Ovarian hyperstimulation syndrome (OHSS) is a medical condition that occurs when ovarian stimulation is performed for the purpose of hyperovulation and can be life-threatening in severe cases.
OHSS often occurs in the luteal phase after ovulation promotion or in early pregnancy.
The incidence of OHSS during ovulation induction varies, according to statistics: 20% to 33% for mild OHSS, 2.9% to 16.3% for moderate, and 0.1% to 7.1% for severe OHSS.
Diagnosis and treatment of ovarian hyperstimulation syndrome (OHSS)
Clinical manifestations and classification of OHSS
OHSS is classified into mild, moderate and severe according to clinical manifestations and laboratory tests.
Mild
Grade I: blood E2 level ≥1500pg/mL (5490pmol/L), ultrasound examination of >10 follicles, enlarged ovaries but ≤5cm in diameter, may be accompanied by mild abdominal distension and discomfort.
Grade II: Gastrointestinal symptoms with nausea, vomiting or diarrhea on top of grade I.
Signs and symptoms usually start 3-6 days after ovulation or 5-8 days after HCG injection.
Moderate
Grade III: On the basis of mild, the ovary further enlarges with a diameter of 5cm to 10cm, ascites <1500ml; abdominal distention and abdominal pain can be felt, abdominal circumference increases, weight gain ≤4.5kg.; blood E2 level ≥3000pg/mL (11010pmol/L).
Severe.
Grade IV: on the basis of moderate abdominal distension and pain aggravated, thirst, even dyspnea; ovarian diameter > 10 cm, increased ascites, weight gain ≥ 4.5 kg.
Grade V: increased abdominal distension and pain on the basis of grade IV, thirst, little urination, nausea, vomiting, abdominal distension and even inability to eat, large amount of ascites or pleural effusion causing dyspnea and inability to lie down; hypovolemia, blood concentration, hypercoagulable state, inadequate perfusion of renal arteries and renal function impairment, oliguria or anuria, electrolyte disturbance, thrombosis, etc. Individual patients may develop adult respiratory distress syndrome. Erythrocyte pressure volume > 45%, white blood cell count > 1.5×109/L; abnormal liver and kidney function indicators.
If the ovarian enlargement does not reach 10cm, but the abdominal volume is >1500ml, or the pleural fluid is >50ml, it is also considered severe.
Treatment of OHSS.
OHSS is a self-limiting disease with a course of about 14 days in the absence of pregnancy; it improves with menstruation in non-pregnant patients and worsens during early pregnancy in pregnant patients.
Mild OHSS is considered unavoidable in superovulation, and patients without excessive discomfort generally do not require special management; most patients recover within 1 week, but need to avoid strenuous activity and ovarian torsion. Outpatient monitoring should be done, and those at risk of exacerbation should continue to be observed for 4-6 d.
Moderate OHSS can also be observed at rest in outpatient clinic. Treatment is based on rest and rehydration, with instructions to drink more water, especially diuretic drinks such as winter melon soup and watermelon. At the same time, the weight and 24h urine volume should be checked daily, and the urine volume should not be less than 1000ml/d, and it is best if it is maintained above 2000ml/d. Complete remission of the disease should not be achieved until after the next menstrual period, and hospitalization is indicated when the erythrocyte pressure product reaches 0.45. Post-pregnancy OHSS has a longer and more severe course and can last up to 2 to 3 months.