Regarding venous thromboembolism in a pregnant woman all of the following statements are correct EXCEPT:
Answer: B: Venous thromboembolism (DVT and/or PE) occurs in 0.1% of pregnancies. At least in 50% of these cases it is associated with an inherited or acquired thrombophilia (a disorder of haemostasis that predisposes an individual to thrombotic events). However, thrombophilia screening done in pregnant patients with DVT or PE will add minimal value in the treatment of these patients during the current pregnancy. The results obtained during the pregnancy can be unreliable as pregnancy and the treatment of DVT or PE both can alter the circulating levels of coagulation factors. Thrombophilia screening should be done after the delivery and especially when the treatment with anticoagulants is ceased and the results may be useful for managing future pregnancies.
Between 70 and 90% of the cases of DVT during pregnancy occur in the left leg because the left iliac vein is compressed by the right iliac artery. The incidence of iliac vein thrombosis may be higher in pregnant patients than in non-pregnant women. The diagnosis of iliac vein thrombosis is generally difficult with compression ultrasonography. MRDTI seems to have a high sensitivity and specificity of this diagnosis and can be safely used in pregnancy.
Reference:
Regarding diagnosis of PE in a pregnant patient, which ONE of the following statements is TRUE?
Answer: C: Diagnosis of PE in a pregnant woman is one of the challenging areas in relation to PE. Furthermore, the inclusion or exclusion of this diagnosis in a patient presents with suspicious symptoms is of great importance becuase PE is described as the leading cause of maternal death in developed countries. Pretest probability scores cannot be directly applied in the diagnostic process in this situation, because they have not been validated in pregnancy. During pregnancy there is a significant ongoing haemostatic processes and this reflects the increasing presence of D-dimer. D-dimer levels increase as the pregnancy advances. Additionally, a negative D-dimer alone may not be helpful to rule out the diagnosis of PE irrespective of the stage of pregnancy.
As delays in treatment are associated with increased risk of maternal death associated with PE, it is reasonable to treat these patients with low molecular weight heparin (LMWH) on suspicion unless contraindications exist. Compression ultrasonography is recommended as the first-line investigation. If USS confirms DVT and the patient is stable, further lung imaging may not add value and will deliver radiation for both the fetus and the mother. When USS is negative further lung imaging is required. CXR is of value to exclude alternative diagnoses.
Either CTPA or V/Q scan is selected depending on the age of gestation, presence of lung diseases such as asthma, availability, local practices and preference. The following facts should be carefully considered when selecting further imaging:
Regarding the use of the pulmonary embolism rule-out criteria (PERC), which ONE of the following statements is FALSE?
Answer: A: The testing threshold (TT) is the pretest probability on clinical grounds below which a clinician may defer a diagnostic test. In other words, this indicates an acceptable missed diagnosis rate in clinical practice. This is important because below the testing threshold even a simple investigation such as D-dimer test has the potential to cause more harm than benefit to the patient. For example, an inappropriately ordered D-dimer test can become positive due to myriad other reasons in a clinically low-risk patient for PE, which in turn leads to further testing of the patient with CTPA. CTPA is associated with an increase in lifetime cancer risk, anaphylaxis to contrast and risk of contrast-induced nephropathy. In contrast, patients falling above the acceptable testing threshold should have further diagnostic investigations.
The authors of PERC estimated that this testing threshold for further testing to be 1.8% and the PERC is based on this assumption. In other words, a missed rate of 1.8% is acceptable to defer diagnostic testing that may cause more harm than the disease itself. In a recent study this testing threshold was found to be 1.4%. However, PERC can be applied only to patients with a suspected PE with a low pretest probability according to the clinician’s overall clinical impression or clinical gestalt. All eight criteria must be met in these low-probability patients to defer further diagnostic testing.
These criteria include:
References:
Regarding management of a haemodynamically stable patient with acute PE, which ONE of the following statements is TRUE?
Answer: C: LMWH is the appropriate initial treatment in most patients with haemodynamically stable PE, including pregnant patients. This choice is based on its ease of use. The efficacy and the safety of LMWH has been shown to be similar to intravenous unfractionated heparin. Intravenous unfractionated heparin is indicated and should be considered in the following circumstances:
Warfarin should be commenced preferably at the commencement of the heparin treatment. Heparin can be ceased when the target international normalized ratio (INR) of 2.0–3.0 is reached and warfarin should be continued for at least 3 months. Extended warfarin treatment is indicated in patients with a high risk for recurrence.
Risk factors for recurrence include:
Risk of recurrence of a pulmonary embolism is <1% per year during the treatment with anticoagulant therapy. This increases to 2–10% per year after the discontinuation of the anticoagulation therapy. Long-term LMWH is indicated for patients with PE provoked by malignancy because the recurrence rate is high.
During pregnancy, LMWH should be continued at least until delivery because warfarin is contraindicated. Warfarin crosses the placenta and may cause teratogenesis in the early part of pregnancy and fetal intracranial haemorrhage in late pregnancy. Both unfractionated heparin and LMWH do not cross the placenta, therefore teratogenesis or fetal haemorrhage will not occur.
Regarding DVT affecting the upper extremity, which ONE of the following statements is TRUE?
Answer: A: DVT can affect the upper extremity veins and in the majority of the cases it affects the axillary and subclavian veins. About 10% of all DVTs are said to involve the upper extremities and 80% of these cases are due to secondary causes including catheterassociated thrombosis (associated with central venous lines, port and catheter for treatment of cancers, pacemaker or defibrillator leads), cancer, surgery or trauma to the upper extremity. DVT of the upper extremity is more likely to be associated with malignancies than DVT of the legs. In comparison, it is less likely to be due to thrombophilia than DVT of the legs. One of the primary causes of DVT in the upper extremity that is worth noting is strenuous exercise involving usually the dominant arm in a young male patient causing DVT in that arm.
D-dimer testing, even in the presence of a low pretest probability, is unreliable in suspected cases of DVT of the upper extremity because these patients have many associated secondary conditions that may result in a positive Ddimer. Therefore it is not recommended as a screening test.
The recurrence rate and rate of post-thrombotic syndrome are less than that occurring with DVT of the legs. PE is an important complication; however, again, the rate is less than that occurring in DVT of the legs (6% vs 15–32%).
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