Deep vein thrombosis due to continuous prone positioning after retinal detachment surgery.

In March 2014, a 56-year-old woman without previous underlying disease underwent encircling scleral buckling, 20-gauge pars plana vitrectomy, cryotherapy around a retinal tear, and gas-fluid exchange with 15% perfluoropropane flush for upper rhegmatogenous retinal detachment of the left eye. However, she developed progressive left leg swelling, pain, warmth, and redness, associated with difficulty in elevating her left leg after continuously maintaining a prone head position when either lying down or sitting for 2 days. When she arrived at the emergency room, she had an elevated D-dimer level. After undergoing Doppler ultrasound imaging, she was diagnosed as having deep vein thrombosis of the left leg. She received anticoagulation therapy with enoxaparin and warfarin overlapping for 7 days. The edema, pain, and paresthesia of her left leg were relieved. However, because of the risk of bleeding with anti-coagulation drug usage, the patient needed to be monitored for 6 months. Prone positioning for gas tamponade is important for anatomic and functional success in retinal detachment surgery; however, timely walking and rest between periods of continuous prone positioning should be encouraged to prevent deep vein thrombosis and other impaired circulation-related complications.

1. Introduction

Prone positioning for gas tamponade after retinal detachment is important for retinal reattachment. Ophthalmologists always tell these patients to maintain the prone position as much as possible for 1–2 months if gas remains in the posterior chamber. However, maintaining a prone position continuously is very difficult for some patients, who may change to a seated prone position with hips and knees flexed and the head on a table. Sitting for long periods of time, as when driving or flying, could lead to blood clot formation in the legs because of lack of movement of the calf muscles, and may result in deep vein thrombosis (DVT) and pulmonary embolism (PE), which is fatal. In this paper, we report a case of leg DVT resulting from continuous seated prone positioning after retinal detachment surgery. Ophthalmologists should reinforce the importance of adequate movement of the legs and body repositioning when long-term prone positioning is required.

2. Case report

A 56-year-old woman was referred to our emergency room for sudden onset of left leg swelling early that morning, which was accompanied by soreness and an inability to elevate the leg. She denied having fever, headache, dyspnea, chest pain, abdominal pain, or lower extremity cold or numb sensations. Two days earlier, she had undergone retinal detachment surgery with encircling buckling, trans plana vitrectomy, cryotherapy, and fluid gas exchange with 15% perfluoropropane. As suggested for better tam-ponade effect, she maintained prone positioning as long as possible whether lying down or seated. However, after sitting motionless in a prone position with leg flexion for 6 hours, severe swelling of the left leg developed, with pain and erythema (Figure 1). In the emergency room assessment, laboratory tests showed D-dimer elevation (>10,000 ng/mL). A venous duplex ultrasound revealed a thrombus with total occlusion of the left common femoral vein, superficial femoral vein, profunda femoral vein, and popliteal vein. Her right lower extremity veins were patent. Left leg DVT was suspected, and she was admitted for further evaluation and management.

Figure 1

The patient's left leg shows swelling, pain, and warmth and redness that is accompanied by difficulty elevating her leg after continuous prone positioning.

She was administered anticoagulation therapy, with enoxaparin (by subcutaneous injection) and warfarin overlapping. The monitored prothrombin time/international normalized ratio (PT/INR) value was low, and the warfarin dose was increased. After two days, enoxaparin was discontinued with a PT/INR value of 1.42. There was no deficiency in antithrombin III, protein C, protein S, or plasminogen. After 1 week on anticoagulation therapy, her left leg swelling and pain were gradually relieved, and she was discharged. However, anticoagulants had to be continued for 6 months. This therapy is associated with an increased risk of bleeding.

3. Discussion

Ophthalmologists advise patients who undergo retinal detachment surgery with air tamponade to maintain a prone position after surgery as much as possible for 1–2 months or until there is no remaining air in the posterior chamber. However, in this patient, DVT developed as a result of being in a continuous seated prone positioning for 6 hours. Deep vein thrombosis and its sequelae such as PE can be severe or fatal. However, these consequences are preventable.1 Patients should be advised that appropriate exercise during prone positioning is important to prevent such complications.

Deep vein thrombosis may arise spontaneously or may be caused by trauma, surgery, or prolonged bed rest.2 Patients have an increased risk of DVT who have antithrombin deficiency,3 lupus anticoagulant,4 previous DVT,5 or cancer,67 or patients who use oral contraceptives or are on hormone replacement therapy.28 Before retinal detachment surgery is performed, a patient should undergo a careful perioperative evaluation to assess the clinical situation and the possible need for prophylaxis in specific high-risk patients.9

Deep vein thrombosis is a clinical challenge for doctors because it can develop in any section of the venous system; however, it arises most frequently in the deep veins of the leg.1 In our patient, DVT developed because of motionless prone positioning with her knee flexed for 6 hours. There are reports of DVT developing in a fiberglass mold maker after 6 weeks of working in a kneeling po-sition,10 and in a patient maintaining a prone position after spine surgery with a central venous catheter in place.11

Anticoagulation treatment for DVT is useful, but it impairs the blood’s ability to clot, which results in an increased risk of bleeding. Ophthalmologists have a role in preventing the development of DVT in patients who need prone positioning.

Deep vein thrombosis resulting from prone positioning after retinal detachment is rare but preventable. Appropriate exercise and rest during continuous prone positioning are suggested as preventative measures.