OVARIAN HYPERSTIMULATION SYNDROME by Dr. Moji Aderonmu
This in simplest terms refers to the conglomeration of symptoms and signs that result from overstimulated and enlarged ovaries, more often than not; due to fertility treatment.
Thus, it is a complication of controlled ovarian hyperstimulation, one of the key steps in in-vitro fertilization. It is also potentially life threatening.
It is somewhat rare, and thus, the overall incidence across the various degrees of severity is at most 6%.
Ovarian hyperstimulation syndrome(OHSS) can be classified as early or late. It is early when it occurs within eight days of giving the human chorionic gonadotrophin (HCG) injection trigger for ovulation and when it occurs after eight days it is termed ovarian hyperstimulation.
Early ovarian hyperstimulation is usually caused by fertility treatment, that is the administration of human chorionic gonadotrophin (HCG) while the late ovarian hyperstimulation is due to the human chorionic gonadotrophin released by the pregnancy.
The underlying pathway by which over hyperstimulation syndrome occurs is the fluid shift from within the vessels (intravascular space) to the third space(s) where ordinarily there shouldn’t be fluid. Examples of third space include the abdominal cavity, the tissue overlying the lungs (pleura) and the heart (pericardium).
Symptoms include nausea, vomiting, diarrhoea, excessive thirst, bloating, abdominal pain, weight gain, reduced urine output, shortness of breath among others.
Some studies have identified risk factors that can help identify women who may develop ovarian hyperstimulation syndrome. These risk factors include having had a previous episode of ovarian hyperstimulation, history of polycystic ovarian syndrome, young age of the woman, and also from the pre-treatment evaluation of antral follicles and hormone levels.
Ovarian hyperstimulation is classified into four categories: mild, moderate, severe and critical. Clinical examination findings and investigations are carried out, which aid in classifying a woman appropriately into any of the above four categories and they include a full blood count, electrolytes urea and creatinine, liver function tests, clotting profile, chest radiograph and abdomino-pelvic ultrasound scan.
The management of ovarian hyperstimulation syndrome is largely supportive. The treatment is given as directed by the symptoms that a woman presents with.
First and foremost, the ovarian hyperstimulation syndrome must be correctly classified thereafter supportive treatment to manage the symptoms is instituted.
Adequate fluid intake, pain killers, prevention of blood clots are the pillars, other interventions are offered as needed.
It is also important to avoid sexual intercourse until OHSS has resolved, to avoid trauma of the already enlarged ovaries.
Other complications that may arise following OHSS include respiratory embarrassment due to the abdominal distention, torsion of the ovaries which is a surgical emergency and also thromboembolism which can affect other organs within the body.
If pregnancy does not occur, OHSS resolves within 10-14 days. When Pregnancy occurs, it takes a longer while for the OHSS to resolve and pregnancy can continue without any adverse outcome.
OHSS can be prevented by choosing the most appropriate protocol for the woman, close monitoring of the cycle, coasting (withholding stimulation medications for a maximum of 4days), cancelling the cycle, cryopreserving all retrieved oocytes and transfer in a Frozen embryo transfer cycle, the use of Progesterone instead of HCG for luteal phase support and the use of Carbegoline.
It goes without saying that this rare complication of fertility treatment can be potentially life threatening and it is imperative as a woman to have a frank conversation with your fertility physician.