$re = '/utm_([a-z]*)?=(([a-z_-]||\d)*)?/m';
$str = 'https://test.com/grazhdanstvo-bolgarii.html?utm_source=google&utm_medium=search&utm_campaign=top&utm_content=text1';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php