Lauren Day picked up the injury during the warm-up for Ireland's pre-tournament match against Scotland last weekend.
Day received a knock on her wrist and while at first it was thought to be a sprain, an X-ray showed that she had in fact fractured a bone.
It is a bitter blow for the talented forward who has worked hard in the last two seasons to gain a place in the Irish Women's squad.
Her place in the panel has been taken by Highfield and Munster prop Laura Guest.
Guest is a secondary school teacher who attended Sacred Heart Clonakilty and University of Limerick. She has been capped nine times for Ireland.
IRELAND SQUAD - WOMEN'S RUGBY WORLD CUP (August 20-September 5):
Backs (12) -
Louise Beamish (UL Bohemians/Munster)
Niamh Briggs (Clonmel/Munster)
Helen Brosnan (Highfield/Munster)
Lynne Cantwell (UL Bohemians)
Amy Davis (Blackrock/Leinster)
Eliza Downey (Cooke/Ulster)
Shannon Houston (Blackrock/Leinster)
Mairead Kelly (UL Bohemians/Munster)
Joanne O'Sullivan (Richmond/Exile)
Tania Rosser (Blackrock/Leinster)
Jackie Shiels (Richmond/Leinster)
Nora Stapleton (Old Belvedere/Leinster)
Forwards (14) -
Louise Austin (UL Bohemians/Munster)
Gillian Bourke (UL Bohemians/Munster)
Orla Brennan (Blackrock/Leinster)
Fiona Coghlan (UL Bohemians/Leinster) (capt)
Laura Guest (Highfield/Munster)
Chris Fanning (Highfield/Munster)
Caroline Mahon (UL Bohemians/Leinster)
Claire Molloy (Bristol/Connacht)
Joy Neville (UL Bohemians/Munster)
Yvonne Nolan (Blackrock/Leinster)
Kate O'Loughlin (Clonmel/Munster)
Marie Louise Reilly (Navan/Leinster)
Sinead Ryan (Blackrock/Leinster)
Carol Staunton (Galwegians/Connacht)
Ireland Women's Rugby World Cup Fixtures:
England v Ireland, Surrey, Friday, August 20, 6.30pm
USA v Ireland, Surrey, Tuesday, August 24, 4.30pm
Ireland v Kazakhstan, Surrey, Saturday, August 28, 4.30pm
Related Links -
Ireland Women - Squad Profiles