What can cause stomach wounds?

Anything that penetrates, punctures, tears/rips the abdominal skin and penetrates to the organs can cause an abdominal wound. If you mean only the stomach (the organ), you can also acquire wounds if something sharp or a foreign body was swallowed/ingested and got stuck in the stomach organ and could not pass into the small intestines. Additionally, chemical ingestion (including drugs) can cause stomach lining erosion, thus creating a "wound" in the stomach lining. Even a simple stomach ulcer (which can be serious/life threatening), can cause a "wound" to the lining of the stomach and can perforate (break through) the stomach wall.
Anything that penetrates, punctures, tears/rips the abdominal skin and penetrates to the organs can cause an abdominal wound. If you mean only the stomach (the organ), you can also acquire wounds if something sharp or a foreign body was swallowed/ingested and got stuck in the stomach organ and could not pass into the small intestines. Additionally, chemical ingestion (including drugs) can cause stomach lining erosion, thus creating a "wound" in the stomach lining. Even a simple stomach ulcer (which can be serious/life threatening), can cause a "wound" to the lining of the stomach and can perforate (break through) the stomach wall.