Pregnancy-related imaging, radiation and surgery

• Pregnancy is not a reason to avoid a needed diagnostic test or operation. The risks of not making the diagnosis, or of delaying necessary surgery, usually outweigh the risks of a correctly chosen imaging study or operation.
• Ultrasonography and MRI without contrast are the imaging techniques of choice in pregnancy because they do not use ionising radiation and have no documented fetal harm. MRI is similar to ultrasonography in diagnosing appendicitis and is preferred when it is readily available. ^[1]
• Radiography, CT and nuclear medicine can and should be used when they are the right test. With rare exceptions the fetal radiation dose is far below the level that is known to cause fetal harm, which is in the range of 50 mGy and above for most deterministic effects.
• The accepted principle from the International Commission on Radiological Protection is that fetal doses below 100 mGy are not a reason to terminate a pregnancy, and doses above 100 mGy are managed case by case. A fetal dose of 50 mGy or less is generally considered negligible against the background risks of pregnancy.
• No currently used anaesthetic agent is known to be teratogenic in humans at standard concentrations at any gestational age, and in-utero exposure to standard concentrations for less than 3 hours has not been shown to affect the developing brain.
• A pregnant woman should never be denied medically necessary surgery or have it delayed because of the pregnancy. Elective surgery is postponed until after delivery. ^[2]

By the end of this page you should be able to:

1. Choose and justify the first-line imaging study for a pregnant patient with an acute problem, and state which studies are safe in pregnancy.
2. Quote the fetal radiation dose thresholds used in counselling (background, under 50 mGy, 100 mGy, 200 mGy, 610 mGy) and explain what each means.
3. Decide when gadolinium contrast and iodinated contrast are justified in pregnancy, and manage breastfeeding after them. ^[1]
4. Plan a non-obstetric operation in pregnancy: timing, obstetric consultation, VTE prophylaxis, corticosteroids, fetal monitoring.
5. Describe the anaesthetic and laparoscopic precautions used to protect the fetus (end-tidal carbon dioxide 3.7 to 4.3 kPa, pneumoperitoneum 12 mmHg, aspiration prophylaxis, left tilt). ^[3]
6. Apply the appendicitis-in-pregnancy facts: incidence, danger of delay, and the laparoscopic-versus-open question.
7. Carry out a focused trauma-in-pregnancy check and know when to involve obstetrics early.

Imaging, radiation and surgery in pregnancy cause three kinds of mistake. The first is under-treatment: a pregnant woman with suspected pulmonary embolism or appendicitis is refused CT because of fear of radiation, and a dangerous condition is missed. The second is over-treatment: MRI with gadolinium given without a compelling reason, or an unnecessary operation performed. The third is delay: everyone is reluctant to operate on a pregnant woman, so appendicitis perforates while people wait. The guidelines in this topic push in one direction. Use the right test without hesitation when maternal benefit demands it. Ultrasonography and MRI first when they answer the question. Do not delay necessary surgery. Keep elective surgery for after delivery. ^[1][2]

The guidelines named in this page are the ACOG Committee Opinion No. 723 on diagnostic imaging during pregnancy and lactation, October 2017, reaffirmed 2026 ^[1]; the ACOG Committee Opinion No. 775 on nonobstetric surgery during pregnancy, April 2019, interim update with clarified wording on sedative drugs, antenatal corticosteroids and venous thromboembolism prophylaxis, reaffirmed 2025 ^[2]; the Evidence-Based Guideline on Laparoscopy in Pregnancy commissioned by the British Society for Gynaecological Endoscopy and endorsed by the Royal College of Obstetricians and Gynaecologists, 2019 ^[3]; and ICRP Publication 117 on radiological protection in fluoroscopically guided procedures, 2010 ^[4]. National radiology societies (for example RCR/HPA advice on diagnostic radiology in pregnancy, and ESUR contrast media guidance) set local thresholds that may be stricter; reconcile these principles with local policy. ^[3]

The whole topic reduces to an algorithm. First establish gestational age and the clinical question. Then choose the imaging study that answers the question with the lowest fetal exposure, without delaying correct diagnosis. If the answer requires an operation, decide whether it is urgent (do not delay) or elective (postpone). Run the peri-operative pathway with an obstetric consultation, VTE prophylaxis and fetal monitoring chosen by gestational age and the nature of the surgery. ^[1][2]

Ultrasonography uses sound waves, not ionising radiation. There are no documented adverse fetal effects from diagnostic ultrasonography, including duplex Doppler imaging. ACOG states that it is not associated with risk, but should still be used prudently and only when it is expected to answer a relevant clinical question or provide medical benefit. Transducers should be operated using the ALARA principle (as low as reasonably achievable acoustic output). Heating potential is lowest with B-mode imaging and highest with colour and spectral Doppler, which is why obstetric presets and the correct probe matter. In pregnancy, ultrasonography is the first-line study for almost every abdominal, gynaecological and fetal problem. ^[1]

MRI gives excellent soft-tissue images without ionising radiation. ACOG says there are no precautions or contraindications specific to the pregnant woman, and no special consideration is needed for the first trimester compared with any other trimester. Therefore MRI is safe in all trimesters. In suspected appendicitis in pregnancy, MRI is similar to ultrasonography for diagnosis and is preferred when readily available, because of lower rates of non-visualisation. ^[1]

If an MRI does not need contrast, it should be done without it. Contrast is only justified when it makes a real difference.

Gadolinium is water soluble and crosses the placenta into fetal circulation and the amniotic fluid, where the fetus swallows and re-absorbs it. Free gadolinium is toxic, so it is given in chelated form, and prolonged amniotic fluid exposure raises the risk of the gadolinium dissociating from its chelate. Animal studies find teratogenicity at high repeated doses. In humans, the largest available retrospective comparison (gadolinium MRI, 397 pregnancies, versus no MRI, 1,418,451 pregnancies) found rheumatologic, inflammatory or infiltrative skin conditions more often in the exposed group and more stillbirths and neonatal deaths, although the study used an unexposed control group rather than MRI without contrast, and the outcomes were rare. ^[1]

ACOG's conclusion is conservative: the use of gadolinium contrast with MRI should be limited, and it may be used in a pregnant woman only if it significantly improves diagnostic performance and is expected to improve fetal or maternal outcome. ^[1]

Iodinated contrast crosses the placenta into the fetal circulation and amniotic fluid, but animal studies show no teratogenic or mutagenic effects, and clinical concerns about effects on the fetal thyroid have not been borne out in human studies. ACOG's position is that although there is no known harm, contrast should only be used when the extra diagnostic information is required to affect care during the pregnancy. ^[1]

Breastfeeding should not be interrupted after gadolinium administration. Less than 0.04% of an intravascular dose of gadolinium is excreted into breast milk in the first 24 hours, and the infant absorbs less than 1% of that from the gastrointestinal tract. ^[1]

For iodinated CT contrast, historically women were told to stop breastfeeding for 24 hours. ACOG states that less than 1% of iodinated contrast given to a lactating woman is excreted into breast milk and less than 1% of that is absorbed by the infant, so breastfeeding can be continued without interruption. ^[1]

ACOG is explicit: there are no animal or human fetal studies of superparamagnetic iron oxide contrast, and no information on its use in pregnancy or lactation. If contrast is needed in pregnancy, gadolinium is the recommended agent. ^[1]

Various units and dose quantities are used; the ones that matter at the bedside are the absorbed fetal dose in milligray (mGy) or gray (Gy). For reference, a fetus receives about 1 mGy from natural background radiation over a whole pregnancy. ^[1]

The central reassurance statement of ACOG CO 723 is that with few exceptions radiation exposure from radiography, CT or nuclear medicine imaging is at a dose much lower than the exposure associated with fetal harm, and if ionising radiation imaging is necessary in addition to, or more readily available than, ultrasonography or MRI, it should not be withheld from a pregnant patient. ^[1]

ACOG's Table 2 (effects of gestational age and radiation dose on radiation-induced teratogenesis) gives the standard thresholds used in counselling. ^[1]

Read those numbers carefully. A fetal dose of less than 50 mGy, a dose higher than any ordinary diagnostic procedure, has not been associated with fetal anomalies, growth restriction or pregnancy loss. Extremely high exposure, above 1 Gy, can be lethal in early embryogenesis, but doses like that are not used in diagnostic imaging. ^[1]

Intellectual disability is the most feared deterministic effect, and the numbers are reassuring for diagnostic imaging. The effect is greatest with exposure at 8 to 15 weeks of gestation. The suggested minimal threshold is in the range 60-310 mGy. The lowest clinically documented dose to produce severe intellectual disability is 610 mGy. Even multiple diagnostic X-ray procedures rarely reach that level. ^[1]

The carcinogenic risk of in-utero exposure to ionising radiation is unclear but probably very small. A fetal exposure of 10-20 mGy may increase the risk of leukaemia by a factor of 1.5-2 over a background rate of about 1 in 3,000. ^[1]

CT is a major source of fetal dose when the abdomen or pelvis is included. The dose depends on the number and spacing of adjacent sections. CT pelvimetry, for example, can expose the fetus to as much as 50 mGy, and can be reduced to about 2.5 mGy with a low-exposure technique that is still adequate for diagnosis. CT of the chest for suspected pulmonary embolism exposes the fetus to a lower dose than ventilation-perfusion scanning. Oral contrast is not absorbed and causes no harm. Intravenous iodinated contrast is discussed above. ^[1]

Radioisotope imaging is used for physiologic function rather than anatomy. Technetium-99m is the most commonly used isotope, including for ventilation-perfusion scanning in pregnancy. These procedures usually yield a fetal dose of less than 5 mGy, which is considered safe in pregnancy. ^[1]

Iodine-131 is different. It crosses the placenta, has a half-life of 8 days and can damage the fetal thyroid, especially after 10-12 weeks of gestation. Iodine-131 should not be used in pregnancy, whether for diagnosis or therapy. If thyroid diagnostic imaging is essential in pregnancy, technetium-99m is the isotope of choice. ^[1]

For lactating women who receive radionuclides, excretion into breast milk varies in concentration and duration between patients and between compounds, so consultation with experts in breastfeeding and nuclear medicine is recommended rather than applying one rule. ^[1]

X-ray procedures that are commonly used for trauma, dental or chest imaging deliver doses orders of magnitude below the thresholds above. ACOG notes that ultrasonography and MRI are not associated with risk and are the imaging techniques of choice, but ionising radiation studies should not be withheld when they are necessary for diagnosis. ^[1]

Should a pregnant woman undergo multiple ionising radiation studies, it is prudent to ask a radiation physicist to calculate the total fetal dose. The principle from the International Commission on Radiological Protection is that termination of pregnancy at fetal doses below 100 mGy is not justified on radiation grounds, while at doses above 100 mGy decisions should be individual, weighing the dose and the stage of pregnancy. ^[4]

ACOG states directly that pregnancy termination should not be recommended solely on the basis of exposure to diagnostic radiation. ^[1]

For pregnant workers, ICRP applies a 1 mSv dose restriction to the embryo or fetus after pregnancy is declared, and explicitly notes this does not require complete removal from radiation work; exposures should be kept below 1 mSv over the pregnancy with careful review of working conditions. ^[4]

For pregnant patients who need interventional radiology or endoscopy with fluoroscopy, the same principles apply: justify the procedure, tailor technique to reduce fetal dose, and monitor dose. ICRP also recommends that medical applications on pregnant patients be justified and tailored to reduce fetal dose. ^[4]

No large randomised trials exist for non-obstetric surgery in pregnancy, so ACOG CO 775 draws on consensus and biological generalisations. The single most important habit is notification: when non-obstetric surgery is planned, the primary obstetric care provider should be notified, and if she is not at the institution where the surgery will be performed, another obstetric care provider with privileges there should be involved. An obstetric consultation should happen before non-obstetric surgery and before some invasive procedures such as cardiac catheterisation or colonoscopy, because obstetricians are uniquely qualified to discuss aspects of maternal physiology and anatomy that affect intra-operative maternal-fetal well-being. ^[2]

ACOG lists three generalisations that are reassuring and worth quoting verbatim in teaching: ^[2]

1. No currently used anaesthetic agent has been shown to have any teratogenic effects in humans when using standard concentrations at any gestational age.
2. There is no evidence that in-utero human exposure to anaesthetic or sedative drugs has any effect on the developing fetal brain, and there are no animal data to support an effect with limited exposures of less than 3 hours.
3. Fetal heart rate monitoring may assist in maternal positioning and cardio-respiratory management and may influence a decision to deliver the fetus. ^[2]

Modern anaesthetic agents, muscle relaxants and opioids are not thought to be teratogenic at therapeutic clinical doses when maternal physiology is maintained. ^[3]

Two sentences from ACOG carry the whole topic: ^[2]

• A pregnant woman should never be denied medically necessary surgery, or have that surgery delayed, regardless of trimester, because this can adversely affect the pregnant woman and her fetus.- Elective surgery should be postponed until after delivery.

If there is a risk of preterm delivery with some non-obstetric procedures, corticosteroid administration for fetal benefit should be considered for patients with fetuses at viable premature gestational ages, and patients should be monitored in the peri-operative period for signs or symptoms of preterm labour. ^[2]

Pregnant women undergoing non-obstetric surgery should be screened for venous thromboembolism risk and should have appropriate peri-operative prophylaxis. Non-obstetric surgery in pregnancy is associated with increased VTE risk, and the BSGE guideline notes that the Royal College classifies any surgical procedure as at least intermediate VTE risk, with low molecular weight heparin to be considered. ^[2][3]

For surgery that cannot be postponed but is not an emergency, the second trimester has traditionally been considered the optimal window. The BSGE guideline cites the older ACOG committee opinion: the second trimester is the best time for non-urgent laparoscopic surgery, because preterm contractions and miscarriage are least likely and pelvic access is easier before the uterus enlarges. ^[3]

Newer evidence extends that window. Small series report good maternal and fetal outcomes for laparoscopic appendicectomy, cholecystectomy and adnexal surgery up to 34 weeks of gestation, which lengthens the historical recommendation to limit laparoscopic surgery to the second trimester. ^[3]

Laparoscopic surgery in pregnancy should be performed in settings with adequate time, laparoscopic expertise and monitoring facilities. When the fetus is beyond the age of viability, pregnant women undergoing laparoscopic surgery should be treated in a unit with adequate obstetric and neonatal facilities in case immediate delivery is needed. ^[3]

Pregnancy increases the risk of pulmonary aspiration of gastric contents. The BSGE guideline states that aspiration prophylaxis should be administered, a strategy for airway management should be made, general anaesthesia with endotracheal intubation is essential, and a laryngeal mask airway is not recommended. A rapid sequence induction should be considered. ^[3]

The two physiological targets are blood pressure and carbon dioxide. Uteroplacental blood flow is essential for fetal oxygenation, so maternal hypotension must be avoided. Maternal arterial carbon dioxide must be controlled, avoiding both hypo- and hypercapnia, to maintain optimal uteroplacental flow and avoid fetal acidosis. End-tidal carbon dioxide can be used as a surrogate marker for maternal arterial carbon dioxide, and invasive arterial monitoring is not routinely required in otherwise healthy stable women; the decision should be made case by case. When maternal blood pressure is maintained close to baseline and end-tidal carbon dioxide is controlled between 3.7 and 4.3 kPa, no adverse outcomes were reported in the series summarised. ^[3]

Laparoscopic pneumoperitoneum changes cardiovascular and respiratory physiology, so the creation of pneumoperitoneum and alterations in maternal positioning should be gradual, with vigilance and monitoring of maternal haemodynamic status. Uterine displacement can improve cardiac output and uteroplacental flow and should be used unless it adversely affects the ability to operate, when gestational age is more than 18 weeks. ^[3]

In most cases general anaesthesia should be employed for laparoscopy in pregnancy. The advantages are securing the airway to reduce aspiration risk, good muscle relaxation for surgical conditions, and controlled ventilation to regulate maternal carbon dioxide. ^[3]

Only laparoscopists who have specialist laparoscopic skills and who perform complex laparoscopic surgery regularly should undertake laparoscopy in pregnant women, because much of the evidence comes from specialised centres. Pregnancy should not be a reason to delay urgent surgery. If the expertise for a laparoscopic approach is lacking, an open operation in experienced hands is acceptable, since maternal and fetal outcomes are good. ^[3]

A multidisciplinary team should care for these patients, involving gynaecologists, general surgeons, anaesthetists, obstetricians and neonatologists as needed. ^[3]

The location of the primary port depends on uterine size, which should be determined by palpation or ultrasonography. Options described include umbilical, supra-umbilical or sub-xiphoid, and Palmer's point in the left upper quadrant mid-clavicular line. Suggested sites in the late second and third trimesters include 1-2 cm below the costal margin on the left or right mid-clavicular line, or 3-6 cm above the umbilicus in the midline. Orogastric decompression may be helpful when Palmer's point is used. ^[3]

Current evidence supports an operating pressure of 12 mmHg. The higher insufflation pressure of 20-25 mmHg is recommended only to create the pneumoperitoneum before inserting the primary trocar, for the short moment before the port is placed. ^[3]

At 12 mmHg or less, no adverse changes in feto-maternal perfusion were demonstrated in a quasi-experimental Doppler study, and many case series report no adverse fetal effects. ^[3]

General laparoscopic risks such as haemorrhage and port-site herniation also apply in pregnancy. Because the uterus enlarges and vascularity of the uterus and adnexae increases, there is an increased risk of vascular and organ trauma, including uterine perforation; this risk has not been quantified. Patients should be counselled about the consequences of uterine perforation: subsequent uterine rupture, infection, preterm delivery, and laceration of the fetus or placenta. Power morcellation should be discouraged in pregnancy because of the risk of uterine trauma. Energy sources (ultrasound, bipolar and monopolar) are safe in pregnancy, with standard electrosurgical precautions including not placing the monopolar return electrode so that the uterus lies between the electrode and the plate. ^[3]

Fetal heart Doppler monitoring may be done before and after surgery to confirm fetal wellbeing and reassure the mother; routine intraoperative monitoring is not needed. ACOG's guidance in CO 775 applies too: if the fetus is previable, it is generally sufficient to ascertain the fetal heart rate by Doppler before and after the procedure; if the fetus is viable, simultaneous electronic fetal heart rate and contraction monitoring should be performed before and after. Intraoperative electronic fetal monitoring may be appropriate when the fetus is viable, monitoring is technically possible, a provider with obstetric surgery privileges is available, consent allows for emergency caesarean delivery for fetal indications, and the nature of the surgery allows safe interruption or alteration for emergency delivery. Surgery should be done at an institution with neonatal and paediatric services, with an obstetric care provider with caesarean delivery privileges readily available and a qualified person to interpret fetal heart rate patterns. ^[2][3]

Antenatal corticosteroids between 24 and 35 weeks, and magnesium sulfate for fetal neuroprotection up to 33 weeks, should be used if there is risk of preterm delivery in accordance with existing NICE guidance, but urgent surgery should not be delayed to administer corticosteroids. Routine tocolysis is not recommended because it has not been shown to improve outcomes. Prophylactic anti-D is not deemed necessary because laparoscopy is not considered a potentially sensitising event. Antibiotics should be used for an infective process, chosen according to local antimicrobial guidance and drug safety in pregnancy. ^[3]

Acute appendicitis in pregnancy is rare but not rare enough to forget: non-obstetric abdominal surgery occurs in about 1-2 per 1,000 pregnancies, and appendicitis occurs in about 1 in 1,000 pregnancies. The presenting picture is often atypical, and delay increases harm: in one retrospective series a 24-hour delay in operating in suspected appendicitis in pregnant women was associated with a 66% increase in perforation. ^[3]

Complicated appendicitis, meaning generalised peritonitis or peritoneal abscess, carries a higher rate of fetal loss and early delivery than simple appendicitis: fetal loss 6% versus 2%, and early delivery 11% versus 4%. ^[3]

For comparison, pregnant women with appendicitis have higher rates of pre-operative systemic infection and systemic inflammatory response syndrome than non-pregnant women, and the authors of that cohort study suggested that factors include suppressed maternal immunity in pregnancy, difficulty making the diagnosis, and reluctance to operate. ^[3]

In suspected appendicitis in pregnancy, timely surgical intervention is preferable because delay may be associated with adverse maternal and fetal outcomes. Conservative (antibiotic-only) management in two large retrospective comparisons was associated with more complications, including a much higher pregnancy loss rate in the conservative group than in the surgical groups. ^[3]

Ultrasonography is first line but has limited sensitivity because the appendix is displaced by the gravid uterus. MRI is similar to ultrasonography in diagnosing appendicitis in pregnancy and is preferred when readily available, because of lower rates of non-visualisation. CT remains fully appropriate when MRI is not accessible within the clinical time frame or when it is needed to diagnose another condition. ^[1]

This is the contested area. ACP? A 2012 systematic review of 11 non-randomised studies found significantly increased fetal loss in the laparoscopic group (relative risk 1.91, 95% confidence interval 1.31 to 2.77). The BSGE reviewers noted this finding was attributable to one large study (McGory et al. 2007), and that a UK registry later (Balinskaite et al. 2017) found no difference in preterm delivery, stillbirth, maternal death or low birth weight between routes, although spontaneous miscarriage was more common in the laparoscopic group; in that study first-trimester operations were almost five times more likely to be laparoscopic. Both the BSGE guideline and ACOG describe this as an association that may be confounded by gestational age rather than a causal effect. ^[3]

The BSGE conclusion is that whilst maternal outcomes are good, controversy persists over an association between laparoscopic appendicectomy and miscarriage. It is not possible to recommend one approach over the other. Only experienced laparoscopists should carry these procedures out, and outcomes should be monitored. ^[3]

Gallbladder disease, cholecystitis and symptomatic gallstones are the other common non-obstetric surgical problem in pregnancy; symptomatic gallstone disease should be managed proactively because conservative management is associated with more recurrent biliary symptoms and hospital visits, and management of complicated gallstone disease (including gallstone pancreatitis, which carries a high fetal mortality) should be early and joint. Laparoscopic cholecystectomy is associated with better composite maternal and fetal outcomes, fewer surgical complications and shorter hospital stay than open surgery, although the case numbers in reported trimesters are small. ^[3]

Pregnant trauma patients need the same primary survey as anyone else, with three modifications. First, priorities: maternal resuscitation comes first, because the fastest way to resuscitate the fetus is to resuscitate the mother. Second, positioning and uterine displacement: as the uterus enlarges, a supine position can obstruct venous return, so left lateral tilt is used, especially beyond the middle of pregnancy. Third, when ionising radiation is needed to assess the mother, the same dose principles in this topic apply: the directly life-saving investigation should not be withheld, fetal dose should be estimated, and the team should avoid unnecessary repeat studies. ^[1][4]

For the obstetric specifics of trauma (fetal monitoring duration, placental abruption assessment, perimortem caesarean delivery), see the plain-text reference "trauma in special populations". Definitions and management of traumatic injuries in the pregnant patient are under the emergency medicine topics on abdominal, thoracic and head trauma, and the MedGrasp topic "trauma in special populations" is the detailed companion to this page for pregnant patients.

Fetal monitoring after trauma, interpretation of uterine contractions, and decisions about emergency delivery are obstetric decisions. Involve obstetrics early, and arrange delivery of the baby if maternal instability demands it, because fetal viability and surgical access are team decisions made with the obstetrician and anaesthetist. ^[2]

• Serial clinical examination and a high index of suspicion for appendicitis matter more than any single test, because decision-to-incision time worsens outcome.
• Where ultrasonography is the only imaging available, an experienced operator can diagnose most appendicitis, cholecystitis, ovarian cysts and placental problems. Request MRI and CT through referral networks when the result changes management.
• Open surgery by a trained surgeon gives outcomes comparable to laparoscopy when laparoscopic expertise and equipment are unavailable. ^[3]
• Estimating fetal dose after radiation exposure can be done by contacting the radiology physics service, and by keeping a cumulative record of studies.
• Any region's national radiation and obstetric guidelines take precedence locally, and the low-resource reader should check them.

Refer early, and before operating, when there is any of the following:

• Medically necessary surgery in pregnancy: consult an obstetric care provider before and peri-operatively. ^[2]
• Suspected appendicitis, cholecystitis or ovarian torsion in pregnancy: surgical review without delay. ^[3]
• Fetal radiation dose likely to exceed 50 mGy from multiple or complex studies: involve radiology physics and maternal-fetal medicine. ^[1][4]
• Trauma in pregnancy beyond minor injury: joint surgical, obstetric and anaesthetic review. ^[2]

• Pregnancy alone never justifies denying or delaying needed diagnosis or surgery.
• Ultrasonography and MRI without contrast are the imaging techniques of choice in pregnancy; MRI is safe in all trimesters including the first, and MRI is preferred to CT for suspected appendicitis when readily available. ^[1]
• CT, radiography and nuclear medicine should be used when clinically indicated. Doses in ordinary diagnostic imaging are far below the 50 mGy level below which no fetal harm has been reported.
• Gadolinium contrast should be limited to situations where it significantly improves diagnostic performance and is expected to improve fetal or maternal outcome. Breastfeeding need not be interrupted after gadolinium.
• Iodinated CT contrast should be used only when the extra information is needed, and breastfeeding can continue uninterrupted. ^[1]
• The thresholds to know are: below 50 mGy no reported risk of anomalies, growth restriction or loss; 100 mGy as the ICRP decision point for termination; 200 mGy for organogenesis anomalies; 60-310 mGy as the suggested minimal threshold for intellectual disability at 8-15 weeks, with the lowest documented severe case at 610 mGy; 10-20 mGy increases relative leukaemia risk 1.5-2 fold over a background of about 1 in 3,000. ^[1]
• No standard anaesthetic agent is teratogenic at standard concentrations at any gestational age; under 3 hours of exposure has no demonstrated effect on the fetal brain. ^[2]
• Medically necessary surgery must not be delayed; elective surgery is postponed until after delivery. Consult an obstetric care provider before operating. ^[2]
• Peri-operative targets: low molecular weight heparin for VTE prophylaxis, corticosteroids when viability is premature and time allows without delaying urgent surgery, and fetal monitoring chosen by gestational age.
• Laparoscopy is acceptable when performed by experienced laparoscopists; operate at 12 mmHg pneumoperitoneum after a brief 20-25 mmHg insufflation, control end-tidal CO2 3.7-4.3 kPa, maintain maternal blood pressure near baseline, use left uterine displacement beyond 18 weeks, and give aspiration prophylaxis with endotracheal intubation.
• Appendicitis occurs in about 1 in 1,000 pregnancies; a 24-hour delay increases perforation by 66%; complicated appendicitis carries 6% fetal loss versus 2% for simple; surgery is preferable to expectant management.
• Laparoscopic versus open appendicectomy in pregnancy remains controversial over a possible association with miscarriage that may be confounded by gestational age; neither approach is recommended over the other, and outcomes should be monitored.