An ovarian cyst is any collection of fluid, surrounded by a very thin wall, within an ovary. An ovarian follicle that is larger than 22mm is termed a functional follicular cyst. They are non-malignant (benign) and harmless and in most cases, don’t even cause symptoms, however, in some cases, rapid distention of the cyst, or a rupture with bleeding, can lead to sudden and severe pain and in some cases, a disruption in hormone balance leads to vaginal bleeding.There are 2 varieties of “functional” ovarian cysts:

  1. Follicle Cysts: In menstruating women, a follicle containing the unfertilized egg will rupture during ovulation. If this does not occur, a follicular cyst of more than 2.5 cm diameter may result. These cysts develop in response to stimulation with follicle stimulating hormone that is either self-produced (by the woman’s own pituitary gland (endogenous) or is induced by agonists (e.g. Lupron/Decapeptyl/Buserelin) that sometimes propagate increased and sustained pituitary FSH release.
  2. Corpus luteum cysts: These appear after ovulation or egg retrieval. The corpus luteum is the remnant of the follicle after the ovum has moved to the fallopian tubes. It usually degrades within 5-9 days. A corpus luteum of > 3 cm is regarded as being cystic.

Follicular cysts: These lesions have special relevance to women about to undergo controlled ovarian stimulation (COS) with gonadotropins for IVF where they can literally, “throw a spanner in the works”, causing a delay, postponement and sometimes even cancellation of the cycle of treatment. Functional Ovarian cysts must be distinguished from “non-functional or cystic ovarian tumors.” By definition, “tumors that are capable of independent growth.” Thus “cystic ovarian tumors do not develop as a result of exposure to gonadotropin stimulation and it is this feature that distinguishes them from “functional” ovarian cysts. Aside from sometimes causing pain and dysfunctional uterine bleeding, unruptured follicular cysts are usually relatively non-problematic. As stated above, in some cases, functional “cysts” undergo rapid distention (often as a result of a minor degree of bleeding inside the cyst itself). In such cases the woman will often experience a sharp or aching pain on one or other side of her lower abdomen and/or deep seated pain during intercourse. The cysts may even rupture, causing sudden lower abdominal pain that exacerbates and may even simulate an attack of acute appendicitis or a ruptured ectopic (tubular) pregnancy. While very unpleasant, a ruptured “functional cyst” seldom produces a degree of internal bleeding that warrants surgical intervention. The pain, typically is made worse by movement. It stabilizes within a number of days but subsides progressively to disappear within about four to seven days.Whenever an ovarian cyst is detected (usually by ultrasound examination), the first consideration should be to determine whether it is a “functional cyst or a “cystic ovarian tumor”. The reason for this is that tumors are subject to a variety of complications such as twisting (torsion), hemorrhage, infection and even malignant change, all of which usually will require surgical intervention.Gonadotropin releasing hormone agonists (GnRHa) such as Lupron, Buserelin, Nafarelin and Synarel, administered daily, starting a few days prior to menstruation, all elicit an initial and rapid, out-pouring (“surge”) in pituitary LH and FSH release. This “surge” lasts for a day or two. Then as the pituitary reservoir of FSH and LH becomes depleted, the blood FSH and LH levels fall rapidly reaching near undetectable blood levels within a day or two. At the same time, the declining FSH result in a drop in blood E2 concentration leading to a withdrawal bleed (menstruation). The progressive exhaustion of Pituitary FSH/LH along with the decline in blood E2, is referred to as ” down-regulation” The continued daily administration of GnRHa or its replacement (supplanting)  with a GnRH antagonist (e.g. Ganirelix, Cetrotide or Orgalutron) results in blood LH concentrations being sustained at a very low level throughout the ensuing cycle of controlled ovarian hyperstimulation (COH) with gonadotropins, thereby optimizing follicular maturation and promoting E2 induced endometrial proliferation.Functional follicular cysts resulting from controlled ovarian stimulation (COS), can occur regardless of whether down regulation with GnRHa (Lupron/Buserelin/Decapeptyl) is initiated in cases where the cycle of stimulation is launched with the woman coming off  a BCP or when the agonist is initiated on day 20-23  (the mid luteal phase) of a natural cycle. When this happens it is due to the initial agonist-induced FSH “surge” sometimes so accelerating follicular growth that it leads to the development of one or more “functional follicular cysts”. These cysts release E2 and cause the blood E2 often to remain elevated (>70pg/ml). Depending on the extent of this effect, it sometimes leads to a delay in the onset of menstruation and thus also to deferment in the initiation of COS. Failure of menstruation to commence within 4-7 days of initiating treatment with GnRHa suggestive of an underlying “functional ovarian cyst” and calls for an ultrasound examination to make the diagnosis. Once diagnosed, depending upon the number and size of cysts detected. There are two therapeutic options:

  1. Wait for the cyst to absorb spontaneously and for menstruation to ensue: While it at first might seem that this approach of continuing  GnRHa therapy in order to cause absorption of the cyst(s) within a week or two might be a good approach , it often has unintended consequences. First there is the real possibility that prolonged uninterrupted GnRHa therapy might blunt subsequent ovarian follicular response to gonadotropin therapy and second, if menstruation does not follow within 10-14 days, the cycle will usually need to be cancelled.
  2. Immediate needle aspiration of the cyst(s) under local anesthesia. I personally favor needle aspiration, sooner rather than later in such cases. Menstruation will usually follow a successful aspiration within 2-4 days. Upon menstruation a blood E2 level is measured and as soon as it drops below 70pg/ml COS can be initiated.
  1. Corpus Luteum cysts: As with follicular cysts, so at times do Corpus Luteum cystsalso bleed, distend and cause fain. They often delay onset of spontaneous menstruation by a week or longer (Halban syndrome”.). In isolated cases, internal bleeding within the cyst substance causes pain, rapid enlargement of the lesion and by ultrasound examination reveals local areas of absorption causing it to appear as a “complex” cystic lesion that simulates a tumor, prompting surgical intervention.  Sadly, there are countless cases where women have had an entire ovary removed due to this happening.

“Functional ovarian cysts” rarely present as a serious health hazard. In the vast majority of cases they spontaneously resolve within 2-4 weeks while “cystic tumors” will not. Accordingly, the persistence of any ovarian cyst that persists for longer than 4 weeks should raise suspicion of it being a tumor rather than with a “functional cyst.” Since ovarian tumors can be (or become) malignant, all ovarian cysts that persist for longer than 6 weeks (whether occurring in non-pregnant or pregnant women), should be considered for surgical removal and this should be followed by pathological analysis.