Ovarian Hyperstimulation Syndrome

History of ovarian stimulation, either by gonadotrophins or anti-estrogen, followed by the typical symptoms of abdominal distension, abdominal pain, nausea and vomiting

Differential Diagnosis

Ovarian cyst / torsion / haemorrhage
Pelvic infection
Intra-abdominal haemorrhage
Ectopic pregnancies
Appendicitis

Pathophysiology

Increased capillary permeability
Leakage of fluid from vascular component
Third space fluid accumulation
Intravascular dehydration

Classification Of Severity of OHSS

Grade	Symptoms
Mild	Abdominal bloating, mild abdominal pain, ovarian size usually <8cm
Moderate	Moderate abdo pain, nausea+/-vomiting, USS evidence of ascites, ovarian size 8-12cm
Severe	Clinical ascites, oliguria, haemoconcentration haematocrit >45%,hypoprotenaemia,Ovarian size usually >12cm
Critical	Tense ascites or large hydrothorax,Haematocrit>55%, WCC>25000,Oligo/anuria,VTE,Adult Respiratory Distress Syndrome

Risk Management

Assesement and documetation of severity of OHSS
OHSS related deaths must be reported to the Confidential enquiries into maternal death, irrespective of whether woman was pregnant
Assisted conception units should provide written information including risks, symptoms of OHSS, actions to take ,24hrs contact no and access to clinician with necessary expertise.
Agreed protocols should be made available by assisted conception units to GPs,Gynaecology departments and Emergency department

Management

Assessment

Body weight, abdominal girth measurement, and pelvic USS to measure ovarian size and check for ascites
Lab Investigation: FBC, Haematocrit, serum creatinine and electrolyte, LFT

Outpatient Management

Treatment of mild and moderate OHSS can be managed on an outpatient basis
Analgesia-Paracetamol,Codeine,Avoid NSAIDS
Drink to thirst, rather than to excess
Avoid strenuous exercise and sexual intercourse to prevent injury or torsion to hyperstimulated ovaries
Women should continue progesterone luteal support but HCG luteal support is inappropriate
Review every 2-3days
Prolonged monitoring if woman conceives

Inpatient Admission

History & exam	Pain, breathlessness, hydration, weight, CVS,Heart Rate,BP, Abdominal girth, ascites, intake and output chart
Investigations	FBC, Hb,Hematocrit, WCC, E/u+Cr,LFT,Clotting,Pelvic USS,Chest Xray or USS,ECG and Echocardiogram If suspecting Pericardial effusion

Admit patient with severe OHSS, keep under review until resolution of the condition
Admit moderate OHSS who are unable to control their pain or nausea with oral treatment.
Multidisciplinary assistance in critical or severe OHSS with persistent haemo-concentration and dehydration
Doctor with experience with OHSS should remain in overall charge
Management is majorly supportive

Symptom Relief:

Analgesia,Paracetamol ,opiates avoid Nsaids, Antiemetics
Assess woman daily and more frequently in critical OHSS
Check abdominal girth, hydration,cardiorespiratory system
Abdominal exams to look for degree of distension, palpable ovaries, presence or absence of ascites and paralytic ileus

Monitor fluid input and output daily, urine output of less than 1000mls/day or a persistent positive fluid balance is a cause for concern
Allow women to drink to thirst
Invasive monitoring should be discussed with anaesthetist in severe OHSS with persistent oliguria and haemoconcentration despite initial colloid volume expansion
Avoid Diuretics as it depletes intravascular volume(may have a role with careful haemodynamic monitoring in cases where oliguria persists despite adequate intravascular volume expansion and a normal intraabdominal pressure)
Women with haemoconcentration,HB>14g/dl,haematocrit>45% may need intensive initial rehydration such as 1L of saline over 1hr
Try Colloids if urine output is less than 0.5ml/kg/hr and patient is haemoconcentrated
If Oliguria and haemoconcentration persists try paracentesis

Management Of Ascites

Paracentesis under USS guidance if persistent oliguria despite adequate fluid replacement
Consider intravenous colloid replacement after drainage of large ascitic fluid.

Thrombosis

Routine screening in women undergoing assisted conception is not warranted
Thrombophylaxis should be provided for all women admitted for OHSS until discharge and possibly longer depending on other risk factors
Incidence of VTE in OHSS 0.7-10%
Unusual neurological symptoms following ovarian stimulation think of thrombotic episode in an uncommon location and refer for appropriate expert opinion.

Pelvic Surgery

Restricted to adnexal torsion or co-incident problems requiring surgery

Reassurance

Pregnancy may continue despite OHSS and no increased risk of congenital abnormalities

Prevention

There are some strategies that can be employed to lower the incidence or severity of OHSS occurring. These include:

Using low-dose stimulation protocols, or natural cycle IVF
Follicular monitoring
Utilising GnRH antagonist cycles rather than GnRH analogues
Utilising progesterone instead of HCG for luteal suppot
Abandoning ART cycles prior to HCG administration and oocyte collection
Delaying embryo transfer following collection and elective freezing of all embryos
Coasting, whereby the HCG trigger is withheld until serum estradiol levels have returned to acceptable levels
GnRH agonist triggering the final maturation of oocytes, but pregnancy rates are reduced

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Table of content

Definition:

Incidence

Risk Factors

Diagnosis

Differential Diagnosis

Pathophysiology

Classification Of Severity of OHSS

Risk Management

Management

Outpatient Management

Inpatient Admission

Symptom Relief:

Management Of Ascites

Thrombosis

Pelvic Surgery

Reassurance

Prevention

Reference

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