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Obstetric anaesthesia01 / 17

Laparoscopy for ovarian torsion at 22 weeks31-year-old woman, 68 kg, 22 weeks pregnant

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Know this first

  • Uterine displacement is needed after 18–20 weeks, and acid prophylaxis after about 20.
  • Pneumoperitoneum 15 mmHg or less; ETCO2 goal 28–34 mmHg.
  • No anaesthetic drug in current use is teratogenic at standard doses.
  • Previable fetus: fetal heart by Doppler before and after surgery.
  • NSAIDs after 30 weeks risk early ductal closure and oligohydramnios.

The patient

31-year-old woman, 68 kg, 22 weeks pregnant, for urgent laparoscopy for suspected left ovarian torsion. Six hours of severe left iliac fossa pain and vomiting; she ate a full meal 3 hours ago. First pregnancy, otherwise well. No regular drugs. Vitals: BP 118/72, HR 104, SpO2 98% on air, RR 20, temperature 37.4 °C.

The examiner asks

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  1. Consider

    What are your main concerns?

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    • A 31-year-old at 22 weeks with suspected torsion, for urgent laparoscopy after a full meal. Patient
    • At 22 weeks she needs uterine displacement and aspiration cover, and she will desaturate fast.
    • Torsion threatens the ovary, and mid-pregnancy is the safest window for surgery anyway. Surgery
    • Abdominal surgery slightly raises her risk of miscarriage and preterm delivery. Disease
    • Standard-dose anaesthetics aren't proven teratogens, so her needs decide the drugs.

  2. Prepare

    How do you prepare her?

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    • Her obstetrician is told now; we agree what happens if labour starts or delivery is needed. Patient
    • At 22 weeks the fetus is previable, so a Doppler fetal heart check before and after.
    • Sodium citrate 15–30 mL within the hour before induction, plus metoclopramide 10 mg IV. Airway
    • Her airway mucosa is swollen and friable: videolaryngoscope ready and a size 7.0 tube.
    • A wedge under her right hip for left uterine displacement on the table. Patient

  3. Plan

    Take me through the anaesthetic.

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    • Full preoxygenation: her FRC is down and oxygen use up, so apnoea drops her saturation quickly. Airway
    • Rapid sequence with propofol 2 mg/kg and rocuronium 1.0 mg/kg; suxamethonium 1–1.5 mg/kg is the alternative.
    • Before insufflation I agree a ceiling of 15 mmHg with the surgeon. Surgery
    • Ventilate to an ETCO2 of 28–34: low CO2 constricts uterine vessels, high CO2 acidifies the fetus. Disease
    • Neostigmine for reversal; sugammadex is advised against in pregnant women having non-obstetric surgery. After surgery
    • Extubated fully awake with her reflexes back.
    • Paracetamol 1 g IV every 6 hours with an opioid; no NSAIDs.

  4. Crisis

    Five minutes after insufflation, ETCO2 rises from 32 to 50 mmHg; BP 84/50, HR 118. What do you do?

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    • Ask the surgeon to let the gas out and check the set pressure. Crisis
    • Check her tilt: pressure in the abdomen and her uterus are both blocking venous return.
    • Phenylephrine 50–100 mcg boluses; her uterine flow has no autoregulation to protect the fetus.
    • Increase her minute ventilation to bring ETCO2 back to 28–34.
    • Sudden hypotension on insufflation: I also exclude CO2 embolism and capnothorax.
    • If it stays high, an arterial gas; the end-tidal gap is normally under 3 mmHg.
    • Restart at a lower pressure once she is stable. After surgery

  5. Crisis

    In recovery she has regular tightenings every 4 minutes with lower abdominal pain. BP 124/76, HR 96. What do you do?

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    • Possible preterm labour after abdominal surgery: obstetrician to see her now. Crisis
    • Fetal heart and uterine activity checked; a tocodynamometer works once the fundus reaches the umbilicus.
    • Treat her pain well; poor analgesia after abdominal surgery may itself provoke preterm labour.
    • Tocolysis is the obstetrician's decision; infection, bleeding or fetal compromise rule it out.
    • If nifedipine is used, I watch her for hypotension.
    • Early mobilisation and thromboprophylaxis; pregnancy and surgery both raise her clot risk. After surgery

Fatal mistakes

  • Leaving her flat with no uterine displacement at 22 weeks.
  • Accepting a high ETCO2, or hyperventilating her to a low one.
  • Regular NSAIDs for her postoperative pain.
  • No fetal heart check before and after surgery.

Checked against: Miller 10e · Faust · Barash 9e

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