OHSS GTG guidance

Question 1

What are the features of mild OHSS

Answer 1

Mild abdo pain
Bloating
Ovarian size <8cm

Question 2

What are the features of moderate OHSS?

Answer 2

Moderate abdominal pain
Nausea and/or vomiting
USS evidence of Ascites
Ovarian size 8-12cm

Question 3

What are the clinical features of severe OHSS?

Answer 3

clinical ascites +/- hydrothorax
oliguria <300ml/day or <30ml/hour
Ovarian size >12cm

Question 4

What are the ovarian size parameters for mild, moderate and severe OHSS?

Answer 4

Mild = <8cm 
Moderate = 8-12cm 
Severe = >12cm

Question 5

In OHSS how is hyponatraemia classified?

Answer 5

<135mmol/l(seen in severe ohss)

Question 6

In OHSS, what classifies as a high haemoconcentration?

Answer 6

Haematocrit >0.45 (severe) >0.55 (critical)

Question 7

In OHSS, what classifies as hyperkalaemia?

Answer 7

> 5mmol/l (seen in severe ohss)

Question 8

In OHSS, what classifies as a low serum osmolality?

Answer 8

<282mOSm/kg (seen in severe ohss)

Question 9

In OHSS what classifies as low albumin?

Answer 9

<35g/l (seen in severe ohss)

Question 10

What are the features of critical OHSS?

Answer 10

Tense ascites/large hydrothorax, oliguria/anuria
Acute respiratory distress syndrome, VTE
Haematocrit >0.55
WCC >25

Question 11

How are the different presentations of ascites classified in OHSS?

Answer 11

Mild – bloating
Moderate – ascites on ultrasound
Severe – clinical ascites +/- hydrothorax
Critical – tense ascites +/- large hydrothorax

Question 12

Which blood test is significant in classifying critical OHSS?

Answer 12

White cell count (>25)

Haemocrit >0.55

Question 13

Which analgesia is contraindicated in OHSS?

Answer 13

NSAIDS

Question 14

What investigations should be considered in OHSS?

Answer 14

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

Question 15

How might coagulation factors change during OHSS?

Answer 15

Fibrinogen rises, antithrombin reduces

Question 16

Which patients should be admitted with OHSS?

Answer 16

• Critical OHSS
• Worsening OHSS despite treatment
• Pain difficult to control
• Nausea and vomiting limiting oral intake
• Unable to attend regular outpatient follow up

Question 17

What are the possible complications of OHSS?

Answer 17

Acute respiratory distress syndrome

Venous Thromboembolism

Renal failure

Ovarian rupture

Death is very rare

Question 18

Which differentials need to be ruled out with OHSS?

Answer 18

PID/Ovarian rupture/ovarian torsion/ectopic pregnancy

Appendicitis/bowel perforation

Question 19

What is the pathophysiology of OHSS?

Answer 19

Ovarian hyperstimulation leading to ovarian enlargement and release of proinflammatory mediators like VEGF which results in increased vascular permeability and prothrombotic state

Question 20

How common is mild OHSS?

Answer 20

Affects 1/3 of IVF cycles (33%)

Question 21

How common is moderate and severe OHSS (combined incidence)?

Answer 21

3-8%

Question 22

Which pre IVF features put certain patients at higher risk of OHSS?

Answer 22

Previous OHSS
PCOS
Increased antral follicular volume
Higher levels of AMH

Question 23

Which is more likely to cause OHSS: GNRH antagonist or agonist?

Answer 23

GNRH AGONISTs

Question 24

How are early and late OHSS defined?

Answer 24

Early - within 7 days of trigger injection

Late >10 days after trigger injection (usually more prolonged and severe)

Question 25

Which symptoms are not typical of OHSS?

Answer 25

Severe pain
Peritonism
Pyrexia

Question 26

Which cases of OHSS have to be reported to HFEA?

Answer 26

Severe and critical

Question 27

Which cases of OHSS can be managed as outpatients?

Answer 27

Mild and moderate

Severe in selected cases

Question 28

What is the outpatient management of OHSS?

Answer 28

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

Question 29

Which blood markers are useful in assessing severity of OHSS?

Answer 29

Haematocrit
CRP
WCC

Question 30

How is fluid balance maintained in OHSS?

Answer 30

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

Question 31

Indications for paracentesis in OHSS?

Answer 31

Ascites causing abdo pain, affecting respiration, causing oliguria due to poor renal perfusion

Question 32

How should VTE thromboprophylaxis be prescribed in women with OHSS?

Answer 32

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

Question 33

Incidence of VTE in severe OHSS

Answer 33

0.7-10%

Question 34

What pregnancy risks are associated with OHSS?

Answer 34

Increased risk of pre-eclampsia and preterm delivery

Question 35

What are the miscarriage rates with singleton pregnancies with ART?

Answer 35

15-20%

Question 36

What is the risk of ectopic pregnancy with ART?

Answer 36

1.4%