Ovarian Hyper-stimulation Syndrome (OHSS) is a serious complication of IVF caused by excessive stimulation of the ovaries (too many follicles are produced). It is uncommon, occurring in only 1-3% of cycles and is more frequently seen in women who have the diagnosis of Polycystic Ovarian Syndrome (PCOS). It is characterised by rather sudden ovarian enlargement and abdominal fluid retention. Symptoms of OHSS occur most vigorously after hCG administration.

If your treatment monitoring indicates that you may develop hyper-stimulation, your clinician will bring this to your attention immediately and in such cases they are likely to cancel the cycle. Occasionally the clinician may decide to proceed to egg collection but freeze all embryos and delay embryo transfer for a month or two because hyper-stimulation may be further aggravated if pregnancy occurs.

In severe cases of OHSS hospitalisation may be required for monitoring and medical treatment, of which the most important component is rehydration and the prevention of clots.

There are three classifications of OHSS severity:

Mild OHSS:

accompanied by enough pelvic pain in the luteal phase to cause a woman to want to rest in bed for a day or two. Symptoms include abdominal bloating, a feeling of fullness, weight gain and diarrhoea.

What to do?

  • Call Life Fertility Clinic and speak with the fertility nurse.
  • Weigh yourself daily and monitor changes.
  • Refrain from intercourse until advised by the fertility nurse.
  • Ensure you drink at least 2 litres of fluid daily (1-2 sports drinks are best, such as Gatorade).
  • Remain as active as is comfortable but avoid strenuous activity.

Moderate OHSS:

requires a hospital stay, mainly for observation and to enable us to give adequate pain relief. Symptoms include sudden weight gain, tight clothing, vomiting, nausea and loose bowel motions.

What to do?

  • Call Life Fertility Clinic and speak with the fertility nurse or your doctor.
  • Your doctor may request daily blood tests and an ultrasound.
  • Weigh yourself daily and monitor changes.
  • Measure your waist daily at the level of the belly button and monitor changes.
  • Keep a measure of your fluid input and monitor your urine output.
  • Ensure you drink at least 2 litres of fluid daily and more if you can tolerate it.  Sports drinks are best, such as Gatorade.
  • Remain as active as is comfortable but avoid strenuous activity.

Severe OHSS:

in about 1 in 500 stimulations there is enough fluid in either the abdomen or the chest to be of serious medical concern. In approximately 1% of women the symptoms of OHSS may become so severe that hospitalisation is necessary. Women will experience a progression of symptoms including nausea, vomiting, marked abdominal pain, diarrhoea and dehydration. Fluid accumulates in the abdominal cavity and chest, causing abdominal swelling and shortness of breath. There is a reduction in the amount of urine produced. These symptoms require constant monitoring by the doctor while the woman is in hospital. Women diagnosed with severe OHSS may take up to 3-4 weeks to recover from their symptoms.

What to do?

  • Contact your IVF Doctor immediately or present to the nearest emergency department.

Adnexal or ovarian torsion (ovarian twisting) is a condition where the stimulated ovary twists on itself cutting off its own blood supply. Ovarian torsion is a rare complication of IVF treatment. The overall risk is about 0.2%. It is greater in the presence of OHSS. Ovarian torsion may cause severe pain and tenderness in the lower abdomen.

If not treated early enough the twisted ovary may die (gangrene). Treatment requires surgery to untwist the ovary and to remove it if necessary.


While less than 5% of cycles are cancelled before egg recovery, there are occasions when cancellation of the cycle may be recommended by the doctor. Such occasions include:

  • Your ovaries are not responding to hormone treatment.
  • Your ovaries are over-responding to the hormones, risking hyper-stimulation (OHSS)
  • Uterine abnormalities such as fibroids or polyps are unexpectedly detected on ultrasound.
  • Personal reasons.

If you are at risk of hyper-stimulation or if a problem is discovered in the uterus, your doctor might suggest that you have a ‘freeze-all’ cycle rather than cancel the cycle completely. In a ‘freeze-all’ cycle, the eggs are collected; fertilised then all suitable embryos are frozen. Because pregnancy or further hormone injections will worsen the risk of OHSS, a ‘freeze-all’ cycle is a safer option in these circumstances. This gives the ovaries time to settle before attempting pregnancy at a later date. When frozen embryos are utilised in a subsequent cycle, there is no ovarian stimulation required.


Although the prospect of twins or triplets may seem attractive to some couples, multiple pregnancies are associated with increased risks of maternal and foetal complications. In addition, multiple pregnancies place enormous strain on the parents including financial difficulties, emotional distress and physical exhaustion.

In IVF the risk of multiple pregnancies is directly related to the number of embryos that are transferred into the uterus. At Life Fertility Clinic, we minimise the risk of multiple pregnancy by adhering to the Reproductive Technology Accreditation Committee (RTAC) code of practice recommendations with regard to embryo transfer number. This code of practice recommends that only one embryo is replaced in a patient’s first treatment cycle particularly for women under 35 years of age and states that a maximum of 2 embryos be transferred in any cycle for women under 40 years of age.

The key to preventing multiple pregnancies in TSI and IUI cycles is effective monitoring with ultrasound. The doctor will review whether treatment can proceed based on the number of follicles seen on ultrasound scan.


Maternal risks associated with multiple pregnancy:

  • Miscarriage.
  • Haemorrhage.
  • Pregnancy induced high blood pressure.
  • Diabetes.
  • Anaemia.
  • Polyhydramnios (excessive amounts of amniotic fluid that surrounds the fetus).
  • Caesarean section.
  • Prolonged hospitalisation resulting in a higher risk of clots and infection.

Foetal complications associated with multiple pregnancy:

  • Preterm delivery – The average length of a pregnancy is 39 weeks for a single pregnancy, 35 weeks for twins and 33 for triplets. Preterm delivery occurs in over 50% of twin pregnancies and in 90% of triplet pregnancies.
  • Multiple pregnancies have a four-fold increase in the rate of preterm delivery and low-birth weight compared to a singleton pregnancy. The proportion of twins and triplets delivering before 30 weeks pregnancy is around 7% and 15% respectively. These babies are more likely to suffer serious, lifelong health problems, such as cerebral palsy and serious disability. The risk per pregnancy of producing a child with cerebral palsy is 8 times greater in twin pregnancies and 47 times greater in triplet pregnancies than in singleton pregnancies.
  • Low birth weight – This is more frequent in multiple pregnancies. The lifelong morbidity is over 25% for babies weighing less than 1 Kg.
  • Increased stillbirth and neonatal death rates.

Since ovarian stimulation medications were first used decades ago there has been concern that their use might increase the risk of cancer. Several large studies have now found that the rates of cancers among women who have used fertility medications are not significantly different from the rest of the population. There is no evidence to date that the medications used in assisted conception have a causal link to either breast or ovarian cancer.


As with any surgical procedure, there are potential risks associated with egg collection. At Life Fertility Clinic, egg collection is performed by vaginal ultrasound. The risks associated with this procedure include:

  • Mild to moderate discomfort.
  • Bleeding during or after egg collection from the ovary or from the top of the vagina. The bleeding is usually minimal, is very rarely a problem and the need for blood transfusion is very rare (about 1 in 500).
  • Infection. This is also a rare complication (about 1 in 300) and can be treated with antibiotics.
  • Injuries to internal organs such as bowel, bladder or blood vessels during the procedure. This is an extremely rare complication (about 1 in 1000).

On occasion (<5% of cycles) the eggs collected and inseminated in an IVF cycle unexpectedly fail to fertilise. Sometimes the sperm do not bind to the egg and initiate fertilisation or the viability of the sperm deteriorates too quickly for fertilisation to occur. Using ICSI on future cycles can overcome this.

Failure to fertilise can also occur (by IVF and ICSI) if the follicles that the eggs were extracted from had begun to fail prior to egg collection or if there are major sperm or egg defects.

On average 70% of eggs collected will fertilise and approximately 50% of these will form an embryo suitable for embryo transfer or freezing when cultured to the blastocyst stage. It is therefore possible for a cycle to be cancelled before embryo transfer because there are no embryos suitable for transfer. This occurs in about 15% of cycles.

Even though embryos may appear normal, they can still fail to implant. This may be for many different reasons but one common cause it thought to be that many embryos have an abnormal chromosome count.


IVF treatment can be stressful and intrusive. There are various reasons for this including:

– Demands of stimulated treatment

Daily injections, the need for blood tests early in the day, ultrasound appointments and phone calls can all be demanding.

– Stresses associated with the procedures

Many aspects of fertility treatment involve invasive procedures which can be daunting, time consuming and cause discomfort. It can also be stressful for men to have to provide a semen sample on the day of a procedure.

– Stresses associated with periods of waiting

Waiting for fertilisation results; embryo development updates; thaw outcomes and the long wait between transfer and pregnancy test can all be very stressful.

– The possibility of treatment not being successful

It is not uncommon for people to experience grief in response to the many losses that can be experienced during fertility treatment as well as other emotional responses such as stress, depression and anxiety.

Life Fertility Clinical staff and counselling services are all on hand to help care for you in stressful times.



For more information or queries regarding any of the services offered at Life Fertility Clinic, please contact us.