I say, and with God's help: Istinja (cleaning oneself after urination) is recommended if one has urinated but not defecated, as it involves washing the front without the back. See: Al-Tawdeeh Sharh Muqaddimat Abi Al-Layth 94/b, Bada'i Al-Sana'i 1/18, and Al-Ikhtiyar 1/48, and God knows best.