ABSTRACT: Imaging studies are important adjuncts in the diagnostic evaluation of acute and chronic conditions. However, confusion about the safety of these modalities for pregnant and lactating women and their infants often results in unnecessary avoidance of useful diagnostic tests or the unnecessary interruption of breastfeeding. Ultrasonography and magnetic resonance imaging are not associated with risk and are the imaging techniques of choice for the pregnant patient, but they should be used prudently and only when use is expected to answer a relevant clinical question or otherwise provide medical benefit to the patient. With few exceptions, radiation exposure through radiography, computed tomography scan, or nuclear medicine imaging techniques is at a dose much lower than the exposure associated with fetal harm. If these techniques are necessary in addition to ultrasonography or magnetic resonance imaging or are more readily available for the diagnosis in question, they should not be withheld from a pregnant patient. Breastfeeding should not be interrupted after gadolinium administration.
Ultrasound imaging should be performed efficiently and only when clinically indicated to minimize fetal exposure risk using the keeping acoustic output levels As Low As Reasonably Achievable (commonly known as ALARA) principle. Ultrasonography involves the use of sound waves and is not a form of ionizing radiation. There have been no reports of documented adverse fetal effects for diagnostic ultrasonography procedures, including duplex Doppler imaging. The U.S. Food and Drug Administration limits the spatial-peak temporal average intensity of ultrasound transducers to 720 mW/cm2. At this intensity, the theoretical increase in temperature elevation for the fetus may be as high as 2C (35.6F) 2 3. However, it is highly unlikely that any sustained temperature elevation will occur at any single fetal anatomic site 3. The risk of temperature elevation is lowest with B-mode imaging and is higher with color Doppler and spectral Doppler applications 4.
Textbook Of Diagnostic Sonography: 2-Volume Set, 7e (Textbook Of Diagnostic Ultrasonography) Downloa
Most causes of hemoabdomen unrelated to an abdominal mass or nodule can be ruled out prior to surgery with appropriate diagnostic imaging, biochemical testing, and coagulation testing.1,10,11 Efforts have been made to help distinguish malignant from nonmalignant masses and nodules prior to surgery. Recently, the hemangiosarcoma likelihood predictor score has been described as a means to predict the likelihood of hemangiosarcoma versus hematoma.13 This score is calculated on the basis of body weight, total solids concentration, platelet count, and radiographic lung pattern to assign a low, medium, or high risk of hemangiosarcoma.13 A higher mass-to-splenic volume ratio and higher splenic weight as a percentage of body weight are also suggestive of benign splenic disease.14 Efforts have also been made to distinguish malignant from nonmalignant lesions through the use of contrast-enhanced ultrasonography, CT, and MRI, but these methods are insufficiently accurate, too expensive, or too time-consuming to be used in an emergency situation for dogs with hemoabdomen.10,11,15,16,17 The gold standard test is histologic examination of a tissue sample, which can only be obtained surgically in dogs with emergent hemoabdomen.9,10,14,16,17,18,19 Diagnostic abdominal ultrasonography, which can help with surgical planning by providing confirmation of a mass or nodule, is often the most advanced diagnostic imaging pursued prior to the decision of whether to perform surgery is made.
Ultrasonographic identification of a cavitated splenic mass or nodule has anecdotally been associated with malignancy in dogs with nontraumatic hemoabdomen; however, rigorous evidence-based findings to support this association have not been published. Ultrasonography of the spleen has been recommended for disease localization, to differentiate cavitary from solid lesions, and to assist in aspiration of lesions,20 and even point-of-care ultrasonography guidelines suggest looking for cavitations.21,22 Splenic hemangiosarcoma has been described to generally appear as a complex mass lesion with mixed echogenicity and cavitations,19 but a definitive diagnosis can only be made through histologic examination.19 Terms such as cavitary, cavitated, and the like have commonly been used to describe the ultrasonographic appearance of abdominal lesions.3,19,20,21,22,23,24,25,26,27,28 Other ultrasonographic patterns such as honeycomb patterns and target lesions have been assessed for their association with malignant hepatic and splenic lesions in dogs and cats and have been shown to have some degree of diagnostic utility.29,30,31,32
Distributions of age and weight were tested for normalcy with the Anderson-Darling test. Continuous data that were normally distributed were summarized as mean SD; continuous data that were not normally distributed were summarized as median and range. Results of histologic examination of splenic tissue were considered the gold standard for diagnostic status. Lesions identified by means of abdominal ultrasonography and for which results of histologic examination were available were classified as splenic, hepatic, or mesenteric and other. The diagnostic test evaluated in the present study was whether a mass or nodule detected during abdominal ultrasonography was described as cavitated or not. The test result was considered positive if the mass or nodule was described as cavitated and negative if the mass or nodule was not described as cavitated. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV), along with their 95% CIs, were then calculated both for detecting hemangiosarcoma and for detecting any malignancy, including hemangiosarcoma. Sensitivity was calculated as the percentage of dogs that had a positive test result among dogs with hemangiosarcoma or among dogs with a malignant mass or nodule detected by abdominal ultrasonography. Specificity was calculated as the percentage of dogs that had a negative test result among dogs that did not have hemangiosarcoma or among dogs that had a nonmalignant mass or nodule detected by abdominal ultrasonography. The PPV was calculated as the percentage of dogs with hemangiosarcoma or any malignant mass or nodule among all dogs with positive test results. The NPV was calculated as the percentage of dogs that did not have hemangiosarcoma or any malignancy among all dogs with negative test results. Sensitivity, specificity, PPV, and NPV were calculated separately for the splenic, hepatic, and mesenteric or other lesions when sufficient numbers of cases were present. Notably, not every lesion detected by means of abdominal ultrasonography was sampled, and some lesions were identified during surgery without first being identified by means of preoperative abdominal ultrasonography. All statistical analyses were performed with standard software (JMP version 15.0.0; SAS Institute Inc) with the performance measures add-in.
Results of the present study, as suspected, did not provide any evidence to support the use of detection of a cavitated lesion during abdominal ultrasonography as an indicator of hemangiosarcoma or other malignancy in dogs. For splenic lesions in particular, the sensitivity, specificity, PPV, and NPV were all low, making the test unreliable. There were not enough cases to properly evaluate diagnostic utility of detecting cavitated nonsplenic masses or nodules, but only 4 (3.8%) of 106 dogs in our study had a cavitated nonsplenic mass or nodule. Further multicenter studies could likely provide additional information for this population. However, our findings suggest that abdominal ultrasonographic examination for the purpose of distinguishing malignant from nonmalignant splenic or nonsplenic lesions in dogs with nontraumatic hemoabdomen will likely not be helpful. On the other hand, abdominal ultrasonography in dogs with nontraumatic hemoabdomen may be helpful in surgical planning and confirming the presence of a bleeding mass or nodule. This could be especially important for clinicians who have the equipment and experience necessary to perform a splenectomy but not a liver lobectomy. And, should the source of bleeding be elsewhere, such as the adrenal glands, kidneys, or gastrointestinal system, preoperative abdominal ultrasonography could be quite valuable in planning and prognostication. To our knowledge, it is not yet known how results of abdominal ultrasonography specifically influence a clinician's decision on how or whether to perform surgery. In a previous study,34 > 50% of dogs with nontraumatic hemoabdomen that underwent preoperative abdominal ultrasonography had a grossly detectable lesion at surgery that was not found with ultrasonography. And, in a study35 in which isolated hepatic masses were detected ultrasonographically, approximately half were not correctly matched to their true lobe or division. In any case, inappropriate attribution of malignancy on the basis of results of preoperative abdominal ultrasonography could lead to unjustified euthanasia of dogs with benign disease and a good prognosis.
The intensivist uses POCUS in the ICU as a diagnostic and monitoring tool, but does not use the examination results to discharge the patient from the hospital. The intensivist has the option of serial reassessment of the patient and may escalate to standard consultative imaging if required. In the emergency department, the final disposition of the patient may be determined by the ultrasonographic evaluation; POCUS performed by EM physicians is therefore a definitive evaluation when it leads to patient discharge from the hospital. However, when doubt or uncertainty exists regarding ultrasonography findings, EM physicians must consider the services of traditional consultative ultrasonography prior to final diagnosis, treatment, and disposition. The authors emphasize the need to call for assistance and advice from a more experienced operator in the presence of uncertain findings.
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