Phlegmasia cerulea dolens
A person with a two hour history of phlegmasia cerulea dolens (left leg, right side of image)

Phlegmasia cerulea dolens (PCD) (literally: 'painful blue inflammation'), not to be confused with precedingphlegmasia alba dolens, is an uncommon severe form of lower extremitydeep venous thrombosis (DVT) that obstructs blood outflow from a vein. Upper extremity PCD is less common, occurring in under 10% of all cases.^[1] PCD results from extensivethrombotic occlusion (blockage by athrombus) of extremity veins, most commonly aniliofemoral DVT, of theiliac vein and/orcommon femoral vein.^[2][3] It is a medical emergency requiring immediate evaluation and treatment.

It is characterized by progressive lower extremity edema distal to the thigh, tight shiny skin,cyanosis (inadequate blood oxygenation),petechiae orpurpura, and sudden severe pain of the affected limb in proportion to the level of venous blockage. Patients often have difficulty walking.Blisters, bullae,paresthesias, and motor weakness may develop in severe cases, along with gangrene in ~50% of cases.^[4][5] Distal pulses are palpable early on but may diminish over time, anddoppler signal can be usually heard throughout disease progression.^[6] The left limb is more commonly affected due to its vascular anatomy (the rightinternal iliac artery directly overlies the left iliac vein).^[7][8]

PCD is associated with an underlyingmalignancy in 20-40% of cases.^[9] There is a high risk of massivepulmonary embolism, even underanticoagulation.^[10]

Risk factors, present in around 50% of documented cases, include malignancy,hyper-coagulable states,cardiac disease,venous stasis, venous insufficiency,May-Thurner syndrome (right iliac artery compressing the left iliac vein that runs beneath it), surgery, trauma,pregnancy,inferior vena cava (IVC) filter, hormone therapy,oral contraceptives, prolonged immobilization,inflammatory bowel disease,heart failure, and central venous catheters. Etiology is unknown in ~10% of PCD cases.^[11][12][13]

When athrombus occludes an extremityvein, pressure backs up in the venous system leading plasma fluid to leak out into theinterstitium of the affected limb. This increases the pressure of that limb compartment, which can collapse the arteries and lead to acuteischemia,gangrene,hypovolemia, and hemodynamic instability.^[14][15]

PCD is best diagnosed with contrast venography, butvenous duplex ultrasonography is used more commonly in clinical practice. Magnetic resonance and computed tomographyvenography can also be used.^[16]

DDx is as follows:^[17]

• Cellulitis
• Venous insufficiency
• Superficial thrombophlebitis
• DVT
• Arterial embolism
• Lymphedema
• Ruptured Bakers cyst

Treatment for PCD includes immediateanticoagulation, fluidresuscitation, bed rest, limb elevation above 60º, limb wrap to reduce pain and edema, and either catheter-basedthrombolysis, percutaneous transluminalangioplasty, or surgical venousthrombectomy +/-fasciotomy to remove theblood clot.^{[18][19][20][21]} Some people also suggest anIVC filter before thrombolysis.^[22]

PCD is fully reversible if the causalvenous thrombus is promptly removed.^[23] In the 40-60% of people who go on to develop venous gangrene, there is a 20-50% risk of amputation and 20-40% mortality rate.^[24][25] Following PCD resolution patients are more likely to develop venous insufficiency andpost-thrombotic syndrome^[26]

A grading system has been established^{[by whom?]}:^[27][28]

• Grade I = non-complicated (noblistering, strong sensory-motor function and strong distal pulses)
• Grade II = impending venousgangrene (blistering, weak sensory-motor function and weak distal pulses)
• Grade III = venous gangrene

PCD is most likely to occur in people in their 50s and 60s, but can occur as early as 6 months old. There is slight male predominance of around 1.5:1.^[29][30]

This phenomenon was first discovered by Fabricus Hildanius in the16th century, and was officially termed "phlegmasia cerulea dolens" by Gregoire in 1938.^[31][32]Phlegmasia originates from theGreek rootphlegma (inflammation),cerulea originates fromLatin rootcaeruleus (dark blue), anddolens originates from Latin worddolens (suffering).^[33]

• Inflammations
• Vascular diseases

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