Lymphocele after posterior lumbar interbody fusion

Lymphocele is defined as abnormal collection of lymphatic fluid composed of fibrotic tissue without a distinct epithelial lining. Lymphoceles are frequently seen following surgical procedures or traumatic injuries. There are several reports of lymphocele formation during spinal surgery mainly in the thoracic and upper lumber region where lymphatic tissues are transected. Lymphocele formation following posterior fusion at L3-S1 (lower lumber surgery) is however an infrequent complication. Once injured, lymphatic vessels are more prone to continuous leakage as it contains no platelet and very few clotting factors. Lymphocele above the level of Cisterna Chyli (CC) is often known as chyloascites or chylothorax, while below CC is known as retroperitoneal lymphocele. Both these structures vary depending upon their lymph content ie. amount of chylomicrons. Small or sterile lymphocele are generally asymptomatic and resolve spontaneously while larger or infected one can compress adjacent structures such as vessels, kidney, ureter, gastrointestinal tract, bladder etc. In such a case if patient presents with fever, abdominal pain, distension, nausea, vomiting, bladder dysfunction, edema of the leg, intervention such as simple aspiration, surgical drainage or catheter drainage with the addition of sclerosing agents, marsupilization is often recommended.
Imaging and clinical findings plays a vital role in narrowing down the differential diagnosis such as postoperative urinoma, seroma, hematoma or abscess. Patient can be monitored with CT, ultrasound or MRI and serial follow up can be done with these modalities. MRI is useful in depicting the nature of composition of the lymphatic fluid. Early lymphocele demonstrates low T1-weighted and high T2-weighted signal intensity similar to spinal canal while chronic may reverse depending upon the chylomicrons. MR lymphangiography is often helpful in delineating the lymphatic channels. The gold standard is conventional lymphography; however is an invasive technique with some associated risk of infection, skin necrosis and pulmonary embolism. The final diagnosis depends upon serum and cyst fluid analysis by needle aspiration.