(1/8) Hello #medtwitter- here's a new clinical tool I learned today! Wondering, who has heard of the LEFt score for DVT, and when we should use it?
(2/8) We all know Well's Score to stratify patients to low risk for DVT mdcalc.com, but when can we not use this reliably?
Answer: Pregnancy! Well's was validated used in older, sicker population and many symptoms in the score are common in pregnant patients.
Answer: Pregnancy! Well's was validated used in older, sicker population and many symptoms in the score are common in pregnant patients.
(3/8) So, how can we use a clinical prediction tool to risk stratify patients, e.g. if they need further testing?
In steps the LEFt rule ( Chan et al., 2009 ; validated with Righini et al., 2013, )
Let's dive in!
In steps the LEFt rule ( Chan et al., 2009 ; validated with Righini et al., 2013, )
Let's dive in!
(4/8) L = Left Sided. In a systematic review (Chan et al., 2010), 88% of patients with DVT had left sided thrombosis (OR 5.5 in validated cohort).
MoA: Especially in late pregnancy, iliac compression ~ May-Thurner syndrome physiology might be the cause.
MoA: Especially in late pregnancy, iliac compression ~ May-Thurner syndrome physiology might be the cause.
(5/8) E = Edema. They found that unilateral edema with relative calf circumference > 2 cm was significantly associated with DVT in their patient population (OR 8.2 in validated cohort)
(6/8). Ft = First Trimester. Interestingly, first trimester is the highest risk in their cohort for DVT (OR 3.6 in validated cohort), and was 8x higher than other trimester in the original study.
? related to procoagulant balance of clotting?
? related to procoagulant balance of clotting?
(7/8) so, how do we use this?
LEFt = 0 has a high NPV, so you can likely forgo further testing if your pre-test probability was low
LEFT 1 or greater cannot rule out DVT, so you should test with compression US
LEFt = 0 has a high NPV, so you can likely forgo further testing if your pre-test probability was low
LEFT 1 or greater cannot rule out DVT, so you should test with compression US
(8/8) If you cannot rule out with LEFt:
1. D-dimer: nonspecific (by 3rd trimester, most patients have D-dimer > 500) but may be able to rule it out.
2. Compression US: limited if negative, as does not rule out DVT in all patients (see UTD algorithm)
1. D-dimer: nonspecific (by 3rd trimester, most patients have D-dimer > 500) but may be able to rule it out.
2. Compression US: limited if negative, as does not rule out DVT in all patients (see UTD algorithm)
Summary:
1⃣ Well's is not validated in pregnant patients with ?DVT
2⃣ LEFt score is! Left leg, unilateral Edema > 2 cm, First Trimester
3⃣ Score 1 or greater cannot rule out, compression US is next step!
Let me know if you use it in your practice! Thoughts and feedback please!
1⃣ Well's is not validated in pregnant patients with ?DVT
2⃣ LEFt score is! Left leg, unilateral Edema > 2 cm, First Trimester
3⃣ Score 1 or greater cannot rule out, compression US is next step!
Let me know if you use it in your practice! Thoughts and feedback please!
Sources:
- up to date
- 10.7326/0003-4819-151-2-200907210-00004
-10.3324/haematol.2012.072009
- 10.1016/j.thromres.2014.07.009
- up to date
- 10.7326/0003-4819-151-2-200907210-00004
-10.3324/haematol.2012.072009
- 10.1016/j.thromres.2014.07.009
and calling in my thrombosis experts for thoughts on the first trimester question! @jzbos @FreedoBaggins @ishtatMD any ideas?
and @gillystein for the ob expertise here :)
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