Ovarian Hyperstimulation Syndrome

Dr. Panagiotis Polyzos MD PhD MSc

Obstetrician Gynaecologist
Doctor of Medicine, University of Athens Medical School

Panagiotis Polyzos, Gynaecologist Obstetrician, is active at the Institute of Life - IVF Unit of Iaso Maternity Hospital.

Contents

Ovarian Hyperstimulation Syndrome

What is Ovarian Hyperstimulation Syndrome?

Ovarian Hyperstimulation Syndrome is a serious systemic complication caused by the circulation of vasoactive substances released by the ovaries following ovarian stimulation protocols. Its pathophysiology is characterized by increased capillary permeability, leading to extensive fluid extravasation, loss of protein-rich fluid into the interstitial space, and widespread intravascular dehydration.

The majority of severe Ovarian Hyperstimulation Syndromes occur after IVF cycles, but ovarian hyperstimulation syndrome can also develop following any form of ovulation induction. The incidence of ovarian hyperstimulation syndrome is higher in young women as well as in in those with polycystic ovaries.

Diagnosis & Differential Diagnosis

The diagnosis of Ovarian Hyperstimulation Syndrome is based on the patient’s history, typically reporting a stimulation protocol with either clomiphene or gonadotropins, and on the clinical presentation, which includes:

  • Severe abdominal pain and distension
  • Nausea and vomiting
  • The differential diagnosis includes:
  • Complications of ovarian cysts (torsion, hemorrhage)
  • Pelvic inflammatory disease
  • Intra-abdominal bleeding
  • Ectopic pregnancy

Ovarian Hyperstimulation Syndrome Severity Classification

Degree & Symptoms

Ovary size < 8 cm.

Moderate abdominal pain
Nausea Vomiting
Ultrasound evidence of ascites

Ovarian size 8 - 12 cm.

Tense ascites or significant pleural effusion
Oliguria
Blood congestion (HT > 45%)
Hypoproteinemia

Ovary size > 12 cm.

Ascites under tension or marked hydrothorax
Hematocrit > 55%
White blood cells > 25.000/ml
Oliguria - Anuria
Thromboembolic episode

 

Both the severity and the frequency of the syndrome require its prevention, as well as early intervention at an initial stage.

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What is appropriate prevention?

1. Personalized ovarian stimulation protocol (especially in women with PCOS or a history of OHSS)
2. Adjustment of gonadotropin dosage and stabilization of E2 (estradiol) levels
3. Prophylactic administration of albumin during oocyte retrieval
4. Embryo cryopreservation and embryo transfer in a subsequent cycle

What is the treatment for immediate treatment?

Α. OUTPATIENT MANAGEMENT – NON-HOSPITALIZED PATIENT

The outpatient management of a patient with OHSS refers to the mild and moderate forms of the syndrome:

Please rest and take a few days off from work or physical activities.

For pain relief and pelvic discomfort, paracetamol or codeine is recommended. Fluid intake should be reasonable, with close monitoring of fluid balance. Excessive fluid intake should be discouraged. Strenuous exercise and sexual intercourse should be avoided due to the risk of ovarian torsion or trauma to hyperstimulated ovaries. Luteal support with progesterone is recommended, while the use of hCG is contraindicated.

Ultrasound monitoring is essential to assess ovarian size and the presence of ascites. Laboratory tests to determine the severity of the condition include:

Hematocrit / Hemoglobin, Serum Creatinine, Electrolytes, and liver function tests.

These values are used in serial measurements to evaluate the progression of the condition. Monitoring is repeated every 2–3 days.

Monitoring should be intensified if the patient develops:

  • Worsening of abdominal pain
  • Increase abdominal distension
  • Shortness of breath
  • Reduced urine output
 
Β. HOSPITALIZED – INPATIENT MANAGEMENT

Women with severe forms of the syndrome should be admitted and treated as inpatients. Additionally, women with moderate OHSS who cannot adequately control their symptoms with oral therapy should also be hospitalized, as well as women for whom continuous and systematic monitoring cannot be ensured for any reason.

Symptomatic Treatment

  • Systematic monitoring of vital signs every 4 hours and fluid balance.
  • Monitoring of body weight and abdominal circumference.
  • Hematological – Biochemical testing (hematocrit, white blood cells, platelets, prothrombin time, activated partial thromboplastin time).
  • Ultrasound examination
  • Analgesia with paracetamol and, if needed, opioids administered orally or parenterally.
  • Intravenous hydration.
  • Administration of antiemetics not contraindicated in possible early pregnancy, such as metoclopramide (Primperan)
  • Prophylactic administration of subcutaneous heparin for thromboembolism prevention

 

Management of OHSS is entirely supportive until the condition resolves. Symptomatic treatment is important, especially for abdominal pain and nausea. Nausea is usually due to ascites, and therefore, measures aimed at reducing abdominal distension provide relief.

 

In cases of stage 4–5 OHSS, immediate admission to an Intensive Care Unit is required. Renal impairment is managed with dopamine and, if necessary, possible dialysis; respiratory distress with urgent thoracentesis and mechanical ventilation; and thromboembolic events with systemic anticoagulant therapy. Worsening of OHSS after embryo transfer always remains a possibility, and one should not be reassured by a temporarily improved clinical condition following ovarian stimulation. Finally, termination of early pregnancy in very severe cases of the syndrome remains the last therapeutic option.

MEDIA

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