Fatal error: Call to undefined method PDOStatement::fetch_assoc()

Fatal error: Call to undefined method PDOStatement::fetch_assoc() in index.php on line 16 Call Stack: 0.0001 644064 1. {main}() index.php:0

<?php 
session_start();
require_once("../resources/php/connection.php");

// use quote or prepared statements to prevent from 
// SQL injection attacks!
$pmname = $pdo->quote($_SESSION['pmname']);
$sql = "SELECT * FROM pm_user WHERE name=$pmname";

$result = $pdo->query($sql);
if($result === FALSE) {
    echo 'oops! the query failed! ';
    print_r($pdo->errorInfo());
}

$row = $result->fetch_assoc();

if($row) {
    echo $row['img'];
} else {
    echo 'the query return no records :(/>/>';
}
?>