Ovarian Hyperstimulation Syndrome

                        A 24 year old lady presented to the nephrologist in our hospital with acute renal failure. She is nulliparous and was undergoing treatment for subfertility and IVF was planned. According to her history, as she failed to bring her records, she was given HMG for ovarian stimulation.  At time of egg collection, she was found to have mild ascites and enlarged ovaries. Eggs were retrieved and 3 embryos were transferred. She then developed dyspnea and renal failure. She also had 2.5L of ascites drained. She was transferred to our hospital.

                       On admission, Urine output was less than 300ml per day and she had developed ascites and dyspnea. Her full blood count revealed Hb of 8.6g/dl. platelets 4,30,000, hematocrit 30%. Electrolytes were within normal limits. Blood urea 42mg/dl, serum creatinine 4.8mg/dl. She underwent hemodialysis on the day of admission in acute medical care unit. Ultrasound scan revealed ascites, pleural effusion and massive enlargement of ovaries with normal looking endometrium. She improved symptomatically the next day. Her abdominal girth went down from 36cm to 32cm. Serum creatinine was still 4.3mg/dl. Hb 9.2g/dl, platelets 4,30,000/cumm. She was transferred to the ward. 

                       On the third day, her creatinine was 2.8mg/dl, abdominal girth was 29cm, no ascites on ultrasound scan. She was discharged with follow up in 4days with urea and creatinine and abdominal ultrasound scan to be repeated then.

Here are the scan pictures of her ovaries taken at admission. The right ovary is abdominal and 9.5cm in size and the left ovary is in the pouch of douglas and measures 6.5cm 

Left Ovary

Right Ovary

                       Ovarian hyperstimulation syndrome(OHSS) is particularly associated with injection of a hormone called hCG which is used for release of oocytes. The risk is further increased by multiple doses of hCG after ovulation and if the procedure results in pregnancy

Symptoms

                      In mild OHSS, patient complains of bloating sensation in the abdomen, nausea, diarrhea, weight gain

                      In moderate OHSS, excessive weight gain (weight gain of greater than 2 pounds per day), increased abdominal girth, vomiting, diarrhea, darker urine and less in amount, excessive thirst, and skin and/or hair feeling dry (in addition to mild symptoms). 

                      In Severe OHSS, symptoms are fullness/bloating above the waist, shortness of breath, pleural effusion, dark urine or anuria, calf and chest pains, marked abdominal distention, and lower abdominal pain can occur. 

It can also be classified according to the sizes of the ovaries, as they can go upto 12-15cm in size.

Pathophysiology  

                     In response to HCG for oocyte retrieval, there is hyperperfusion of the ovaries resulting in fluid shift to third space. The HCG given will result in multiple luteinised follicles which in turn lead to excess estrogen, progesterone and cytokines. There is excess production of vascular endothelial growth factor under the influence of HCG which is the cause for increased vascular permeability of ovaries.

Risk Factors

                     Young age, multiple follicular development, multiple doses of HCG

Complications

                     ovarian torsion, ovarian rupture, thrombophlebitis and renal failure can occur.

Treatment

                    In mild OHSS, supportive aand conservative treatment with monitoring of abdominal girth and clinical symptoms is all that is necessary.

In moderate OHSS, aspiration of pleural effusion or paracentesis may be necessary. monitoring of blood counts and electrolytes is necessary. Ultrasound scan for monitoring size of ovaries and strict maintenance of fluid input, output chart is essential.

In severe OHSS, posponement of embryo transfer is advised as severity of symptoms can be reduced.

Prevention

                    Use GnRH antagonists can eliminate the risk of OHSS, but there is slight decrease in success rate of IVF with this. Use of FSH should not be indiscriminate and HCG should be withheld in cases of suspicion.