• * The center of assisted medical procreation of the CHU St Pierre is specialised in reproductive medicine. Reference center: quality label ISO 9001 obtained in 2008 and accredited by the AFMPS (Agence Fédérale des Médicaments et Produits de Santé).


Severe complications following in vitro fertilization are infrequent (about 2 %) but they need to be correctly diagnosed and taken care of in order to minimise the risk of after-effects.


1- Complications associated with ovarian stimulation:

  • Discomfort associated with stimulation: at the end of stimulation, there may be abdominal discomfort linked to the size of the ovaries
  • Ovarian hyperstimulation syndrome (“OHSS”): this is a complication whereby the stimulation of the ovaries escapes control and causes a pathological increase in hormone levels and abnormal vascular permeability. This results in 2 concomitant phenomena: fluid escaping into virtual cavities such as the abdomen (ascites), the pleura (pleural effusion), the lungs (oedema) and rarely the pericardium, and at the same time, an increase in blood viscosity with a risk of thrombosis.
    This syndrome has several degrees of severity.
    In general, it is a benign infection that resolves spontaneously and is treated with rest, verification of fluid intake with blood tests and ultrasound scans, and possibly treatment with anticoagulants.
    In more serious cases, hospitalisation is suggested for closer monitoring. It may be necessary to remove fluid that has accumulated in the abdomen. Rare severe cases require monitoring in the intensive care unit.
  • Ovarian torsion (0.1 to 0.8%): the stimulated ovaries increase from 3 to 10 times their size. Because of their weight, they can turn on their vascular axes and stop the blood flow. The risk is correlated to the volume of the ovaries (more frequent in OHSS) and can occur well after oocyte retrieval (4-11 weeks). It is a painful complication that often occurs suddenly, accompanied by nausea and vomiting. Surgery (laparoscopic detorsion) is the preferred treatment.


2- Complications associated with oocyte retrieval:

  • Bleeding: vaginal and abdominal blood loss is common after oocyte retrieval. In rare cases, blood loss is abnormally abundant and may require specific treatment: a stitch in the vagina or in case of uncontrolled abdominal bleeding, a surgical intervention to ensure haemostasis.
  • Infection: the fine hollow needle passed through the vagina can carry germs into the abdominal cavity. This can lead to an infection which is most often accompanied by a temperature and pelvic pain. If it is diagnosed in time, the infection can be treated easily with antibiotics.
  • Damage to the pelvic organs: the vaginal approach to oocyte retrieval can cause injury to the digestive system or to the urinary tract. These complications occur very rarely (0.04 %).


3- Complications associated with early pregnancy: 

  • Ectopic pregnancy (2 to 11%): even though the embryo(s) has(have) been correctly deposited in the uterine cavity, it(they) can sometimes adhere to the fallopian tubes and embed itself(themselves) there. This complication occurs more frequently in cases of abnormal fallopian tubes.
  • Heterotopic pregnancy (0.75 to 1 %): this is a very rare complication whereby one of the embryos embeds itself in the uterus and the other in the fallopian tube.
  • Multiple pregnancies: inBelgium, the legal limit of the number of embryos that can be transferred has reduced the rate of twins to 11 % (rate >25 % before legal limit) and triplets to less than 1 %. Although they are often welcomed by infertile couples, multiple pregnancies are a real risk factor for the pregnancy itself and the health of the future children. In the case of twins, half the births are premature and the children are 4 times more likely to have to stay in a neonatal clinic.




Plan du site CHU Saint Pierre - Bâtiment 200, 5è étage . Département de Gynécologie-Obstétrique

Centre de Fécondation In vitro - 322, Rue Haute - Bruxelles Tel +32(0)2 535 3406 Fax +32(0)2 535 3409