Anesthesia for In Vitro Fertilization
Broadly speaking IVF involves the following steps:
- Ovarian stimulation
- Egg collection
- Sperm processing & Fertilization & embryo transfer
Rule of Anesthesiologist:
The vaginal ultrasound probe for egg retrieval forms one of the most stressful and painful components of entire assisted reproductive treatment.
Pain during oocyte retrieval is cause by the puncture of the vaginal skin and ovarian capsule by the aspirating needle as well as manipulation within the ovary during the entire procedure. So anesthetist should provide adequate pain relief to immobilize the patient and eliminate the danger of piercing any vessel during the procedure. The ideal pain relief during egg collection should be effective and safe, easy to administer and monitor, short acting and reversible with a few side effects
Coexisting illnesspatients presenting in the IVF clinic needs to be investigated for any co morbid illnesses. In India tuberculosis is the most important cause of infertility, so we need to know the drug interactions of antitubercular. These patients are generally kept on aspirin or heparin so as to prevent the hypercoaguable state occurring as a result of gonadotrophic injections. Aspirin should ideally be stopped 3 days prior to the procedure. In case of heparin we need to know the activated prothrombin time Thyroid can also be a cause of infertility so it becomes mandatory to assess the thyroid function test and take appropriate anesthetic precautions.
Some of the patients might be receiving treatment for psychomotor disorders like depression. It’s therefore important to adjust the dosages of anesthetic agents especially narcotics.
Anxiety the majority of patients presenting in the IVF clinic are in late thirties and the immense family pressure makes them more susceptible to psychomotor illness like depression. Moreover this problem aggravated by the hormonal manipulations occurring during IVF.
There many options available to the anesthetist:
- Monitored sedation with/ without local anesthesia.
- General anesthesia.
- Regional anesthesia.
Monitored sedation is well tolerated and best suited in day care settings. Midazolam was found to be safe for sedation in egg collection.
General Anesthesia : All anesthetic agents being used in general anesthesia have been detected in the follicular fluid. Using balanced anesthesia with N2O and opioids can be an option for anesthesiologist.
Propofol widely used in assisted reproduction and has added advantages of antiemetic with faster recovery. Though increased exposure to propofol leads to increase propofol follicular concentration.
N2O inactivates methionine synthetase thereby decreasing the amount of thymidine available for DNA synthesis in dividing cells. The inactivation of methionine proceeds slowly in human liver, the effect of N2O is minimal. Furthermore, the low solubility of N2O exposes the oocyte to this gas for a brief duration.
Benzodiazepinemidazolam is the most commonly used Benzodiazepine. A combination of midazolam and fentanyl was found to be safe for egg collection.
Narcotics fentanyl found to be favorable agents when used in combination with propofol.
Inhalational agents no significant effect of N2O and isoflurane anesthesia on human IVF pregnancy rate.
- Paracerviacal block with different doses of lidocaine with sedation
- Using midazolam + fentanyl to enhance the analgesia.
- Spinal anesthesia is also an effective method by using spinal lidocaine or bupivacaine with low dose fentanyl.
- Epidural anesthesia also forms a variable option.
IVF is an upcoming specialty, anesthesia during Assisted reproductive technique is required during egg collection. Variety of techniques like conscious sedation, general anesthesia and regional anesthesia has been tried, However irrespective of the technique, the key point in IVF anesthesia is to provide the anesthetic exposure for least duration to avoid its effects on embryo fertilization.