OHSS Flashcards
Risks factors for OHSS
a. Ovulation induction, especially with hCG or GnRH analogues
b. Ovulation induction for PCOS
c. Previous history of OHSS
d. Increased size and number of follicles before egg retrieval
High antral count
e. Increased oestradiol levels
f. Ongoing pregnancy
• high AMH
• Large number of oocytes retrieved (> 20)
Pathophysiology
•Exposure of ovaries to human chorionic gonadotrophin (hCG) or luteinising hormone (LH) following controlled ovarian stimulation by follicle-stimulating hormone (FSH) underlies most cases of OHSS
Exposure of hyperstimulated ovaries to hCG leads to the production of proinflammatory mediators
hief among these is vascular endothelial growth factor (VEGF)
Increased vascular permeability - ascites, or rarely pleural or cardiac effusions but intravascular compartment is dry
hypovolaemia, with a typical loss of 20% of their calculated blood volume in the acute phase of OHSS
reduced serum osmolality and sodium
This paradoxical combination of hypovolaemia and hypo-osmolality has been ascribed to a ‘reset’ of the osmotic thresholds of vasopressin and thirst to lower osmolality and sodium levels as these women remain able to concentrate and dilute their urine around the new, lower, level of osmolality
key proinflammatory mediators are believed to be involved in the pathogenesis
Management
• OHSS is self-limiting and requires supportive management
• analgesia and antiemetics that are safe in pregnancy, Avoid NSAIDS
• Fluid balance - oral intake is the most physiological, persistent haemoconcentration despite volume replacement may need invasive monitoring and should be managed with the anaesthetic team
Human albumin solution 25% may be used as a plasma volume expander in doses of 50–100 g, infused over 4 hours and repeated 4- to 12-hourly.
Strict fluid balance recording should be followed for these patients.
• lots of crystalloid just increases ascites
• Avoid diuretics are the further delete intravascular volume (may have a role in oliguric despite fluid replacement and ascites drainage)
Ascites - Consider Paracentesis TA or TV
Manage Thrombosis risk
Risk assessment - signs OHSS is worsening
● increasing abdominal distension and pain
● shortness of breath
● tachycardia or hypotension
● reduced urine output (less than 1000 ml/24 hours) or positive fluid balance (more than 1000 ml/24 hours)
● weight gain and increased abdominal girth
● increasing haematocrit (greater than 0.45).
Indications for paracentesis
Indications for paracentesis include
o Severe abdo distension and pain secondary to ascites
o SOB and resp compromise secondary to ascites and increased intra abdominal pressure
o oliguria despite adequate volume replacement, secondary to increased abdominal pressure causing reduced renal perfusion
How common is it
All woman undergoing fertility treatment should be counselled accordingly
• IVF mild 30%, moderate or severe 3-8%
• Hospitalisation 0.3%
• OHSS is the commonist complication of IVF
• Rare post ovulation induction with clomifene or gonadotrophs,
• Very very rare but possible in a spontaneous pregnancy
How long does it last
In most women, the condition resolves over a period of 7–10 days. 37 If conception occurs, endogenous hCG can lead to a worsening of OHSS, whereas, in the absence of pregnancy, recovery is usually complete by the time of the withdrawal bleed.
What is early vs late OHSS
‘Early’ OHSS usually presents within 7 days of the hCG injection and is usually associated with an excessive ovarian response.
‘Late’OHSS typically presents 10 or more days after the hCG injection and is usually the result of endogenous hCG derived from an early pregnancy
• Late OHSS tends to be more prolonged and severe than the early form
Who should be admitted
● are unable to achieve satisfactory pain control
● are unable to maintain adequate fluid intake due to nausea
● show signs of worsening OHSS despite outpatient
intervention
● are unable to attend for regular outpatient follow-up
● have critical OHSS
Who should provide care
- MDT approach
- ICU if critical OHSS
- Experienced clinician
- Must inform fertility team
- Often present to less experienced clinicians - centres should have procotols inplace
Daily assessment as an inpatient should include
Daily - Body weight, abdominal girth, and fluid intake and output should be measured on a daily basis, along with full blood count, haematocrit,serum electrolytes, osmolality and liver function tests.
Discuss VTE risk
Cause
Rate
Tx
Severe OHSS is a prothrombotic state due to haemoconcentration and vascular endothelial dysfunction.
The incidence of thrombosis been estimated to lie between 0.7% and 10% of cases of OHSS.
• Women with severe or critical OHSS and those admitted withOHSS should receive LMWH prophylaxis.
• And those with risk factors such as reduced mobility, obesity or a pre-existing thrombophilia
• The duration of LMWH prophylaxis should be individualised according to patient risk factors and outcome of treatment
• Women with moderate OHSS should be evaluated for predisposing risk factors for thrombosis and prescribed either antiembolism stockings or LMWH if indicated.
• In addition to the usual symptoms and signs of venous thromboembolism (VTE), thromboembolism should be suspected in women with OHSS who present with unusual neurological symptoms, even if they present several weeks after apparent improvement in OHSS
