OHSS GTG guidance Flashcards
What are the features of mild OHSS
Mild abdo pain
Bloating
Ovarian size <8cm
What are the features of moderate OHSS?
Moderate abdominal pain
Nausea and/or vomiting
USS evidence of Ascites
Ovarian size 8-12cm
What are the clinical features of severe OHSS?
clinical ascites +/- hydrothorax
oliguria <300ml/day or <30ml/hour
Ovarian size >12cm
What are the ovarian size parameters for mild, moderate and severe OHSS?
Mild = <8cm Moderate = 8-12cm Severe = >12cm
In OHSS how is hyponatraemia classified?
<135mmol/l(seen in severe ohss)
In OHSS, what classifies as a high haemoconcentration?
Haematocrit >0.45 (severe) >0.55 (critical)
In OHSS, what classifies as hyperkalaemia?
> 5mmol/l (seen in severe ohss)
In OHSS, what classifies as a low serum osmolality?
<282mOSm/kg (seen in severe ohss)
In OHSS what classifies as low albumin?
<35g/l (seen in severe ohss)
What are the features of critical OHSS?
Tense ascites/large hydrothorax, oliguria/anuria
Acute respiratory distress syndrome, VTE
Haematocrit >0.55
WCC >25
How are the different presentations of ascites classified in OHSS?
Mild – bloating
Moderate – ascites on ultrasound
Severe – clinical ascites +/- hydrothorax
Critical – tense ascites +/- large hydrothorax
Which blood test is significant in classifying critical OHSS?
White cell count (>25)
Haemocrit >0.55
Which analgesia is contraindicated in OHSS?
NSAIDS
What investigations should be considered in OHSS?
Examination: weight and abdominal girth, vital signs including hypotension
Baseline investigations: FBC/haematocrit, U&E, LFT including albumin, CRP, serum osmolality, coagulation (fibrinogen, antithrombin), beta HCG
Imaging: ultrasound (ovarian size and ascites)
May consider: ABG/CXR/ECG/Echo/CTPA
How might coagulation factors change during OHSS?
Fibrinogen rises, antithrombin reduces
Which patients should be admitted with OHSS?
- Critical OHSS
- Worsening OHSS despite treatment
- Pain difficult to control
- Nausea and vomiting limiting oral intake
- Unable to attend regular outpatient follow up
What are the possible complications of OHSS?
Acute respiratory distress syndrome
Venous Thromboembolism
Renal failure
Ovarian rupture
Death is very rare
Which differentials need to be ruled out with OHSS?
PID/Ovarian rupture/ovarian torsion/ectopic pregnancy
Appendicitis/bowel perforation
What is the pathophysiology of OHSS?
Ovarian hyperstimulation leading to ovarian enlargement and release of proinflammatory mediators like VEGF which results in increased vascular permeability and prothrombotic state
How common is mild OHSS?
Affects 1/3 of IVF cycles (33%)
How common is moderate and severe OHSS (combined incidence)?
3-8%
Which pre IVF features put certain patients at higher risk of OHSS?
Previous OHSS
PCOS
Increased antral follicular volume
Higher levels of AMH
Which is more likely to cause OHSS: GNRH antagonist or agonist?
GNRH AGONISTs
How are early and late OHSS defined?
Early - within 7 days of trigger injection
Late >10 days after trigger injection (usually more prolonged and severe)
Which symptoms are not typical of OHSS?
Severe pain
Peritonism
Pyrexia
Which cases of OHSS have to be reported to HFEA?
Severe and critical
Which cases of OHSS can be managed as outpatients?
Mild and moderate
Severe in selected cases
What is the outpatient management of OHSS?
Aim to drink 1 litre of H20 /day
If producing < 1 litre urine/day or positive balance >1000ml – seek medical assistance
Analgesia with paracetamol and opiates
Review every 2-3 days unless worsening symptoms
Which blood markers are useful in assessing severity of OHSS?
Haematocrit
CRP
WCC
How is fluid balance maintained in OHSS?
First line is oral
Second line initial may be crystalloid
Third line with MDT input can consider colloid in the form of human albumin solution
Try to avoid diuretics unless guided by ITU
Indications for paracentesis in OHSS?
Ascites causing abdo pain, affecting respiration, causing oliguria due to poor renal perfusion
How should VTE thromboprophylaxis be prescribed in women with OHSS?
Prophylactic dose for women with severe and critical OHSS
Teds and consider prophylaxis for moderate OHSS depending on other risk factors
Duration – individualised but if severe, late onset, or associated with pregnancy – consider continuing until end of first trimester
Incidence of VTE in severe OHSS
0.7-10%
What pregnancy risks are associated with OHSS?
Increased risk of pre-eclampsia and preterm delivery
What are the miscarriage rates with singleton pregnancies with ART?
15-20%
What is the risk of ectopic pregnancy with ART?
1.4%
