Objectives

• List the pertinent questions the sonographer should ask the patient

• Describe the effect of hormones on the ovarian cycle.

• Define the sonographic characteristics of a simple ovarian cyst

• Discuss the sonographic findings in a complex ovarian mass

• Describe the sonographic findings in the common solid ovarian mass

• Define what a functional ovarian cyst is

• Name the characteristics found in polycystic ovarian disease

• Describe the locations that endometriosis may be found

• Describe the sonographic findings in ovarian neoplasms

• Discuss the sonographic findings in a dermoid cyst

• Define the ultrasound and Doppler parameters used in ovarian torsion

• List the sonographic criteria for ectopic pregnancy

Introduction

Ultrasonography has proven clinically useful to characterize adnexal masses, evaluate abnormal bleeding, assess infertility, monitor follicle growth, and aid in the localization of transvaginal needle aspiration and biopsy. Both transabdominal and transvaginal sonography are important in these evaluations. Transabdominal imaging furnishes a global survey of anatomy, whereas transvaginal imaging provides improved texture determination and characterization of internal architecture of the ovary, vascular anatomy and adnexal area.[17] It is important to note that information from the clinical pelvic examination is required for optimal interpretation of the ultrasound, thus necessitating good communication between the referring physician and the sonologist/ sonographer.

The complete sonographic assessment begins with a history and limited physical assessment. This is followed by a complete sonographic examination, including transabdominal and transvaginal ultrasound (in most patients). The transvaginal probe offers a superb way of performing an internal physical examination with the ability to "see" with the probe what the physician is feeling on physical examination. The transvaginal probe allows the sonographer to identify which organs are tender and most likely the cause of the patient's discomfort.

It is the sonographer's job to ask the RIGHT questions to the patient. Too often there is very limited or irrelevant information provided. If the sonographer asks the right questions and follows a logical line of reasoning, the patient will most likely lead the sonographer to the differential diagnosis. The job of the sonographer is to know the correct questions to ask to suggest the diagnosis. The role the sonographer plays in the examination process is entirely different from other imaging specialties. If the sonographer has no idea as to what the diagnosis could be, the appropriate images will not be recorded and the information transferred to the sonologist will be limited. The sonologist's job is to report the findings in light of the total picture and "confirm" the diagnosis and expand the differential diagnosis.

The assessment with the transvaginal probe is akin to a physical or "sonophysical" examination. The sonographer should answer these questions:

• Is a mass present?

• Is this the mass the clinician feels?

• Is this now or was it ever, the cause of the patient's pain?

If the sonographer can identify the exact area or organ where the source of the mass or pain arises from, the treatment options are usually obvious and the clinician's job is half completed. Without this information and with a sonographic impression of "no abnormality detected", one really is not much further ahead than before the examination was begun.

Ovarian Physiology

The normal ovary has over two million primary oocytes at birth although only 10 of these mature each cycle throughout the reproduction years. Of the 10 Graafian follicles that begin to mature, only one becomes dominant and grows to a size of 18-20 mm by mid-cycle when it ruptures. The other nine follicles become atretic and fibrous. The oocyte is released and taken up by the fallopian tube awaiting the arrival of the sperm. After release, the follicle collapses, there is some hemorrhage into the cavity and the granulosa cells in the inner lining proliferate and swell to form the corpus luteum of menstruation. This lasts 14 days and then the corpus luteum degenerates and fibroses.

A middle aged woman will ovulate nearly 400 times in her reproductive cycle and a quarter of a million follicles will be stimulated to varying degrees over this time. It is not surprising that such a dynamic organ as the ovary can form over one hundred different types of tumors, both benign and malignant. These masses are described on ultrasound as primarily cystic, complex, or predominantly solid; however the final diagnosis is left to the pathologist. Precise histologic diagnosis on the basis of ultrasonography alone is usually impossible. The primary role of sonography is to indicate the need for surgical or medical intervention.

Ovarian Evaluation

Cystic Pelvic Mass. The ovary's function is to mature oocytes until ovulation, under the influence of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the pituitary. At the same time the ovary synthesizes androgens (male hormones) and converts them to estrogens (female hormones). If fertilization occurs, the corpus luteum ovary produces progesterone after ovulation to sustain the early pregnancy until the placenta can do so at 10 to 12 weeks of gestation.

Usually only one follicle enlarges from 3 mm to approximately 24 mm over about 10 days in the mid- and late-follicular phase of the cycle. This is followed by ovulation with formation of the resulting corpus luteum. With an inadequate preovulatory LH surge an abnormal unruptured follicle will persist for up to 60 days as a webbed cystic structure from 1 to 10 cm in size. These so-called functional cysts may produce discomfort and/or delayed menses but can be observed to regress within two cycles with serial ultrasound studies.

The majority of ovarian masses are simple cysts, most of which are benign. Sonographic criteria for a simple cyst include a thin smooth wall, anechoic contents, and unilocular with good acoustic enhancement (see Fig. 1).

Figure 1. Septated 1 cm Follicle Cyst

Common Cystic Ovarian Mass

• Follicular cyst

• Corpus luteum cyst of pregnancy

• Cystic Teratoma

• Paraovarian Cyst

• Hydrosalpinx

Complex Mass.
Complex masses may be benign or malignant. A simple cyst that hemorrhages may appear as a complex mass with areas of anechoic fluid and solid clusters of clotted red blood cells. In patients of reproductive age the classic differential of a complex adnexal mass is ectopic pregnancy, endometriosis, and PID. (Fig.2) Dermoids and other benign tumors can appear in a similar fashion.


Figure 2. PID and bilateral tubo-ovarian abscess

Complex cysts can be remembered by the acronyn CHEETAH. This refers to Cystadenoma - (serous or mucinous), Hemorrhagic, Endometrioma, Ectopic, Teratoma, Abscess, and Hydrosalpinx.

Common Complex Masses

• Cystadenoma (serous or mucinous)

• Hemorrhagic

• Endometrioma (low level echoes)

• Ectopic Pregnancy

• Teratoma (dermoid)

• Abscess

• Hydrosalpinx

Solid Mass.
The primary criteria for a malignant ovarian mass usually includes a diameter greater than 4 cm, a thick wall or septum greater than 3 mm, along with solid to mostly solid texture or nodularity. In addition, ascites, enlarged nodes, or a fixed mass on the transvaginal examination are signs of extension locally or remote from the primary mass. (Fig. 3)



Figure 3. Ovarian Carcinoma (bilat) - 42 y/o G3P3. pain, mass on physical exam

Mixed solid to cystic ovarian masses are typical of all the epithelial ovarian tumors, the most common are the serous types: the cystadenoma and cystadenocarcinoma. The more sonographically complex the tumor, the more likely it is to be malignant, especially if associated with ascites. An ovary with a volume twice that of the opposite side should be considered abnormal. When a solid mass is found, care should be taken to identify a connection with the uterus to differentiate an ovarian lesion from a pedunculated fibroid.

The differential diagnosis of a solid-appearing adnexal mass includes, pedunculated fibroid, dermoid, fibroma, thecoma, granulosa cell tumor, Brenner tumor, and metastasis. TOA, hemorrhagic cysts, and ectopic pregnancy also may appear to have solid characteristics.

Common Solid Masses

• Adenocarcinoma

• Solid Teratoma

• Arrhenoblastoma

• Fibroma

• Dysgerminoma

Doppler of the Ovary. When any abnormality of the ovary is detected, including a cyst, Doppler examination should be performed. In the case of cysts, color Doppler is helpful in differentiating an echo-free, potential cyst from adjacent vascular structures. Color also can be used to localize flow for pulsed Doppler, which should be obtained on all ovarian masses. (see Fig. 3).

Pulsed Doppler interrogation of the adnexal branch of the uterine artery, the ovarian artery, or intratumoral flow is performed to determine the resistive index (RI = systolic - diastolic/systolic) or pulsatility index (PI = systolic - diastolic/mean). Patients with normal menstrual cycles are best scanned in the first 10 days of the cycle; this avoids confusion with normal changes in intraovarian blood flow, since high diastolic flow occurs in the luteal phase around the corpus luteum.[23]

A debate in literature exists regarding the value of a resistive index in distinguishing between benign and malignant adnexal masses. The largest study in the literature uses a cutoff of greater than 0.4 as a normal RI in a nonfunctioning ovary.[13] Other investigators employ a PI of greater than 1 as normal.[7] Intratumoral vessels, low-resistance flow, and absence of a normal diastolic notch in the Doppler waveform are all signs that are worrisome for malignancy [7]; however, abnormal waveforms can be seen in inflammatory masses, metabolically active masses (including ectopic pregnancy), and corpus luteum cysts.[8] The most significant problem in the use of a resistive index is that it is not a sensitive indicator of malignancy. One recent study found a low resistive index in only 25% of malignant lesions.[14]

Benign Adnexal Cysts

Functional ovarian cysts result from the normal function of the ovary and are the most common cause of ovarian enlargement in young women. Functional cysts include follicular cysts, corpus luteum cysts, and hemorrhagic cysts. Most cysts measure less than 5 cm in diameter. Most regress during the subsequent menstrual cycle, so a follow-up examination in 6 weeks usually documents change. Hormonal therapy is sometimes administered to suppress a cyst.

Follicular Cyst.
A follicular cyst occurs when a mature follicle fails to ovulate or involute. These cysts are usually unilateral and vary from 3-8 cm in size, but they can be as large as 20 cm in diameter. The cysts have also been associated with a short menstrual cycle. The cyst may regress spontaneously (usually within 2 cycles) and can be followed with ultrasound. If the cyst remains for 3 cycles it is likely not functional.

If a cyst less than 6 cm persists in the premenopausal patient, (or 4cm in the post menopausal patient), it is likely simple and can be monitored with ultrasound. Larger masses may be neoplastic and surgical intervention is usually considered. Ultrasonically guided needle aspiration has become popular for deflating recurrent simple ovarian cysts in carefully selected cases.

The differential diagnosis of simple adnexal cysts includes functional cyst, paraovarian cyst, cystadenoma, cystic teratoma, endometrioma, and rarely TOA.

Follicular Cysts

• Occurs when a dominant follicle does not succeed in ovulating and remains active though immature

• Usually unilateral

• Thin-walled, translucent, watery fluid, may project above or within surface of the ovary

• May grow 1 to 8 cm

• Usually disappear spontaneously by resorption or rupture

• Clinical: asymptomatic to dull, adnexal pressure and pain, abnormal ovarian function, torsion of the ovary resulting in severe pain

• US: simple cyst

Corpus Luteum Cysts.
Corpus luteum cysts result from reabsorption of the blood in the corpus hemorrhagium. The persistent cyst may cause pain, tenderness, and delayed menstruation. These cysts usually are less than 4 cm in diameter (Fig. 4). They are prone to hemorrhage and rupture. Owing to the hemorrhagic nature of these cysts, they usually appear as a complex mass with central blood clot and echogenic septations.

Figure 4. Corpus Luteum Cysts

This appearance is difficult to distinguish from ectopic pregnancy and endometriosis. Corpus luteum cysts are particularly common during the first trimester of pregnancy, when maximum size is reached by 10 weeks, and resolution occurs by 16 weeks. Duplex Doppler reveals prominent diastolic flow in corpus luteum cysts. This low-velocity waveform is present throughout the luteal phase of the cycle.[23]

Corpus Luteum Cysts.

• Cysts result from hemorrhage within a persistently mature corpus luteum

• Filled with blood and cystic fluid

• May grow 1 to 10 cm in size

• May accompany IUP

• Clinical: irregular, menstrual cycle, pain, mimic ectopic pregnancy, rupture

• US: "cystic" type lesion; may have internal lacy pattern of fibrinous bands within the clot secondary to hemorrhage

Polycystic Ovarian Disease.
Polycystic ovarian disease, which includes Stein-Leventhal syndrome (infertility, oligomenorrhea, and hirsutism), is an endocrinologic disorder associated with chronic anovulation. Pathologically, the ovaries contain an increased number of follicles. Sonographically, the ovaries appear normal or enlarged with echogenic stroma.[19] The number of small follicles is often increased bilaterally (> 1 cm), usually to more than 5 in each ovary. Endovaginal ultrasonography is more sensitive for detecting these small follicles than is transabdominal scanning.[22] This "disease" is now referred to as polycystic ovary syndrome (PCOS) where the diagnosis is based on elevated levels of serum LH or ratio of LH to FSH. A common feature, especially in obese women, is insulin resistance and slightly elevated serum insulin levels with a predisposition of three times the normal population, to developing diabetes. Some success in lowering androgen levels has been achieved with insulin lowering agents.[26]

Polycystic Ovarian Disease

• Stein-Leventhal syndrome

• Bilaterally enlarged polycystic ovaries

• Occurs in late teens through twenties

• May have endocrine imbalance

• Spectrum of ultrasound appearances

• Clinical: amenorrhea, obesity, infertility, hirsutism

• US: multiple tiny cysts around the periphery of the ovary; ovary may be normal size or enlarged

Paraovarian Cysts.
Paraovarian cysts account for approximately 10% of adnexal masses. These cysts are remnants of the Wolfiaan duct that parallels the upper third of the vagina, uterus, and fallopian tubes. Paraovarian cysts have thin, deformable walls that are not surrounded by ovarian stroma. They may be easily missed and mistaken for ovarian cysts; however these cysts are confirmed by separating them cyst from the ovary with the transvaginal examination. Patient's are asymptomatic when the paraovarian cysts are small and non-tender, but the cysts may become large with extention into the upper abdomen. The cysts can arise anywhere in the adnexal structures; if they fill the pelvis, their point of origin may not be clear. Their size does not change with the hormone cycle

Paraovarian Cysts

• Usually simple

• Can bleed or torse

• Wolfian duct remnants

• Comprise 10% of all adnexal masses

• Located in broad ligament

• Clinical: asymptomatic US: simple cyst adjacent to ovary

• US: simple cyst adjacent to ovary

Theca Lutein Cysts.
Theca lutein cysts appear as bilateral enlarged ovaries with multiloculated cystic masses. This condition is associated with high levels of human chorionic gonadotropin (HCG). Theca lutein cysts are seen most frequently in association with gestational trophoblastic disease (30%) polycystic ovarian disease syndrome, or Clomid therapy infertility patients. The abnormality may resolve after treatment in a few months.

Theca Lutein Cysts

• Bilateral ovarian enlargement with multiloculated cysts

• Associated with high levels human chorionic gonadotropin

• Seen in 30% of patients with trophoblastic disease

• Clinical: nausea and vomiting

• US: multilocular cysts in both ovaries

Fluid Collections in Adhesions.
Fluid collections in adhesions can create cystic structures of odd shapes throughout the abdomen. Omental cysts tend to be higher in the abdomen, and urachal cysts are midline in the anterior abdominal wall peritoneum above the bladder.

Benign Cysts in Fetuses and Adolescents
Small simple cysts (1 to 7 mm) normally occur in fetuses and newborn girls because of stimulation by maternal hormones.[18] In premenarchal girls, small follicles less than 9 mm are common.[4] Larger cysts also are seen in otherwise healthy premenarchal girls.[4] These may be followed closely if they are regressing, as long as the child's growth and development appear normal. Occasionally, ovarian cysts produce symptoms of precocious puberty in young girls. These may arise spontaneously, or in association with other hormonal derangements.

Endometriosis

Endometriosis is a common condition in which functioning endometrial tissue is present outside the uterus. Usually the ectopic tissue is found on the ovaries, the external surface of the uterus, or scattered over the peritoneum, (especially in the dependent parts of the pelvis). The endometrial tissue cyclically bleeds and proliferates. In the diffuse form, this leads to disorganization of the pelvic anatomy with an appearance similar to PID or chronic ectopic pregnancy.

Two possible explanations for the etiology of endometriosis are presented. The first looks at the chronic reflux of menstrual fluid through the tubes and into the pelvis may in some women produce implantation and proliferation of endometrial cells with cyclic bleeding. The second theory involves the evolution of endometrial activity in susceptible cells which retain the embryonic capacity to differentiate in response to chronic irritation (for instance by menstrual fluid) or to hormonal stimulation. The resulting tissue bleeds and proliferates in response to cyclic hormones, producing pain, scarring and distortion of adherent pelvic organs and endometrium lined collections of blood known as endometriomas in the ovary. These may become moderately larged and may create a surgical emergency by rupturing or by causing the ovary to twist on the vessels which supply it (torsion).

Endometriosis or endometrioma may appear as bilateral or unilateral ovarian cysts with patterns ranging from anechoic to solid, depending on the amount of blood and it's organization. The ovaries are typically adherent to the posterior surface of the uterus or stuck in the cul-de-sac, and may be intimately associated with the rectosigmoid and difficult to define. Obscured organ borders and multiple irregular cystic masses are also suggestive of either disseminating cancer or pelvic infection, and the clinical picture and serial sonographic studies determine when and if exploratory surgery is indicated.[20]

Ovarian Neoplasms

Mixed cystic and solid masses are the most frequent presentation of the common epithelial tumors of the ovary. Ultrasonography can describe the tumor morphology but cannot (with the exception of dermoid cysts) distinguish benign from malignant tumors.[2] Simple cysts are probably benign, whereas cysts with thick septations and solid elements are frequently malignant.[16] Abnormal tumor vascularity and low resistive or pulsatility index are also worrisome for malignancy. Ascites, extension to adjacent organs, peritoneal implants, lymphadenopathy, and hepatic metastases support the diagnosis of malignant disease.

Epithelial Tumors

Of the epithelial tumors, 70% are benign and 30% malignant.[15] The two most common types are serous and mucinous tumors. The benign or low-malignant-potential form is termed adenoma and the malignant form is termed adenocarcinoma. The prefix cyst is added if the lesion is cystic, and fibroma is added if the tumor is more than 50% fibrous. Serous and mucinous tumors can be very large. They often fill the pelvis and extend into the abdomen.

Some investigators believe that benign-appearing tumors (which are anechoic, thin walled, have no septation, and are acoustically enhanced) can be aspirated safely.[1,9] Others believe that cystadenomas have a low malignant potential and that any persistent cyst greater than 5 cm should be removed surgically.[11]

Figure 5. Ovarian Mucinous Cystadenoma

Mucinous Cystadenoma. This is a type of epithelial tumor that is lined by the mucinous elements of the endocervix and bowel. When benign, it is a mucinous cystadenoma; when malignant, it is a cystadenocarcinoma. Mucinous cystadenoma comprises 20% of all benign tumors and is the second most common benign epithelial neoplasm of the ovary after serous ovarian adenoma. This type of tumor is usually found in middle aged women. In 75% of patients, the with mucinous tumors show are simple or septate thin-walled multilocular cysts.(Fig. 5) The mass often contains internal echoes with compartments differing in echogenicity. This tumor is large, measuring 15-30 cm in diameter, and can weigh more than 100 pounds. The tumor is usually unilateral with only 5% found bilateral.

• Unusually large (15-30 cm)

• Usually unilateral

• Cyst filled with sticky, gelatin-like material

• Multilocular cystic spaces

• Benign type more common than malignant

• Clinical: Pressure, pain, increased abdominal girth

• US: simple or septate thin-walled multilocular cysts

Mucinous Cystadenocarcinoma. The invasive form of the tumor is found in 10% of menopausal women. This mass may be unilateral or bilateral (20% of patients). Mucinous cystadenocarcinomas can also become very large and are more likely than the benign form to rupture. If they rupture, they are associated with pseudomyxoma peritonei. This causes loculated ascites with mass effect. On ultrasound, the mucoid ascites appears as hypoechoic fluid with bright punctate echoes. Malignant cysts tend to have very thick, irregular walls and septations.

Mucinous Cystadenocarcinoma

• Bilateral

• May occur in menapausal women (10%)

• Large, likely to rupture - ascites

• Clinical: pelvic pressure, pain when ruptured

• US: ascites appears as hypoechoic fluid with bright punctate echoes; thick, irregular walls and septations

Serous Cystadenoma. The serous cystadenoma tumor comprises 30% of ovarian tumors, making it the most common benign tumor of the ovary in middle aged females. This tumor is usually unilateral (7% to 30% are bilateral). Sonographically the benign masses are thin walled, unilocular with thin septa, and may have papilla.

Serous Cystadenoma

• Usually unilateral

• Smaller than mucinous cysts

• Multilocular cysts with septations

• Clinical: pelvic pressure, bloating

• US: multilocular cyst - may have nodule

Serous Cystadenocarcinoma. This type of tumor comprises 60% - 80% of all ovarian carcinomas. More than half of these tumors are bilateral (50% to 70%). Their size is smaller than the mucinous cysts; borders are irregular with a loss of capsular definition. The tumor may be accompanied by bilateral ovarian enlargement. Multilocular cysts contain chambers of varying size with septated, internal papillary projections. The malignant tumors are thick walled and multilocular with multiple papilla. Calcifications may be present. Solid elements or bilateral tumors suggest malignancy. Ascites forms secondary to peritoneal surface implantation. The tumor may spread to the lymph nodes, i.e. periaortic, mediastinal, supraclavicular.

Other Epithelial Tumors. Less common varieties of epithelial tumors are endometrioid, clear cell, Brenner, and undifferentiated carcinoma. These cannot be distinguished sonographically; however they are found unilateral and are benign. The Brenner tumor is found in 1.5% to 2.5% of patients; peak age ranges from 40 to 70 years. They are usually small, unilateral, and have calcifications.

Germ Cell Tumors

Germ cell tumors include teratoma, dysgerminoma, embryonal cell carcinoma, choriocarcinoma, and endodermal sinus tumor. With the exception of teratomas, all are rare. They often occur as mixed tumors with elements of two or three varieties of germ cell tumors. This tumor usually in found in adolescents. They are associated with elevated AFP and HCG levels. Clinical symptoms include pelvic and/or abdominal pain and a palpable mass (average diameter is 15 cm). The tumor is usually unilateral; 40% of tumors will calcify. The tumor ranges in texture from homogeneously solid (3%), predominantly solid (85%), to predominantly cystic (12%).

Teratoma

Figure 6. Dermoid

Dermoid Tumor. Dermoid cyst or teratoma is the most common germ cell tumor, comprising 20% of ovarian tumors. The tumor has been found in young children although about 80% occur in women of childbearing age. Approximately 30% are malignant, especially if found in the pre-adolescent female. Clinical findings include abdominal mass and/or pain secondary to torsion or hemorrhage. This tumor is usually unilateral. Teeth, bones, and fat can be seen on plain films. With the increased use of ultrasound many, if not most, dermoids are found as asymptomatic masses.

Dermoids have a wide spectrum of sonographic appearances depending on which elements (ectoderm, mesoderm, or endoderm) are present. On sonography there may be fat-fluid levels, calcification, or an echogenic mass with shadowing and bright linear bands that represent hair. The scan may "look" normal, so it is important to correlate the sonographic findings with the clinical findings. It is important to perform both transabdominal and transvaginal examinations to evaluate for a dermoid tumor.

Ultrasonography may demonstrate a completely cystic mass, a cystic mass with an echogenic mural nodule, a fat-fluid level, high-amplitude echoes with shadowing (e.g., teeth or bone), or a complex mass with internal septations (Fig.6). Echogenic dermoids often are confused with bowel. If a palpable pelvic mass is present that is not identified on ultrasonography, an echogenic dermoid must be considered. Indentation on the bladder wall will be a clue that a mass is present. The calcification within the pelvic cavity is also shown on the radiograph.

Rare dermoids that are composed of thyroid tissue is termed a struma ovarii (thyroid tissue) and may produce unsuppressible thyrotoxicosis. Malignant degeneration into squamous cell carcinoma frequently occurs in teratomas, usually in older women.

Dermoid

• Size ranges from small to 40 cm

• Unilateral, round to oval mass

• Contains fatty, sebaceous material, hair, cartilage, bone, teeth

• Clinical: asymptomatic to abdominal pain, enlargement and pressure; pedunculated, subject to torsion

• US: cystic/ complex/ solid mass, echogenic components; acoustic shadowing

Immature and Mature Teratomas.
Immature teratomas occur in adolescents 10 to 20 years of age. These are rapidly growing solid malignant tumors with many tiny cysts. Alpha-feto protein (AFP) is elevated in 50%. The tumor is unilateral and small in size, although it may grow to a larger dimension. On ultrasound the texture ranges from cystic to complex; it usually is solid with internal echoes.

Metastatic Disease
The ovary is a common site of metastasis from bowel (Krukenberg tumor), breast, and endometrium, as well as from melanoma and lymphoma. Metastatic disease to the ovaries frequently is bilateral and is often associated with ascites. Metastases are usually completely solid or solid with a "moth-eaten" cystic pattern.[21]

Ovarian Carcinoma

Every year ovarian cancer kills more women than does cancer of the uterine cervix and body combined. In the United States, 15,000 women die from this disease annually and approximately 1 in 70 women develop the disease. Ovarian carcinoma is the leading cause of death from gynecologic malignancy in the United States. About 80% of cases involve women over 50 years of age with the risk of cancer increasing with age. New chemotherapeutic and surgical techniques have done little to decrease mortality. The five year survival rate is between 20% to 40% overall (Stages I through IV).

The primary clinical problem with this disease is the asymptomatic and undetectable nature of the cancer in the earliest stages. Often the patient will seek medical attention after ascites has initiated abdominal distention. The five-year survival for stage IV ovarian cancer is 5%; stage I tumors diagnosed early and confined to the capsule show a survival of 90% at five years.

The strongest risk factor is a family history of ovarian or breast cancer. Women with carcinoma of the breast have increased risk of developing ovarian cancer and women with ovarian cancer are three to four times likely to develop breast cancer. Other risk factors include nulliparity, infertility, uninterrupted ovulation, and late menopause.

Clinical symptoms include vague abdominal pain, swelling, indigestion, frequent urination, constipation, weight change (ascites). Over 70% of the women first seen by their doctor are in their advanced stages of the disease. Although the median age of diagnosis is 63 years, the peak age ranges between 55 to 59 years, although it may also affect women in their forties.

The histology of ovarian cancer (5) may arise primarily from:

• epithelial tumors (60-70%)

• serous cystadenocarcinoma (50%)

• endometroid tumor similar to endometrial adenocarcinoma (15-30%)

• mucinous cystadenocarcinoma (15%)

• clear cell carcinoma (5%)

• Brenner tumor (2.5%)

• or undifferentiated tumor (<5%)

Germ cell tumors contribute 15-30% of the malignancies and are more common in girls and young women (age 4-27 years): mature teratoma, dysgerminoma, immature teratoma, endodermal sinus tumor, malignant mixed germ cell tumor, choriocarcinoma, or embryonal carcinoma. Metastases (5-10%) and stromal tumors (5%) comprise the remaining tumors that contribute to ovarian cancer.

On laparotomy, the cancer is classified into one of these 4 stages:

• STAGE I: limited to ovary

• STAGE Ia Limited to one ovary

• STAGE Ib Limited to two ovaries

• STAGE Ic Positive peritoneal lavage (ascites)

• STAGE II: limited to pelvis

• STAGE IIa Involvement of uterus/ fallopian tubes

• STAGE IIb Extension to other pelvic tissues

• STAGE IIc Positive peritoneal lavage (ascites)

• STAGE III: limited to abdomen = intraabdominal extension outside pelvis/ retroperitoneal nodes/ extension to small bowel/ omentum

• STAGE IV: hematogenous disease (liver parenchyma)/ spread beyond abdomen

The treatment for ovarian carcinoma includes surgery and chemotherapy initially followed by a second laparoatomy in six months and follow up CA 125 blood tests and C.T. scans. The CA 125 test is a serum marker for ovarian cancer; it is elevated in over 80% of epithelial ovarian cancers. It has not been found effective as a screening tool because only 50% of stage I malignant ovarian tumors have CA 125 levels higher than 35 U/mL and the method has a high false positive rate that is attributed to non-malignant gynecologic disease. When combined with an adnexal mass on ultrasound, ovarian cancer is suspected. CA 125 levels may be elevated in benign conditions such as endometriosis, pelvic inflammatory disease, uterine fibroids, pregnancy, and in other types of cancer not arising from the ovaries.

Ultrasound screening finds adnexal cysts in 1-15% of post-menopausal women. In these patients, only 3% of the ovarian "cystic" masses measuring less than 4cm were malignant; therefore a cyst greater than 4cm is recommended to be surgically removed. Ultrasound of the post-menopausal woman with enlarged ovaries should be evaluated with transvaginal and color /spectral Doppler. If a mass is seen, the sonographer should demonstrate if the mass if purely anechoic or complex with a solid texture and papillae within. If the Doppler waveform shows a low resistive pattern with the RI less than 0.4, malignancy should be further evaluated. Extension of the mass beyond the ovary into the omentum, peritoneum, or liver metastases should also be evaluated with ultrasound or other imaging technology. Malignant ascites may also be present.

Ovarian Torsion

Torsion of the ovary is caused by partial or complete rotation of the ovarian pedicle on its axis. Torsion usually occurs in childhood and adolescence and is common in association with adnexal masses. Clinical features include severe lower abdominal pain, nausea, vomiting, and fever. A palpable mass in felt in over 50% of patients. The right ovary is three times more to torse than the left.

Figure 7. Ovarian Torsion

Ovarian torsion produces an enlarged edematous ovary, usually greater than 4 cm in diameter.[10] The classically described appearance is of multiple tiny follicles around a hypoechoic mass, but the most common presentation is that of a completely solid adnexal mass (Fig. 8 ). A larger cyst with or without hemorrhage may also be present. Free fluid often is present in the pelvis. Doppler examination usually reveals absent blood flow to the torsed ovary if the torsion is complete. If a small amount of flow is present then the ovary can be salvaged if the ovary is able to untwist itself.

Ectopic Pregnancy

The sonographic appearances of ectopic pregnancy have been well documented with both transabdominal and endovaginal techniques. The most important finding when scanning for ectopic pregnancy is the identification of a normal intrauterine gestation. The visualization of the embryonic heart motion firmly makes the diagnosis of intrauterine pregnancy, however gestations earlier than 5-6 weeks may not show evidence of heart motion. In addition, as many as 20% of patients with ectopic pregnancy demonstrate an intrauterine saclike structure known as the pseudogestational sac. The pseudogestational sac does not contain a living embryo or yolk sac, the sac is located in the center of the endometrial cavity (unlike the burrowed gestational sac which is placed eccentrically), and homogeneous echoes are seen within the pseudogestational sac.

The sonographer needs to ask two important questions prior to performing a pelvic sonogram to rule out the presence of an ectopic pregnancy: "Are you possibly pregnant?" and "Have you had a pregnancy test?". Be sure to include the last menstrual period on the ultrasound images. Never totally exclude the possibility of an ectopic pregnancy and always correlate with the beta hCG (>1800 mIU should demonstrate a sac on ultrasound).

The identification of an extrauterine sac within the adnexa is one of the most frequent findings of an ectopic pregnancy. Extrauterine gestational sacs often demonstrate a thickened echogenic ring, separate from the ovary which represents trophoblastic tissue or chorionic villi. The sonographer should look for the presence of an embryo or yolk sac. It is also important to survey the upper abdomen as a routine part of the pelvic examination to search for free fluid in Morison's pouch or along the flanks. Echogenic free fluid does not always mean a ruptured ectopic pregnancy, although the more fluid present, the greater the chance of finding a ruptured ectopic on ultrasound.

Other Pelvic Masses

Not all pelvic masses are gynecologic in origin. Pelvic kidneys, omental cysts, peritoneal or post-operative pseudocsyts, distended impacted feces in the rectosigmoid, a distended bladder, hydroureters, colonic cancer or masses, diverticular abscesses, and retroperitoneal masses can all be identified by ultrasound. The location, size, consistency, and source of adnexal masses can be defined by a flexible combination of transvaginal and transabdominal scanning. It is of key importance to try to distinguish solid ovarian masses from pedunculated myomas by identifying the uterine connection and searching for an ovary. It is also of prime importance to use the endovaginal probe to assess mobility of the masss and the presence of tenderness. Is this the site of maximum tenderness and can you illicit the pain the patient feels? Any fluid present in the pelvis can be used to outline dependent portions of the pelvic organs by tilting the patient, using a transvaginal approach, or both. Large palpable tumors arising out of the pelvis are best viewed with transabdominal technique.

Ultrasound is useful in defining symptomatic or palpable masses as described previously. It allows the surgeon to observe functional-appearing cysts without resorting to immediate surgery and to plan strategy for surgical exploration and treatment when necessary. Obvious signs of malignancy, such as sonolucent liver metastases or nodular peritoneum outlined by ascites, assist in preoperative assessment. With current equipment, excellent resolution is available, and the experienced sonographer may frequently identify the tumor by its texture if the clinical context is understood. However the histologic diagnosis is the job of the pathologist.

References

• Take Quiz
  
  
•