Ovarian cyst

Cyst rupture

When the surface of cyst breaks, the contents can leak out; this is called a ruptured cyst. The main symptom is abdominal pain, which may last a few days to several weeks, but they can also be asymptomatic. ^[9]

A ruptured ovarian cyst is usually self-limiting, and only requires keeping an eye on the situation and pain medications for a few days, while the body heals itself. ^[5] Rupture of large ovarian cysts can cause bleeding inside the abdominal cavity. ^[5] Rarely, enough blood will be lost that the bleeding will produce hypovolemic shock, which can be a medical emergency requiring surgery. ^{[5] [10]} However, normally, the internal bleeding is minimal and requires no intervention. ^[5]

Ovarian torsion

Ovarian torsion is a very painful medical condition requiring urgent surgery. ^[2] It can be caused by a pedunculated ovarian cyst that twisted in a way that cuts off the blood flow. ^[2] It is most likely to be seen in women of reproductive age, though it has happened in young girls (premenarche) and postmenopausal women. ^[11] Ovarian torsion may be more likely during pregnancy, especially during the third and fourth months of pregnancy, as the internal anatomy shifts to accommodate fetal growth. ^[5] Diagnosis relies on clinical examination and ultrasound imaging. ^[5]

Cysts larger than 4 cm are associated with approximately 17% risk.^{[ citation needed ]}

Functional

Functional cysts form as a normal part of the menstrual cycle. There are several types of functional cysts:

• Follicular cyst, the most common type of ovarian cyst. ^[2] In menstruating women, an ovarian follicle containing the ovum (an unfertilized egg) normally releases the ovum during ovulation. ^[2] If it does not release the ovum, a follicular cyst of more than 2.5 cm diameter may result. ^[6] A ruptured follicular cyst can is painful. ^[2]
• A luteal cyst is a cyst that forms after ovulation, from the corpus luteum (the remnant of the ovarian follicle, after the ovum has been released). ^[2] A luteal cyst is twice as likely to appear on the right side. ^[2] It normally resolves during the last week of the menstrual cycle. ^[2] A corpus luteum that is more than 3 cm is abnormal. ^{[6] [8]}
• Theca lutein cysts occur within the thecal layer of cells surrounding developing oocytes. Under the influence of excessive hCG, thecal cells may proliferate and become cystic. This is usually on both ovaries. ^[6]

Non-functional

Non-functional cysts may include the following:

• An ovary with many cysts, which may be found in normal women, or within the setting of polycystic ovary syndrome
• Cysts caused by endometriosis, known as chocolate cysts
• Hemorrhagic ovarian cyst
• Dermoid cyst – the most common non-functional ovarian cyst, especially for women under the age of 30, ^[11] they are benign (non-cancerous) with varied morphology. ^[13] They can usually be diagnosed from ultrasound alone. ^[13] Depending on size, growth rate (usually slow), and the age of the woman, treatment might involve surgical removal or watchful waiting. ^[13] They are also called mature cystic teratomas. ^[11]
• Ovarian serous cystadenoma – more common in women between the age of 30 and 40. ^[11]
• Ovarian mucinous cystadenoma – although there is usually only one of these, they can grow very large, with diameters sometimes exceeding 50 cm (20 inches). ^[11]
• Paraovarian cyst
• Cystic adenofibroma
• Borderline tumoral cysts

• 
  Transvaginal ultrasonography of a hemorrhagic ovarian cyst, probably originating from a corpus luteum cyst. The coagulating blood gives the content a cobweb-like appearance.
• 
  Transvaginal ultrasonography showing a 67 x 40 mm endometrioma, with a somewhat grainy content.

Ultrasound

Usually, an experienced sonographer can readily identify benign ovarian cysts, often with a level of accuracy that rivals other approaches. ^[5]

Follow-up imaging in women of reproductive age for incidentally discovered simple cysts on ultrasound is not needed until 5 cm, as these are usually normal ovarian follicles. Simple cysts 5 to 7 cm in premenopausal females should be followed yearly. Simple cysts larger than 7 cm require further imaging with MRI or surgical assessment. Because they are large, they cannot be reliably assessed by ultrasound alone; it can be difficult to see posterior wall soft tissue nodularity or thickened septation due to limited ultrasound beam penetrance at this size and depth. For the corpus luteum, a dominant ovulating follicle that typically appears as a cyst with circumferentially thickened walls and crenulated inner margins, follow up is not needed if the cyst is less than 3 cm in diameter. ^[8] In postmenopausal women, any simple cyst greater than 1 cm but less than 7 cm needs yearly follow-up, while those greater than 7 cm need MRI or surgical evaluation, similar to reproductive age females. ^[16]

For incidentally discovered dermoids, diagnosed on ultrasound by their pathognomonic echogenic fat, either surgical removal or yearly follow up is indicated, regardless of the woman's age. For peritoneal inclusion cysts, which have a crumpled tissue-paper appearance and tend to follow the contour of adjacent organs, follow up is based on clinical history. Hydrosalpinx, or fallopian tube dilation, can be mistaken for an ovarian cyst due to its anechoic appearance. Follow-up for this is also based on clinical presentation. ^[16]

For multilocular cysts with thin septation less than 3 mm, surgical evaluation is recommended. The presence of multiloculation suggests a neoplasm, although the thin septation implies that the neoplasm is benign. For any thickened septation, nodularity, vascular flow on color doppler, or growth over several ultrasounds, surgical removal may be considered due to concern of cancer. ^[16]

Scoring systems

Most ovarian cysts are not malignant; however, some do become cancerous. ^[2] There are several systems to assess risk of an ovarian cyst of being an ovarian cancer, including the RMI (risk of malignancy index), LR2 and SR (simple rules). Sensitivities and specificities of these systems are given in tables below: ^[17]

Ovarian cysts may be classified according to whether they are a variant of the normal menstrual cycle, referred to as a functional or follicular cyst. ^[6]

Ovarian cysts are considered large when they are over 5 cm and giant when they are over 15 cm. In children, ovarian cysts reaching above the level of the umbilicus are considered giant.

Associated conditions

In juvenile hypothyroidism multicystic ovaries are present in about 75% of cases, while large ovarian cysts and elevated ovarian tumor marks are one of the symptoms of the Van Wyk and Grumbach syndrome. ^[18]

The CA-125 marker in children and adolescents can be frequently elevated even in absence of malignancy and conservative management should be considered.

Polycystic ovarian syndrome involves the development of multiple small cysts in both ovaries due to an elevated ratio of leutenizing hormone to follicle stimulating hormone, typically more than 25 cysts in each ovary, or an ovarian volume of greater than 10 mL. ^[19]

Larger bilateral cysts can develop as a result of fertility treatment due to elevated levels of HCG, as can be seen with the use of clomifene for follicular induction, in extreme cases resulting in a condition known as ovarian hyperstimulation syndrome. ^[20] Certain malignancies can mimic the effects of clomifene on the ovaries, also due to increased HCG, in particular gestational trophoblastic disease. Ovarian hyperstimulation occurs more often with invasive moles and choriocarcinoma than complete molar pregnancies. ^[21]

Risk of cancer

Accurately differentiating an cyst from a cancer is critical to management. Medical imaging showing a simple, smooth bubble of watery liquid is characteristic of a benign cyst. ^[8] If the cyst is large, is multilocular, or has complex internal features, such as papillary (bumpy) projections into the cyst or solid areas inside the cyst, it is more likely to be cancerous. ^[13]

A widely recognised method of estimating the risk of malignant ovarian cancer based on initial workup is the risk of malignancy index (RMI). ^{[13] [22]} It is recommended that women with an RMI score over 200 should be referred to a centre with experience in ovarian cancer surgery. ^[23]

The RMI is calculated as follows: ^[23]

RMI = ultrasound score × menopausal score × CA-125 level in U/ml.

There are two methods to determine the ultrasound score and menopausal score, with the resultant RMI being called RMI 1 and RMI 2, respectively, depending on what method is used: ^[23]

RMI 2 is regarded as more sensitive than RMI 1, ^[23] but the model has low specificity, which means that many of the suspected cancers turn out to be overdiagnosed benign cysts. ^[13] The calculation is often inaccurate during pregnancy, especially when CA-125 levels peak towards the end of the first trimester. ^[5]

The International Ovarian Tumor Analysis (IOTA) group has produced a different model. Theirs relies on "simple descriptors" and "simple rules". ^[5] An example of a simple descriptor for a benign cyst is "Unilocular cyst of anechoic content with regular walls and largest diameter less than 10 cm". ^[5] An example of a simple rule is acoustic shadows are associated with benign cysts. ^[5]

Histopathology

In case an ovarian cyst is surgically removed, a more definite diagnosis can be made by histopathology:

Type	Subtype	Typical microscopy findings	Image
Functional cyst	Follicular cyst	A variable inner layer of granulosa cells which are luteinized after puberty [24] An outer layer of usually luteinized theca interna [24]
	Corpus luteum cyst	A convoluted cyst lining of luteinized granulosa cells [25] A prominent inner layer of fibrous tissue [25] An outer layer of theca cells [25]
Cystadenoma	Serous cystadenoma	Cyst lining consisting of a simple epithelium, whose cells may be either: [26] columnar and tall and contain cilia, resembling normal tubal epithelium cuboidal and have no cilia, resembling ovarian surface epithelium
	Mucinous cystadenoma	Lined by a mucinous epithelium
Dermoid cyst		Well-differentiated components from at least two, and usually three, [11] germ layers (ectoderm, mesoderm and/or endoderm). [27]
Endometriosis		At least two of the following three criteria: [28] Endometrial type stroma Endometrial epithelium with glands Evidence of chronic hemorrhage, mainly hemosiderin deposits
Borderline tumor		Atypical epithelial proliferation without stromal invasion. [29]
Ovarian cancer		Many different types, but generally severe dysplasia/atypia and invasion.
Simple squamous cyst		Simple squamous epithelium and not conforming to diagnoses above (a diagnosis of exclusion)

Expectant management

If the cyst is asymptomatic and appears to be either benign or normal (i.e., a cyst with a benign appearance and a size of less than 3 cm diameter in premenopausal women or less than 1 cm in postmenopausal women ^[8] ), then delaying surgery, in the hope that it will prove unnecessary, is appropriate and recommended. ^[8] Normal ovarian cysts require neither treatment nor additional investigations. ^[8] Benign but medium-size cysts may prompt an additional pelvic ultrasound after a couple of months. ^[8] (The larger the cyst, the sooner the follow-up imaging is done. ^[8] )

Symptom management

Pain associated with ovarian cysts may be treated in several ways:

• Pain relievers such as acetaminophen, nonsteroidal anti-inflammatory drugs, ^[1] or opioids.
• While hormonal birth control prevents the development of new cysts in those who frequently get them, ^[1] it is not useful for the treatment of current cysts. ^[3]

Surgery

Although most cases of ovarian cysts are monitored and stabilize or resolve without surgery, some cases require surgery. ^[35] Common indications for surgical management include ovarian torsion, ruptured cyst, concerns that the cyst is cancerous, and pain; ^[11] some surgeons additionally recommend removing all large cysts. ^[11]

The surgery may involve removing the cyst alone, or one or both ovaries. ^[11] Very large, potentially cancerous, and recurrent cysts, particularly in menopausal women, are more likely to be treated by removing the affected ovary, or both the ovary and its Fallopian tube (salpingo-oophorectomy). ^[11] For women of reproductive age, the aim is to preserve as much of the reproductive system as possible. It's often possible to just remove the cyst and leave both ovaries intact, which means the fertility should be unaffected. ^[36]

Simple benign cysts can be drained through fine-needle aspiration. ^[5] However, the risk of recurrence is fairly high (33–40%), and if a cancerous tumor was misdiagnosed, it could cause the cancer to spread. ^[5]

The surgical technique is typically a minimally invasive or laparoscopic approach performed under general anaesthesia, ^[11] unless the cyst is particularly large (e.g., 10 cm [4 inches] in diameter), or if pre-operative imaging, such as pelvic ultrasound, suggests malignancy or complex anatomy. ^[13] For large cysts, open laparotomy or a mini-laparotomy (a smaller incision through the abdominal wall) may be preferred. ^[13] Minimally invasive surgeries are not used when ovarian cancer is suspected. ^{[13] [11]} Additionally, if the pelvic surgery is being done, some women choose to have prophylactic salpingectomy done at the same time, to reduce their future risk of cancer. ^[11]

If the cyst ruptures during surgery, the contents may irritate the peritoneum and cause internal adhesions. ^[11] The cyst may be drained before removal, and the abdominal cavity carefully irrigated to remove any leaked fluids, to reduce this risk. ^[11]