An improved sanitary pad for use in a thong-style pair of underwear to absorb and retain anticipated menstrual flow volume and at the anticipated flow rate contains a double layer of absorbent material in a waisted, water impervious flexible channel. The waisting of the channel is sized to accommodate the narrow lateral width of the thong saddle. The upright substantially flat or otherwise smooth sides of the channel guide flow entering a capture zone of the pad saddle away from the capture zone to longitudinally outer reservoir zones formed in the front and rear of the pad. In one embodiment flexible guides, which may be longitudinal rails of a flexible water-impervious substance or material, run longitudinally or substantially parallel to the sides of the channel, spaced inwardly therefrom, to assist in guiding or urging flow in and below the capture zone longitudinally towards the reservoir zones.
