21.What diagnosis differentiates inguinal hernia from? When there is a mass in the groin, it should be differentiated: incisional hernia, enlarged lymph nodes, aneurysm, varicose veins, soft tissue tumor, abscess, cryptorchidism, endometriosis, etc. When there is pain in the groin, it should be differentiated: enthesitis, inflammation of the pubic bone, hip arthritis, synovitis, radiating lumbago, endometriosis, etc. 22. What are the types of inguinal hernia? Theoretically, the typing of inguinal hernia is of great importance in order to individualize the surgery and to select the appropriate surgical approach. The typing is also important for the analysis of scientific data: based on a clear typing, it is possible to compare the advantages and disadvantages of various treatment modalities in clinical trial studies. However, there are many different staging methods, and the Hernia and Abdominal Wall Surgery Group of the Chinese Society of Medical Surgeons did not specifically recommend which staging method to use in its 2012 guidelines. 23. Under what circumstances is an inguinal hernia prone to recurrence? Factors known to contribute to inguinal hernia recurrence include the surgical approach, the type of hernia (straight hernias are more likely to recur than hiatal hernias), and previous recurrent hernias (the more recurrences, the higher the recurrence rate with reoperation).