Imaging Modalities for Diagnosis of Urethral Diverticula - Essay Example

Imaging Modalities for Diagnosis of Urethral Diverticula Introduction Urethral diverticula are localized saccular outpouchings of theurethra with mass effect in the anterior vaginal wall. The diverticula may be septated or unilocular, single or multiple. Similarly, they tend to have either a narrow or wide neck that is usually posterolateral to the urethra. Urethral may be acute or chronic and may at times lead to the development of abscess. In female, the defect tends to complicated by infection obstruction of the bladder outlet, the formation of calculi, and malignant. In females, urethral diverticula are usually first felt as diverticula arising from an infected and dilated peripheral urethral glands that lead to the formation of pseudodiverticulum. Patel and Chappel (2006, p249) present that the prevalence rate of urethral diverticula is estimated at 6% of the women population and can also affect all age groups. Many cases of urethral diverticula are normally asymptomatic, which renders most instances misdiagnosed. Therefore, high precision imaging techniques are critical for the diagnosis of the condition. Uretral diverticulum can be diagnosed using a number of imaging modalities such as double balloon urethrography, cross-sectional imaging, urethroscopy, and cystourethrography. Magnetic Resonance Imaging (MRI) can as well be used for the diagnosis of Urethral diverticulum, especially in the diagnosis of narrow-neck. It is therefore deemed as the most sensitive technique. Kawashima et.al (2004, pS200) also presents that transvaginal ultrasound can also be employed for the diagnosis particularly in women. However, the modality tends to be limited in differentiating paravaginal cysts from urethral diverticula. This has been associated to the fact that the mass effect exerted on the bladder base by the masses surrounded by the diverticula can create an imaging appearance that is almost identical to that seen in elderly male patients with enlarged prostate glands. Urethrography Contrast urethrography has been used in diagnosis of the congenital defect in male, which has also been identified as the main method for imaging of the male urethra. Consequently, there are two main types of contrast urethrography, for the diagnosis of the posterior or descending urethra, a descending urethrogram is used whereas for the anterior or ascending urethra, an ascending urethrogram is used. In general the modality employs the use of fluoroscopic facilities preferably, digital imaging with fluoroscopic capture facilities and a Balloon Foley catheter with a contrast medium that is distended into the urethra (Yoram, Ramon and Golomb 2003, p537). The key to the success of this modality is adequate distension of the urethra. Once the catheter is fully distended, oblique images will be formed indicating the full length of urethra from the navicular fossa to the external urethral sphincter (Rufford and Cardozzo 2004, pp1044,1045). Despite its effectiveness for the imaging diagnosis of the Urethral diverticula, contrast urethroscopy for males is associated with urinary tract infection, urethral trauma or contrast allergy that tends to arise from the distention of the catheter to the urethra. Patel and Chappel (2006, p249), however, assert that although it is the widely used technique for diagnosing urethral diverticula, it is sometimes regarded ineffective, especially when the diverticulum is collapsed or non-communicative and the ostium is invisible. They further present that the technique is of minimal use for the assessment of the shape and size of the diverticulum. The technique has a 67% chance of accuracy (Rufford and Cardozzo 2004, p1045). Double-balloon urethrogram (DBU) Another imaging modality that can be employed in the diagnosis of urethral diverticulum is the double-balloon urethrogram (DBU) sometimes referred to as positive pressure urethrogram. The technique involves the use of a double-balloon catheter that is distended into the urethra. A contrasting media is then injected into the catheter under high pressure thereby allowing the filling of all urethral communications. Patel and Chappel (2006, p250) posit that in various studies that have been done to compare the efficiency and reliability of this modality with other techniques, DBU has been found to have the highest sensitivity and accuracy. In a study conducted in 12 patients aimed at comparing DBU to other techniques such as the Voiding Cystourethrogram (VCUG), it was revealed that DBU had a 100% degree of sensitivity compared to 67% of VCUG. It was also reported that DBU had a high propensity of providing better data pertaining to the characteristics as well as the extent of the urethra diverticulum detected. Similarly, Patel and Chappel (2006, p250) document that in another study done to carry out a comparison between the two imaging modalities in 32 patients; there was 100% sensitivity in DBU as confirmed by surgery in contrast to 44% recorded by the VCUG technique. The 100% sensitivity was attributed to the DBU’s potential to detect even the smallest urethral diverticula, which VCUG modality missed. Ultrasonography Another imaging modality that can be used for the diagnosis of urethral diverticulum is the ultrasonography. There are various ultrasonographic techniques such as the transperineal, transvaginal and the endourethral ultrasound (Kawashima et.al 2004, pS198). Kawashima et.al (2004, pS198) presents that transvaginal and transperinal ultrasound can be very effective in the diagnosis of urethral diverticula. They derive their basis for this claim from a study conducted on 33 women with 15 urethral diverticula cases by Siegel in 1998. In the study, the women were each imaged with Ultrasound and VCUG techniques. The ultrasound technique detected 13 urethral diverticula cases out of the total 15 known cases. As a matter of fact, the study also revealed that compared to VCUG, ultrasound also revealed that the necks of the diverticula in all the 13 identified cases while the latter revealed the necks only in two patients. In another transvaginal ultrasound study conducted by Gerard in 2003 involving 25 urethral diverticula suspected cases, 10 patients were accurately diagnosed with the condition using ultrasound (Kawashima et.al 2004, pS198). There were no missed cases, however, when other rapid invasive modalities such as VCUG and urodynamics were used, there were three and eight missed cases respectively for each modality. Patel & Chapple (2008, p261) further point that compared to other methods like VCUG and DUB, ultrasound has almost 95% sensitivity and therefore may have high diagnostic validity. Another advantage that this technique also poises arises in the fact that it provides the ability to image in different orientations thereby allowing for clarification of the spatial relationships of any detectable diverticulum. On the contrary, the accuracy of the ultrasound technique just like the MRI, are usually operator dependent. Not only is the technique deemed safe, but it is also widely available owing to its relatively cheap cost. Patel & Chapple (2008, p261) asserts that the modality does not involve any form of radiation thus posing a reduced risk of infection as compared to their invasive counterpart modalities such as the DUB that involves insertion of catheters. Furthermore, ultrasonography has also been recognized for its precise approximation of the size of derviticula coupled up by the technique’s ability to visualize any communication. Ultrasound may also be particularly effective in the providing detailed urethral diverticulum that distinguishes it from multiple urethral diverticula, especially when compared to the MRI modality. Magnetic Resonance Imaging (MRI) MRI is another non-invasive imaging modality that can be used in the diagnosis of urethral diverticulum. It is deemed as the most expensive modality (Yoram, Ramon and Golomb 2003, pp537, 539). Based on a study that was conducted to analyze the effectiveness of MRI over other invasive imaging techniques such as DUB, MRI correctly recognized 13 cases of urethral diverticula out of 13 women involved in the study who underwent surgery for the same. On the other hand, urethroscopy correctly singled out 10 cases out of the 13. Similarly, Portein and Kielb (2008, p2) also report that in another separate study involving four patients with urethra diverticula conducted by Nietlich in 1998, MRI greatly aided in the diagnosis of all the four cases whereas the invasive DBU modality was negative for three cases. According to Portein and Keilb (2008, p2) MRIs have been increasingly used in the diagnosis of urethral diverticulum due to its multiplanar imaging capabilities that provide outstanding tissue contrast. They further expound that based on another study that was conducted by Daneshgari in 1999, the effectiveness of MRI modality was demonstrated when three cases of urethral diverticula were diagnosed by MRI after other invasive diagnostic methodologies such as VCUG as well as the non-invasive ultrasonography had failed to diagnose. Additionally, Ockrim, Allen and Shah (2009, p1550) present that MRI has been reported to detect urethral diverticula in patients who had negative double-balloon urethrography and VCUG studies. Therefore, they propose that some of the advantages of MRI are that it resolves the normal anatomy as well as urethral pathology with some exceptional multiplanar resolution. Moreover, Patel and Chappel (2006, p262) further posit that another advantage of the MRI modality over other invasive techniques arises from the fact that the patient does not necessarily require the insertion of catheters. Similarly, in the MRI technique, void is not necessary for the diagnosis process. Subsequently, unlike other modalities such as ultrasound, MRI eliminates the need for radiation exposure implying that it can be rapidly carried out in simple breath-hold sequence. Charlote, Hines, and Williams (2008, p465) contend that when MRI was compared to VCUG, it was revealed that VCUG failed to detect nearly 7% of urethral diverticula cases. Moreover, it was also reported that whereas MRI showed almost a 95% accuracy of the size and complexity of the diverticula, VCUG was found to underestimate these aspects. Conclusion As therefore seen, urethra diverticula are localized circular outgrowths of the urethra that affect the vaginal wall especially in females. The condition can be diagnosed using a variety of image-based modalities. These modalities are either invasive or non-invasive, with the invasive approaches being rapid and associated with urethral infections, whereas the non-invasive employ the use of scanners or exposure to radiation. Urethethroscopy entails insertion of contrast medium through catheters in the urethra. On the other hand, the double-balloon urethrography entails insertion of a double balloon catheter followed by the injection of a contrasting media under high pressure. It has an average successful rate of 56% for identifying correct urethral diverticula cases. Similarly, efficient imaging modality for diagnosing the condition is ultrasound technique. The technique is deemed as the second most effective in identifying the condition as well as determination of the exact size of the diverticula. MRI is the most effective technique as reported in most studies. The technique has almost 90% accuracy and sensitivity compared to the invasive techniques. However, its use is limited by the expensive nature of the technique. In general, for accurate diagnosis of the condition, a high degree of suspicion is necessary. References Al-Kawaz, Ula M. "Urethral Diverticulum after Endoscopic Urethrotomy, A Case Report." Journal of Medical Sciences 7, no. 3 (2009): 107-109. 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