Chapter 186. Nonobstetrical Surgery in the Pregnant Patient

See also Chapter 180.

• Airway and airway equipment:
  • Mallampati classification may underestimate difficulty of intubation
  • Evaluate carefully neck mobility (presence of “buffalo hump” posteriorly)
  • Look at the patient supine as well as sitting (enlarged breasts, position of neck)
  • Have extra equipment (airway cart) immediately available when planning general anesthesia for a pregnant patient
  • Difficult intubation is more likely (risk increased about 4-fold)
  • Enlargement of lingual tonsils (protrusion of tongue) is an important reason for Mallampati 3–4 scores: this results in reduced orohypopharyngeal junction diameter
  • Increased risk of injury resulting in swelling and bleeding during laryngoscopy
  • When difficulty in intubation is anticipated, the route of choice for fiber-optic intubation is “oral” rather than nasal
• NPO guidelines:
  • Fasting time for pregnant patients before elective cases is the same as that for the nonpregnant population
• When is a pregnant patient considered to have a full stomach?
  • Presence of heartburn is suggested to be indicative of reduced lower esophageal sphincter (LES) tone (<20 cm H2O) and potential regurgitation during induction and mask ventilation
  • Early onset heartburn is hormonally driven
  • From about 20 weeks the enlarging uterus mechanically distorts the position of the stomach and the LES and increases intra-abdominal pressure
  • Gastric emptying is “not” reduced in pregnancy until advanced stages of labor
• Looking after the fetus (see detailed discussion about fetal well-being and anesthesia):
  • Every pregnant patient should have an identified designated obstetrician with hospital privileges available before any elective surgery; in an emergency, attempts should be made to contact the on-call obstetrician
• Laboratory tests:
  • Routine laboratory tests are similar to those for the nonpregnant female: CBC to evaluate for presence of anemia. All other tests should be performed as clinically indicated
  • Ketosis and hypoglycemia are common in pregnant patients when NPO for a prolonged period of time. This is well tolerated and routine testing is not recommended
  • Type and screen should be done for all cases in case labor ensues; extent of maternal hemorrhage is unpredictable
• Postoperative planning:
  • Patients who are <24 weeks pregnant are recovered in the general PACU and are discharged to the general floor (fetus is not considered viable)
  • Patients who are >24 weeks pregnant are recovered and are transported to labor and delivery once stable postoperatively (monitoring, staff, and neonatology is immediately available should labor ensue)
  • ICU admission criteria are similar to those for nonpregnant patients; obstetrical input into ICU care should be arranged

• Effect of maternal surgery on the offspring with emphasis on teratogenicity of anesthetic agents:
  • No anesthetic drug has been shown to be clearly dangerous to the human fetus
  • Incidence of stillbirth and birth defects is unchanged
  • Incidence of low birth weight is increased
  • Incidence of neural tube defects increased if surgery is in the first trimester
  • Although some agents (N2O, benzodiazepines) have been implicated in adverse neonatal outcome, these studies have been either refuted or associated with exposure in excess of an average anesthetic
  • There is no optimal anesthetic ...