rad review of Ultrasound below the

RAD Magazine, 47, 549, 14-16 Dr Nicholas Ridley Consultant radiologist [email protected] Dawn McCafferty Sonographer Dr Gabriela Soares Clinical fellow, SHO Great Western Hospital Swindon

Introduction Figure 1 Transvaginal (TV) ultrasound is a very common investiga- Line drawing showing the main anatomical features tion principally focusing on the and . It is easy and the positions of the various . Note their to overlook the structures that can be seen below and adja- relationship to the symphysis line. cent to the cervix which include the , bladder, and perineal structures. On occasion there may be specific requests to view pathology associated with the perineum or vagina. Pathology in this region can include Bartholin’s, Skene’s and Gartner cysts. Urethral pathology can include diverticula, the effects of prolapse and iatrogenic findings such as silicone injections and tension-free vaginal tape (TVT). Incidental soft tissue masses such as lipomas may also be seen. Malignant lesions include vulval and vaginal carcinoma and cervical carcinoma extending inferiorly. Dynamic scanning can demonstrate the degree of prolapse with , rectoceles and enteroceles. Technique Using a transvaginal probe good views can normally be obtained of the vagina, urethra and perineal structures by withdrawing the probe slowly and reviewing the structures in turn. Getting the patient to Valsalva (strain down) can Figure 2 demonstrate cystoceles and rectoceles. Anterior angulation Skene’s duct (SK). Note relationship to the ure- of the urethra should be documented as this can cause out- thra (U) and the symphysis (S). flow obstruction. Transperineal scanning (TPUS) can be performed when indicated. This is normally not uncomfortable for the patient, This article specifically addresses the use of ultrasound; but of course the patient should be fully informed as to the however, it must be noted that MRI is a very useful imaging nature of the procedure and kept as covered as possible. modality in assessing the pelvis and the perineum. A linear 12-14MHz probe is ideal for superficial abnor- More advanced techniques for assessing the perineum malities. An abdominal 3MHz probe is useful for looking at and associated musculature include the use of 3D ultra- deeper structures. This can also show important abnormal- sound.12,16 ities such as the endometrial thickness in patients with post- Sonovaginography, in which gel or saline is instilled into menopausal bleeding who are unable to tolerate TV scanning the vaginal vault, can enhance the visualisation of vaginal and the transabdominal views are suboptimal. wall disease such as endometriosis and tumour.13 It should It is easy to get ‘lost’ when scanning the perineum and a not necessarily be used as a first-line technique.14 good marker is the symphysis pubis lying anteriorly. The urethra lies just behind this. The vagina lies between this Cysts and the anal margin (figure 1). The anus and rectum are Cysts are commonly seen in the perineum and the vaginal easily seen in transverse due to the thick low echogenic wall. Bartholin’s cysts are the most common cystic lesions outer muscular layer. Scanning should be performed trans- of the and arise from cystic dilatation of an obstructed versely and longitudinally with and without Valsalva. It is Bartholin’s duct. They usually lie at the posterior third of often worth getting the patient to indicate the precise site the majora and are usually hypoechoic with a well- of a mass. defined cyst wall. Echo enhancement is frequently seen pos- The level of the symphysis pubis can be used as a marker teriorly. can occur within the cysts and may to aid in the differentiation of cysts. For example Bartholin’s produce echogenic contents.7 cysts lie below this level and posteriorly, Skene’s duct cysts Gartner duct cysts have a similar imaging appearance to lie below the line and adjacent to the urethra and Gartner that of Bartholin’s gland cysts but are located above the duct cysts and urethral diverticula lie above. The line at the level of the most inferior aspect of the pubic symphysis in symphysis is also useful for seeing the extent of prolapse.1 the anterolateral wall of the upper portion of the vagina. rad review of ultrasound

Figure 4 Transvaginal scan showing development of a cysto- cele (C) on Valsalva. It projects below the symphy- seal line and there is angulation anteriorly of the urethra (U). B = bladder.

Figure 3 Urethral diverticula. Note the two periurethral diverticula (D). S = symphysis, B = bladder, U = urethra.

They are most often isolated findings, but can also be asso- ciated with abnormalities of the urinary system, eg renal agenesis, crossed fused ectopia. They are usually asymp- tomatic but occasionally are associated with dyspareunia. They can sometimes measure several centimetres.3 Skene’s duct cysts arise from blocked paraurethral glands. Skene’s glands are located just laterally to the external ure- thral meatus (figure 2). They can usually be distinguished from urethral diverticula by their position inferior to the pubic symphysis. Occasionally they can be seen more prox- imally, which may cause diagnostic confusion. Depending on the content they may have no internal echoes, or the echoes may diffusely line the interior of the cyst.16,17 Infection can cause pain, dysuria, and dyspareunia. It is homologous to the prostate being formed embryologi- Figure 5 cally from the same tissues. TVT tape. Transperineal scan showing the TVT tape Hydrocele of the canal of Nuck is an uncommon condition. artefact as an echobright line. The round with a small protrusion of extends through the inguinal ring into the inguinal canal, Prolapse corresponding to the processus vaginalis in males. Failure Pelvic floor dysfunction is a common condition that typically of obliteration results in either an indirect affects women older than 50 years and decreases the quality or a hydrocele of the canal of Nuck, which can extend to the of life. Weakening of muscles and support structures can . Ultrasound shows a cystic mass lying medial involve all three pelvic compartments and cause a combina- to the pubic bone.17 tion of symptoms, including constipation, urinary and faecal incontinence, obstructed defecation, pelvic pain and perineal The urethra bulging. Vaginal delivery is considered a major predisposing Urethral diverticula are estimated to occur in 1-6% of factor.9 Prolapse can be detected during transvaginal and women, especially those with stress incontinence. They can transperineal ultrasound and the findings may be helpful be associated with dysuria, post void dribbling, haematuria diagnostically. Using the symphysis pubis as a guide, asking and infection. Up to 10% of patients may develop stones the patient to Valsalva can demonstrate the development of within the diverticulum. Repeated infection and irritation cystoceles, urethral angulation and rectoceles (figure 4). As can predispose to malignant transformation of the urothelial the bladder prolapses inferiorly the urethra is angled ante- lining. They usually arise from the mid urethra and may riorly and this may lead to bladder outflow obstruction. wrap around the urethra with a horseshoe configuration.1 During these manoeuvres it is important not to put too They are usually cystic on ultrasound and communicate with much pressure on the probe or prolapse can be partially pre- the urethra (figure 3). They can be multilocular.4 vented. The technique is relatively easy to learn and there Large upper urethral diverticula wrapped around the ure- is significant teaching material available to demonstrate the thra can have mass effect on the base of the bladder (the principles.8 Transperineal ultrasound has been shown to be female prostate sign).15 valuable in quantifying pelvic organ prolapse.5 rad review of ultrasound

Descent of the bladder to ≥10mm and of the rectum to A clinical history should be taken in patients with bladder ≥15mm below the symphysis pubis are strongly associated outflow obstruction and specific scans taken during Valsalva. with symptoms.8 3D ultrasound techniques may open up Transperineal scanning is relatively easy to learn and can new possibilities for observing functional anatomy and exam- aid diagnosis in some cases. ining muscular and fascial structures of the pelvic floor.6 Transvaginal and transperineal ultrasound in addition to References showing rectoceles can also demonstrate perianal scar tissue 1, Hosseinzadeh K, Heller M T, Houshmand G. Imaging of the female per- and muscle defects. It may be used as an alternative to ineum in adults. Radiographics 2012;32(4). 2, Hamed S T, Mansour S M. Surface transperineal ultrasound and vaginal endoanal ultrasound. abnormalities: applications and strengths. BJR 2018;91(1085):20170326. 3, Wang X et al. Transvaginal sonographic features of perineal masses in Artefacts the female lower urogenital tract: a retrospective study of 71 patients. There are a number of artefacts that may be encountered Ultrasound Obstet Gynecol 2014;43(6):702-10. 4, Chou C P, Levenson R B, Elsayes K M et al. Imaging of female urethral at the time of scanning. Periurethral injection of silicone diverticulum: an update. Radiographics 2008;28(7)1917-30. appears as a snowstorm appearance of increased echogenic- 5, Dietz H P, Haylen B T, Broome J. Ultrasound in the quantification of ity around the upper urethra. TVT used for incontinence is female pelvic organ prolapse. Ultrasound Obstet Gynecol 2001;18(5):511- normally placed around the mid urethra. Correct positioning 14. 6, Dietz H P. Ultrasound imaging of the pelvic floor. Part II: three-dimen- can be assessed during ultrasound and correlates with suc- sional or volume imaging. Ultrasound Obstet Gynecol 2004;23(6):615-25. 10 cessful treatment outcome. It can migrate and cause symp- 7, Cheung Y T et al. Ultrasonography of benign vulvar lesions. toms (figure 5). Ultrasonography 2018;37(4):355-60. Ring pessaries may cause confusion when encountered 8, Dietz H P, Lekskulchai O. Ultrasound assessment of pelvic organ prolapse: the relationship between prolapse severity and symptoms. Ultrasound on scanning. They are seen as an echo poor, well defined Obstet Gynecol 2007;29(6):688-91. structure in the vaginal canal. 9, Chamie L et al. Translabial US and dynamic MR imaging of the pelvic floor: normal anatomy and dysfunction. Radiographics 2018;38(1):287-308. Solid masses 10, Kociszewski J et al. Tape functionality: sonographic tape characteristics and outcome after TVT incontinence . Neurourol Urodyn Lipomas may be seen in the perineum as with other parts 2008;27(6):485-90. of the body. Sebaceous cysts may also be encountered. Vulval 11, Bourgioti C et al. MR imaging of endometriosis: spectrum of disease. and vaginal carcinoma are rarely found de novo on ultra- Diagnost Interven Imag 2017;98(11):751-67. sound but any solid mass should be highlighted to the clin- 12, Shobeiri et al. Evaluation of and masses by 3-dimensional endovaginal and endoanal sonograph. J Ultrasound in Medicine ician. Cervical carcinoma may grow down the vagina. Rarely, 2013;32(8):1499-507. metastatic disease (including from the breast) may affect 13, Vinagre C et al. Sonovaginography in differential diagnosis of vaginal the vulva. and paravaginal abnormalities: preliminary results (abstract). 25th World Endometriosis affecting the vagina is rare and is usually Congress on Ultrasound in Obsterics and Gynaecology 2015. 11 14, Saccardi C, Cosmi E, Borghero A et al. Comparison between transvaginal associated with perineal scars due to . Patients sonography, saline contrast sonovaginography and magnetic resonance with known adnexal endometriosis may have marked imaging in the diagnosis of posterior deep infiltrating endometriosis. introital pain with no specific ultrasonic features. Ultrasound Obstet Gynecol 2012;40(4):464-69. Atrophic vaginitis is common but ultrasound does not 15, Kawashima A, Sandler C M, Wasserman N F et al. Imaging of urethral 2 disease: a pictorial review Radiographics 2004;24 Suppl 1:S195-216. show any specific features. 16, Kruger et al. Skene’s gland duct cysts: the utility of vaginal/transperineal Ultrasound has limited use day-to-day in the analysis imaging in diagnosis and mapping for surgery. A case series and review and diagnosis of skin conditions but high resolution probes of the literature. S Afr J Obstet Gynaecol 2016;22(2):62-64. are proving to be of some value to dermatologists, mainly 17, Chaudhari V V, Patel M K, Douek M et al. MR imaging and US of female urethral and periurethral disease. Radiographics 2010;30(7):1857-74. in a research setting.6 Conclusion A careful and deliberate review of the structures below the cervix when performing transvaginal ultrasound scanning may reveal a diverse range of clinically relevant pathology.