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Non-obstetric surgery in pregnancy
A pregnant woman who needs necessary surgery is operated on in any trimester; the best protection for the fetus is maintaining the mother's oxygenation, blood pressure, normocapnia and uterine perfusion — not avoiding anaesthetic drugs.
Why it matters in the exam
The exam asks when non-urgent surgery in pregnancy is best done (the second trimester), whether anaesthetic drugs are dangerous to the fetus, from which stage uterine displacement and aspiration precautions are needed, when the fetal heart is monitored, whether laparoscopy is allowed, and which drugs are avoided (NSAIDs after week 20). It also asks about radiation exposure from imaging.
Under ACOG, necessary surgery is not delayed in any trimester; elective surgery is deferred until after delivery; surgery that is not urgent but not elective is best in the second trimester. No accepted anaesthetic drug has been shown to cause malformations at clinical concentrations. Hypoxaemia, hypotension, hyperventilation (which constricts uterine vessels) and hypoglycaemia threaten the fetus much more than the drugs do. Normal PaCO2 in pregnancy is low — around 30–32 mmHg — so that is the target.
From about week 20 the uterus is displaced to the left and the woman is treated as having a full stomach. Laparoscopy is allowed in any trimester, at an insufflation pressure of 10–15 mmHg with EtCO2 monitoring. The fetal heart is monitored before and after surgery when the fetus is viable, and during surgery when possible and a team can intervene. NSAIDs are avoided after week 20 (oligohydramnios and ductal closure), thromboprophylaxis is given, and an Rh-negative woman receives anti-D after trauma. A radiation dose below 50 mGy does not raise the risk of malformations.
Key points
- Necessary — any trimester; non-urgent — second trimester; elective — after delivery.
- The danger to the fetus: hypoxaemia, hypotension, hyperventilation — not the drugs.
- From week 20: uterine displacement and a full stomach.
- PaCO2 target 30–32 mmHg.
- No NSAIDs after week 20; anti-D for an Rh-negative woman after trauma.
Summary table
| Issue | Rule | Exam point |
|---|---|---|
| Timing | Necessary — any trimester; non-urgent — second trimester; elective — after delivery | Do not delay necessary surgery |
| Drugs | No accepted anaesthetic drug has been shown to be teratogenic | The real danger: hypoxaemia and hypotension |
| Physiology | Uterine displacement from week 20; full stomach; PaCO2 target 30–32 mmHg | Avoid hyperventilation |
| Fetal monitoring | Before and after surgery when viable; during — when intervention is possible | Coordinate with an obstetrician |
| Drugs to avoid | NSAIDs after week 20 | Oligohydramnios and ductal closure |
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Sources
- ACOG Committee Opinion 775: Nonobstetric Surgery During Pregnancy, 2019 (reaffirmed 2023) — Recommendations
- Miller's Anesthesia, 9th edition (2020) — Anesthesia for Nonobstetric Surgery during Pregnancy
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.