to be poor (with a sensitivity ranging 50–94 % [13]) in comparison with other diagnostic modalities such as CT scan or MRI. This wide discrepancy in sensitivity is related to some tumor factors (e.g., size, location, macroscopic aspects), patient factors (gender, body mass index, bladder filling), and operator-dependent factors (different levels of experience [14]; moreover, the type of US device and the technical modality of performing the ultrasound examination may explain such a wide variation in results for the diagnosis and staging of bladder cancer.

35.4.1.1 Sensitivity and False-Negative Findings

The main limits of bladder ultrasound scanning depend upon spatial resolution and thus on the size, shape, and side of the bladder tumor.

Moreover, apart from the characteristics of bladder tumors, the ultrasound scan is limited by:

Bladder filling, which should be suboptimal in cases of acute or chronic cystitis
Bladder content, which is altered in cases of bladder catheterization by the balloon itself or by the presence of an air bubble or the contemporary presence of lithiasis
Bladder wall characteristics, such as in cases of progressive changes in the bladder wall observed in patients with lower urinary tract obstruction (bladder wall hypertrophy, diverticulosis, trabeculations)

Size: bladder lesions smaller than 5 mm may not be identified on ultrasound, especially on the bladder dome. On the other hand, the ability to diagnose vegetating/papillary lesions >5 mm is high.

Shape: flat or slow-growing non-vegetative tumors, such as carcinoma in situ, are not diagnosed by imaging.

Side: during abdominal US, the rain effect at the anterior bladder wall reduces spatial resolution [15] (Fig. 35.12), even for tumors >5 mm. Some small wall defects at the bladder neck or trigone could be confused with a median lobe (Fig. 35.13).

Fig. 35.12

A large, exophytic mass at anterior bladder wall. Note the difficulties in the correct identification of tumor’s base, mainly due to the side of the tumor

Fig. 35.13

An infiltrating bladder tumor at the bladder neck. At transverse abdominal US, due to tumor’s side and reduced bladder filling, the ultrasound appearance of tumor is confusing. At linear transrectal US, bladder tumor is easily identified and distinctive from the normal prostate

35.4.1.2 Specificity and False-Positive Findings

A false-positive finding on an ultrasound scan is particularly frequent in cases of macroscopic hematuria or in cases of reduced bladder filling.

The most frequent cause of false-positive findings is represented by bladder wall hypertrophy caused by lower urinary tract obstruction. Bladder wall hypertrophy or diverticulosis or trabeculations could be confused with wall defects.

Other false-positive findings are represented by endovesical clots, which are frequent in cases of macroscopic hematuria independent from the primary cause. Clots appear as variably sized hyperechoic masses, usually on the bladder floor; they are mobile, depending on decubitus movements. In cases of clot adhesion to the bladder wall, the use of color Doppler will show the absence of a color signal.

Other common conditions associated with false-positive findings include acute or chronic cystitis. In acute conditions (Fig. 35.14), there is diffuse increased hypoechogenicity and an increased thickness of the bladder wall at the mucosa layer, especially at the level of the bladder floor and at the trigone. Anechoic bladder content is substituted by fine, mobile echoic pattern.

Fig. 35.14

A typical abdominal US in case of acute cystitis. The bladder filling is markedly reduced, and the irregular increased thickness of bladder wall is diffused

In chronic conditions, increased hyperechogenicity and thickness of the bladder wall at the mucosa level is more nonspecific, except in cases of tuberculosis or bilharziasis.

Another common cause of false positives is the presence of small or irregular prostatic median lobes.

Another rare condition associated with false-positive findings is the presence of urachal remnants.

Table 35.2 shows false-negative and false-positive findings related to bladder and tumor ultrasound scan.

Table 35.2

Main reasons for false-negative and false-positive findings at bladder ultrasound scan

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