Benign Gynaecological Disease

Ultrasound (US)

Transabdominal and transvaginal ultrasound (TVUS) imaging are the primary initial imaging techniques for examining the female pelvis. Indications include evaluation of a suspected pelvic mass or uterine enlargement, acute pelvic pain, investigation of postmenopausal bleeding and characterisation of ovarian masses, as well as guiding invasive procedures such as biopsy and drainage.

Ultrasound (US) has many advantages: it is relatively inexpensive, provides multiplanar views, is widely available and lacks ionising radiation or contrast medium administration ( Fig. 35.1 ).

Computed Tomography (CT)

The role of computed tomography (CT) in benign gynaecological conditions has largely been replaced by MRI, although it may be used to investigate acute pelvic pain where US is equivocal.

Magnetic Resonance Imaging (MRI)

The role of MRI in gynaecology has evolved rapidly over the last decade. High-resolution images with excellent distinction between the soft-tissue pelvic structures provide exquisite detail and anatomy of the gynaecological tract. It is now the investigation of choice for assessment of Müllerian duct anomalies and indeterminate adnexal mass characterisation following initial US assessment ( Fig. 35.2 ). MRI is also valuable in the assessment of many benign gynaecological diseases as a problem-solving tool.

Hysterosalpingography (HSG) and Fallopian Tube Catheterisation

Hysterosalpingography (HSG) is used to investigate infertility. It is best performed in the first 10 days of the cycle, but not during active bleeding. Contraindications are pregnancy and active pelvic infection. Complications include pain, pelvic infection, haemorrhage and vasovagal attacks ( Fig. 35.3 ).

Fallopian tube catheterisation uses small catheters and guidewires to cannulate the fallopian tubes and establish patency if there is cornual occlusion. Pregnancy rates of approximately 60% have been reported following the procedure ( Fig. 35.4 ).

Sonohysterography

This technique involves placement of a 5F balloon catheter through the cervix and instilling sterile saline or a microbubble solution under direct US visualisation ( Fig. 35.5 ). The procedure is well tolerated with contraindications and complications similar to HSG. The advantage over standard HSG is the lack of radiation exposure and that the patient can undergo the procedure at the same appointment with the standard gynaecological US assessment. It is indicated for evaluation of masses detected in the uterine cavity at US, and fallopian tube patency.

Müllerian Duct Anomalies

These disorders are classified according to Buttram and Gibbons and the American Fertility Society.

Class I: Uterine Agenesis or Hypoplasia

This results from the failure of the normal development of both Müllerian ducts; however, the ovaries are normal in these patients, helping to distinguish the condition from other syndromes such as androgen insensitivity and gonadal dysgenesis.

The commonest subtype of uterine agenesis is the Mayer–Rokitansky–Küster–Hauser (MRKH) syndrome. There is uterine and vaginal agenesis or hypoplasia with intact ovaries and fallopian tubes. Detection of uterine remnants may be difficult on US, and sagittal and axial MRI are more reliable ( Fig. 35.6 ).

Class II: Unicornuate Uterus

This results from the failure of the normal development of one Müllerian duct, and is associated with increased spontaneous abortion and obstetric complications.

Unicornuate uterus may be suspected on US or HSG ( Fig. 35.7A ). On T ₂ weighted (T ₂ weighted image) magnetic resonance (MR) images, the unicornuate uterus demonstrates a curved, elongated uterus with tapering of the fundal segment off midline (the ‘banana-like’ configuration), which is best seen on the axial oblique (long-axis) images (see Fig. 35.7B ). Normal uterine zonal anatomy is maintained. If a rudimentary horn is present, it may be functional and contain endometrium, or be non-functional. Functional rudimentary uterine horns, which do not communicate with the main horn, will accumulate blood products and lead to haematometra. There is an associated increased risk of endometriosis ( Fig. 35.8 ).

Class III: Uterus Didelphys

Non-fusion of the Müllerian ducts results in uterus didelphys with two separate normal-sized uterine horns and cervices. A longitudinal vaginal septum is present in 75% of cases. Uterus didelphys can be demonstrated on US ( Fig. 35.9A ) and MRI examination is helpful to further assess the duplication and associations. On coronal oblique T ₂ weighted image, the two uterine horns can be appreciated, which are usually widely separated with preservation of the endometrial and myometrial widths (see Fig. 35.9B and C ).

Class IV: Bicornuate Uterus

Incomplete fusion of the cephalad extent of the uterovaginal horns with resorption of the uterovaginal septum results in a bicornuate uterus. Obstetric complications relate to the degree of non-fusion of the horns. Widely divergent horns on HSG can suggest the diagnosis ( Fig. 35.10A ), although MRI examination is necessary to assess this appearance further and differentiate from a septate uterus (see Fig. 35.10B ). T ₂ weighted coronal images show the communicating uterine horns with a concave fundus. They are separated by an intervening cleft ≥1 cm in the external fundal myometrium, which demonstrates normal myometrial signal intensity on all sequences. Normal zonal anatomy is seen in each horn.

Class V: Septate Uterus

This is the commonest Müllerian duct abnormality, with incomplete resorption of the fibrous septum between the two uterine horns. The septum may be partial or complete, extending to the external cervical os. The differentiation between the septate and the bicornuate uterus is clinically important because the septate uterus has the worst obstetric outcome of all Müllerian duct abnormalities. The fibrous septum is best demonstrated on coronal oblique T ₂ weighted image MR images, with the key differentiating factor being the external uterine contour, which is convex, flat or concave (≤1 cm) in contrast to the bicornuate uterus ( Fig. 35.11 ). The dimensions are important to assess accurately on MRI as these patients may be candidates for surgical resection of the septum, most commonly with a hysteroscopic metroplasty.

Class VI: Arcuate Uterus

This is considered a normal variant and is thought to have no significant effects on fertility or pregnancy. On imaging there is a smooth, broad indentation of the fundus of the uterine cavity, with a normal external uterine contour ( Fig. 35.12 ).

Vaginal Anomalies

Vaginal agenesis can occur in MRKH and androgen insufficiency syndrome.

Defects in vertical and lateral fusion of the Müllerian ducts can result in vaginal septa formation. It may cause obstruction, preventing loss of menstrual blood and leading to haematocolpos or haematometrocolpos and cyclical pain. An imperforate hymen is the most common abnormality detected (prevalence 0.1%). On clinical examination it has a thin bluish appearance, from blood products, and transilluminates. Further imaging is often not required. A transverse septum is thicker, often appearing pink in colour with no transillumination. Imaging of the length of the defect allows surgical planning. It is possible in didelphys to have one uterine horn with a perforated hymen and normal menstruation and the other horn to have an imperforate hymen and haematocolpos.

On MRI, a transverse septum is identified as low signal intensity fibrous tissue on T ₂ weighted image sagittal images, with loss of vaginal zonal anatomy ( Fig. 35.13 ). Dilatation of the vagina with intraluminal fluid of intermediate T ₂ and high T ₁ fat-suppressed signal intensity and the occasional presence of fluid/debris levels can also be shown to confirm blood products in haematometrocolpos. Treatment focuses on allowing normal sexual function either by excision of the membrane in imperforate hymen, interposition of bowel or a split skin graft in a transverse septum.

Imaging of Ambiguous Genitalia

This is a broad spectrum of disorders, including male (46XY)/androgen insufficiency syndrome and female (46XX) pseudo and true hermaphroditism and gonadal dysgenesis, including Turner's syndrome. Imaging is important for depicting internal genitalia and identifying gonads. US is the initial imaging investigation of choice, but MRI is often used as a problem-solving tool. Streak ovaries, as seen in Turner's syndrome, are particularly difficult to detect and appear as low signal stripes on T ₂ weighted image MRI. Gonads naturally demonstrate restricted diffusion and diffusion weighted imaging (DWI) can be helpful to identify occult gonads. Additional high signal intensity foci should raise the suspicion of malignant change.

Fibroids

Fibroids, or leiomyomas, are benign smooth muscle tumours found in up to 40% of women. They are usually multiple and are classified according to their location ( Fig. 35.14 ):

• submucosal (projecting into and distorting the uterine cavity);

• intramural (within the myometrium); and

• subserosal (protruding out of the serosal surface of the uterus).

Symptoms may be caused by mass effect and location of the fibroids and include menorrhagia, pain, urinary symptoms, infertility and obstetric complications. Torsion of narrow-based subserosal fibroids can cause acute pelvic pain.

As well as medical treatments and hysterectomy, other procedures such as myomectomy, uterine arterial embolisation (UAE) and MR-guided high-intensity focused ultrasound (HIFU) ablation may be appropriate for some patients wishing to preserve fertility.

US is often the initial radiological investigation, with MRI reserved for patients with inconclusive US or for pre-treatment myomectomy and UAE planning.

Ultrasound

The fibroid uterus is typically enlarged with an irregular or lobulated outline. The US appearance of fibroids depends on the proportion of smooth muscle, fibrosis and degeneration, as described in Table 35.1 ( Fig. 35.16b ). Calcification secondary to necrosis or degeneration appears as shadowing echogenic foci on US or calcifications on HSG (see Fig. 35.15 ) and CT.

TABLE 35.1

Imaging Characteristics of Fibroids, Degenerative Changes and Lipoleiomyomas

	Ultrasound	T1	T2	Gadolinium Contrast
Normal ( Figs. 35.14 and 35.15 )	Solid, round, well-circumscribed, hypoechoic mass, Acoustic shadowing if calcified	Intermediate	Well-defined low signal areas	Enhanced less than adjacent myometrium
Cystic degeneration ( Fig. 35.16A )	Anechoic foci within leiomyoma	Isointense to normal myometrium	Well-defined high signal cystic areas	Fluid areas have no enhancement
Red degeneration ( Fig. 35.16B-D )		High signal areas	Moderate to high areas Peripheral low signal rim of haemosiderin	None or variable
Hyaline degeneration	Similar to normal leiomyoma	Iso or intermediate signal	Low T 2 signal areas	Minimal
Myxoid degeneration		Low T 1 signal	Very high T 2 signal	Minimal or laminated
Lipoleiomyoma ( Fig. 35.17 )	Hyperechoic foci	High signal Suppress on fat-saturated sequences	Moderate to high T 2 signal	Variable