X Ray of a Human Stomach With a Baby

CMAJ. 2008 Dec two; 179(12): 1293–1296.

Review

"Doc, will that ten-ray harm my unborn child?"

Abstract

Abstruse: Exposure to ionizing radiation tin can be a source of anxiety for many meaning women and their health care providers. An awareness of the radiation doses delivered by different techniques and the acceptable exposure thresholds can help both patients and practitioners. Nosotros describe exposure to radiodiagnostic procedures during pregnancy and suggest an approach to appraise the potential chance.

Case ane: A 29-yr-quondam patient underwent an upper gastrointestinal series as part of the diagnosis of prolonged heartburn. She comes to see you i week afterwards and is very upset because her flow is 1 week late and she was about 4 weeks pregnant at the time of the process. The patient asks you to schedule the termination of her pregnancy on the communication of several family unit members.

Case 2: A 40-year-old woman arrives at the emergency section with astute pleuritic chest pain and shortness of breath. The patient is xv weeks' pregnant. To dominion out a pulmonary embolus, should yous perform a ventilation-perfusion scan or computed tomography (CT) angiography?

Case three: A 37-year-old woman who is 20-weeks meaning reports persistent pain in her right upper thigh that is exacerbated subsequently jogging. The pain is localized and has no radicular properties. A physical examination shows localized tenderness on the right hip joint without whatever abnormal neurological findings. Yous suspect hip bursitis but desire to order a radiograph to rule out osteoarthritis with degenerative changes. The patient is nervous near the possible effects of the radiation on her baby; how would yous counsel her?

Many women are exposed to radiation from diagnostic imaging procedures before they know they are meaning or because it is necessary during a known pregnancy. These patients oft question the potential furnishings of the radiation on the developing fetus, and they may perceive radiation as being very harmful.^1–4 A realistic and informed arroyo to counselling these patients can minimize the anxiety felt past both patients and health care providers.

Humans are exposed to both groundwork and man-made sources of radiations. For the purpose of this review, "radiation" refers to ionizing radiation (e.g., x-rays, γ-rays, radionuclides) and non to other forms of radiation (e.one thousand., long-wavelength electromagnetic waves such equally radar, microwaves, diathermy and FM radio waves).

Ionizing radiation in the form of x-rays and γ-rays are short-wavelength electromagnetic rays. Low-free energy photons in x-rays and high-energy photons in γ-rays can alter the normal structure of a living cell both directly and indirectly. The direct machinery involves disruption of the cantlet's structure to produce an ionized compound and a costless electron. The indirect mechanism involves radiolysis of water and generation of complimentary radicals.⁵

Ionizing radiation tin can cause 2 types of effects.⁵ Starting time, loss of tissue role (deterministic result) tin can occur. This type of injury has tissue-specific thresholds and may involve various repair and compensatory mechanisms. If the radiation dose is fractionated, there is greater repair and proliferation, hence there is greater tolerance of the tissue to the radiations. 2d, damage tin can occur from a single random modification in a jail cell component (e.grand., DNA) (stochastic effect). There is no dose threshold for stochastic effects.

Since invention of the 10-ray in 1895, ionizing radiation has been harnessed for diagnostic and therapeutic purposes. With the atomic bombings in World State of war II, the world became aware of the serious potential carcinogenic, teratogenic and mutagenic effects of ionizing radiations. Despite the increase in concern nearly the health furnishings of ionizing radiation, the medical employ of x-rays has continued to grow. In 1980, the number of radiographs performed in the United states of america was 225 million, including about 80 one thousand thousand fertile men and women.^five In 2006, the estimated total number of radiographs in the US was most 330 1000000.⁶ The fetus is exposed to unavoidable (groundwork) radiations from cosmic rays, terrestrial radiation from basis and building and naturally occurring radioisotopes that are inhaled or ingested. The total fetal dose from background radiation sources is 0.1 rad or less during the entire pregnancy.^five

Radiation effects

Loftier levels of acute exposure to radiation (every bit low as 100 rad, commonly in a higher place 400 rad) can cause acute radiation syndrome and fifty-fifty death. Ionizing radiation has several biological furnishings on reproduction.^v

• Irradiation of the testes and ovaries can cause infertility. This tin exist either temporary or permanent depending on the dose (equally low every bit 15 rad) and duration of the radiation.

• Loftier-dose (hundreds of rads) abdominal or pelvic irradiation (due east.g., for treatment of Wilms tumour) may cause somatic damage to abdominopelvic structure and interfere with conception and gestation.

• At nowadays, at that place has been no correlation shown betwixt exposure to ionizing radiations in utero and genetic disorders.

• The fundemental effects of ionizing radiation on the developing fetus are intrauterine growth retardation and defects in the central nervous system (microcephaly, mental retardation). The about vulnerable period is viii–15 weeks' gestation. This effect is associated with radiation doses above 10–xx rads.

• Low risk of neoplasm cannot be ruled out after in utero exposure to less than 10 rad. In utero irradiation is non considered likely to significantly increase the lifetime chance of neoplasm development in a person who lives to sometime historic period and who receives additional radiation throughout his or her life.

The dose of the ionizing radiation required to cause specific developmental furnishings depends on the stage of gestation (Table 1). When assessing radiation exposure during pregnancy, it is important to tally the cumulative dose delivered to the patient. Although a single procedure is usually not associated with reproductive gamble, this may not exist the case for multiple procedures (e.one thousand., radiographs received by trauma patients).

Tabular array 1

Dose limits

Exposure to a cumulative dose of less than v rads during pregnancy has not been shown to affect the result of the pregnancy compared to control populations exposed to background radiation estimated as less than 0.1 rad over 9 months.^{ii , 5 , seven} Co-ordinate to the U.s.a. National Council on Radiation Protection, fetal gamble of malformation increases above background levels at radiation doses above fifteen rads.

The US National Council on Radiation Protection states that the risk of induced miscarriages or major congenital malformations in embryos or fetuses exposed to doses of 5 rads or less is negligible compared to the spontaneous risk among nonexposed women.⁸ Spontaneous chance includes a 15% chance of having a spontaneous abortion, three% risk for major malformation and iv% risk of fetal growth restriction.^{5 , 7 , nine , ten} The Radiations Safety Commission of the US Center for Disease Control and Prevention recommends that unborn babies of laboratory workers should non be exposed to more than than 0.v rad cumulatively from all sources of radiation during the entire gestational menstruation.⁸ Typically, occupational radiation exposure is measured by tags or dosimeter bluecoat. At present, no such devices are required for pregnant women undergoing diagnostic radiation.

Estimated exposure

Well-nigh radiodiagnostic examinations result in less than 5 rads radiations to the fetus.^{2 , 3 , 5 , 10} An estimate of radiation doses used for diagnostic imaging procedures can be obtained from most radiology departments (Tabular array 2). It is estimated that about 85% of a person's lifetime exposure to radiation will come up from natural sources (background radiation) and most 15% will come from man-fabricated sources.¹¹ The majority of man-fabricated radiation volition result from diagnostic radiology devices (most 97% from CT scanners).

Table ii

Straight exposure of a fetus to radiation occurs when the fetus is located within the field being imaged. Indirect exposure is due to scattered radiation from maternal tissues. The fetal dose depends on the radiation dose delivered and the distance betwixt the fetus and the surface area beingness imaged. Radiation exposure dose is inversely related to the distance (to the ability of ii) from the radiation source. A lead shield may reduce indirect exposure, but internal scatter in the female parent volition allow some radiation to reach the fetus.¹² If thinly layered bismuth radioprotective latex or leaded garments are used to shield the mother's radiosensitive organs, the radiations dose that reaches the fetus can be cut by 50%.¹³

Fetal doses resulting from radiological examination of the mother'southward skull, caput, neck, breast and extremities are extremely low (< 0.01 rad) because of the relatively low maternal radiations dose, beam direction and distance betwixt the primary field and the fetus.ⁱ A contempo written report claiming an clan between dental radiography in pregnancy and low nascency weight^xiv has been criticized for lack of biological plausibility.¹⁵ A publication past the International Commission of Radiological Protection reviewed experimental information about the in utero event of radiation in animals and humans. They concluded that the hazard of induction of malformation at low doses can exist discounted. Data most the induction of severe mental retardation after irradiation from atomic bombs during the nigh sensitive prenatal period support a dose threshold of 6–31 rad between 8 and fifteen weeks and 25–28 rad betwixt xvi and 25 weeks.^xvi The data about loss of intelligence caliber afterward the bombing of Hiroshima and Nagasaki of xx–30 points per 100 rad exposure are more than difficult to interpret. However, even in the absenteeism of a true dose threshold, any effect on intelligence quotient at low doses would be undetectable.

The International Commission of Radiological Protection reported that the risk of induction of childhood solid tumours is similar to that of leukemia and that the gamble of cancer in after life is similar to that following irradiation during childhood. In contrast, there are studies that suggest an increase in childhood cancer subsequently in utero exposure to i rad. The excess absolute risk coefficient at this level of exposure is half-dozen% per 100 rad.^five The British Oxford Survey of Childhood Cancer estimated the take chances of cancer to be 0.022 per 100 rad. This is in agreement with the estimate of the Life Span Study from Japan that included survivors of the atomic flop (0.028 per 100 rad).^five

The American College of Obstetricians and Gynecologists has advised practitioners that, although there is no evidence that magnetic resonance imaging (MRI) is associated with adverse fetal furnishings, it should exist avoided during the first trimester. However, because the fetal radiation dose is minimal, MRI should non be delayed if information technology is considered critical for the diagnosis of a serious maternal status.

Perceived gamble of radiation

Pregnant women who have undergone radiodiagnostic procedures take a high perception of teratogenic risk (perceived risk of 25.5% for major malformations). In contrast, women who accept not undergone radiodiagnostic procedures have a lower perception of teratogenic hazard (fifteen.seven%).ⁱ A questionnaire survey conducted in Israel reported that 40% family physicians (northward = 86) and 70% of obstetricians (due north = 20) would recommend therapeutic abortion to women who received radiodiagnostic procedures (intravenous pyelograms, abdominal radiography, barium enema) during early pregnancy.^two

Similar trends have been reported in Canada. In a recent Canadian survey, 400 family physicians and 100 obstetricians were asked about their perception of the fetal risks associated with intestinal radiographs and CT scans during early pregnancy and whether they would recommend a therapeutic abortion following such exposure.^three Of the respondents, 40% of family physicians perceived the teratogenic risk associated with intestinal radiographs to be in a higher place baseline (≥ 5%), and 61% estimated the adventure associated with CT scans to be 5% or greater. Of obstetricians, eleven% estimated the take a chance associated with radiographs to exist five% or greater, and 34% estimated the risk associated with CT scans to be 5% or greater. Among family physicians one% would recommended an abortion if the patient had received a radiograph, and six% would recommend an abortion after a CT scans. None of the obstetricians reported that they would recommend an ballgame after a radiograph, but v% would recommended an abortion afterwards a CT browse during early pregnancy.³

The loftier perception by physicians of teratogenic risk associated with radiation could lead to unnecessary anxiety for pregnant women who take been inadvertently exposed and who seek counselling. It could also lead to delays in needed care for pregnant women. In ane prospective study, half dozen women (10% of participants) exposed to low-dose diagnostic radiation during pregnancy chose to end the pregnancy,⁴ stating that it was because of anxiety often caused past medico's communication. Educational interventions about radiation exposure should exist considered to facilitate accurate risk estimation past physicians.

The cases revisited

Case 1: You explain to your patient that the upper gastrointestinal series would accept exposed her fetus to doses of radiation of 0.36 rad, or near iv times the estimated dose of background environmental radiation that she would receive during the entire pregnancy. This is about 14-fold lower than the level that international radiations experts have suggested is the lower threshold for observable differences in pregnancy outcomes. You explain to your patient that many physicians and patients are unaware of the relatively high baseline risks for agin outcomes in all pregnancies (with or without diagnostic ten-ray exposure) for major malformations (three%) and fetal growth restriction (4%).

Case ii: Information technology is critical that a pulmonary embolism be ruled out. A ventilation-perfusion scan would expose the fetus to radiation as low every bit 0.06–0.1 rad, which is well below the potentially teratogenic dose (5 rad). A regular breast CT browse would expose the fetus to 0.45 rad, which is too well below the range of fetal risk. However, CT angiography is associated with college doses and involves assistants of a contrast agent. As her physician, your decision should be based on the individual operator and the diagnosis sensitivity and specificity of the unit.

Case 3: You advise your patient that a radiograph of the hip is associated with a fetal radiation dose of up to 0.37 rad. This is far beneath the fetal radiation dose considered as prophylactic. Although this dose is not associated with reproductive risk, this procedure is not clearly indicated and will not affect handling. The characteristics of your patient's pain suggest exercise-induced bursitis. Rest and analgesics are the handling of option, fifty-fifty if the diagnosis is osteoarthritis. At this time, the radiograph tin can be postponed while the patient is observed for any change.

Conclusion

The teratogenic furnishings of in utero exposure to ionizing radiation are dose-dependent with a well-defined threshold. There is no indication that radiodiagnostic doses of ionizing radiation during pregnancy increase the incidence of gross congenital malformations, intrauterine growth retardation or abortion. The risks of such exposure are far below the spontaneous risks. The vast majority of radiodiagnostic procedures involve fetal radiation doses that are beneath the threshold of 5 rad. In cases of maternal exposure to ionizing radiation, fetal exposure should be estimated. Health care providers should be careful not to misfile maternal and fetal exposures because this may lead to erroneous decisions. The demand for radiodiagnostic procedures during pregnancy should exist carefully considered and the risks should be weighed against the benefits. A radiodiagnostic process should not be withheld from a meaning woman if the procedure is clearly indicated and if information technology can bear on her medical care. Unnecessary procedures (e.g., pre-employment screen, routine periodic check-up) should be delayed because these procedures exercise not immediately contribute to patient's health care and might provoke feet.

Key points

• Exposure to diagnostic radiation during pregnancy is associated with high levels of feet amongst pregnant women and their health care providers.

• This anxiety may lead women to consider terminating an otherwise wanted pregnancy.

• The vast majority of diagnostic radiations procedures expose the fetus to radiations levels far below the teratogenic range.

• Physicians should utilize testify-based counselling to allay misperceptions of take a chance.

Footnotes

This article has been peer reviewed.

Competing interests: None declared.

REFERENCES

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Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2585137/

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