CHAPTER 24
Surgery in Pregnancy
1 Describe the incidence of nonobstetric surgery performed during pregnancy in the United States.
2 Analyze alterations in the pregnant patient’s physiology and the risks associated with anesthesia.
3 Discuss optimal timing for nonobstetric surgery when performed during pregnancy.
4 Describe potential complications of nonobstetric surgery for the pregnant patient.
5 Describe the potential effects of nonobstetric surgery and anesthesia on the fetus.
6 Assess the patient’s response to surgery and the potential for preterm labor.
7 Outline important parameters of general maternal preoperative assessment.
8 Discuss basic and specific considerations in anesthetic choices for the pregnant patient requiring nonobstetric surgery.
9 Describe assessment of symptoms of the pregnant patient with acute cholecystitis.
10 Describe assessment of symptoms of appendicitis in the pregnant patient.
11 Describe assessment of symptoms of the pregnant patient with ovarian cyst/tumor requiring surgical intervention.
12 Discuss the use of laparoscopy as a surgical technique in pregnant patients in need of cholecystectomy or appendectomy.
13 Describe the patient at risk for cervical incompetence.
14 Define the function and types of surgical approaches to cervical cerclage.
15 Discuss procedure-specific assessment of the pregnant patient in need of cervical cerclage.
16 Discuss indications for endoscopic gastrointestinal procedures that might be present in the pregnant patient.
17 Discuss the risks that might be present for pregnant patients undergoing esophagogastroduodenoscopy (EGD) or endoscopic retrograde cholangiopancreatography (ERCP).
18 Outline methods for risk reduction in pregnant patients undergoing endoscopic gastrointestinal procedures.
19 Describe the potential maternal complications associated with intrauterine fetal surgery.
20 Discuss specific life-threatening fetal anomalies that might be amenable to treatment by intrauterine fetal surgery.
21 Describe the utility of intrauterine fetal surgery in correction of nonfatal fetal anomalies such as myelomeningocele or obstructive uropathy.
22 Select appropriate nursing actions based on acquired knowledge of the alterations in the pregnant patient’s physiology, and integrate that knowledge into preoperative, intraoperative, and postoperative care.
23 Define psychosocial stressors affecting the pregnant patient undergoing surgery.
24 Describe the care of the pregnant surgical patient and her family based on analysis of the patient’s needs in this emotionally and physically stressful situation.
25 Formulate nursing interventions to prevent postoperative surgical complications in the pregnant surgical patient.
INTRODUCTION
A Incidence of nonobstetric surgery performed during pregnancy ranges from 0.75% to 2%. Of this incidence approximately 42% occur in the first trimester, 35% in the second trimester, and 23% in the third trimester (Birnbach & Browne, 2005; Mhuireachtaigh & O’Gorman, 2006).
1. Incidence is probably underestimated in first trimester because pregnancy might be unrecognized at time of surgery.
1. Laparoscopy for appendicitis is the most common first-trimester procedure. Incidence is estimated at 1 per 1500 to 2000 pregnancies (Mhuireachtaigh & O’Gorman, 2006).
2. Other situations that might lead to surgery during pregnancy include:
a. Nongynecologic: acute cholecystitis (1 to 8 per 10,000 pregnancies [Mhuireachtaigh & O’Gorman, 2006]), intestinal obstruction, trauma with visceral injury, vascular accidents (ruptured aneurysms), peptic ulcer, rectal cancer, breast tumors, or other malignancies; rarely, maternal cardiac or neurosurgical conditions
b. Gynecologic: cervical incompetence, ovarian cyst, torsion of fallopian tube, tubo-ovarian abscess, uterine myoma with degeneration or torsion
c. Intrauterine fetal surgery as an intervention for certain prenatal congenital defects
CLINICAL PRACTICE
A Concepts essential to planning and management
1. Anesthetic management priorities
a. Possibility of increased maternal morbidity
(1) Risk of preterm delivery after surgery during pregnancy is approximately 8.8%.
(2) Risk of spontaneous abortion after surgery is approximately 8% in the first trimester and 6.9% in the second trimester.
b. Possibility of increased fetal risk from:
2. Pregnancy-induced changes in maternal physiology of importance during anesthesia and surgery
a. Pregnancy-induced changes result from:
(1) Increases in human chorionic gonadotropin, progesterone, and estrogen; responsible for most first-trimester changes
(2) Mechanical effects of the gravid uterus
(3) Increased metabolic demand
(4) Hemodynamic changes due to presence of low-pressure placental circulation (Hill & Pickinpaugh, 2008)
(1) Increased pulse rate and stroke volume result in cardiac output increases of 30% to 50% during pregnancy.
(2) By 8 weeks’ gestation, 57% of the overall increase in cardiac output and 78% of the total increase in stroke volume have occurred (Hill & Pickinpaugh, 2008).
(3) 90% of overall decrease in peripheral resistance has occurred by 24th week due to increased synthesis of vasodilators such as prostacyclin (Mhuireachtaigh & O’Gorman, 2006).
(4) During the second trimester, the weight of the uterus compresses the inferior vena cava when mother is supine (25% to 30% decrease in venous return and cardiac output), which can produce supine hypotensive syndrome, especially in the face of anesthetics that abolish compensatory mechanisms (Kilpatrick & Monga, 2007).
(5) A gravid uterus can also compress the aorta in a supine patient (leading to decreased uteroplacental blood flow and fetal compromise).
(6) Combined hypotensive effect of general or regional anesthesia and aortocaval compression, leading to fetal asphyxia
(7) Chronic vena caval obstruction in the third trimester predisposes to venous stasis, phlebitis, and lower-extremity edema (Hill & Pickinpaugh, 2008)
(8) Distention of epidural venous plexus due to vena caval compression contributes to the spread of smaller amounts of local anesthetics administered epidurally during pregnancy.
(1) Under the influence of progesterone, alveolar ventilation is increased by 25% by 20 weeks’ gestation due to a 15% increase in respiratory rate and an increase in tidal volume of 40%; increased 45% to 70% by term, leading to chronic respiratory alkalosis (Paco2 is 28 to 32 mm Hg; slightly alkaline pH). Chronic respiratory alkalosis shifts maternal oxygen-hemoglobin dissociation curve to the right, promoting increased oxygen delivery to the fetus. The increase in arterial pH is limited by an increase in renal bicarbonate excretion (Kilpatrick & Monga, 2007; Mhuireachtaigh & O’Gorman, 2006).
(2) Functional residual capacity (FRC) decreases 20%, leading to decreased oxygen reserve.
(3) Decreased FRC, increased oxygen consumption, and decreased buffering capacity cause rapid hypoxemia and acidosis if stressed by hypoventilation or apnea.
(4) Capillary engorgement of nasal and pharyngeal mucosa predisposes to bleeding, trauma, and obstruction.
(1) Blood volume expansion begins in first trimester, increases to 30% to 50% by term; increased plasma volume causes dilutional anemia. Moderate blood loss is well tolerated, but reserve is decreased when significant hemorrhage occurs.
(2) Pregnancy-induced leukocytosis makes white blood cell (WBC) count an unreliable indicator of infection; might be as high as 15,000/μL during pregnancy with increases up to 20,000/μL during labor.
(3) Hypercoagulable state of pregnancy (increased fibrinogen, factors II, VII, VIII, X, and XII) leads to high postoperative risk of thromboembolic events.
(1) Lower esophageal sphincter incompetence and distortion of gastric and pyloric anatomy increases risk of esophageal reflux with possible aspiration and resultant pneumonia (Kilpatrick & Monga, 2007).
(2) All pregnant patients, after 16 weeks’ gestation, are considered to be at increased risk for aspiration (Mhuireachtaigh & O’Gorman, 2006).
3. Potential effects of surgery and anesthesia on the fetus
a. Greatest risk to fetus is intrauterine asphyxia.
(1) Transient decrease in maternal Pao2 is well tolerated because of increased affinity of fetal hemoglobin for oxygen.
(2) Maternal hypercarbia leads to fetal acidosis, which might cause fetal myocardial depression and hypotension (Hill & Pickinpaugh, 2008).
(3) Maternal hypocarbia from stress-induced or positive-pressure hyperventilation might produce decreased fetal oxygenation due to resultant umbilical artery constriction and shift of the maternal oxygen-hemoglobin dissociation curve to the left (acidosis); administration of 100% oxygen to mother will result in oxygen tension in fetus of approximately 65 mm Hg, which is the maximum possible (Hill & Pickinpaugh, 2008).
(4) Uteroplacental perfusion might be reduced as a result of maternal hypotension, which might occur in response to deep general anesthesia, sympathetic blockade from high spinal or epidural blockade, aortocaval compression, hemorrhage, or hypovolemia (Kilpatrick & Monga, 2007).
(5) The administration of alpha-adrenergic vasopressor agents, preoperative anxiety, and/or very light levels of general anesthesia might produce increased maternal circulating catecholamines, which can lead to decreased uterine blood flow.
(a) Greatest risk of structural abnormalities occurs with drug exposure from approximately day 31 to day 71 after the first day of the last menstrual period (LMP) (Mhuireachtaigh & O’Gorman, 2006).
(b) Currently administered inhaled or local anesthetics, narcotics, and skeletal muscle relaxants in clinical concentration are not deemed to be teratogenic or carcinogenic (Mhuireachtaigh & O’Gorman, 2006).
(c) Long-standing relative contraindication and concern over first-trimester use of benzodiazepine agents has been removed. Research failed to demonstrate link with increased incidence of cleft lip/palate (Mhuireachtaigh & O’Gorman, 2006).
(a) No congenital defects have been noted after brief periods of hypoxia, hypercarbia, or hypoglycemia.
(b) Effect of maternal stress and anxiety is questionable because of the lack of supportive research.
(c) Central nervous system congenital anomalies are associated with maternal fever (>39° C) (102.2° F) during the first half of pregnancy.
(d) Ionizing radiation: No congenital defects from exposure below 10 rads (average chest radiograph exposure = 8 mrads).
(e) The increased incidence of abortion, early delivery, and perinatal mortality associated with anesthesia and surgery might be attributed to the surgical site and/or underlying conditions; no clear relationship between outcome and type of anesthesia has been demonstrated.
B General maternal preoperative assessment
1. History and physical examination
b. Urgency of need for surgery
c. Presence of underlying chronic or acute illness
e. Current medications (prescription, over-the-counter, herbal, and recreational)
f. Surgical history: previous procedures and responses to anesthesia
h. Pain evaluation: location, intensity, characteristics, duration, and patient tolerance
j. Evaluation of fetal heart rate (FHR) by Doppler or continuous fetal monitoring
k. Evaluation of uterine activity
l. Respiratory status: dyspnea, evidence of distress, history of recent fever, or congestion, asthma, inhalant allergies, or smoking
m. Cardiovascular status: presence of pregnancy-induced hypertension (PIH), history of rheumatic fever, or mitral valve dysfunction
n. Hepatic status: history of hepatitis and alcohol consumption
a. Stress factors producing anxiety
(1) Fear of loss or harm to fetus
(3) Lack of understanding of planned procedure, anesthesia options, and possible outcomes
3. Laboratory and diagnostic procedures
c. Preoperative laboratory evaluation: complete blood count (CBC), urinalysis (UA), and type and crossmatch of blood products as indicated
d. Electrocardiogram (ECG); chest radiograph (shielded) if indicated because of preexisting cardiovascular or pulmonary disease (e.g., floppy mitral valve, questionable aspiration pneumonitis, history of rheumatic fever)
C Surgical choices: Open laparotomy versus laparoscopic approach
1. Overall safety of laparoscopy during the first half of pregnancy has been confirmed (Lu & Curet, 2007).
2. Laparoscopy is safe up to 26 to 28 weeks, when there is less risk of spontaneous abortion or premature labor due to manipulation. There is increased risk of uterine puncture during the third trimester due to large size of the uterus (Kilpatrick & Monga, 2007; Lu & Curet, 2007; Moreno-Sanz, Pascual-Pedreno, Picazo-Yeste, & Seoane-Gonzalez, 2007).
3. Risk may be lessened during laparoscopy if:
a. Intraperitoneal pressure is maintained at 10 to 15 mm Hg or lower to protect uterine perfusion (Kilpatrick & Monga, 2007).
b. Carbon dioxide should be used for production of pneumoperitoneum.
c. Patient should be placed in reverse Trendelenburg in the left-side-down position, if possible.
d. Intraoperative fetal monitoring is performed, if possible, because carbon dioxide used for insufflation can be absorbed, leading to fetal respiratory acidosis and hypercapnia (Kilpatrick & Monga, 2007; Moreno-Sanz et al, 2007).
4. Advantages of laparoscopy include better visualization, smaller incision, less pain, less operative time, decreased recovery time, earlier ambulation, and decreased risk of thromboembolic disease.
5. Open laparotomy is required when sufficient access is not possible with laparoscopy or when profound uterine relaxation is required to facilitate the planned procedure.
a. Low-dose benzodiazepine and/or narcotic to allay maternal anxiety
b. Histamine receptor type 2 (H2) antagonist and 30 mL of clear antacid as a precaution against acid aspiration after 16 weeks’ gestation (Mhuireachtaigh & O’Gorman, 2006)
2. Choice of anesthetic technique
(1) No studies correlate improved maternal or fetal outcome with any specific anesthetic technique.
(2) Local and regional techniques are useful for cervical cerclage or urologic or lower-extremity procedures.
(3) General anesthesia is required for most abdominal procedures.
(1) After 18 to 20 weeks, left displacement of uterus is necessary when patient is positioned on the operating table to avoid supine hypotensive syndrome and aortocaval compression.
(2) Basic perioperative monitoring: blood pressure, ECG, and pulse oximetry; general anesthesia requires the addition of capnography, temperature monitor, and nerve stimulator to assess skeletal muscle relaxation.
(3) General anesthetic choices
(a) High concentration oxygen plus a potent opioid (fentanyl or sufentanil) and/or a moderate concentration of a volatile agent (e.g., isoflurane, desflurane, sevoflurane), and a skeletal muscle relaxant
(b) Nitrous oxide (N2O) might be safely chosen, especially after the sixth week of gestation.
(a) Epidural and spinal anesthesia
[i] Fetal hypoxia occurs if maternal systolic blood pressure drops below 100 mm Hg; in healthy pregnant women, 1 to 2 L of crystalloid fluid may be infused to prevent maternal hypotension.
[ii] Patients with PIH experience decreased placental flow at higher systolic pressures than do normal pregnant women.
(b) Increased vascularity and sensitivity to local anesthetics present during pregnancy; observe for signs of toxicity after injection (e.g., tingling, tinnitus, shivering, unexplained confusion or drowsiness). The therapeutic dose and the toxic plasma levels of local anesthetics are decreased approximately 30% during pregnancy (Mhuireachtaigh & O’Gorman, 2006).
3. Other intraoperative considerations
(1) If feasible, with external tocodynamometer intraoperatively and in immediate postoperative period to detect any need for administration of tocolytic agents.
(2) Unexplained change in FHR: evaluate maternal position, blood pressure, oxygenation, acid-base balance, whether surgeon or retractor placement is impairing uterine perfusion.
(3) Maternal hypothermia can cause a decrease in baseline fetal heart rate, as well as beat-to-beat variability, but it does not cause spontaneous decelerations.
(4) Management plan must be in place regarding what to do in the face of persistent fetal distress (i.e., feasibility of cesarean section).
b. Prevention of aortocaval compression
c. Prevention of preterm labor
(1) Procedures with minimal uterine manipulation occurring after the first trimester of pregnancy carry the lowest risk for preterm labor.
(2) Prophylactic use of tocolytic agents is not without complications but has been suggested for patients at greatest risk (e.g., for cervical cerclage); if unsuccessful, beta2-agonist tocolytic agents might complicate anesthesia because of production of tachycardia. Arg16 homozygosity of the beta2 adrenergic receptor appears to confer better response to beta2 agonist therapy for tocolysis (Landau, 2008).
d. Compression hose should be placed on the patient to decrease the risk of deep vein thrombosis; low-molecular-weight heparin administration may be considered to protect against embolism (Moreno-Sanz et al, 2007).
1. Maternal and fetal physiologic dynamics related to surgery and anesthesia
a. Interventions: preoperative
(1) Monitor and record vital signs.
(2) Provide intravenous (IV) hydration.
(a) Maintenance by 16- or 18-gauge intracatheter infusion of nondextrose crystalloid solution (Ringer’s lactate or normal saline)
(b) 1 to 2 L might be ordered for volume expansion before administration of epidural or spinal anesthetic or if patient is fluid depleted due to illness.
(3) Use left lateral positioning in the second and third trimesters to prevent aortocaval compression, which might result in decreased uteroplacental blood flow; if left lateral position is not possible, place a wedge (pillow or rolled blanket) under right hip to displace uterus to the left.
(4) Use FHR monitoring: Doppler or external fetal monitor after 18 weeks gestation if positioning allows (Mhuireachtaigh & O’Gorman, 2006).
(5) Assess preoperative laboratory test results for abnormalities that might alter or complicate perioperative care.
(6) Communicate findings to other members of the healthcare team.
b. Interventions: postoperative (in addition to those just mentioned)
(1) Monitor vital signs frequently within the first 1 to 2 postoperative hours.
(a) Overall, general anesthetics produce varying degrees of vasodilation and impair compensatory mechanisms, thereby increasing the potential for postoperative hypotension.
(b) A major side effect of regional anesthesia (spinal or epidural) is hypotension due to sympathetic paralysis and resultant peripheral vasodilation; increased fluid and lateral positioning might stabilize this transient event.
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