Total Pageviews

Thursday, 29 May 2014

IVF trigger shot

IVF trigger shot is the last injection that is given approximately 36 hours before the egg collection. This is one of the most crucial steps of IVF and if done incorrectly or missed will prevent retrieval of eggs.

"Why trigger?" and "Trigger what?" are the most natural questions that would come to mind. The eggs that are developing in the growing follicles during ovarian stimulation are not fit to form an embryo. They have not yet completed their maturation division that leads to halving of the number of chromosomes. This has been discussed already in my earliest posts. In addition, the egg encased in the clump of cumulus cells (called COC or cumulus oocyte complex) is still attached by a stalk to the wall of the follicle. Till such time that this stalk is intact, aspiration of follicle fluid will not yield the egg that is present in the follicle.

In the natural cycle, these final events and the ovulation are triggered by the release of a large amount of LH hormone (called LH surge) from pituitary gland. In IVF cycles the natural release of hormones from pituitary gland are restricted due to the IVF medicines (as explained in my previous post on agonists and antagonists). Hence there is a need to artificially facilitate these important steps.

The trigger injections are in the form of Human Chorionic Gonadotrophin (hCG) which is the same as pregnancy hormone. This hormone is very similar to LH in structure and so can carry out the functions of an LH surge. Based of the source, hCG comes is of two types: urinary and recombinant. Both are equally effective. Recombinant hCG however is a little more expensive than urinary for obvious reasons.

Alternative trigger injection in the next post....

Sunday, 25 May 2014

Ectopic pregnancy

Ectopic pregnancy refers to those pregnancies that settle in a site other than the normal - the uterine cavity. The commonest is the fallopian tube. Other sites are cervix, ovary and the abdominal cavity. An ectopic is a potentially dangerous situation because unlike the uterus (which the nature has built to allow expansion so as to accomodate a growing pregnancy), the expansion afforded at these abnormal sites is limited and at some point the tearing/bursting of the organ can lead to life-threatening haemorrhage. This necessitates immediate surgery to deal with the bleeding and save the life of the woman. Where the ectopic pregnancy is diagnosed early it can also be managed using an injection of an anti-cancer drug (methotrexate) to kill the growing cells of the pregnancy. 

Why does an ectopic pregnancy occur? For simplicity, I am restricting myself to those that occur in the fallopian tubes. Tubes are delicate structures and any infection or inflammation can cause injury leading to partial or complete block of the tube.  The mucosa or the inside skin of the tube may become damaged leading to the dysfunctional movement of a newly formed embryo towards the uterus. The embryo therefore may get stuck and start growing in the tube itself. In many women, it may be impossible to identify the episode/cause of the damage.

For someone who has had an ectopic pregnancy in the past, what are the implications? Women who have an ectopic pregnancy are at risk of another ectopic pregnancy. This happens because, the event/agent that caused injury or damage to one tube may well have affected the other tube. It is not uncommon to conceive spontaneously and have uneventful normal pregnancy (and delivery) after an ectopic pregnancy. However, a delay in conceiving should be managed appropriately. Depending on the clinical circumstances, IVF may be recommended. Even if Intrauterine insemination is attempted, the trial of this treatment should be short with the escalation to IVF. This will avoid the additional implications of declining egg quality with age. A short-sighted approach of low-cost treatments for too long may otherwise be a disservice to the couple involved.

Sunday, 18 May 2014

Is too much stimulation in IVF good?

In the context of ovarian stimulation, caution should be exercised with respect to the follicles that grow as a result. What is the ideal number? The answer to this question varies with the treatment, with the physician treating and with the patient as well. You could wonder why too little or too much is a problem.

Whereas 2-3 follicles are acceptable in an IUI cycle, the same cannot be said for IVF cycle. In the context of IVF cycle too little understandably would not lead to a good pregnancy rate - the aim of fertility treatment. 

The fact that too much can also be a problem is less commonly realized by patients. When the ovarian stimulation is being done in conjunction with IUI, a higher number of follicles that start growing could ultimately lead to a higher order multiple pregnancy with the set of complications that come with it. In IVF, if we think logically, more follicles should mean more eggs, more embryos and more success rate. However, where there are more than 15-20 eggs, a disproportionate number of eggs are immature and these do not contribute to the formation of embryos. More eggs does not therefore mean more good eggs and more good embryos. 

To make matters worse is a complication called OHSS - Ovarian Hyper Stimulation Syndrome. OHSS happens as a result of a cascade of chemical reactions in the blood stream that results in leaky blood vessels. As a result fluid accumulates in the tummy cavity and sometimes in the chest around lungs and heart. This can be quite uncomfortable or even intensely painful to the woman. The leaking of fluid leads to the blood becoming thicker. Affected women are therefore at a risk of developing blood clots in the major veins. Deep vein thrombosis (as this condition is called), can occasionally cause death. Understandably, every IVF clinician strives to avoid this complication.

Sunday, 11 May 2014

Immature eggs?

Anyone who has gone through IVF is likely to have come across this term: Immature eggs. When I say this to my patients during the course of IVF, many roll their eyes! It  is really not that complicated. As I had mentioned in my post on egg quality, eggs need to go through a reduction division of its genetic material in order to maintain normality. The big question is how do we know whether the egg has undergone this process?

The reduction division takes place in two stages. While the first stage is complete before fertilization, the second division only occurs after the sperm has entered the egg. 

At the end of the first stage, the egg splits into two cells each with one set of the two sets of chromosomes that are present to begin with. Normally, the division of the genetic material is equal but the cytoplasm (the cell fluid that surrounds the nucleus or genetic material) is divided disproportionately. The egg keeps almost all of the cytoplasm while the other cell - now called polar body has only a small amount.

A mature egg therefore looks like the picture given below. The small polar body is clearly visible. The absence of polar body means the first stage of reduction division is not complete and this egg cannot be used to make embryos for the fear of forming embryos with more than normal amount of genetic material.  

Thursday, 8 May 2014

Egg collection

After a bit of a hiatus (for which I apologise), this post will explain the process of egg collection or oocyte retrieval. It may sound scary but it isn't, really! The time of the egg collection is dictated by that of the trigger injection (hCG or GnRH analog). The time interval is slightly shorter if analog trigger is given. The procedure can be done either under sedation or short general anaesthesia. Commonly it is a short procedure and takes 15- 20 minutes. It may take longer or shorter time depending on the number of follicles that have developed as well as the type of anaesthesia.

Egg collection is almost always done through the vaginal approach. The ultrasound probe (that is used for the internal scan) has an attachment which enables the surgeon to guide the needle into each of the follicles, one at a time and take the fluid out. The eggs come along with the fluid. The fluid from the follicles is collected in test tubes and taken to the laboratory where the eggs are separated and kept in culture medium at optimal conditions in the incubator till the next step of fertilization.

Occasionally massive enlargement of uterus (from fibroids), prior surgery or rarely congenital anomalies may lead to displacement of the ovaries and may require egg collection to be done from the abdominal route. This can either be done through the abdomen using the ultrasound guidance or through keyhole surgery.

Depending on the anesthesia given for the procedure the recovery time may vary from 1-3 hours. Common symptoms to expect are nausea or vomiting (especially after general anesthesia), mild/minimal vaginal bleeding, and abdominal pain/tenderness. Heavy bleeding, severe pain, fever, smelly vaginal discharge, persistent vomiting should be reported to the doctor. If you have any other symptoms, please also consult/inform your specialist.