Ovarian Hyperstimulation Syndrome

Question 1

What is the reported incidence of OHSS?

Answer 1

Clinicians must remain alert to possibility ofOHSS in all women undergoing fertility treatment & women should be counselled accordingly

Question 2

How is OHSS diagnosed and what differential diagnoses should be considered?

Answer 2

• Clinicians need to be aware of symptoms & signs of OHSS, as diagnosis is based on clinical criteria.
• In women presenting with severe abdominal pain or pyrexia, extra care should be taken to rule out other causes of the patient’s symptoms. The input of clinicians experienced in the management of OHSS should be obtained in such cases

Question 3

How is the severity of OHSS classified?

Answer 3

• The severity of OHSS should be graded according to a standardised classification scheme.

Question 4

How should OHSS be reported?

Answer 4

• Licensed centres should comply with Human Fertilisation and Embryology Authority (HFEA) regulations in reporting cases of severe or critical OHSS among their patients.
• Units that treat women with OHSS should inform licensed centre where fertility treatment was carried outto promote clinical continuity and to allow licensed centre to meet its legal obligations.

Question 5

How should care be delivered for women at risk of OHSS?

Answer 5

• Fertility clinics should provide verbal and written information concerning OHSS to all women undergoing fertility treatment, including a 24-hour contact telephone number.
• All acute units where women with suspected OHSS are likely to present should establish agreed local protocols for the assessment and management of these women and ensure they have access to appropriately skilled clinicians with experience in the management of this condition.
• Licensed centres that provide fertility treatment should ensure close liaison and coordination with acute units where their patients may present.

Question 6

How should women suspected of suffering from OHSS be assessed?

Answer 6

Women presenting with symptoms suggestive of OHSS should be assessed face-to-face by clinician if there is any doubt about the diagnosis or if severity is likely to be greater than mild.

Question 7

Which patients with OHSS are suitable for outpatient care?

Answer 7

• Outpatient management is appropriate for women with mild or moderate OHSS and in selected cases with severe OHSS.

Question 8

What management is appropriate in the outpatient setting for patients with OHSS?

Answer 8

• Women undergoing outpatient MX of OHSS should be appropriately counselled & provided with information regarding fluid intake and output monitoring. In addition, they should be provided with contact details to access advice.
• Nonsteroidal anti-inflammatory agents should be avoided, as they may compromise renal function.
• Women with severe OHSS being managed on outpatient basis should receive thromboprophylaxis
  with LMWH. The duration of treatment should be individualised, taking into account risk factors and whether or not conception occurs.
• Paracentesis of ascitic fluid may be carried out on outpatient basis by abdominal ortransvaginal route under ultrasound guidance.
• Insufficient evidence to support use of gonadotrophin-releasing hormone antagonists or dopamine agonists in treating established OHSS.

Question 9

How should women with OHSS managed on an outpatient basis be monitored?

Answer 9

• Women withOHSS being managed on an outpatient basis should be reviewed urgently if they develop
  symptoms or signs of worsening OHSS. In absence of these, review every 2–3 days is likely to be adequate.
• Baseline laboratory investigations should be repeated if severity of OHSS is thought to be worsening. Haematocrit is a useful guide to degree of intravascular volume depletion.

Question 10

When should women with OHSS be admitted?

Answer 10

• Hospital admission should be considered for women who:
  ● 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.

Question 11

Who should provide care to women with OHSS?

Answer 11

• Multidisciplinary assistance should be sought for the care of women with critical OHSS and severe OHSS who have persistent haemoconcentration and dehydration.
• Features of critical OHSS should prompt consideration of the need for intensive care.
• clinician experienced in MX of OHSS should remain in overall charge of woman’s care.

Question 12

How should women with OHSS be monitored?

Answer 12

• Women admitted with OHSS should be assessed at least once daily. More frequent assessment is appropriate for women with critical OHSS and those with complications.

Question 13

How should the symptoms of OHSS be relieved?

Answer 13

• Analgesia and antiemetics may be used in women with OHSS, avoiding nonsteroidal agents and medicines contraindicated in pregnancy.

Question 14

What is the appropriate management of fluid balance?

Answer 14

• Fluid replacement by the oral route, guided by thirst, is most physiological approach to correcting intravascular dehydration.
• Women with persistent haemoconcentration despite volume replacement with intravenous colloids may need invasive monitoring and this should be managed with anaesthetic input.
• Diuretics should be avoided as they further deplete intravascular volume, but they may have role in multidisciplinary setting if oliguria persists despite adequate fluid replacement and drainage of ascites.

Question 15

How should ascites and effusions be managed?

Answer 15

• Indications for paracentesis include the following:
  ● severe abdominal distension and abdominal pain secondary to ascites
  ● shortness of breath & respiratory compromise secondary to ascites & increased intra-abdominal pressure
  ● oliguria despite adequate volume replacement, secondary to increased abdominal pressure causing reduced renal perfusion.
• Paracentesis should be carried out under ultrasound guidance & can be performed abdominally or vaginally.
• Intravenous colloid therapy should be considered for women who have large volumes of fluid removed by paracentesis.

Question 16

How should the risk of thrombosis be managed?

Answer 16

• Women with severe or critical OHSS and those admitted with OHSS should receive LMWH prophylaxis.
• Duration of LMWH prophylaxis should be individualised according to patient risk factors & outcome of treatment.
• Women with moderate OHSS should be evaluated for predisposing risk factors for thrombosis & prescribed either antiembolism stockings or LMWH if indicated.
• In addition to usual symptoms & signs of 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.

Question 17

When is surgical management indicated?

Answer 17

• Surgery is only indicated in patients withOHSS if there is coincident problem such as adnexal torsion, ovarian rupture or ectopic pregnancy and should be performed by an experienced surgeon.

Question 18

What are the risks associated with pregnancy and OHSS?

Answer 18

• Clinicians should be aware, and women informed, that pregnancies complicated by OHSS may be at increased risk of pre-eclampsia and preterm delivery

Question 19

Mild OHSS

Answer 19

1 - Abdominal bloating
2 - Mild abdominal pain
3 - Ovarian size usually < 8 cma

Question 20

Moderate OHSS

Answer 20

1 - Moderate abdominal pain
2 - Nausea ± vomiting
3 - Ultrasound evidence of ascites
4 - Ovarian size usually 8–12 cma

Question 21

Severe OHSS

Answer 21

1 - Clinical ascites (± hydrothorax)
2 - Oliguria (< 300 ml/day or < 30 ml/hour)
3 - Haematocrit > 0.45
4 - Hyponatraemia (sodium < 135 mmol/l)
5 - Hypo-osmolality (osmolality < 282 mOsm/kg)
6 - Hyperkalaemia (potassium > 5 mmol/l)
7 - Hypoproteinaemia (serum albumin < 35 g/l)
8 - Ovarian size usually > 12 cma

Question 22

Critical OHSS

Answer 22

1 - Tense ascites/large hydrothorax
2 - Haematocrit > 0.55
3 - White cell count > 25 000/ml
4 - Oliguria/anuria
Thromboembolism
Acute respiratory distress syndrome

Question 23

Relevant history of suspected to be suffering from OHSS

History

Answer 23

1 - Time of onset of symptoms relative to trigger
2 - Medication used for trigger (hCG or GnRH agonist)
3 - Number of follicles on final monitoring scan
4 - Number of eggs collected
5 - Were embryos replaced and how many?
6 - Polycystic ovary syndrome diagnosis?

Question 24

Relevant history of suspected to be suffering from OHSS

Symptoms

Answer 24

1 - Abdominal bloating
2 - Abdominal discomfort/pain, need for analgesia
3 - Nausea and vomiting
4 - Breathlessness, inability to lie flat or talk in full sentences
5 - Reduced urine output
6 - Leg swelling
7 - Vulval swelling
8 - Associated comorbidities such as thrombosis

Question 25

Examination and investigation of suspected OHSS

Examination

Answer 25

General:

• assess for dehydration,
• oedema (pedal, vulval and sacral);
• record heart rate, respiratory rate, blood pressure,
• body weight

Abdominal:

• assess for ascites,
• palpable mass,
• peritonism;
• measure girth

Respiratory:

• assess for pleural effusion,
• pneumonia,
• pulmonary oedema

Question 26

Examination and investigation of suspected OHSS

Investigations

Answer 26

1 - Full blood count
2 - Haematocrit (haemoconcentration)
3 - C-reactive protein (severity)
4 - Urea and electrolytes (hyponatraemia and hyperkalaemia)
5 - Serum osmolality (hypo-osmolality)
6 - Liver function tests (elevated enzymes and reduced albumin)
7 - Coagulation profile (elevated fibrinogen and reduced antithrombin)
8 - hCG (to determine outcome of treatment cycle) if appropriate
9 - Ultrasound scan: ovarian size, pelvic and abdominal free fluid. Consider ovarian Doppler if torsion suspected

Question 27

Examination and investigation of suspected OHSS

Other tests that may be indicated

Answer 27

• Arterial blood gases
• D-dimers
• Electrocardiogram (ECG)/echocardiogram
• Chest X-ray
• Computerised tomography pulmonary angiogram (CTPA) or ventilation/perfusion (V/Q) scan