Chyle is a milky fluid consisting of lymph / interstitial fluid and emulsified fats. The largest conduit of it is in the thoracic duct that starts in the abdomen ascend to the neck and enters the venous system at the junction of the internal jugular vein and the subclavian vein.
A chyle leak can occur at the time of a neck dissection clearing lymph nodes from the territory where the thoracic duct enters the venous system. A chyle leak has been incurred by every regularly practicing surgeon who undertakes neck dissection. More often than not it occurs when large nodes have to be cleared from the root of the neck where the duct is.
It can lead to a profuse loss of this milky fluid which is protein rich and patients can therefore become fluid depleted and malnourished rapidly with a high output fistula. Special feeds can be instituted to decrease output, pressure can also help decrease output. Surgical exploration can sometimes localise the leak. Occasionally thoracoscopic ligation of the duct in the chest can be undertaken.
This is a serious condition and is best avoided and when incurred should be carefully managed from a surgical and dietetic perspective.