Obstetrics and gynecology
A Assisted reproductive technologies
Assisted reproductive technologies (ARTs) refers to all techniques used to retrieve and fertilize human oocytes. In vitro fertilization (IVF) is the most common technique used to artificially fertilize human oocytes.
The procedure is performed by initially stimulating maturation of the follicle with a gonadotropin-releasing hormone agonist that induces pituitary gland suppression and creates quiescent ovaries to prevent the production of a single dominant follicle. Follicle-stimulating hormone (FSH) and human menopausal gonadotropin are then administered, which induces 10 to 15 ovarian follicles. The patient is then given human chorionic gonadotropin (hCG), which induces the follicle to then mature and move into the follicular fluid. The oocyte is retrieved transvaginally, transabdominally, or via laparoscopy with an ultrasonically guided probe 34 to 36 hours after hCG administration. All visible follicles are collected, washed, incubated for 4 to 6 hours in a culture medium, and examined microscopically. Most follicles contain only one oocyte. Fertilization occurs in the IVF laboratory. The oocyte is identified and has minimal exposure to ambient room temperature, room air, and especially any chemical odors. Sperm are washed and centrifuged. Fresh media is added next to the centrifuged sperm, and those sperm that swim to the media, which can number 50,000, are placed with the oocyte. Timing must be coordinated with proper maturation of the uterine endometrium. ART is found to increase the risk of multiple gestations. Also, it has been reported that atypical implantations of the fertilized ovum or zygote, such as abdominal, cervical, ovarian, or tubal pregnancy, occur more frequently with ART. Common ART techniques are listed in the table on pg. 413.
Common Assisted Reproductive Technology Techniques
| In vitro fertilization (IVF) | Oocytes are removed, fertilization occurs in the laboratory, and the embryo is placed transcervically into the uterus or into the distal portion of the fallopian tube(s). |
| Gamete intrafallopian transfer (GIFT) | Oocytes and sperm are transferred into one or both fallopian tubes for fertilization. |
| Advantage: oocyte retrieval and gamete transfer occur with a single procedure. | |
| Disadvantages: Requires at least one patent fallopian tube and laparoscopic surgery. Fertilization cannot be confirmed. | |
| Zygote intrafallopian transfer (ZIFT) | Fertilized embryos are placed into the fallopian tube. |
| Advantages: Fertilization is confirmed. Laparoscopic surgery can be avoided if fertilization has not occurred. The embryos can be transferred at an appropriate developmental stage. | |
| Disadvantage: Requires a two-stage procedure, with added risks and costs. Requires at least one patent fallopian tube. | |
| Tubal embryo transfer (TET) | Cleaving embryos are placed into the fallopian tube. |
| Peritoneal oocyte and sperm transfer (POST) | Oocytes and sperm are placed into the pelvic cavity. |
Modified from Speroff L. Clinical gynecologic endocrinology and infertility. 6th ed. Baltimore: Lippincott Williams & Wilkins; 1999: 1133-1148; Tsen LC. Anesthesia for assisted reproductive technologies. Int Anesthesiol Clin 2007;45:99-113.
Patients are assessed for antibodies to human immunodeficiency virus types 1 and 2 (HIV-1, HIV-2) and human T-cell lymphotropic virus type 1 (HTLV-1), hepatitis B antigen, and antibodies to hepatitis B and C. Patients are also tested for Chlamydia, syphilis, gonorrhea, and cytomegalovirus. Smokers require twice as many attempts at successful IVF than nonsmokers, so smoking is extremely discouraged.
a) IVF is generally performed on patients who are American Society of Anesthesiologists (ASA) class 1 or 2 in their third or fourth decade of life.
b) Although IVF is a relatively simple procedure for the reproductive endocrinologist to perform, especially outside the operating room, IVF is an uncomfortable procedure and requires that patients do not move for the probe to be guided for retrieval and later reimplantation.
c) The vaginal wall must be pierced for the desired ovary to be accessed. Also, major blood vessels are present in the proximity of the ovaries, and their injury could lead to complications.
d) Anesthesia requirements vary with the individual needs of the patient and the reproductive endocrinologist. Multiple ART procedures may need to be performed until one of them is successful, so safe yet inexpensive anesthetic techniques are desirable.
e) Minimal sedation, moderate sedation and analgesia, regional intrathecal anesthesia, paracervical block, or general anesthesia can be administered to assist in making the procedure as comfortable and successful as possible.
f) Moderate sedation with analgesia is usually sufficient for most patients. None of the anesthetic procedures caused differences in reproductive outcome.
g) Anesthetic medications generally considered safe for use in anesthesia for ART are listed in the box on pg. 414. Anesthesia providers should consider using safe anesthetic techniques with quick onset and a short duration.
h) It should be noted that propofol, lidocaine, thiopental, thiamylal, and alfentanil have been shown to accumulate in the follicular fluid.
i) Midazolam, when titrated in small doses to provide mild to moderated sedation and anxiolysis, has been shown to be safe, with no accumulation in follicular fluid or teratogenicity.
j) Ketamine (0.75 mg/kg) with midazolam (0.06 mg/kg) moderate sedation and analgesia has been safely used as an alternative to general anesthesia with isoflurane.
k) The literature has suggested the use of caution when using a potent inhaled agent (especially sevoflurane and desflurane) because of possible negative effects to ART outcomes.
l) Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, indomethacin, ketoprofen, ketorolac, meloxicam, naproxen, or oxaprozin are avoided because of inhibition of prostaglandin synthesis and possible effects on embryo implantation.
m) Droperidol and metoclopramide have both been shown to induce rapid hyperprolactinemia and should be avoided. Low plasma prolactin levels are associated with higher incidences of pregnancy.
n) The common anesthetic agents that could cause potential problems with ART are listed in the box below. The necessity for any medication given to the patient should be carefully considered, and the anesthetic technique should be kept simple and basic.
B Cesarean section
A cesarean section (C-section) is the surgical removal of a fetus through an abdominal and uterine incision. A low transverse incision is the most common; in an emergency, a rapid vertical midline incision may be used. Indications for a C-section are failure of labor to progress, previous C-section, fetal distress, malpresentation of the fetus or umbilical cord, placenta previa, and genital herpes or other local infections.
a) A focused assessment should include obstetric and anesthetic history, maternal health, airway, allergies, and baseline vital signs. In emergency cases, the time for assessment will be brief. Special attention should be paid to airway assessment because failed intubation is a major cause of maternal morbidity and mortality.
b) Key points regarding physiological changes in pregnancy
(1) Cardiac output increases mostly because of the increase in stroke volume but also because of increase in heart rate.
(2) The greatest demand on the heart is immediately after delivery when cardiac output increases 180%.
(3) Blood volume is markedly increased and prepares the parturient for the blood loss associated with delivery.
(4) Plasma volume is increased to a greater extent than red blood cell volume, resulting in a dilutional anemia.
(5) Minute ventilation increases 45%, and this change is mostly caused by the large increase in tidal volume.
(6) Oxygen consumption is markedly increased. Carbon dioxide production is similarly increased.
(7) Pregnant women have an increased sensitivity to local anesthetics and a decreased minimum alveolar concentration (MAC) for all general anesthetics.
(8) Platelets, factor VII, and fibrinogen are increased.
(9) Intragastric pressure is increased in the last trimester, which, in combination with increased acid volume, often results in heartburn.
(10) All pregnant women are at increased risk of aspiration because of the physiologic changes to the gastrointestinal system.
a) A nonparticulate antacid (e.g., sodium citrate, 30 mL) and metoclopramide 10 mg IV are routinely administered at most institutions regardless of the anesthetic technique chosen. Sedation is best avoided. Benzodiazepines have been implicated as possible teratogens, and it is best to avoid maternal amnesia during childbirth.
b) Laboratory tests should include a type and screen, complete blood count (CBC), electrolytes, blood urea nitrogen, creatinine, glucose, prothrombin time, and partial thromboplastin time. In emergency C-sections, there may not be time to complete these tests.
c) The parturient should have at least one large-bore intravenous (IV) lines in place before induction of anesthesia.
d) An IV antibiotic should be administered either before abdominal incision or immediately after clamping of umbilical cord.
(2) If there is a history of pregnancy-induced hypertension, an arterial line is recommended.
(3) If there is severe preeclampsia, a central line is also recommended, with a pulmonary catheter in cases of hemodynamic instability.
b) Positioning: Supine with left lateral uterine displacement. This is accomplished by placing a wedge under the right hip. Failure to use left lateral uterine displacement can result in aortocaval compression.
(1) The tabletop should be set up for a general anesthetic.
(2) Set out a smaller endotracheal tube (6-6.5) as well (because of airway edema).
(3) Have ephedrine, phenylephrine, and oxytocin drawn up. Ensure immediate availability of Methergine and Hemabate.
(4) Have difficult airway equipment available.
(5) Unless there is maternal hypoglycemia, avoid giving IV solutions with glucose because they may lead to neonatal hypoglycemia.
5. Perioperative management and anesthetic techniques
The guidelines for general, spinal, and epidural anesthesia are listed below.
a) General anesthesia for C-section
(1) Histamine2-receptor antagonist or proton pump inhibitor or metoclopramide intravenously
(b) Denitrogenation (administration of 100% oxygen)
(c) Traditional 3 to 5 minutes versus 4 vital capacity breaths
(5) Rapid-sequence IV induction
(a) Propofol, ketamine, or etomidate
(b) Succinylcholine (rocuronium or vecuronium if succinylcholine is contraindicated)
(6) Intubation with a 6.0- to 7.0-mm cuffed endotracheal tube
(7) Administration of a low concentration (e.g., MAC) of an inhalation agent with nitrous oxide
b) Epidural anesthesia for C-section
(3) Intravascular volume replacement with Ringer’s lactate or normal saline (10-20 mL/kg)
(5) Supplemental oxygen by face mask or nasal prongs
(6) Epidural catheter at L2 to L3 or L3 to L4
(9) Therapeutic dose: 5-mL boluses of 2% lidocaine + 1:400,000 epinephrine. Alternatively, 5-mL boluses of 0.5% bupivacaine, 0.5% ropivacaine, or 3% 2-chloroprocaine (boluses of lidocaine or 2-chloroprocaine every 1 to 2 minutes; boluses of bupivacaine or ropivacaine every 2 to 5 minutes)
(10) Aggressive treatment of hypotension: Exaggerated left uterine displacement; IV fluids; ephedrine or low-dose phenylephrine (or both)
c) Spinal anesthesia for C-section
(4) Replacement with Ringer’s lactate or normal saline (15-20 mL/kg)
(6) Supplemental oxygen by face mask or nasal prongs
(7) Prophylactic intramuscular (IM) ephedrine (25-50 mg) in patients with a baseline systolic blood pressure of less than 105 mmHg
d) Tasks at delivery and postdelivery maintenance
(1) The length of time from uterine incision to delivery has been shown to correlate with the degree of neonatal acidosis. The interval should be recorded. An interval of 3 minutes seems to be the critical value; neonates delivered later than 3 minutes after uterine incision are more likely to be depressed.
(2) After the umbilical cord has been clamped, the anesthesia provider’s options for anesthetic maintenance increase because the administered drugs will no longer reach the baby. If adequate uterine contraction is achieved with oxytocin, there is no reason why the use of an inhalation anesthetic cannot be continued.
(3) A low-dose inhalation agent (up to 1 MAC), with or without nitrous oxide, and either fentanyl or sufentanil may be used. If uterine tone does not allow the use of an inhalation agent, an opioid and nitrous oxide technique is useful.
(4) When opioids are used, nitrous oxide is usually needed. If nitrous oxide is not used, the anesthesia provider may consider giving a small dose of midazolam for amnesia. Opioid administration should be customized to the circumstances. One option is giving up to 5 mcg of fentanyl per kilogram, adjusting the dose according to the expected duration of the case and the patient’s response. Another opioid choice is morphine 10 mg IV and 10 mg IM.
(5) After the placenta has been delivered, oxytocin should be given immediately unless the obstetrician’s plan for uterine contraction calls for the use of another agent.
(a) The half-life of oxytocin varies from 4 to 17 minutes. It is metabolized by the liver, kidney, and plasma enzyme pathways in the parturient.
(b) Commercially available preparations of oxytocin contain a preservative that causes systolic and especially diastolic hypotension, flushing, and tachycardia when infused at high doses.
(c) The amount of oxytocin added to the IV solution should be tailored to the volume of solution remaining in the bag, the flow rate of the IV, and the patient’s condition. If the IV bag is nearly empty or if IV solution is being administered rapidly, less oxytocin should be added to the bag.
(d) In general, the obstetrician is likely to desire the administration of 20 to 40 units of oxytocin over the first hour postpartum.
(e) If an unusually large blood loss results in hypotension and if fluid resuscitation is needed, it may be helpful to infuse the oxytocin at an appropriate rate and to start a second IV line for administering fluid volume at a rapid rate.
(f) If the solution with the added oxytocin is infused fast enough to replace volume, then it is likely that the high dose of oxytocin may cause further hypotension.
(6) If oxytocin does not adequately stimulate uterine contraction, the next drug used is usually an ergot alkaloid (Methergine, Ergotrate).
(a) Because of their potent vascular effects, ergot alkaloids are not administered intravenously. Ergot alkaloids normally cause an increase in blood pressure, central venous pressure, and pulmonary capillary wedge pressure.
(b) IV administration may result in arterial and venous constriction, coronary artery constriction, severe hypertension, cerebral bleeding, headache, nausea, and vomiting.
(c) An IM dose of 0.2 mg is commonly administered for stimulating uterine contractions.
(d) In some cases, the obstetrician may choose to administer oxytocin or ergotamine directly into the uterine muscle to maximize effect.
(e) Ergot alkaloids are metabolized and eliminated chiefly by the liver. The plasma half-life is approximately 2 hours, but uterine effects last much longer.
(f) Ergot alkaloids potentiate sympathomimetics, especially α-agonists (including ephedrine). Severe hypertension, cerebrovascular accidents, and retinal detachment have occurred when the two drugs were used simultaneously. These effects may persist even when the vasopressor is given well after the last dose of methylergonovine maleate.
(7) When the uterus does not contract well despite the use of oxytocin and ergot alkaloids, prostaglandin F2a (Hemabate, 250 mcg) is administered either IM or directly into the uterine muscle.
(a) Prostaglandins are potent stimulators of uterine contractions. The contractions induced by prostaglandins are strong and painful.
(b) Nausea, vomiting, and diarrhea are frequent side effects. In addition to causing uterine contractions, prostaglandins may cause hypotension by relaxing vascular smooth muscle; however, cases of severe hypertension after prostaglandin administration have also been reported.
(c) Prostaglandins may cause a recalcitrant uterus to contract and stop bleeding. If they do not, the surgeon is likely to extend the procedure and include hysterectomy, for which the anesthesia provider must be prepared.
(1) Even with the administration of metoclopramide, the parturient often has a large volume of gastric contents. Suctioning of the stomach with an orogastric tube while the patient is anesthetized decreases the incidence of vomiting after awake extubation.
(2) Before extubation, the anesthesia provider should verify full recovery of neuromuscular function. Because C-section is usually a brief procedure involving fairly limited exposure to anesthetic, emergence is often quick. Advance preparation limits patient discomfort before extubation.
C Dilatation and curettage
Dilatation and curettage (D & C) involves dilation of the cervix and scraping of the endometrial lining of the uterus. The procedure is done to diagnose and treat uterine bleeding, cervical lesions, or stenosis. D & Cs are also used to complete an incomplete or missed abortion and are then referred to as suction D & Cs with the gestational week.
2. Preoperative assessment and patient preparation
a) History and physical examination: Assess for any cardiac, respiratory, neurologic, or renal abnormalities. Assess for a history of hiatal hernia or reflux; if a suction D & C, assess the gestational week; if greater than 16 weeks, consider the patient to have a full stomach.
4. Perioperative management and anesthetic technique
a) Drugs: Anxiolytic agents (midazolam [Versed], 0.01-0.02 mg/kg), narcotics (fentanyl, 1-2 mcg/kg), oxytocin (Pitocin) for suction D & Cs, and induction agents (propofol) can be used.
b) This procedure can be done either with a short-acting spinal or saddle block as a general anesthetic by mask, laryngeal mask airway, or with an endotracheal tube with inhalation agent or nitrous oxide or with heavy sedation (midazolam [Versed], fentanyl, and propofol).
c) Postoperatively, assess for bleeding, nausea, and cramping. Treat with narcotics, NSAIDs, and antiemetics.
d) Volume depletion and anemia can occur rapidly or slowly over time. IV rehydration and assessment of hemoglobin and hematocrit values are imperative.
D Gynecologic laparoscopy
Laparoscopy is a common endoscopic technique in gynecologic procedures. It is frequently used to diagnose or treat pelvic conditions that may include sterilization, adhesions, pain, endometriosis, ectopic pregnancies, ovarian cysts and tumors, infertility, and vaginal hysterectomy. A pneumoperitoneum is achieved by insertion of a trocar and insufflation of carbon dioxide.
2. Preoperative assessment and patient preparation
a) Monitoring equipment: Standard
b) Additional equipment: Fluid warmer and Bair Hugger; other equipment as needed
4. Perioperative management and anesthetic technique
E Hysterectomy: Vaginal or total abdominal
Hysterectomy is commonly performed to treat uncontrolled uterine bleeding, dysmenorrhea, uterine myoma, gynecologic cancer, adhesions, endometriosis, and pelvic relaxation syndrome. Frequently, laparoscopy is used; for ovarian cancer prophylaxis, a bilateral salpingo-oophorectomy may be performed as well.
a) History and physical examination: As indicated by the patient’s history and medical condition
(1) Laboratory tests: As indicated by the patient’s history and medical condition
(2) Diagnostic tests: As indicated by the patient’s history and medical condition
(3) Preoperative medications: Anxiolytics are given as indicated; consider prophylaxis for postoperative nausea and vomiting.
(4) IV therapy: Two 16- to 18-gauge IV lines are used; consider a central line or an arterial line (or both) if the procedure is radical.
(5) An epidural catheter may be placed for intraoperative or postoperative pain relief.
a) Monitoring equipment is standard.
b) Consider an arterial line and central venous pressure catheter if large blood loss is expected.
c) Additional equipment includes a fluid warmer and Bair Hugger.
(1) Anesthetic and adjunct agents and antibiotics are used.
(2) IV fluids: For vaginal hysterectomy, calculate for moderate blood loss; crystalloids at 4 to 6 mL/kg/hr. Estimated blood loss is 750 to 1000 mL. For abdominal hysterectomy, calculate for a moderate to large blood loss; crystalloids at 6 to 10 mL/kg/hr. Estimated blood loss is 1000 to 1500 mL.
(3) Blood: Type and crossmatch for 2 to 4 units of packed red blood cells if significant blood loss is expected.
4. Perioperative management and anesthetic technique
General or regional anesthesia is used, with a subarachnoid block or epidural with a sensory level of anesthesia of T4 to T6.
a) Complications: Nausea, vomiting, anemia
b) Pain management: Patient-controlled analgesia; epidural opiates or an epidural local anesthetic such as 0.125% or 0.25% bupivacaine with fentanyl, 1 mcg/mL at an infusion of 8 to 10 mL/hr. Ketorolac 15 to 30 mg IV or IM every 6 hours may also be used for pain relief.
F Loop electrosurgical excision procedure
The loop electrosurgical excision procedure is performed for the diagnosis and treatment of cervical intraepithelial neoplasia. This form of electrosurgery uses a loop electrode for excision and fulguration to prevent cervical bleeding. Other types of therapies that may be used to ablate cervical lesions are cryosurgery and carbon dioxide laser surgery.
2. Preoperative assessment and patient preparation
a) Monitoring equipment: Standard. If a pregnancy is more than 16 weeks’ gestation, fetal monitoring may be used.
b) Drugs: Standard tabletop agents are used.
c) IV fluids: Calculate for minimal blood loss, 2 to 4 mL/kg/hr. Estimated blood loss is 50 to 200 mL.
4. Perioperative management and anesthetic technique
a) Local, monitored anesthesia care, or regional or general anesthesia is used.
b) Induction: Standard induction is indicated.
c) In pregnant patients, rapid-sequence induction is used.
d) In nonpregnant patients, mask ventilation may be appropriate.
e) Maintenance: Standard, inhalational agent, oxygen, and opioid. Muscle relaxation is not required.
G Pelvic exenteration
Pelvic exenteration is performed for the treatment of advanced, recurrent, radioresistant cervical carcinoma. It is considered a radical surgical approach because all pelvic tissues, including the cervix, bladder, lymph nodes, rectum, uterus, and vagina, are resected. Vaginal reconstruction and appropriate colon and urinary diversions are also performed.
2. Preoperative assessment and patient preparation
a) History and physical examination: As indicated by the patient’s history and medical condition
(1) Laboratory tests: CBC, electrolytes, blood urea nitrogen, creatinine, calcium, magnesium, phosphate, prothrombin time, partial thromboplastin time, urinalysis, and renal function tests
(2) Diagnostic tests: As indicated by the patient’s history and physical examination
(3) Premedication: Anxiolytics as indicated
(4) IV therapy: Two 14- to 16-gauge IV catheters
(5) Central and arterial line; pulmonary arterial catheter considered if the patient has a significant cardiac history
(6) An epidural catheter possible for postoperative pain relief
a) Monitoring equipment: Standard; arterial line and central venous pressure useful because of major fluid shift, potential for major bleeding, obtaining laboratory values for a long duration, and possible need for vasoactive infusion. Foley catheter to monitor fluid status.
b) Additional equipment: Fluid warmer; forced air warmer
