Patient handout

May-Thurner syndrome (left iliac vein compression DVT)

PRODUCTION

1. Your condition

This handout is for may-thurner syndrome (left iliac vein compression dvt). Your care team identified this based on: left whole-leg swelling + thigh/groin pain in young woman (age 20–45) — pretest probability for may-thurner is high; right-side dvt in this demographic should not assume mts.

Other reasons your team may use this plan: compression us shows non-compressible left common iliac / external iliac / common femoral vein → confirm proximal dvt and proceed to venography for mts evaluation; left iliofemoral dvt with minor or no provoking factor (ocp, post-partum, recent surgery, immobility) — anatomic substrate (cockett lesion) likely contributing; mandate venography + ivus during cdt; recurrent left-sided dvt despite therapeutic ac — strong suspicion of underlying iliac compression requiring stent.

2. Your medications

Take these medications exactly as prescribed. Do not stop or change a dose without talking to your provider.

Medication	Starting dose	How	When	What it does
apixaban	10 mg BID × 7 d → 5 mg BID	PO	BID × ≥3 months minimum (extended if unprovoked or persistent stenosis)	AMPLIFY (Agnelli NEJM 2013 PMID 23808982) — DOAC first-line; ACCP 2021 first-line for proximal DVT; aggressive AC required after stent to prevent in-stent re-thrombosis
rivaroxaban	15 mg BID × 21 d → 20 mg daily with food	PO	BID then daily × ≥3 months	EINSTEIN-DVT (Bauersachs NEJM 2010 PMID 21128814) — non-inferior to enoxaparin/VKA; common alternative DOAC
enoxaparin	1 mg/kg SC BID; reduce to 1 mg/kg daily if CrCl <30	SC	BID	ASH 2020 (PMID 33007077); LMWH preferred during the acute peri-procedural window for ease of hold/resume around CDT and stenting
alteplase	0.5–1 mg/h via catheter for 12–24 h (max ~24 mg/24 h)	IV_catheter	continuous infusion	ATTRACT (Vedantham NEJM 2017 PMID 29211671) — pharmacomechanical CDT reduces moderate-severe PTS in iliofemoral subgroup; CaVenT (Enden Lancet 2012 PMID 22136717) — early CDT iliofemoral PTS reduction at 5 yr
heparin	80 U/kg bolus + 18 U/kg/h infusion targeting aPTT 1.5–2.5×	IV	continuous	Reversibility for procedural bleeding and ease of hold/resume during CDT and stent placement (ACCP 2021)
warfarin	5 mg daily; INR target 2-3	PO	daily	TRAPS (Pengo Blood 2018 PMID 30002145) — warfarin > rivaroxaban in triple-positive APS; reasonable alternative if DOAC contraindicated

Plan: May-Thurner syndrome — combined AC + catheter-directed thrombolysis + iliac venous stenting (Hofmann 2024)

3. When to call your provider

Contact your care team if any of the following happen:

New VTE despite AC → reassess stent + switch DOAC class or escalate dose
Pregnancy → switch to LMWH per ASH 2018
New left-leg symptoms → image stent

4. When to seek emergency care

Call 911 or go to the nearest emergency room right away if you have:

Massive acute occlusive iliofemoral DVT in MTS anatomy producing phlegmasia cerulea dolens (cyanosis, severe pain, arterial compromise)(life-threatening)
Recurrent left-leg DVT or duplex US showing thrombus within previously placed iliac venous stent
Thrombus extension from left iliac vein into the IVC despite therapeutic AC
Major bleed during catheter-directed thrombolysis (Hgb drop ≥2 g/dL, transfusion, ICH, retroperitoneal)(life-threatening)
Patient with prior MTS stent becoming pregnant OR new MTS-pattern DVT during pregnancy

5. Follow-up

Lifetime stent surveillance; AC duration reassessment based on stent patency + provoking-factor reversibility; OCP discontinuation discussion; pregnancy planning counseling (LMWH bridge if pregnancy desired)

6. Sources

Guideline: Hofmann LV 2024 May-Thurner consensus + CIRSE 2014 iliac venous stenting + ACCP/CHEST 2021 + ATTRACT 2017 iliofemoral subgroup