ADO.NET :: Check For Null Values From DataReader

I have the following code

public class ProductDetails
{
private string _productid;
public string ProductID
{
get { return _productid; }
}
private string _description;
public string Description
{
get { return _description; }
}
private string _image;
public string Image
{
get { return _image; }
}
public ProductDetails(string productid, string description, string image)
{
_productid = productid;
_description = description;
_image = image;
}
}
public class DataAccess
{
private static string connectionString = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
public ProductDetails GetProductDetails()
{
SqlConnection con = new SqlConnection(connectionString);
SqlCommand cmd = new SqlCommand("ProductDetails", con);
cmd.CommandType = CommandType.StoredProcedure;
string productid = HttpContext.Current.Request.QueryString["productid"];
cmd.Parameters.Add(new SqlParameter("productid", SqlDbType.NVarChar)).Value = productid;
con.Open();
SqlDataReader reader = cmd.ExecuteReader();
reader.Read();
ProductDetails pro = new ProductDetails(
(string)reader["ProductID"], (string)reader["Description"], (string)reader["Image"]);
reader.Close();
return pro;
}
}
protected void PopulateControls()
private DataAccess da = new DataAccess();
{
ProductDetails product = da.GetProductDetails();
if (product.Description == String.Empty)
{
lblDescription.Visible = false;
}
else
{
lblDescription.Text = product.Description;
}
}

In the last piece i want to check if the Description field is null or empty in order to hide the label control but i get an error if i write: if (product.Description == DBNull.Value) and can only use ring.Empty. But i want to check for NULL values as well..