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, and local cytokines are released. It is almost certain that vascular endothelial growth factor (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 woman accumulates fluid in the third space, primarily in the form of ascites, she actually becomes hypovolemic and is at risk for respiratory, circulatory (such as arterial thromboembolism since blood is now thicker), and renal problems. Women 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. Classification
OHSS is divided into the categories mild, moderate, severe, and critical.
It is often recommended that patients being started on immunosuppression be screened for chronic strongyloidiasis; however, this is often impractical (screen tests are often unavailable) and in developed countries, the prevalence of chronic strongyloidiasis is very small, so screening is usually not cost-effective, except in endemic areas. The reality of global travel and need for modern advanced healthcare, even in the so-called "developed world", necessitates that in non-endemic areas there is easily accessible testing and screening for neglected tropical diseases such as strongyloidiasis.It is important to note that there is not necessarily any eosinophilia in the disseminated disease. Absence of eosinophilia in an infection limited to the gastrointestinal tract may indicate poor prognosis. Eosinophilia is often absent in disseminated infection. Steroids will also suppress eosinophilia, while leading to dissemination and potential hyperinfection.Escalated disseminated infections caused by immunosuppression can result in a wide variety and variable degree of disparate symptoms depending on the condition and other biological aspects of the individual, that may emulate other diseases or diagnoses. In addition to the many palpable gastrointestinal and varied other symptoms drastic cachexia amidst lassitude is often present, although severe disseminated infections can occur in individuals without weight loss regardless of body mass index. Diagnosis
Diagnosis rests on the microscopic identification of larvae (rhabditiform and occasionally filariform) in the stool or duodenal fluid. Examination of many samples may be necessary, and not always sufficient, because direct stool examination is relatively insensitive, with a single sample only able to detect larvae in about 25% of cases.