· Ovarian cysts- Malignancy is suggested by thick walled cysts, excresences, thick septa (especially if incomplete),pulsatility index <1, resistance index <0.4 (elevated diastolic flow). A unilocular ovarian cyst with a simple cyst appearance and a diameter less than 5cm is nearly always benign.
(a) Follicular cysts- Functional ovarian cysts. Usually small (1-2.5 cm) in diameter, often multiple thin walled and occur in an otherwise normal ovary. If these cysts persist they may cause endometrial hyperplasia with associated prominent endometrial echo complex.
(b) Corpus luteum cysts- They are usually smooth walled, anechoic or hypoechoic structures, although they may give the appearances of a complex adnexal mass. Rupture may occur, resulting in free pelvic fluid.
(c) Theca lutein cysts- Often bilateral, thick walled, well defined septate structures which may grow to 10 cm in diameter. Theca lutein cysts are usually secondary to an underlying disorder such as hydatidiform mole, choriocarcinoma or ovulation induction therapy.
(d) Hemorrhagic ovarian cysts- Both benign and malignant ovarian cysts may be complicated by hemorrhage. The US appearance is very variable, depending on the state of blood within the cyst. The cyst may appear anechoic, solid, complex or septate and debris levels may be present.
(e) Polycustic ovary- 35—40% — large ovaries with (greater or equally to 5)
cysts of 5—8 mm in each ovary, 30% — normal size ovaries. Serial
examinations show failure of follicles to change size or configuration. 25% — hypoechoic ovary with no discrete individual cysts,
5% — enlarged ovary isoechoic with uterus. There is a 5—17% risk
of ovarian neoplasm and increased incidence of endometrial carcinoma. A normal US does not exclude polycystic ovary syndrome.
(f) Ovarian remnant syndrome- Rarely adnexal cystic masses may occur after partial oophorectOm ies. The small amount of residual ovarian tissue may be hormonally stimulated and produce a hemorrhagic functional cyst. Sonographicatly an echogenic mass which can be quite large may be identified.
(g) Paraovarian cysts- These account for 10% of all adnexal masses. They arise from wolffian duct remnants and are usually placed in the broad ligament. They do not regress on serial scans. Hemorrhage, torsion or rupture may occur. A specific diagnosis is not possible unless a normal ovary is identified in addition to an ipsilateral adnexal mass.
(h) Endometromas- Endometrjosj is a common Condition. (At pelvic surgery 8—20% of Women have evidence of endometriosis,presenting as adnexal pelvic masses.) A more localized form of the disease consists of discrete larger lesions termed endometriomas or chocolate cyst These are fairly Well defined, thick walled cysts' with low level internal echoes. Recurrent bleeding may give rise to cystic areas with variable internal echoes which ma;- mimic solid masses.
(i) Torsion of the ovary- The risk of torsion increases with ovarian size, Particularly with cysts Or tumors Over S cm in diameter. Sonography may reveal a unilaterally enlarged ovary that appears hypoechoic. An associated cystic or solid mass may be seen. Engorged vessels may appear as small multiple cystic structures of uniform size at the periphery of the torted ovary. Associated free fluid may be present in the pelvis in a third of the cases.
(j) Hyper-stimulated ovary syndrome- Ovarian hyperstimulation may result during assisted conception. It is diagnosed when the ovary measures over 5 cm in the longest diameter and contains multiple follicles. Ascites and pleural effusions can occur. Electrolyte imbalance and venous thrombosis are complications.
(k) Serous cystadenocarcinoma- These neoplasms are quite large, and over half of them are over 15 cm. They are often multiloculated with thick septa, with numerous papillary projections and echogenic material within the locules.
(l) Mucinous cystadenomas- Usually unilateral with prominent septations. The locules may contain low level echoes representing mucin. Rupture of the tumor may cause pseudomyxoma peritonei.
(m)Serous cystadenoma- The initial appearance is indistinguishable from a simple cyst. They may be bilateral and can undergo malignant transformation to cystadenocarcinoma. They are usually unilocular but may contain thin walled septa with occasionally papillary projections. Ascites may rarely occur.
(n) Mucinous cystadenocarcinoma- These are rare tumors; US features may be indistinguishable from mucinous cystadenomas a serous cystadenocarcinomas. They are bilateral in a quarter of patients. Metastases from mucinous cystadenocarcinomas or rupture of the tumor may lead pseudomyxoma peritonei.
(o) Endometroid carcinoma- These tumors are frequently bilateral. US appearances are varied and may range from cystic, with papillary projections, to complex solid areas with necrosis and hemorrhage.
(p) Brenner's tumor
(q) Other cystic masses- Ectopic pregnancy. pelvic inflammatory disease, pyosalpinx and tubo-ovarian abscesses may be indistinguishable from other adnexal masses on sonography alone. Clinical history is frequently of primary importance in achieving a diagnosis. They may be solid or complex, and are often associated with fluid in the culde-de-sac.
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