Discussion
May-Thurner syndrome (MTS) is a condition in which the left common iliac
vein is compressed between the right common iliac artery and the lumbar
vertebrae. The chronic pulsatile pressure on the vein leads to
endothelial damage, intimal proliferation, and fibrin replacement,
resulting in luminal stenosis and fibrosis, and in severe cases,
complete occlusion would be expected (6). The prevalence of this
anatomical variation is reported as up to 20% in the general population
(7), and Over 25% of the asymptomatic population show more than 50%
stenosis of LCIV in their screening CT-scan (8). The symptoms could
include a range from asymptomatic iliac vein stenosis, to symptoms of
chronic vein stasis of the lower limb such as pain, swelling, varicose
veins, and pelvic congestion syndrome. It’s also possible to develop
acute deep vein thrombosis (DVT), with the following complications such
as post-thrombotic syndrome (9). MTS often occurs in women in their 20
and 30s, and is more common in the left leg, although some cases of the
right side or bilateral MTS have been reported (10). The diagnosis of
MTS is based on initial duplex ultrasound for assessment of the presence
of any DVT, but the optimal visualization of the venous system is made
by CT or MR venography, which let us directly visualize the compressive
effect of the artery on the vein, and also the possible collateral
formation due to chronic obstruction of the venous return flow (11).
However, the gold-standard test for diagnosis is invasive venography,
especially with IVUS usage, where we can preciously determine the
intraluminal area and diameters (12). Most of the patients initially
have lower limb venous hypertension but haven’t any symptoms, but
gradually they would experience some tightness and heaviness in their
legs, especially after long hours of standing. The recommended treatment
for MTS is venoplasty with a stent implantation (13). In a systematic
review of 1569 patients with an established diagnosis of MTS, the
endovascular interventions were performed more than surgical procedures
or medical treatment, while the results showed open surgery was
associated with significantly higher complications compared to
interventional procedures (p=0.021) (14). In a study by Khalid Bashar et
al., five years follow-up of 782 patients after stenting of the CIV due
to symptomatic non-thrombotic iliac vein lesions, showed a 94% of stent
patency rate (15).
We faced a previously unknown case of MTS, with several pelvic
collaterals, which led to the misdirection of the wire into the renal
parenchyma. Jenab et al. reported a 40 years old lady with a previously
known history of symptomatic MTS, who had undergone iliac venoplasty
with stenting, and during the procedure, a secondary spinal epidural
hematoma was developed because of the misdirection of a 0.035-inch
hydrophilic stiff wire into the paraspinal space throughout the
collateral network of vertebral-pelvic venous plexus. The patient
complained of severe back pain 12 hours after the procedure and
developed an abrupt loss of sensory-motor function in the upper and
lower extremities. MRI showed the epidural hematoma from cervical to
lumbar spaces, which was treated with emergent laminectomy and hematoma
removal (16). In our case, as a result of the inappropriate wiring,
severe hematuria was developed, due to continuous blood flow, from a
higher-pressure space of the iliac vein into a lower-pressure space of
the renal pelvis. Lattimer et al. studied the hemodynamics of the
femoral vein in individuals with venous outflow resistance (such as MTS
patients) and concluded that in these circumstances, hemodynamic
velocity parameters of the femoral vein are markedly increased (17).
With this regard, the heart team decided to perform balloon venoplasty
of the left CIV. After the procedure, the collateral vessels were gone,
possibly due to a significant decrease in the femoral vein pressure. A
few hours later, hematuria was stopped as a result of the cessation of
collateral blood flow.