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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_207_библиотеки_им_акад_М_И_Перельмана
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Transvaginal Oocyte Retrieval
Darcy E. Broughton, Kenan R. Omurtag
https://t.me/med1917
GENERAL PRINCIPLES
Definition
Transvaginal oocyte retrieval (TVOR) is the method utilized to obtain oocytes to be utilized for in vitro fertilization (IVF) after
controlled ovarian hyperstimulation (COH). This involves transvaginal aspiration of ovarian follicles under ultrasound guidance.
Historically, oocyte retrieval was performed laparoscopically or transabdominally with ultrasound guidance.
1
The transvaginal
approach was pioneered in 1985 and is associated with improved safety, patient acceptability, and IVF outcomes.
2–5
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IMAGING AND OTHER DIAGNOSTICS
The timing of TVOR is dependent upon the patient’s ovarian response to stimulation with gonadotropins. In the 2 weeks
preceding TVOR there are frequent transvaginal ultrasounds for monitoring of follicular development (Fig. 7.1). This
imaging, in combination with measurement of estradiol levels, guides changes in dosing and ultimately the timing of the hCG
trigger injection. Criteria for trigger and retrieval vary by IVF center; in our clinic hCG is administered when there are ≥2
follicles measuring 18 mm or greater. TVOR is typically performed 36 hours following the hCG injection.
6
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PREOPERATIVE PLANNING
TVOR must be performed under anesthesia, most commonly general anesthesia (GA; propofol) or conscious sedation (CS;
benzodiazepines and ketamine or systemic opioid).
7,8
Other less utilized options include regional anesthesia under
spinal/epidural blockade or local anesthesia with paracervical block.
8,9
Worldwide, CS is used in 60% to 70% of TVORs.
10
In an RCT comparing GA with CS, pain scores were lower in the GA group, but the procedure was still considered
tolerable in the CS group.
11
The administration of GA has the benefits of rapid onset and recovery as well as less
postoperative nausea and vomiting, but requires the presence of specially trained anesthesia staff and more intensive
monitoring that may be prohibitive in stand-alone IVF clinics.
12
Local anesthesia alone is likely inadequate, but has been
used in situations where anesthesia may be contraindicated. In a prospective study of TVOR under paracervical block, 28%
of women needed administration of a sedative.
9
There is no evidence that route of anesthesia affects embryo quality or
pregnancy rates (PRs).
13,14
Figu re 7 .1. Ultrasound image of a hyperstimulated ovary wit h multiple follicles.
The ability to access the ovaries via the transvaginal route should be assessed prior to TVOR. The ovaries may be difficult
to access in patients with extensive adhesive disease due to endometriosis or prior surgery, large fibroids, prior ovarian
transposition due to radiation therapy, or anomalies such as Mullerian agenesis. Monitoring ultrasounds performed prior to
and during stimulation can alert the clinician to potential challenges.
6
It has become standard of care to administer a dose of prophylactic IV antibiotics at the time of TVOR. There is no quality
prospective data that prophylaxis decreases the incidence of pelvic infections, perhaps because this is an extremely rare
complication of TVOR.
15
Studies have shown that implantation and PRs are lower when embryo transfer catheters have
positive microbial cultures.
16–18
The proportion of patients with colonized catheter tips decreases when antibiotics are given
at the time of TVOR.
19
There is no standard choice of antibiotic; the first line is most commonly a cephalosporin such as
cefazolin or cefoxitin, similar to other gynecologic procedures.
The patient should be asked to empty her bladder immediately prior to the procedure; a full bladder can position the ovaries
away from the transvaginal probe.
6
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SURGICAL MANAGEMENT
Positioning
The patient is positioned in low lithotomy with adjustable stirrups and her arms out to the sides.
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Approach
Almost all TVORs can be completed with a transvaginal approach. However, as mentioned above, one or both ovaries will
be inaccessible in 1% to 2% of cases.
20
Options include passing the needle through the cervix and/or myometrium to enter
the ovaries if feasible. This technique does not appear to adversely impact PRs.
20
Care should be taken to avoid the fundal
endometrium, the most common site of subsequent implantation.
20
Another oft-used technique is to provide abdominal
pressure to bring the ovaries into the pelvis to facilitate a vaginal approach. If the ovaries, still, cannot be reached from the
vagina, a transabdominal approach with ultrasound guidance can be used, using the same probe and needle.
21
This strategy
yields comparable numbers of oocytes retrieved, fertilization, and PRs.
22
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Procedures and Techniques
Preparing the patient
The vagina should be rinsed with saline or a povidone-iodine solution to decrease the bacterial load. If a povidone-iodine
solution is used, copious flushing of the vagina must be performed after this due to potential toxic effects on oocytes.
7
As a
result of the latter, we prefer saline universally.
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Preparing the equipment
A sterile operating table should be available with tubes of culture media in a warming tray. The vaginal ultrasound probe
should be prepared with a sterile cover and needle guide attached.
The retrieval needle is commonly 17 gauge (range 15–18), attached to an electric vacuum aspirator controlled with a foot
pedal. The vacuum should be tested prior to the procedure with aspiration of culture media. The preferred negative
pressure setting varies by center; in our practice we routinely use 125 mm Hg. The majority of centers use a range of 120
to 140 mm Hg, but values from 80 to 200 mm Hg appear in the literature.
23–25
Needles can be either single lumen or double
lumen.
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Ultrasound-guided assessment of the pelvis
The transvaginal ultrasound probe is inserted with the needle guide firmly attached. A survey of the pelvis should be
performed, with identification of ovaries and surrounding structures including bladder, bowel, and iliac vessels. The ovaries
should be visualized in both transverse and longitudinal axes to help differentiate follicles from blood vessels, which can
appear similar on cross-section (Te ch Fig. 7.1).
6
Color Doppler can also be employed for this purpose.
7
Te ch Fig ure 7.1. Iliac vessel (V) in cross-section, mimicking an ovarian follicle.
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Follicular aspiration
The needle is then passed first through the guide and then through the vaginal wall in either the left or right fornix to enter
the respective ovary. Once a follicle has been entered, the vacuum is activated and the follicular fluid and oocytes are
aspirated into the warmed tubes of culture media. The probe is maneuvered to bring follicles in close proximity to the
needle, avoiding multiple punctures to the vaginal wall. All follicles of a reasonable size should be entered and aspirated.
6
This process is repeated on the contralateral side, taking care to maintain correct orientation of the probe.
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