All About Ovarian Hyperstimulation Syndrome

What Is OHSS and How Do You Avoid It?

Ovarian hyperstimulation syndrome (OHSS) can develop from IVF and ovulation induction therapies; however, with good care and common sense, it can be avoided. It’s been over 16 years since any patient developed significant OHSS while being treated at Michigan Reproductive Medicine and the few women that developed the moderate to severe form all completely recovered and did well, as did their babies.

In my blog post, I’ll answer the following questions:

1. What is Ovarian Hyperstimulation Syndrome?
2. What are conditions that raise the risk for a woman developing OHSS?
3. What is the chance of getting OHSS?
4. How can this condition be prevented?
5. How is OHSS treated?
6. Will OHSS hurt my chances for becoming pregnancy and having a healthy baby?

What is Ovarian Hyperstimulation Syndrome (OHSS)?

OHSS is a serious condition. Women may experience a broad spectrum of signs and symptoms ranging from mild, moderate to severe forms. When this condition develops, most women will experience enlarged ovaries (see ultrasound image), mild forms with abdominal bloating, discomfort, shortness of breath and mild weight gain—this primarily water weight. However some women may develop a severe form of OHSS: it can cause massive fluid accumulation in the belly and around the lungs, heart and other areas. Fluid accumulation may cause breathing and circulation problems. The blood has a higher tendency to clot and can cause deep vein thrombosis, stroke and/or pulmonary embolus. The kidneys can be compromised as well. Complications stemming from OHSS can be life-threatening if not carefully monitored and/or treated.

OHSS occurs in patients who have a high response to ovulation induction medication and is especially acute for those patients who, with a high response to medication, then receive an HCG injection during ovulation induction or to trigger ovulation in preparation for egg retrieval. It rapidly intensifies the moment pregnancy occurs when the placenta normally infuses the pregnancy hormone, HCG, into her circulation. It is therefore imperative to prevent OHSS by careful monitoring, using conservative administration of medications, and patient education. Fertility clinics should always have guidelines and treatment plans to prevent this serious disorder.

What Conditions Raise the Risk for a Woman Developing OHSS?

Patients susceptible to OHSS include those who have

• Polycystic ovary syndrome (PCOS),
• Younger ages: 20’s to early 30’s,
• High anti-Mullerian Hormone (AMH) level,
• High antral follicular count (AFC),
• Known sensitivity to fertility drugs described as a high number of follicles developing at a low dose of medication or have had OHSS in the past.

Generally, OHSS may develop when

• Peak estradiol is high (typically above 2500),
• Number of lead/mature follicles stimulated is also high (15 or more),
• More than one embryo is transferred: high order multiple fetal pregnancies of twins or more in the cycle of ovarian stimulation. The more babies, the more the placentas and thus the source of hCG is increased and the more hCG released into the pregnant woman’s circulation.

In rare cases, the OHSS occurs in spite of normal estradiol or normal follicular stimulation. In practically all cases of OHSS, the HCG trigger injection was given, which then prompts the body to respond by shifting water from our blood stream into our largest body cavities: the abdomen and chest spaces. This large water volume movement is often termed “third spacing of fluid”. If HCG is withheld or Lupron, a trigger medication alternative to HCG is used, OHSS rarely occurs.

For you science buffs, here is a deeper dive diagram into the physiology of this disorder:

 

What is the Chance of Getting OHSS?

At Michigan Reproductive Medicine, the chance of getting OHSS is extremely small, less than 1%. We do our best to protect our patients from this life-threatening condition.

Studies show that ten to fifteen percent of patients will develop mild to moderate hyper-stimulation syndrome going through IVF. These patients will have mild to moderate abdominal pain, abdominal bloating or increased waist size, nausea, vomiting, diarrhea, tender ovaries, and mild weight gain.

Reports indicate that 1-2% of patients going through IVF will get severe OHSS. These patients will have rapid weight gain, severe abdominal pain, persistent nausea and vomiting, blood clots in legs, decreased urination, shortness of breath and tight or enlarged abdomen. With these symptoms, hospitalization is almost always required.

How Can OHSS Be Prevented?

 There are multiple options:

1. Withhold hCG trigger shot.
2. Use a Lupron trigger shot instead of the hCG trigger shot.
3. Cancel the current cycle.
4. Lower the dosages of ovulation induction medications or continue monitoring without any additional stimulation medication (coasting).
5. Freeze all created embryos and delay embryo transfer until the high stimulation has subsided.
6. Elective single embryo transfer (eSET).

How Can OHSS Be Treated?

Patients with mild to moderate OHSS are generally observed for worsening symptoms. Patients should monitor their weight and be aware of signs that need to be immediately addressed by their doctor. Patients with severe OHSS may need their excess fluid drained before even more serious symptoms occur. Fluid can be drained from the abdomen with a needle through the abdomen or vagina using ultrasound guidance. If performed abdominally, a catheter can be left in place temporarily to allow continuous drainage so that a repeat procedure is not necessary. If needed, fluid may also be removed from the chest or other areas. Patients with severe OHSS are at risk for blood clots. Patients are often placed on anticoagulation medication and receive IVF fluids as preventative measures. Some patients with particularly severe OHSS may need intensive monitoring in the hospital and if need be in an intensive care unit (ICU). Rare cases have been reported where the state of pregnancy caused such severe OHSS, that termination of pregnancy was performed as a life-saving intervention.

Will OHSS Hurt Chances For Pregnancy and Having a Healthy Baby?

 No, getting OHSS does not hurt one’s chances of achieving pregnancy; however, it’s best to avoid the chance of pregnancy until the risk for OHSS has been eliminated. For example, if a patient planned to have a fresh embryo transfer during a fresh IVF cycle and the stimulated ovaries appear to be over-responsive, it’s best to change the treatment plan, not perform a fresh embryo transfer and instead, freeze all embryos and wait for symptoms to disappear. A frozen embryo transfer can then be performed.

Due to modern vitrification freezing technology used here at MRM, our patients’ frozen embryo transfer pregnancy rates are every bit as good, if not better than fresh embryo transfer pregnancy rates. Research studies are suggesting the uterine lining may not be as receptive to an embryo successfully implanting when OHSS is present. For these reasons, it’s smart and safe to freeze all embryos and delay embryo transfer until OHSS symptoms have ended.

We at Michigan Reproductive Medicine do our best to get all patients through their fertility treatments safely and successfully. Our goal is to avoid OHSS wherever possible and protect patients from hospitalizations, invasive procedures to drain OHSS-related fluid from the various areas the body and from thromboembolic disease- blood clots forming in blood vessels. With care, common sense and education, the life threatening condition of OHSS can be avoided.

This blog was written by Dr. Manny Singh, MD