Fig. 26.1
O™ocyte-retrieval procedure. A needle is passed through the vaginal fornix into the ovary (under ultrasound guidance) to enter and aspirate multiple follicles (By permission of Mayo Foundation for Medical Education and Research. All Rights Reserved) (Source: Mayo foundation for Medical Education
The goal is provision of intravenous analgesia, sedation or anesthesia, which relieves pain, but also allows the patient to remain relatively motionless. By keeping the patient comfortable, retrieval of the oocyte form the ovarian follicles is easier for the operator. Once the needle enters the ovary, minor redirections within the ovary are not as stimulating so bolus agents should be timed in anticipation of initial needle placement into the ovary on each side. Some units flush and aspirate each follicle necessitating a wider needle and prolonging total procedure time.
Complications such as bleeding should be suspected in any patient who becomes hypotensive following the procedure. The anesthesia technique must clearly be outlined to the patient to prevent a complaint of awareness when sedation only was the technique utilized.
Pre-assessments/Timing/Facility Location
The patient population undergoing IVF are mainly ASA 1 or II women with few co-morbidities. However the increase in utilization of these techniques for a number of other pathologies places more of an emphasis on the need for adequate pre-operative assessment and investigations. If the stimulation of oocytes has already begun, deferring a case can lead to complications such as ovarian hyperstimulation syndrome. Therefore fitness for anesthesia should be determined prior to this, and an avenue for anesthesia assessment or consultation should exist for the referring fertility specialist.
Infertility may be a consequence of certain co-morbidities that also have implications for anesthesia:
- 1.
Morbid obesity. These patients require assessment of their cardiovascular risk as well as suitability for sedation and ambulatory surgery. Many centers, 84 % in the US, have policies on a maximum body mass index (BMI) for IVF procedures, citing anesthesia concerns as a main reason for this [5].
- 2.
Hypo or hyperthyroidism as a cause of infertility is often considered and will likely have been screened for and treated prior to IVF.
- 3.
Patients with a diagnosis of cancer may be undergoing oocyte retrieval prior to receiving treatment with chemotherapy or radiotherapy. These particular patients can have organ specific dysfunction such as pleural effusions. Appropriate clinical history and examination would guide further investigations or interventions in these patients.
Timing of oocyte retrieval is important for oocyte number and embryo quality. The optimum time frame for oocyte retrieval is 24–36 h after hCG administration. The consequence of not adhering to this time window has the potential for spontaneous ovulation and resultant loss of oocytes. Every effort must be made to optimize a patient prior to surgery so that there are no undue delays or cancelations. Once hormonal preparation is commenced these cases are no longer as deferrable as elective general surgical cases without adverse impact on outcomes.
Routine fasting guidelines for patients should be mandatory as would be expected in other forms of day-case surgery. 6 h for solid foods and 2 h for clear liquids are appropriate in this population. Consider an anti-reflux agent in patients who have symptomatic gastroesophageal reflux disease. Some units consider spinal anesthesia in patients that have not adhered to fasting guidelines. Policies should exist for the management of postoperative nausea and vomiting (PONV). Prophylactic antiemetics are generally not utilized even with a prior history of PONV. Metoclopramide can have an impact on prolactin causing increased plasma concentration. This occurs via inhibition of gonadotrophin-releasing hormone [6]. Concerns around unknown effects of anti-emetics on the IVF process are the reasons cited for withholding antiemetics although there is no good evidence that other agents such as ondansetron are contraindicated. Intravenous fluids can enhance the patients’ feeling of wellbeing and further reduce PONV incidence [7]. Appropriate discharge analgesia should be standard and usually consists of acetaminophen, while avoiding NSAIDs. Use of anti-inflammatory drugs are avoided as certain prostaglandins in the embryo and endometrium are important for implantation [8]. However, as embryo transfer usually does not occur for a further 48 h a single dose short acting agent may be appropriate for patients with problematic post-procedural pain.
Pre-medication with benzodiazepine anxiolytics should not be considered routine practice for day case procedures however they should be considered on a patient with high levels of anxiety.
The location or facility used to perform sedation for IVF must conform to the appropriate standards expected of an anesthesia suite. These include:
Appropriate monitors including continuous ECG, non-invasive blood pressure monitoring, pulse oximetry and continuous CO2 Capnography.
A reliable oxygen source, airway equipment and suction.
Appropriate anesthesia pharmacological agents including reversal agents.
Resuscitation equipment including a defibrillator and drugs.
A post-anesthesia care unit where the patient can be appropriately monitored while they recover from their anesthesia agents until discharge criteria are met.
Transportation solutions to an appropriate centre in the event of prolonged recovery or other complications such as anaphylaxis or bleeding.
Anesthesia Techniques
Intravenous sedation/anesthesia are currently the most commonly used techniques for patients undergoing oocyte retrieval via the trans-vaginal route. Other options for analgesia include spinal anesthesia. Para-cervical nerve block administered by the gynaecologist can reduce the requirement for intravenous agents. Some unusual methods employed for patient comfort include hypnosis, electro-acupuncture, and even no pain relief whatsoever. Application of topical local anesthetic creams have also been utilized to reduce sedation requirements.
Conscious Sedation
Conscious sedation, defined as a ‘minimally depressed level of consciousness that retains the ability of the patient to maintain a patent airway independently and continuously and to respond to verbal commands’ is recommended by the UK National Institute for Clinical Excellence (NICE) to be offered to all women undergoing trans-vaginal retrieval of oocytes [9]. The institute proposes adhering to the Academy of Medical Royal Colleges (AOMRC) UK’s safe sedation practice guideline when administering sedative drugs [10].
Conscious sedation is usually achieved by administration of intravenous benzodiazepines and/or opioids. Patients can self-administer from a timed pump in the form of patient controlled analgesia (PCA), or more traditionally a care provider can administer the drugs. Patient satisfaction is high with both methods of delivery, but pain scores in one study were typically higher in the PCA group [11].
As conscious sedation by definition does not require an anesthetist to secure the airway, it is normally delivered by non-anesthesia personnel. Practice surveys in the UK have confirmed that a great deal of variation in personnel delivering care exists [12]. Non-utilisation of anesthesia physicians confers inherent economic benefit, as IVF is costly and mainly carried out in privately funded clinics. This must be balanced with consideration of patient safety, particularly in those with serious medical conditions such as obesity, obstructive sleep apnoea and cancer. The latter group are increasingly presenting for oocyte harvesting for use after cessation of chemotherapy. All of these patient groups should be attended to in larger centres with an available anesthetist.
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