SAFETY OF DIAGNOSTIC TECHNIQUES [12,
9]
Epidemiological studies have established the potential of ionizing radiation to induce leukemia and solid tumours.
The radiation effect on fetal life seems to be dose dependent Table 1.
In addition,
the adverse effects of radiation are directly related to the stage of gestation: the earlier the stage,
the more detrimental the expected effects Table 2.
In pregnant women with cancer,
staging imaging techniques should be limited to those associated with the lowest exposure to ionizing radiation.
Abdominal plain films,
isotope scans,
and computerized tomography (CT) should be avoided.
In contrast,
chest x-ray and abdominal ultrasound (US) are indicated as staging procedures.
The most appropriate would be to start using procedures that do not use ionizing radiation (ultrasound and MRI).
If they are not conclusive,
we can use ionizing radiation techniques after an individualized evaluation of the risk-benefit relationship,
and optimizing the procedure,
so the received fetal dose is the lowest possible.
If a CT including the pelvis or abdomen is necessary,
we should optimize the acquisition parameters (thickness and pitch),
in order to not exceed the 25 mSv dose.
The absolute risk of noxious effects in the fetus is insignificant in a dose lower than 50 mGy.
Ultrasound is the preferred imaging modality for breast,
abdomen and pelvis.
Chest X-ray and mammography with abdominal shielding can be safely carried out.
Magnetic resonance imaging (MRI) without gadolinium can be used if any of the previously mentioned modalities were inconclusive or in cases of suspicious bone or brain metastases.
CT and positron emission tomography (PET) scans should be avoided throughout the course of pregnancy.
US: There are no adverse effects known Fig. 1.
MRI: Although there is no evidence of fetal risk,
some international organizations recommend a wise use in the first trimester of pregnancy.
In any case,
if necessary,
it is preferable to any study with ionizing radiation.
Plain radiography and CT: Cranial,
cervical and thoracic spine and extremities studies (excluding pelvis and hips) could be performed in a pregnant woman if they are essential for the diagnosis.
In some clinical situations it could be necessary to perform studies that include the abdomino-pelvic region,
as in the case of emergent acute abdominal pathology with an inconclusive ultrasound study Fig. 2.
Iodinated contrast media: The Food and Drug Administration (FDA) classifies iodinated contrast media with a B level of security.
Paramagnetic intravenous contrasts (gadolinium): There are not known adverse effects in human fetuses with the regular used dose; the FDA classifies it as a type C drug.
There is no contraindication for the administration of iodinated contrasts or gadolinium during lactation.
BREAST CANCER [8,
9,
10]
Epidemiology
The incidence of breast cancer during pregnancy is approximately 1 in 3,000 pregnancies.
Pregnancy-associated breast cancer is defined as carcinoma that is diagnosed during pregnancy or within 1 year postpartum.
Diagnosis and Staging
Breast cancer in pregnancy typically presents as a painless lump palpated by the woman.
Physiological breast changes associated with pregnancy,
including engorgement,
hypertrophy,
and nipple discharge obscure detection for patient and physician.
Therefore,
delay in diagnosis is common.
Due to a difference in radiographic density,
the sensitivity of mammography in detecting cancerous changes in breasts of pregnant women is about 68%,
while the one of the ultrasonography is around 93%.
A percutaneous biopsy of any lesion that does not meet all the criteria for a simple cyst is strongly recommended.
Breast US is the first diagnostic instrument used when a breast mass and the axillary area needs to be assessed,
since it is non-ionising and has high sensitivity and specificity.
Subsequently,
when breast cancer in pregnancy is diagnosed,
bilateral and multicentric disease can be ruled out with mammography.
MRI with contrast is possible during pregnancy,
but should only be used when it will alter clinical decision making,
and when US is inadequate.
If MRI is needed,
approved contrast agents include gadobenate dimeglumine and gadoterate meglumine.
The standard examination to obtain a histological diagnosis is a biopsy under local anaesthesia,
which can be done safely during pregnancy with a sensitivity of 90%.
Gestational and puerperal hormones induce physiological hyperproliferative changes of the breast,
which could lead to a false positive or false negative result with fine-needle aspiration cytology.
Therefore,
this procedure is not recommended.
When the estimated risk of metastatic disease is low,
postponement of staging until after delivery can be considered.
Radiologists and nuclear medicine physicians should be part of diagnostic strategy planning to estimate cumulative fetal toxicity and reduce radiation exposure.
Metastatic investigations for breast cancer during pregnancy include chest radiograph,
liver US,
and a non-contrast skeletal MRI.
A radionuclear bone scan,
with adequate hydration and an indwelling catheter to prevent retention of radioactive agents in the bladder,
can be used when MRI is not available or when additional information is needed.
PET is not a standard staging instrument in breast cancer in non-pregnant,
nor therefore in pregnant patients.
In our center there was a case of a patient who,
being lactating,
felt a tumour in the right breast.
The mammography was not very valuable because the breast was very dense due to breastfeeding,
son an ultrasound was performed.
Then we did a percutaneous biopsy guided by ultrasound of the breast nodule,
a fine needle puncture aspiration of the axillary adenopathy and MRI with intravenous contrast Fig. 3.
CERVICAL CARCINOMA [7,
6]
Epidemiology
Reports of the incidence vary between 0.02% and 0.9%.
Recently,
the incidence has seemed to decline due to better public awareness for early detection.
Diagnosis and Staging
Pregnant women have a higher chance of being diagnosed with stage I disease because of frequent pelvic examinations.
Radiological staging is used to discriminate between immediate treatment and watchful waiting.
MRI is the best imaging procedure for assessing the local extension of the disease and the involvement of lymph node.
It can be done without a paramagnetic agent in cervical cancer,
is safe and have acceptable sensitivity and specificity.
In the early stages,
MRI provides a safe method of follow up until the time of delivery.
Regardless of pregnancy,
diffusion-weighted imaging (DWI) is the most valuable sequence to assess the primary cervical tumour.
Chest radiograph study can be performed safely after the first trimester to assess distant disease,
only in cases of locally advanced disease.
However,
a proper shielding of abdomen is recommended.
In our service we had a case of a 24-week pregnant woman who came to the ER due to dysmenorrhea.
In the speculoscopy the cervix was edematous and in the vaginal touch it was hardened and apparently fixed to the adjacent structures.
In transvaginal ultrasound an image compatible with highly vascularized endocervical tumor was visualized,
for which an urgent MRI was requested.
The thoracic CT for staging was performed after delivery Fig. 4.
ADNEXAL MASSES AND OVARIAN CANCER [1,
2,
3,
4,
5,
6]
Epidemiology
The incidence of ovarian cancer is estimated to be between 1 in 10,000 and 1 in 100,000 deliveries.
Although the occurrence of ovarian masses in pregnancy is relatively common,
the majority of them are benign and will resolve spontaneously within the first 16 weeks of pregnancy.
Only 1-8% of the adnexal masses are malignant.
However,
malignancy is not the only risk associated with an adnexal mass in pregnancy; masses that persist into the second trimester are at risk for torsion,
rupture or labor obstruction.
Awareness on the possibility of ovarian cancer in pregnancy is important and careful evaluation of persisting adnexal masses is required to avoid delay in diagnosis.
Diagnosis and Staging
Most pelvic masses are usually discovered incidentally during routine US done for the follow-up of a pregnancy.
The most common ovarian masses include functional cysts,
resembling a follicular cyst of corpus luteum.
Non-functional masses such as dermoid cyst,
endometriomas and epithelial masses don´t resolve spontaneously.
Making a proper diagnosis by imaging can be challenging because of pregnancy-related morphological changes,
especially when intracystic beeding occurs.
Transvaginal and abdominal US is the preferred imaging technique to evaluate pelvic masses in pregnancy,
because it has a high sensitivity and specificity.
Suspected malignancy in the case of an adnexal lesion is based on this ultrasonographic criteria: tumour size (>5cm),
tumour morphological characteristics (septations or solid components),
colour Doppler flow and the presence of extraovarian disease.
The more complex features a mass contained,
the higher the risk for malignancy.
The estimation of fluxometric parameters in pregnancy is demanding,
due to the decreased blood flow impedance and the increased blood flow velocity.
The reported sensitivity and specificity for malignancies are 88 and 96%,
respectively.
MRI is particularly useful when ultrasound is not conclusive,
when is a high risk of malignancy,
to evaluate large masses that are difficult to visualize with ultrasound and assess whether the tumour is widespread in the abdomen and have nodal metastases.
The use of DWI can reduce the need of gadolinium contrast.
Pelvic CT exposes the fetus to irradiation to at least 2 to 4 cGy.
It should be considered only if maternal benefits from the scan are higher than the risk of fetal radiation exposure.
Thoracic scan with a lead shield covering the pelvis could be done to evaluate the extension of the disease when it is an advanced-stage tumour.
The most common and serious complication of ovarian tumour during pregnancy is torsion,
which usually presents at gestational weeks 8-16,
when the uterus grows intensely.
The reported torsion rate of adnexal masses during pregnancy is 10-15%.
Most patients with non-epithelial tumours (germ-cell and sex-cord stromal tumours) have bulky masses.
Therefore,
they are more likely to have symptoms (acute abdominal symptoms such as torsion or bleeding): nevertheless,
more than 90% of them are diagnosed with early stage.
The overall prognosis of epithelial ovarian cancer is worse than non-epithelial ones.
In our service there have been several cases of adnexal masses,
all of them were pregnant women who came to the hospital with abdominal pain,
so an ultrasound and MRI were performed in all cases.
The first one is a sex cord-stromal ovarian tumour on a 22-weeks pregnant woman Fig. 5. Thorax Rx was performed with protection (informed consent is passed) to evaluate drainage of the pleural effusion.
The second one is a dermoid cyst (mature cystic teratoma) on a 18-weeks pregnant woman Fig. 6.
The third case is a 14-weeks pregnant woman with bilateral teratomas Fig. 7.
MELANOMA [8,
14]
Epidemiology
The incidence of malignant melanoma during pregnancy is 2.8 per 1,000 deliveries.
Diagnosis and Staging
The diagnosis of melanoma is always made by tumor excision and pathological examination.
Ultrasound examination may be employed assessing regional draining lymph nodes and guiding fine needle aspiration.
Inour hospital we had a case of a 33-weeks pregnant woman who palpated a left inguinal adenopathy Fig. 8. The staging study was performed after delivery.
LYMPHOMAS
Epidemiology
The incidence of Hodgkin’s disease ranges from 1 in 1,000 to 1 in 6,000 pregnancies.
Staging
Staging should always include chest x-ray,
bone marrow biopsy,
and abdominal ultrasound.
As an example,
a 24-weeks pregnant woman came to the ER because she had a cold.
Fig. 9.
Thoracoabdominal CT of staging was performed after delivery.
GESTATIONAL TROPHOBLASTIC DISEASE [13]
Gestational trophoblastic disease (GTD) is a spectrum of benign and malignant gestational tumours,
including hydatidiform mole (complete and partial),
invasive mole,
choriocarcinoma,
placental site trophoblastic tumour,
and epithelioid trophoblastic tumour.
The latter four entities are referred to as gestational trophoblastic neoplasia (GTN).
These conditions are aggressive with a propensity to widely metastasize.
Imaging Findings
US remains the imaging modality of choice for initial evaluation.
Less than 50% of all molar pregnancies are detected at US.
The detection rate is better for complete hydatidiform mole (CHM) (58%–95%) than for PHM (partial hydatidiform mole) (17%–29%).
MRI is superior to US in evaluation of extrauterine tumour extension and pelvic lymph nodes and may be useful in tumours that are poorly visualized at US.
The MRI appearance of GTN is nonspecific; an accurate differentiation between GTN and benign processes such as retained products of conception is likewise difficult.
CT: While CT is useful in evaluation and staging of metastatic disease,
it has a limited role in evaluation of the primary tumour.
Approximately 30% of patients with GTN have metastases at the time of diagnosis,
most commonly to the lungs.
Therefore,
imaging of the lungs is recommended for all patients with GTN.
However,
there is an ongoing debate regarding whether chest radiography is sufficient or whether there is a need for chest CT.
We had 2 different cases in our hospital:
- The first one is a pregnant woman diagnosed with pneumonia with poor evolution and hemotysis Fig. 10.
- The second case is a woman with abdominal pain and positive pregnancy test.
Fig. 11.