Ovarian Hyperstimulation Syndrome

Published Date: 19th July 2016

Publication Authors: , Mackin D, , Tempest N

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Background 

Ovarian Hyperstimulation Syndrome (OHSS) is characterised by presence of multiple luteinized cysts within the ovaries leading to ovarian enlargement. It is commonly associated with assisted fertility treatment. Spontaneous OHSS is an extremely rare event in natural conceptions although a few cases have been described in association with multiple or molar gestations, hypothyroidism and polycystic ovary syndrome. We

describe a patient with a naturally conceived singleton pregnancy associated with spontaneous OHSS without any evidence of an endocrinological disorder.

Case 

A 32-year-old primigravida with normal BMI booked for antenatal care at 11 + 4 weeks of gestation following spontaneous conception. Past medical history was unremarkable. All booking investigations were normal including TFTs. Booking Scan confirmed a viable pregnancy consistent with gestation and bilateral large multifollicular ovaries (right: 240 mL, left: 301 mL), with no evidence of ascites. Follow-up scans were performed to monitor ovarian volumes. Serum b-hCG was 121 742 mIU/mL. She was asymptomatic. Detailed anomaly scan at 20 + 3 weeks showed no abnormalities. Ovarian volumes normalised spontaneously by 24 weeks (right: 233 mL, left: 150 mL). Gestational diabetes was diagnosed at 24 weeks of gestation due to recurrent glycosuria. Blood sugar levels were optimised with diet and exercise. Spontaneous preterm labour occurred at 29 weeks resulting in a live female infant weighing 1.350 kg. Mother and baby were well 6 weeks postnatally. The patient has had a second baby without recurrence of OHSS.

Discussion 

OHSS is an extremely rare event in spontaneous single pregnancies. Literature review suggests occasional association with multiple or molar gestations, hypothyroidism or polycystic ovary syndrome and activating mutations of the FSH receptor (FSHR) gene. TSH and hCG may lead to spontaneous OHSS in patients with FSHR mutation. Differential diagnosis includes hyperreaction luteinalis, luteomas of pregnancy, and theca lutein cysts.

Conclusion 

OHSS is a potentially serious complication associated with assisted fertility treatment, particularly IVF. Most cases of OHSS are managed conservatively however; severe cases require multidisciplinary input.

El Daief, S; Mackin, D; Tempest, N; Nwosu, EC. (2013).  A case of natural conception associated with ovarian hyperstimulation syndrome . BJOG: An International Journal of Obstetrics and Gynaecology. 120 (Supplement), 198-9

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