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Questions and Answers
What is a critical factor that anesthetists need to manage during cervical cerclage procedures?
Which characteristic is NOT commonly associated with second-trimester spontaneous abortions due to cervical incompetence?
Which method is NOT typically used for diagnosing cervical incompetence?
What is the incidence range of cervical incompetence?
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What intervention is important to avoid maternal complications during a cervical cerclage?
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What is the primary surgical approach most commonly used for cervical cerclage placement?
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Which statement differentiates the McDonald technique from the Shirodkar technique for cervical cerclage?
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What is the most common mode of delivery after a transabdominal cervical cerclage?
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What key factor limits the overall use of transabdominal cerclage?
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What should be done with a cervical cerclage prior to the onset of labor if a vaginal delivery is planned?
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What cardiovascular change occurs during the second trimester that affects the anesthesia management of a parturient?
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How does aortocaval compression syndrome influence maternal hemodynamics during the second trimester?
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What significant change occurs in the respiratory system during pregnancy, particularly by the second trimester?
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What gastrointestinal concern is heightened in parturients during pregnancy, especially under general anesthesia?
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At what stage of pregnancy does the reduction in functional residual capacity typically begin?
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What is a common physiological adaptation to pregnancy affecting maternal cardiac dynamics?
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Which of the following is an important factor to consider in anesthetic management of the parturient?
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What is a significant risk associated with the gastrointestinal changes in a parturient during pregnancy?
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What is a potential disadvantage of using general anesthesia during cervical cerclage?
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What psychological factor is important to address in patients undergoing cervical cerclage?
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How can uterine relaxation achieved through general anesthesia affect the procedure of cervical cerclage?
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Why is establishing rapport with the patient particularly important during cervical cerclage?
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What is a consequence of postoperative vomiting following cervical cerclage under general anesthesia?
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What is the primary reason for implementing left uterine displacement in late pregnancy?
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What precaution regarding gastric aspiration is emphasized for pregnant women undergoing cerclage in late pregnancy?
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What key factor must be considered regarding fetal monitoring during cervical cerclage applied after 16 to 20 weeks of gestation?
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Which disadvantage is associated with regional anesthesia in pregnant patients during surgical procedures?
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How does aortocaval compression influence the management of anesthesia in late pregnancy?
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What is the rationale behind minimizing fetal exposure to anesthetic agents during surgical procedures in pregnancy?
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What condition can complicate intubation during anesthesia for pregnant women?
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What indication suggests the need for additional treatment for gastric volume and acidity in late pregnancy?
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Which medication is commonly used as a preoperative precaution for pregnant women undergoing cervical cerclage?
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What is the recommended maximum level of sensory blockade for neuraxial anesthesia during cervical cerclage?
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What physiological effect is most likely to occur when a pregnant patient is positioned in lithotomy during surgery?
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Which factor can lead to a decrease in uterine blood flow (UBF) during cervical cerclage?
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What is a crucial step to maintain placental perfusion during cervical cerclage?
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How does spinal or epidural anesthesia impact blood volume distribution in a patient undergoing cervical cerclage?
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Which of the following methods would require a higher level of spinal blockade during cerclage placement?
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What risk can occur if leg holders are improperly positioned during cervical cerclage?
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What is the primary concern associated with advanced cervical dilation when performing emergency cerclage?
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What is a common misconception regarding the effectiveness of cervical cerclage in preventing preterm delivery?
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Which risk associated with cervical cerclage is often overlooked in discussions about procedure outcomes?
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What procedure is recommended when bulging membranes occur alongside advanced dilation?
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What complication may arise postoperatively in patients who underwent cervical cerclage?
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Study Notes
Anesthesia Considerations
- Minimize fetal drug exposure during anesthesia to ensure fetal safety.
- Critical to maintain placental perfusion by avoiding maternal hypotension.
Maternal Complications Prevention
- Specific interventions include preventing aspiration and alleviating aortocaval compression to avoid complications during procedures.
- Addressing maternal anxiety is essential for overall well-being and successful outcomes.
Pathophysiology of Cervical Incompetence
- Incompetent cervix can result from trauma or structural/function deficiencies leading to repeated second-trimester spontaneous abortions.
- Second-trimester losses often present with:
- Painless cervical dilation.
- Rupture of membranes following herniation.
- Short labor resulting in premature birth of an immature fetus.
Incidence and Diagnosis
- Incidence of cervical incompetence ranges from 0.001% to 1.84%.
- Diagnosis is made through:
- Observation of cervical shortening or dilation.
- Protrusion of membranes through the cervical os.
- Past history of recurrent pregnancy loss can aid in diagnosis.
Assessment Techniques
- Serial examinations performed using:
- Manual examination.
- Ultrasound.
- Magnetic resonance imaging (MRI).
- Used to evaluate cervical dilation and length and to decide the necessity of cervical cerclage.
Cervical Cerclage Overview
- Cervical cerclage is a surgical procedure for pregnant women with an incompetent cervix to prevent preterm birth.
- The most common technique used is transvaginal placement of the cerclage.
Surgical Techniques
-
McDonald Technique:
- Suture placed without dissecting the cervical mucosa, resulting in less blood loss.
-
Shirodkar Technique:
- Involves dissection of the bladder to the level of the internal cervical os, leading to slightly greater blood loss.
Alternative Approaches
-
Transabdominal Cerclage (TAC):
- Utilized in rare cases with failed transvaginal cerclage or inadequate cervical structure.
- First described in 1965, traditionally performed via open laparotomy.
- Can also be done laparoscopically; recent advancements include the use of robotic-assisted surgery techniques.
Pre-Pregnancy and Risks
- TAC might be performed before pregnancy to minimize risks associated with surgical manipulation of the uterus and reduce bleeding.
- Overall incidence of TAC is low due to diagnostic and technical challenges.
Delivery Considerations
- Cervical cerclage must be removed prior to or at the start of labor for vaginal deliveries.
- Usually, cesarean sections are recommended following a transabdominal cerclage to avoid complications.
- Low incidence of cervical dystocia (failure to dilate) is associated with cerclage placement.
Physiologic Changes in Pregnancy Affecting Anesthesia Management
-
Cardiovascular Changes:
- Heart rate increases by 25%, stroke volume by 125%, and cardiac output by 50% starting at 2-3 weeks gestation, continuing into the second trimester.
- Maternal blood pressure decreases due to lowered systemic vascular resistance, especially around the 20th week.
- Increased perfusion noted to uterus, kidneys, skin, and skeletal muscle throughout gestation.
- Aortocaval compression syndrome can lead to a 50% increase in femoral venous pressure, causing reduced blood return to the heart and potential severe hypotension and uteroplacental insufficiency from 13-16 weeks gestation.
-
Respiratory Changes:
- Oxygen consumption increases due to fetal and placental metabolic demands.
- 45% increase in tidal volume, predominantly occurring in the first trimester; corresponds with increased minute ventilation and decreased PaCO2 leading to increased pH.
- Reduction in functional residual capacity begins in the fifth month; however, this does not primarily drive decreased lung volume at the time of cerclage.
-
Gastrointestinal Changes:
- Decreased difference in barrier pressure between the lower esophageal high-pressure zone and intragastric pressure increases risk of heartburn (pyrosis) and pulmonary aspiration during general anesthesia.
- Rotational and displacement changes at the gastroesophageal junction heighten incidence of gastroesophageal reflux.
- Considered a full stomach, necessitating appropriate precautions in any anesthesia approach.
Gastric Aspiration Precautions
- Risk of aspiration and pyrosis is lower in early pregnancy because the gastroesophageal junction is not displaced.
- Administering a nonparticulate antacid is advised for all parturients.
- In late pregnancy, additional management for gastric volume and acidity may be necessary.
- Rapid sequence induction is standard for pregnant women to minimize aspiration risk.
Left Uterine Displacement (LUD)
- Aortocaval compression can be detected by 13 to 16 weeks of gestation, requiring LUD for all pregnant women.
- Late pregnancy may still see vascular effects from aortocaval compression, necessitating LUD despite weight increases from fetus, placenta, and amniotic fluid.
Fetal Monitoring
- Confirmation of fetal heart rate (FHR) is sufficient before a cerclage in early pregnancy.
- Continuous FHR monitoring is advised for cerclages performed after 16 to 20 weeks of gestation to ensure fetal well-being.
Avoidance of Teratogenicity
- No anesthesia drugs conclusively proven teratogenic in humans at therapeutic doses, but associations exist; minimizing fetal exposure is prudent.
Regional Neuraxial versus General Anesthesia
- Regional anesthesia minimizes fetal exposure to anesthetic medications and allows spontaneous breathing without intubation.
- Increased blood volume during pregnancy can cause peripheral tissue edema, making intubation more difficult.
- Spinal anesthesia uses lower drug amounts for adequate sensory blockade and optimal surgical conditions.
- A primary disadvantage of regional anesthesia includes maternal hypotension from sympathetic fiber blockade, potentially affecting placental perfusion.
- General anesthesia offers effective uterine relaxation for procedures like cervical cerclage, which can reduce uterine irritability and premature contractions.
- Disadvantages of general anesthesia include higher fetal drug exposure, difficulties in intubation, increased aspiration risk, and potential postoperative vomiting, possibly straining the cerclage.
Psychological Impact of Prior Pregnancy Losses
- Many women undergoing cervical cerclage may have experienced previous miscarriages due to early prematurity, leading to heightened anxiety.
- Anxiety may intensify if there is cervical dilation or bulging membranes present.
- Establishing a strong rapport with patients is crucial as minimal premedication for anxiolysis or intraoperative sedation is used to reduce fetal exposure.
Preoperative Medications for Cervical Cerclage
- Minimal preoperative medication is typically used, often limited to nonparticulate antacids like Bicitra.
- Aspiration precautions may include H2 blockers (e.g., cimetidine) and gastrokinetics (e.g., metoclopramide).
- No anesthetic agents or techniques have been confirmed teratogenic, but unnecessary exposure should be minimized during organogenesis (15 to 56 days' gestation).
- Cerclage is rarely performed after the organogenesis period, although emergency surgery may be necessary.
Physiological Changes in Lithotomy Position
- Lithotomy position causes increased central blood volume and decreased perfusion pressure in extremities.
- Elevating legs above heart level enhances the volume and perfusion changes; Trendelenburg position further increases these shifts.
- Spinal or epidural anesthesia may cause sympathectomy, contributing to blood volume shifts.
- Hypotension risk increases when returning to supine position; it is crucial to maintain maternal blood pressure for placental perfusion.
- Improper positioning or pressure from leg holders can lead to nerve injuries; proper padding and alignment are essential.
Neuraxial Anesthesia Level for Cervical Cerclage
- Cervical cerclage requires sensory blockade below T10; a low spinal or saddle block suffices.
- Transabdominal cerclage necessitates a higher blockade than T4, which is used for cesarean deliveries.
Maintaining Placental Perfusion
- Uterine blood flow (UBF) is determined by uterine arterial and venous pressure and vascular resistance.
- UBF calculation: UBF = (Uterine arterial pressure - Uterine venous pressure) / Uterine vascular resistance.
- Decreased UBF can result from lower uterine arterial pressure or increased vascular resistance.
- To sustain UBF and prevent fetal hypoperfusion, maternal blood pressure can be supported with intravenous fluids.
- Caution is needed with vasopressors (e.g., ephedrine, phenylephrine); while effective for hypotension, they can raise uterine vascular resistance.
Adverse Maternal and Fetal Outcomes
- Potential complications after cervical cerclage include aspiration, hypotension, and positioning injuries.
- Maternal risks involve anesthetic complications such as nausea and vomiting, as well as risks from the procedure itself including infection, premature uterine contractions, and bleeding.
- Additional surgical risks entail tearing or scarring, leading to possible cervical failure during labor.
- Possible fetal complications consist of amniotic membrane rupture, chorioamnionitis, and the risk of premature delivery.
- Cervical cerclage is less effective for preventing preterm delivery, especially with a shortened cervix.
- Despite a reduction in deliveries before 34 weeks, neonatal mortality rates remain unchanged.
- Increased risk of maternal postpartum fever is associated with cervical cerclage procedures.
Emergency Cerclage Procedure
- Emergency cerclage can be performed if advanced cervical dilation or bulging of membranes occurs.
- The procedure involves using a sterile inflatable balloon to elevate fetal membranes into the uterine cavity.
- After positioning, a cerclage is placed over the balloon introducer.
- The balloon is deflated, and the cerclage is tightened as the introducer is withdrawn.
- This technique may see greater use due to balloons that can inflate up to 10 cm, providing protection during the procedure.
- Risks related to emergency cerclage include maternal infection, chorioamnionitis, rupture of membranes, and premature delivery.
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Description
This quiz covers key considerations in anesthesia during pregnancy, focusing on minimizing fetal drug exposure and maintaining placental perfusion. It also discusses maternal complications and the pathophysiology and diagnosis of cervical incompetence, highlighting prevention strategies and outcomes.
