Is intraoperative (in the operating room) monitoring safe for a pregnant woman?

Intraoperative Monitoring in Pregnant Women: Safety and Guidelines

Yes, intraoperative monitoring can be safely performed in pregnant women when medically necessary, with appropriate anesthetic modifications and fetal monitoring protocols based on gestational age. 1

Key Safety Principles for Intraoperative Monitoring

Maternal Positioning and Oxygenation

• After 20 weeks gestation, position the patient with left uterine displacement (left lateral decubitus or partial left lateral tilt) to prevent aortocaval compression and maintain adequate cardiac output 1, 2
• Maintain maternal oxygen saturation >95% throughout the procedure to ensure adequate fetal oxygenation 3
• Avoid hypoxemia, hyperoxia, hypotension, acidosis (hypercarbia), and hyperventilation (respiratory alkalosis) as these are critical elements of safe anesthetic management 1, 2

Anesthetic Considerations

• Modern anesthetic agents have not been shown to be teratogenic when used in standard doses 1
• Propofol and fentanyl-based anesthesia can be safely used for intraoperative neurophysiological monitoring 4
• Multimodal analgesia including regional analgesia techniques, local anesthetic infiltration, and judicious opioid use is safe in pregnancy 1, 2

Fetal Monitoring Requirements

For Previable Fetuses (<23 weeks)

• Preoperative and postoperative fetal heart rate detection by Doppler is sufficient 1
• No intraoperative monitoring is necessary during the procedure 1

For Viable Fetuses (≥23 weeks)

There is divergence in guideline recommendations:

ACOG Position:

• Simultaneous fetal heart rate tracing and contraction monitoring should be performed before and after surgery 1
• Intraoperative fetal heart rate monitoring may be appropriate when the fetus is viable, monitoring is possible, and emergent cesarean delivery would be considered 1
• Fetal heart rate monitoring may assist in maternal positioning and cardiorespiratory management 1

BSGE/SAGES Position:

• Preoperative and postoperative fetal heart rate monitoring are recommended past the age of viability, but intraoperative fetal heart rate monitoring is not recommended 1

Practical Approach

• For viable pregnancies undergoing major procedures, perform continuous electronic fetal monitoring for at least 4 hours postoperatively 3
• Intraoperative monitoring should be considered based on the woman's preferences, gestational age, and anticipated risk of cardiovascular instability 5
• Some fetal heart rate changes (lower baseline, less variability) can be anticipated depending on anesthetic agents and should not routinely prompt delivery 5

Evidence from Neurophysiological Monitoring Cases

Intraoperative neurophysiological monitoring (IONM) has been successfully performed in pregnant women:

• A case report of a 29-week pregnant patient undergoing spinal surgery with motor-evoked potentials (MEP) and somatosensory-evoked potentials (SSEP) monitoring demonstrated no new neurological deficits and successful outcomes 4
• Another case of a 29-week pregnant woman undergoing cervical intraspinal tumor excision with IONM showed no damaging effects at the maternal-fetal level 6
• A pregnant patient at 29 weeks with intracranial meningioma underwent successful cesarean delivery followed by tumor resection, highlighting the importance of multidisciplinary planning 7

Critical Safety Measures

Preoperative Planning

• Surgery should be performed at an institution with obstetrical, neonatal, and pediatric services 1
• Early involvement of an obstetrical anesthesiologist is essential 1
• Non-urgent surgery should be postponed until after pregnancy, but pregnancy should not delay urgent surgery 1

Intraoperative Management

• Use capnography for intraoperative CO₂ monitoring and avoid maternal hypo- and hypercapnia 1, 8
• Maintain CO₂ insufflation at 10-15 mmHg if laparoscopy is performed, with operating pressure at 12 mmHg 1, 8
• Insert a nasogastric tube in semiconscious or unconscious patients to prevent aspiration 3

Postoperative Care

• Adequate pain relief is essential to prevent reactive preterm contractions 1, 2
• Paracetamol is the analgesic of choice for mild to moderate pain during any stage of pregnancy 1, 9, 2
• Short-term narcotic use is safe if paracetamol is inadequate 1
• Avoid NSAIDs after 28 weeks gestation due to risk of premature ductus arteriosus closure and oligohydramnios 1, 9

Special Considerations

Thromboembolism Prophylaxis

• Pregnant patients undergoing surgery are at very high risk for venous thromboembolism 1
• Screen for venous thromboembolism risk and provide appropriate perioperative prophylaxis 1
• Consider pharmacologic prophylaxis with low-molecular-weight heparin 1
• Use intra- and postoperative sequential compression devices and encourage early ambulation 1

Corticosteroids and Tocolytics

• Corticosteroid administration should be considered for patients with fetuses at viable premature gestational ages 1
• Routine prophylactic use of tocolytics is not recommended 1

Emergency Preparedness

• Obtain consent for emergency cesarean section in case of severe complications when the fetus is viable 1
• Have adequately trained staff and equipment readily available 1