Stephanie The1
(1)
Department of Women’s and Children’s Health Pelvic Floor Unit, Westmead Hospital, Sydney, NSW, Australia
Stephanie The
Email: wdu@optusnet.com.au
Electronic supplementary material
The online version of this chapter (doi: 10.1007/978-3-319-04310-4_7) contains supplementary material, which is available to authorized users.
Knowledge of the sonographic anatomy of female pelvic organs is important in the assessment of incontinence and the pelvic floor. A number of gynaecological conditions can present with stress or urge incontinence, and the presence of a large pelvic mass may worsen pelvic floor symptoms. This chapter outlines the technique of imaging of the female pelvic organs for the non-gynaecologist and common gynaecologic pathologies which may be encountered during pelvic ultrasound imaging.
The female pelvic organs can be imaged by transabdominal (Fig. 7.1) or transvaginal (Fig. 7.2) routes. Generally the best images are obtained by the transvaginal approach as the organs are closer to the intracavity transducer which is a high frequency transducer thus obtaining better quality images.
Fig 7.1
Transabdominal imaging of pelvic organs
Fig 7.2
Transvaginal imaging of pelvic organs
Technique of Transabdominal Imaging of the Pelvic Organs (Video 7.1)
Transabdominal ultrasound of the pelvic organs is generally performed with a full bladder. This allows for an overview of the entire pelvis (Fig. 7.1). A large pelvic mass may only be seen transabdominally and can be missed if only a transvaginal ultrasound is performed.
· Begin by scanning just above the pubic symphysis in the sagittal plane. Use the bladder as an acoustic window to the pelvis. Angle the transducer into the pelvis and identify the uterus (Fig. 7.3). Assess whether the uterus is anteverted or retroverted. Look for any uterine masses by sweeping the transducer from one side to the other. Rotate the transducer 90° to assess the uterus in the transverse plane. Sweep the transducer up and down the uterus.
Fig 7.3
Transabdominal image of the uterus in the mid-sagittal plane
· The endometrium should be assessed in the sagittal plane from the endocervical canal to the fundus. Rotate the transducer and assess the endometrium in the transverse plane.
· Following assessment of the endometrium, angle the transducer laterally towards the adnexae to assess the ovaries. The ovaries are hypoechoic ovoid structures which are generally located between the uterus and the iliac vessels (Fig. 7.4). Examine the ovary in two planes and then assess the other ovary. Assess the adnexal regions and Pouch of Douglas.
Fig 7.4
Transabdominal image of left adnexa showing the uterus and the left ovary
Transvaginal Assessment of Female Pelvic Organs (Video 7.2)
Transvaginal ultrasound scan is performed with an endocavity transducer. The patient should be asked to empty her bladder prior to the ultrasound scan.
· Begin by inserting the transducer in the sagittal plane to identify the uterus. To find the uterus, the transducer may need to be swept slightly to the left or right of the mid-sagittal plane or directed anteriorly or posteriorly.
· Once the uterus is identified, rotate the transducer so that a true mid-sagittal view of the uterus is obtained (Fig. 7.5). In the mid sagittal plane the endometrium should be seen from the cervix up to the fundus (calipers).
Assess the uterus by sweeping from one side to the other in the sagittal plane and then cranially and caudally in the transverse plane to examine the whole uterus.
· The endometrium should be assessed in the sagittal plane from the endocervical canal to the fundus. Rotate the transducer and assess the endometrium in the transverse plane.
· Then look for the ovaries in the transverse plane by withdrawing the transducer out slightly and angling towards to the left or right fornix of the vagina. Sweep cranially and caudally to find the ovary. Assess the ovary in two planes then assess the other ovary.
· Look at the surrounding structures between the uterus and ovaries for any other adnexal masses.
· Return to the midline and angle the transducer posteriorly to assess for free fluid in the Pouch of Douglas.
· At the end of the examination, assess the vagina during withdrawal of the transducer from the vagina. Gartner’s duct cysts are often only seen as the transducer is being removed.
The Normal Female Pelvis
In order to recognize pelvic pathology, it is important to be familiar with the anatomy of the normal pelvis. The following are images of the normal pelvis.
Figure 7.5 shows an anteverted uterus, where the fundus of the uterus is directed towards the bladder. The majority of women have an anteverted uterus. In this image the endometrial stripe is seen in the proliferative phase (first half of the menstrual cycle) as a triple layer appearance. The uterus is usually 6–10 cm in length when measured from the cervix to the fundus in a menstruating woman.
Fig. 7.5
Transvaginal image of an anteverted normal uterus in the mid sagittal plane
There is a Nabothian follicle in the cervix (blue arrow). These are commonly seen and is a normal finding. Figure 7.6 shows a retroverted uterus, where the fundus of the uterus is directed away from the bladder. In this image the uterus is in the secretory phase of the menstrual cycle. The endometrium has lost the triple layer appearance and is thick and echogenic (blue arrow).
Fig 7.6
Transvaginal image of a retroverted normal uterus in the mid sagittal plane
Figure 7.7 is of an anteverted uterus in the menstrual phase of the cycle. The endometrial echo is seen as a thin, regular echogenic stripe (blue arrow).
Fig. 7.7
Transvaginal image of a normal uterus in the menstrual phase of the cycle
The postmenopausal uterus is small and should be 4–6 cm in length, with a thin endometrial stripe. The endometrium should measure <4 mm in thickness (Fig. 7.8).
Fig. 7.8
Transvaginal image of a normal postmenopausal uterus
In this image of a normal ovary (Fig. 7.9) it can be seen as an oval hypoechoic structure. A few follicles can be identified – red arrows (usually about 6). There is a dominant follicle which measures 15.4 mm in diameter (calipers).
Fig. 7.9
Transvaginal image of a normal ovary in a woman of reproductive age
The normal ovary is usually about 4 × 3 × 2 cm in size in a woman of reproductive age. The ovary is usually found lateral to the uterus on each side, lying between the uterus and the iliac vessels. Occasionally the ovary is in the Pouch of Douglas or superior to the uterus.
Figure 7.10 is an image from a postmenopausal woman where the ovary is small and has little or no follicular activity.
Fig. 7.10
Transvaginal image of a normal postmenopausal ovary
Notes:
· The uterus may be anteverted or retroverted. However the majority of women have an anteverted uterus.
· The endometrium should be able to be visualised from the endocervical canal to the fundus of the uterus.
Common Pelvic Pathology
The following conditions are not meant to be an exhaustive list of pathology that may be encountered in the pelvis, but rather a short list of the more common pathologies that may be encountered in pelvic imaging. The general principles for managing some of the commonly encountered pathologies for the non-gynaecologist are outlined in Tips 7.1.
Leiomyomas (Fibroids)
These are common benign tumours arising from the smooth muscle cells of the uterus. Even though they are seen in up to 50 % of women, they are mostly asymptomatic. However fibroids can cause symptoms such as menorrhagia or pressure symptoms such as urinary frequency (especially if large).
Sonographically, fibroids are hypoechoic masses and can be intramural (within the walls of the uterus), subserosal (located under the serosal surface and distorting the serosal surface) or submucous (the fibroid projects partially or completely into the uterine cavity).
Figure 7.11a shows a retroverted uterus with an intramural fibroid (a) in the posterior myometrium. Here the fibroid is intramural because it is located wholly within the walls of the uterus. There is also a subserous fibroid (b) which distorts the anterior serosal surface. The fibroids can be seen as well defined hypoechoic solid masses with posterior shadowing. The blue arrows are pointing to the endometrium.
Fig. 7.11
(a) Transvaginal image of a uterus which contains an intramural fibroid (a) and a subserous fibroid. (b) Transabdominal image of an anteverted uterus with a posterior subserous fibroid (F)
Figure 7.12a shows a thickened endometrium that measures 16.8 mm. This is due to the presence of a well defined hypoechoic mass within the endometrium (blue arrow), which is a small fibroid. As the fibroid is within the endometrial cavity it is classified as a submucous fibroid. Figure 7.12b shows a submucous fibroid (blue arrow) disrupting the endometrium (red arrow).
Fig 7.12
(a, b) Submucous fibroids
Adenomyosis
This condition arises as a result of ectopic endometrial tissue within the myometrium. The benign invasion of the myometrium can result in smooth muscle hyperplasia. Women with adenomyosis may complain of menorrhagia or dysmenorrhea.
Figure 7.13 shows a bulky uterus with a thick posterior uterine wall. Compare the thickness of anterior wall (red arrow) to the posterior wall (blue arrow). Here the myometrium has a coarse heterogenous echotexture with some tiny myometrial cysts (white arrows) and streaky acoustic shadowing. The endometrium and its junction with the myometrium is often poorly defined (large arrow).
Fig. 7.13
Transvaginal image of a uterus with adenomyosis
Intrauterine Contraceptive Device (IUCD)
Figure 7.14 shows an IUCD which is visualized as a linear echogenic structure within the endometrial cavity (red arrow) with shadowing posteriorly (blue arrow).
Fig. 7.14
Image of a uterus which contains and intrauterine contraceptive device
Endometrial Polyp
These occur as a localized overgrowth of the endometrium and are seen as a protrusion into the endometrial cavity. Polyps can also arise as a result of tamoxifen treatment. Endometrial polyps are generally benign, but can cause abnormal bleeding such as intermenstrual bleeding, metorrhagia and infertility.
Polyps are best seen in the early proliferative phase of the cycle, when the endometrium is the thinnest and most hypoechoic.
In Fig. 7.15a an endometrial polyp can be seen as a small round echogenic mass within the endometrium (blue arrow). Application of Power Doppler shows the presence of a small feeding vessel within the mass.
Fig. 7.15
(a) Transvaginal ultrasound of a uterus which contains an endometrial polyp (blue arrow). (b) Saline sonohysterogram demonstrating the endometrial polyp
The presence of the polyp (blue arrow) is confirmed with infusion of saline into the cavity (Fig. 7.15b).
Endometrial Hyperplasia
Endometrial hyperplasia is a thickening of the endometrium which is caused by hyperplasia of the endometrial glands.
In Fig. 7.16, the endometrium is unusually thick and echogenic (blue arrow) with some cystic spaces (red arrows).
Fig. 7.16
Transvaginal ultrasound image of a uterus which has endometrial hyperplasia
Endometrial Carcinoma
In this postmenopausal woman (Fig. 7.17) who presented with vaginal bleeding, the endometrium is thickened (blue arrow) and there is invasion to the serosal surface of the uterus (red arrow).
Fig. 7.17
Transvaginal image of a postmenopausal uterus in the transverse plane with an endometrial carcinoma
Ovarian Cysts
Simple Ovarian Cyst
This image (Fig. 7.18) shows a thin walled cyst which is filled with anechoic fluid. The diameter of the cyst is 42.7 mm, which is >25 mm. Up to 25 mm, these anechoic structures may be a follicle. There is a crescent of normal ovarian tissue seen (arrow).
Fig. 7.18
Simple ovarian cyst
Ovarian cysts are often functional (especially if they are <5 cm) and usually resolve with time. Cysts are only classified as simple if they contain fluid which is completely anechoic, and do not contain septations, solid elements or nodules (see Tips 7.2).
Haemorrhagic Cysts (Corpus Luteal Cyst) arise after ovulation and are therefore most commonly seen in the second half of the menstrual cycle.
Figure 7.19 is an image of a haemorrhagic cyst with a typical heterogenous ‘lacy’ appearance with thin walls. Colour Doppler imaging shows circumferential peripheral vascularity (“ring of fire”).
Fig. 7.19
Corpus luteal cyst
Polycystic Ovaries
The Rotterdam Consensus Statement defines the polycystic ovary as having 12 or more follicles measuring between 2 and 9 mm in diameter, and/or an ovarian volume of greater than or equal to 10 cc [1].
Figure 7.20 shows an ovary with multiple follicles (blue arrows) which are peripherally arranged in the ovary. The stroma is echogenic (red arrow), which is also often seen in a polycystic ovary.
Fig 7.20
Transvaginal ultrasound image of a polycystic ovary
Endometriomas
Endometriosis occurs as a result of the presence of functioning endometrial tissue outside the uterus. This can result in a cystic structure, known as an endometrioma.
Figure 7.21 is an ovary containing a well defined cystic mass which is filled with homogenous echogenic material with a characteristic “ground glass” appearance (red arrow). This cyst has well defined walls, as well as a fluid – fluid level (blue arrow).
Fig. 7.21
Transvaginal image of an ovary which contains an endometrioma
Mature cystic teratomas (Dermoid) arise from the germ cell elements of the ovary. They are mostly derived from ectodermal components and therefore often contain hair, teeth and fatty sebaceous material which gives them a characteristic ultrasound appearance.
Figure 7.22 shows some of the features typically seen with a dermoid. These tumours are usually mostly cystic with mixed solid and cystic components. Typical features can include a highly echogenic mass (arrow) with posterior acoustic attenuation due to the fatty component of sebaceous material in the cyst. There is a fluid-fluid level.
Fig. 7.22
Transvaginal image of an ovary which contains a dermoid cyst
Another feature (not shown) include multiple thin echogenic lines caused by hair in the fluid in a dot-dash pattern.
Solid Ovarian Tumours
Although rare, they are important to identify because 65 % of solid ovarian tumours are found to be malignant [2].
Figure 7.23 shows a solid mass with heterogenous echotexture. Colour Doppler imaging shows the presence of vessel within the mass. The walls are smooth. There is posterior acoustic attenuation (blue arrow). The patient underwent surgical excision and pathology showed a fibroma, which is a benign solid ovarian tumour.
Fig. 7.23
Image of an ovary with a fibroma (solid ovarian tumour)
Hydrosalpinx
A hydrosalpinx occurs as a result of tubal blockage. This may be due to endometriosis, infection or adhesions. Hydrosalpinx can be asymptomatic but may be a cause of infertility.
Figure 7.24a, b shows a thin-walled tubular structure, filled with anechoic fluid. There is a crescent of normal ovary (yellow arrow). Other features are the incomplete septa (blue arrows) and complete septa within the dilated Fallopian tube. The ipsilateral ovary should be clearly seen and separate from this structure.
Fig. 7.24
(a, b) Hydrosalpinx
Tips 7.1 Keypoints in Imaging of Gynaecologic Organs for Non-gynaecologists
· Use the bladder and uterus as a guide to orientation in the pelvis (the bladder is anterior and the rectum posterior).
· Fibroids are common – they only need removal if the patient is symptomatic because of heavy bleeding (menorraghia) or has pressure symptoms, such as prolapse or incontinence.
· The endometrium should be <4 mm thick in a postmenopausal woman. Gynaecologic referral should be considered if endometrial thickness is >4 mm or the woman has postmenopausal bleeding
· Simple cysts <5 cm – usually functional and will resolve
All other cysts need referral unless the appearance suggest a haemorrhagic corpus luteum (Fig. 7.19).
Tips 7.2 Sonographic Criteria for Simple Cysts (Also See Chap. 1)
· Thin, smooth wall
· Anechoic contents
· No septa or nodules
· Posterior acoustic enhancement
References
1.
Timmerman D, Testa AC, Bourne T, Ameye L, Jurkovic D, Van Holsbeke C, Paladin D, Van Calster B, Vergote I, Van Huffel S, Valentin L. Simple ultrasound-based rules for the diagnosis of ovarian cancer. Ultrasound Obstet Gynaecol. 2008;31(6):681–90.CrossRef
2.
Revised 2003 consensus on diagnostic criteria and long-term health risks related to polycystic ovary syndrome. The Rotterdam ESHRE/ASRM-Sponsored PCOS Consensus Workshop Group. Fertility and Sterility, vol 81. No. 1. Jan 2004.