Search by XPath under a given element

The only way I know in PHP to perform an XPath query on the DOM is DOMXPath, which only works on a DOMDocument:

public __construct ( DOMDocument $doc )

Is there a similar mechanism to search relatively to a DOMElement?

The problem being, I need to search an abritrary XPath (that I have no control over) relatively to a DOMElement.

I've tried to do:

$domElement->getNodePath() . '/' . $xPath;

But if the XPath contains a | (or character), this approach doesn't work.