Ovarian hyperstimulation syndrome
Encyclopedia
Ovarian hyperstimulation syndrome (OHSS) is a complication from some forms of fertility medication
Fertility medication
Fertility medication are drugs which enhance reproductive fertility. For women, fertility medication is used to stimulate follicle development of the ovary...

. Most cases are mild, but a small proportion are severe.

Causative medications

Ovarian hyperstimulation syndrome is particularly associated with injection of a hormone called human chorionic gonadotropin
Human chorionic gonadotropin
Human chorionic gonadotropin or human chorionic gonadotrophin is a glycoprotein hormone produced during pregnancy that is made by the developing embryo after conception and later by the syncytiotrophoblast .. Some tumors make this hormone; measured elevated levels when the patient is not...

 (hCG) which is used for triggering oocyte release. The risk is further increased by multiple doses of hCG after ovulation and if the procedure results in pregnancy.

Using a GnRH agonist in instead of hCG for triggering oocyte release results in an elimination of the risk of ovarian hyperstimulation syndrome, but a slight decrease of the delivery rate of approximately 6%.

Symptoms

Symptoms are set into 3 categories: mild, moderate, and severe. Mild symptoms include abdominal bloating and feeling of fullness, nausea, diarrhea, and slight weight gain. Moderate symptoms include excessive weight gain (weight gain of greater than 2 pounds per day), increased abdominal girth, vomiting, diarrhea, darker urine and less in amount, excessive thirst, and skin and/or hair feeling dry (in addition to mild symptoms). Severe symptoms are fullness/bloating above the waist, shortness of breath, urination significantly darker or has ceased, calf and chest pains, marked abdominal bloating or distention, and lower abdominal pains (in addition to mild and moderate symptoms).

Classification

In mild forms of OHSS the ovaries are enlarged (5–12 cm) and there may be additional accumulation of ascites
Ascites
Ascites is a gastroenterological term for an accumulation of fluid in the peritoneal cavity.The medical condition is also known as peritoneal cavity fluid, peritoneal fluid excess, hydroperitoneum or more archaically as abdominal dropsy. Although most commonly due to cirrhosis and severe liver...

 with mild abdominal distension, abdominal pain
Abdominal pain
Abdominal pain can be one of the symptoms associated with transient disorders or serious disease. Making a definitive diagnosis of the cause of abdominal pain can be difficult, because many diseases can result in this symptom. Abdominal pain is a common problem...

, nausea, and diarrhea. In severe forms of OHSS there may be hemoconcentration, thrombosis
Thrombosis
Thrombosis is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel is injured, the body uses platelets and fibrin to form a blood clot to prevent blood loss...

 and distension, oliguria
Oliguria
Oliguria is the low output of urine, It is clinically classified as an output below 300-500ml/day. The decreased output of urine may be a sign of dehydration, renal failure, hypovolemic shock, HHNS Hyperosmolar Hyperglycemic Nonketotic Syndrome, multiple organ dysfunction syndrome, urinary...

 (decreased urine production), pleural effusion
Pleural effusion
Pleural effusion is excess fluid that accumulates between the two pleural layers, the fluid-filled space that surrounds the lungs. Excessive amounts of such fluid can impair breathing by limiting the expansion of the lungs during ventilation.-Pathophysiology:...

, and respiratory distress
Dyspnea
Dyspnea , shortness of breath , or air hunger, is the subjective symptom of breathlessness.It is a normal symptom of heavy exertion but becomes pathological if it occurs in unexpected situations...

. Early OHSS develops before pregnancy
Pregnancy
Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...

 testing and late OHSS is seen in early pregnancy.

Criteria for severe OHSS include enlarged ovary, ascites, hematocrit > 45%, WBC > 15,000, oliguria, creatinine 1.0-1.5 mg/dl, creatinine clearance > 50 ml/min, liver dysfunction, anasarca. Critical OHSS includes enlarged ovary, tense ascites with hydrothorax and pericardial effusion, hematocrit > 55%, WBC > 25,000, oligoanuria, creatinine > 1.6 mg/dl, creatinine clearance < 50 ml/min, renal failure, thromboembolic phenomena, ARDS.

Complications

OHSS may be complicated with ovarian torsion, ovarian rupture, thrombophlebitis and renal insufficiency. Symptoms generally resolve in 1 to 2 weeks, but will be more severe and persist longer if pregnancy occurs. This is due to human chorionic gonadotropin
Human chorionic gonadotropin
Human chorionic gonadotropin or human chorionic gonadotrophin is a glycoprotein hormone produced during pregnancy that is made by the developing embryo after conception and later by the syncytiotrophoblast .. Some tumors make this hormone; measured elevated levels when the patient is not...

 (hCG) from the pregnancy acting on the corpus luteum
Corpus luteum
The corpus luteum is a temporary endocrine structure in mammals, involved in production of relatively high levels of progesterone and moderate levels of estradiol and inhibin A...

 in the ovaries in sustaining the pregnancy before the placenta
Placenta
The placenta is an organ that connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply. "True" placentas are a defining characteristic of eutherian or "placental" mammals, but are also found in some snakes and...

 has fully developed. Typically, even in severe OHSS with a developing pregnancy, the duration does not exceed the first trimester.

Pathophysiology

OHSS has been characterized by the presence of multiple luteinized cysts within the ovaries leading to ovarian enlargement and secondary complications, but that definition includes almost all patients undergoing ovarian stimulation. The central feature of clinically significant OHSS is the development of vascular hyperpermeability and the resulting shift of fluids into the third space,;

As hCG causes the ovary to undergo extensive luteinization, large amounts of estrogens, progesterone
Progesterone
Progesterone also known as P4 is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy and embryogenesis of humans and other species...

, and local cytokines are released. It is almost certain that vascular endothelial growth factor
Vascular endothelial growth factor
Vascular endothelial growth factor is a signal protein produced by cells that stimulates vasculogenesis and angiogenesis. It is part of the system that restores the oxygen supply to tissues when blood circulation is inadequate....

 (VEGF) is a key substance that induces vascular hyperpermeability, making local capillaries "leaky", leading to a shift of fluids from the intravascular system to the abdominal and pleural cavity. Supraphysiologic production of VEGF from many follicles under the prolonged effect of hCG appears to be the specific key process underlying OHSS. Thus, while the patient accumulates fluid in the third space, primarily in the form of ascites
Ascites
Ascites is a gastroenterological term for an accumulation of fluid in the peritoneal cavity.The medical condition is also known as peritoneal cavity fluid, peritoneal fluid excess, hydroperitoneum or more archaically as abdominal dropsy. Although most commonly due to cirrhosis and severe liver...

, she actually becomes hypovolemic and is at risk for respiratory, circulatory, and renal problems. Patients who are pregnant sustain the ovarian luteinization process through the production of hCG.

Avoiding OHSS typically requires interrupting the pathological sequence, such as avoiding the use of hCG. One alternative is to use a GnRH agonist instead of hCG. While this has been repeatedly shown to "virtually eliminate" OHSS risk, there is some controversy regarding the effect on pregnancy rates if a fresh non-donor embryo transfer is attempted, almost certainly due to a luteal phase defect. There is no dispute that the GnRH agonist trigger is effective for oocyte donors and for embryo banking (cryopreservation) cycles.

Epidemiology

Sporadic OHSS is very rare, and may have a genetic component. Clomifene citrate
Clomifene
Clomifene or clomiphene or Clomid or Clomifert is a selective estrogen receptor modulator that increases production of gonadotropins by inhibiting negative feedback on the hypothalamus...

 therapy can occasionally lead to OHSS, but the vast majority of cases develop after use of gonadotropin
Gonadotropin
Gonadotropins are protein hormones secreted by gonadotrope cells of the pituitary gland of vertebrates. This is a family of proteins, which include the mammalian hormones follitropin , lutropin , placental chorionic gonadotropins hCG and eCG and chorionic gonadotropin , as well as at least two...

 therapy (with administration of FSH
FSH
FSH may refer to:* Follicle-stimulating hormone* Fox Sports Houston, a regional Fox Sports Net affiliate station for the Houston, Texas area* Facioscapulohumeral muscular dystrophy* International Civil Aviation Organisation code for Flash Airlines...

), such as Pergonal, and administration of hCG
Human chorionic gonadotropin
Human chorionic gonadotropin or human chorionic gonadotrophin is a glycoprotein hormone produced during pregnancy that is made by the developing embryo after conception and later by the syncytiotrophoblast .. Some tumors make this hormone; measured elevated levels when the patient is not...

 to trigger ovulation
Ovulation
Ovulation is the process in a female's menstrual cycle by which a mature ovarian follicle ruptures and discharges an ovum . Ovulation also occurs in the estrous cycle of other female mammals, which differs in many fundamental ways from the menstrual cycle...

, often in conjunction with IVF
In vitro fertilisation
In vitro fertilisation is a process by which egg cells are fertilised by sperm outside the body: in vitro. IVF is a major treatment in infertility when other methods of assisted reproductive technology have failed...

. The frequency varies and depends on patient factors, management, and methods of surveillance. About 5% of treated patients may encounter moderate to severe OHSS. Risk factors include young age, the development of many ovarian follicles under stimulation, extreme elevated serum estradiol concentrations, the use of hCG as the "trigger" agent, the continued use of hCG for luteal support, and the occurrence of a pregnancy (resulting in hCG production).

Mortality is low, but several fatal cases have been reported.

Prevention

Physicians can reduce the risk of OHSS by monitoring of FSH therapy to use this medication judiciously, and by withholding hCG medication.

Regarding dopamine agonist
Dopamine agonist
A dopamine agonist is a compound that activates dopamine receptors in the absence of dopamine. Dopamine agonists activate signaling pathways through the dopamine receptor and trimeric G-proteins, ultimately leading to changes in gene transcription.-Uses:...

s as prophylaxis, a systematic review and meta-analysis concluded that prophylactic treatment with cabergoline
Cabergoline
Cabergoline , an ergot derivative, is a potent dopamine receptor agonist on D2 receptors. In vitro, rat studies show cabergoline has a direct inhibitory effect on pituitary lactotroph cells...

 reduces the incidence, but not the severity of OHSS, without compromising pregnancy outcomes.

OHSS may also be prevented by coasting, which is ovarian hyperstimulation in IVF without hCG
Human chorionic gonadotropin
Human chorionic gonadotropin or human chorionic gonadotrophin is a glycoprotein hormone produced during pregnancy that is made by the developing embryo after conception and later by the syncytiotrophoblast .. Some tumors make this hormone; measured elevated levels when the patient is not...

administration for final maturation of follicles. A study of high risk patients showed no incidence of OHSS in 21 patients, versus ~20% in the control group. On the other hand, live birth rate may be slightly decreased, with the same study resulting in 38% in coasting vs. 45% among controls, as well as decreased cumulative live birth rate (52% vs. 59%), presumably because of more difficulty in timing oocyte retrieval with full maturation.

Treatment

Treatment of OHSS depends on the severity of the hyperstimulation.
Mild OHSS can be treated conservatively with monitoring of abdominal girth, weight, and discomfort on an outpatient basis until either conception or menstruation occurs. Conception can cause mild OHSS to worsen in severity.

Moderate OHSS is treated with bed rest, fluids, and close monitoring of labs such as electrolytes and blood counts. Ultrasound may be used to monitor the size of ovarian follicles. Depending on the situation, a physician may closely monitor a patient's fluid intake and output on an outpatient basis, looking for increased discrepancy in fluid balance (over 1 liter discrepancy is cause for concern). Resolution of the syndrome is measured by decreasing size of the follicular cysts on 2 consecutive ultrasounds.

Aspiration of accumulated fluid (ascites) from the abdominal/pleural cavity may be necessary, as well as opioids for the pain. If the OHSS develops within an IVF protocol, it can be prudent to postpone transfer of the pre-embryos since establishment of pregnancy can lengthen the recovery time or contribute to a more severe course. Over time, if carefully monitored, the condition will naturally reverse to normal - so treatment is typically supportive, although patient may need to be treated or hospitalized for pain, paracentesis, and/or intravenous hydration.

Further reading

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK