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CAP Home > CAP Reference Resources and Publications > CAP TODAY > CAP Today Archive 2003 > April 2003 Q and A
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  Q & A

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cap today

April 2003

Richard A. Savage, MD

Q. Our anesthesiology department has requested a thromboelastograph, or TEG, to assess coagulation in the operating room. How useful is the TEG and when should it be used? Should medical technologists or perfusionists operate it? Who should interpret the results? Is the TEG useful for ob-gyn and emergency room patients?

A. We use the thromboelastograph primarily to assess hemostasis during liver transplantation and cardiopulmonary bypass. We run the TEG in an operating room satellite lab and transmit the resulting TEG curve to the operating room using closed-circuit television. This setup allows everyone in the operating room to see the TEG output. We’ve been doing this for more than 10 years. Our model of TEG prints a paper report that is easy to transmit via a black-and-white television camera. I have found that the modern TEG manufactured by Haemoscope produces an output on a computer screen that is more difficult to transmit.

We decided to operate the TEG in the laboratory to provide results to as many users as possible with the fewest instruments; to allow the lab to remove heparin when needed (intraoperative TEGs during cardiopulmonary bypass); and to consolidate all stat coagulation testing for the operating rooms, including the frequently ordered prothrombin times, fibrinogens, and platelet counts.

The output from the TEG is a complex mix of coagulation factor levels, platelet counts, and fibrinolysis. The maximum amplitude on the TEG is directly related to platelet count and fibrinogen concentration. A decline in amplitude after reaching the maximum is related to excess fibrinolytic activity. The “r” and “k” clotting times are related to coagulation factor levels but are also dependent on platelet phospholipid. Adding contact activators such as kaolin makes the “r” value similar to an activated clotting time, while adding thromboplastin makes it similar to a prothrombin time. The TEG angle is the most complex variable because it relates to, and is affected by, nearly everything.

A normal TEG suggests that bleeding is not caused by a coagulation factor deficiency, platelet count or function, or excess fibrinolysis. This finding can be useful in patients who are bleeding after cardiopulmonary bypass. Decreased amplitude suggests reduced platelet count or fibrinogen.

The TEG’s most useful indication is for excessive fibrinolysis, which occurs in liver transplant patients due to lack of tissue plasminogen activator clearance during the anhepatic phase and during cardiopulmonary bypass due to an excess release of t-PA from endothelium. Excess fibrinolysis is usually not reported on any other test. D-dimer is not a good surrogate for measuring excess fibrinolysis because it is more a measure of intravascular fibrin than lysis.

If you have stat PT, fibrinogen, and platelet count available, the main result from the TEG would be an indication of fibrinolysis. We do TEG and standard coagulation testing for the operating rooms.

Bibliography
Chandler WL. The thromboelastography and the thromboelastograph technique. Semin Thromb Haemost. 1995;21(suppl.4): 1–6.

Chandler WL, Patel MA, Gravelle L, et al. Factor XIIIA and clot strength after cardiopulmonary bypass. Blood Coagul Fibrinolysis. 2001;12:101–108.

Spiess BD, Gillies BS, Chandler W, et al. Changes in transfusion therapy and reexploration rate after institution of a blood management program in cardiac surgical patients. J Cardiothorac Vasc Anesth. 1995; 9: 168–173.


Wayne L. Chandler, MD
Department of Laboratory Medicine
University of Washington
Seattle

Member, CAP Coagulation
Resource Committee

Q. We recently encountered a situation in which a dermatologist who interprets his own slides refused to send a patient’s previous slides to our institution, where the patient was now being treated. The slide review was requested to help direct patient care and was not expected to have medicolegal implications. The patient had executed a proper release form, but the dermatologist refused to comply. (The laboratory that cuts his blocks did send a recut, but it was nonrepresentative.) It would not be practical for us to review the slides in the dermatologist’s office because he is located several states away. Do the laws and code of ethics that apply to pathologists in situations of this type apply also to dermatologists? What can the patient do to get the dermatologist to comply with her request, short of initiating legal action, which would probably be protracted and expensive?

A. I would restate the first question—do the laws and code of ethics that apply to pathologists in situations of this type also apply to dermatologists?—as follows: Do the same legal and ethical obligations applicable to pathologists in this sort of situation apply also to dermatologists, and, if so, do these obligations require the dermatologist to transfer the slides?

The same legal requirements that govern pathologists apply equally to dermatologists practicing in the same state. However, the letter does not identify the jurisdiction in which the dermatologist practices or the source of insurance coverage for the patient. Thus, I cannot determine which state law controls this incident or whether Medicare or Medicaid regulations apply.

In any event, the Principles of Medical Ethics of the American Medical Association apply equally to pathologists and dermatologists. Those principles govern directly if the physicians are members of the AMA or of a medical society, such as the College of American Pathologists, that has adopted the principles. Even for physicians who are not members, the principles provide important guidance on ethical issues.

In my opinion, the dermatologist’s refusal to provide the slides appears to violate Principle IV of the Principles of Medical Ethics as construed by the Council on Ethical and Judicial Affairs (CEJA) in Opinion 7.01. (See AMA Code of Medical Ethics, 1998–1999 edition). Principle IV provides as follows: “A physician shall respect the rights of patients, of colleagues, and of other health professionals . . . .” That principle was interpreted in a manner bearing on the question at issue here in Opinion 7.01, titled “Records of Physicians: Availability of Information to Other Physicians.” Opinion 7.01 of CEJA reads as follows:

“The interest of the patient is paramount in the practice of medicine, and everything that can reasonably and lawfully be done to serve that interest must be done by all physicians who have served or are serving the patient. A physician who formerly treated a patient should not refuse for any reason to make records of that patient promptly available on request to another physician presently treating the patient. Proper authorization for the use of records must be granted by the patient. Medical reports should not be withheld because of an unpaid bill for medical services.” (Emphasis supplied.)

Opinion 7.01 strongly suggests that the refusal of the dermatologist to provide the slides at the request of the patient is unethical. The dermatologist appears to be a “physician who formerly treated [the] patient.” The dermatologist is being requested to make the slides available to the institution at which the patient is currently being treated. Moreover, the patient presumably has given the proper authorization. Accordingly, Opinion 7.01 seems applicable.

Of course, slides are not paper or electronic “medical records.” But the same governing principle that requires transmission of medical records—that is, that “everything that can reasonably and lawfully be done” to serve the interest of the patient—would appear to require that the slides be sent. To be sure, the dermatologist may have concerns about potential liability issues if the patient subsequently sues for malpractice and the dermatologist is unable to produce the relevant slides. However, that concern is addressed by having (1) a signed statement from the patient directing a transfer of the slides and (2) a signed statement from the receiving institution acknowledging receipt of the slides and promising to provide them if needed for medicolegal reasons.

The second question is: Short of initiating legal action, what can the patient do to get the dermatologist to transfer the slides? At the outset, I would recommend that the institution that is supposed to receive the slides (or the pathologist at that institution) contact the dermatologist to discuss the refusal to provide the slides. If the dermatologist’s refusal is based on potential medicolegal concerns, it might be possible to allay those concerns through the sort of documentation discussed in the preceding paragraph. Alternatively, if there is some other basis for the refusal, reasonable efforts could be made to work out a solution. Further, the dermatologist can gently be reminded of his or her potential legal liability if the patient’s condition worsens by virtue of the refusal to provide the slides.

If the dermatologist is intransigent, several steps can be taken short of initiating litigation:

  1. If the dermatologist is a member of a hospital medical staff, that medical staff can be contacted and asked to intervene.
  2. If the patient is covered by a managed care organization and the dermatologist is on the panel of providers for that MCO, the MCO can be asked to put pressure on the dermatologist.
  3. A complaint can be filed with the board of medical examiners in the state in which the dermatologist is licensed asking the state board to take action. None of these steps should involve significant costs or risk of liability.

Jack R. Bierig
CAP General Counsel
Sidley Austin Brown & Wood
Chicago

Q. Should positive urines for proteins be confirmed by the sulfosalicylic acid method when using the standard protein dipstick test since the standard test is less sensitive than the microalbumin dipstick test?

A. This question suggests that the microalbumin test could be used to confirm a positive result for protein using urine dipstick methodology. It also raises the issue of confirming a positive dipstick result with an alternative procedure, such as sulfosalicylic acid.

The microalbumin test is designed specifically to monitor patients with established diabetes mellitus for excretion of small amounts of albumin below what can be detected by urine dipstick testing. A positive result for microalbumin allows early therapeutic intervention to forestall the onset of diabetic nephropathy. Indications for this test, therefore, are unrelated to those for regular urine dipstick screening, and neither test should be used to corroborate the results of the other.
Both the dipstick test and the SSA procedure, however, are acceptable methods to detect proteinuria in the general population and are of comparable sensitivity. The dipstick is selective for albumin, while SSA will precipitate a broad range of proteins, including albumin. Because the dipstick test is generally considered to be a screening test, as opposed to a diagnostic test, there is no regulatory requirement for reflex testing to confirm results, and the CAP checklists do not specifically address this issue.

If the dipstick result is read manually, instead of by an instrument, the color change between “negative” and “Tr/1+” is very subtle and may be difficult to interpret. Furthermore, the color change may be difficult to detect in urines that are intensely colored by a variety of agents, such as bilirubin or hemoglobin.
In conclusion, whether you wish to go through the extra effort and expense to establish a confirmatory test for urine specimens that are positive for protein will depend on such factors as the reason for testing, the population being tested, the methodology you employ for reading the strips, and the desire to correlate results between various testing sites.

David J. Blomberg, MD
Department of Pathology
Miller-Dwan Medical Center
Duluth, Minn.

Member, CAP Hematology/Clinical Microscopy
Resource Committee

Q. For how long following stroke, disseminated intravascular coagulation, or trauma surgery, and postpartum is a decrease in protein C or S acceptable?

A. Protein C, protein S, and antithrombin become temporarily decreased by thrombosis, disseminated intravascular coagulation, and surgery. Protein S, and occasionally antithrombin, become decreased during pregnancy or estrogen use.
The amount of time needed to return to the normal range following a thrombotic event, surgery, or recovery from DIC has not been well documented. It probably varies, depending on the severity and duration of the illness and the type of surgery. Studies involving cardiopulmonary bypass have shown that protein C,1,2 protein S,2 and antithrombin1,2 on average remain lower than their preoperative baseline on the first post-bypass day but are already back in the normal range (or for antithrombin, near-normal).

It does not appear to be necessary to defer testing of protein C, protein S, or antithrombin following most thrombotic events, DIC, or surgeries, except for cardiopulmonary bypass procedures or severe events. However, if a low value is obtained in one of these conditions, the assay should be repeated once the patient has fully recovered. How long one should wait has not been defined, but anecdotal experience indicates that a few days to one week is probably adequate for most patients. If the value remains low, retesting can be performed after another two to three months of clinical stability.

In studies of protein S levels following pregnancy, protein S remains low at one to two weeks postpartum and returns to normal when measured again at six to eight weeks postpartum.3,4 In at least one postpartum case, however, it took 12 weeks for protein S to return to normal.5 It is therefore reasonable to wait at least two to three months after pregnancy or discontinuing estrogen to measure protein S. It probably is not necessary to defer testing of antithrombin during pregnancy or estrogen use, but if a low value is obtained, repeat testing should be performed no sooner than two months after delivery or discontinuing estrogen.

References

  1. Feindt R, Volkmer I, Seyfert UT, et al. The role of protein C as an inhibitor of blood clotting during extracorporeal circulation. Thorac Cardiovasc Surg. 1991; 39: 338–343.
  2. Boldt J, Schindler E, Welters I, et al. The effect of the anticoagulation regimen on endothelial-related coagulation in cardiac surgery patients. Anaesthesia. 1995; 50: 954–960.
  3. Kjellberg U, Andersson NE, Rosen S, et al. APC resistance and other haemostatic variables during pregnancy and puerperium. Thromb Haemost. 1999; 81: 527–531.
  4. Fernandez JA, Estelles A, Gilabert J, et al. Functional and immunological protein S in normal pregnant women and in full-term newborns. Thromb Haemost. 1989; 61: 474–478.
  5. Comp PC, Thurnau GR, Welsh J, et al. Functional and immunologic protein S levels are decreased during pregnancy. Blood. 1986; 68: 881–885.

Elizabeth M. Van Cott, MD
Director, Coagulation Laboratory
Department of Pathology
Massachusetts General Hospital

Boston Member, CAPCoagulation
Resource Committee

   
 

 

 

   
 
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