The femoral cone and its clinical implications

The transversus abdominis aponeurosis and its investing sheath of transversalis fascia are the first line of defense against groin herniation. If transversus abdominis fibers insert on the superior pubic ramus as a narrow band, a cone shaped defect will result. With an increase in intra-abdominal pressure, preperitoneal fat, with or without a peritoneal sac, can enter this femoral cone. It is an asymptomatic internal hernia that will be detected only if the preperitoneal space is explored during inguinal herniorrhaphy. This is stage I in the development of a femoral hernia. Should the contents within the femoral cone protrude through its narrow distal orifice, a stage II external hernia results. Incarceration or strangulation may then occur. Herniation into and through the femoral cone was encountered in 159 instances while repairing 3,609 hernias of the groin in adults. Sixty-seven external (stage II) hernias were diagnosed preoperatively. Sixteen per cent were irreducible, 18 per cent were incarcerated and 3 per cent were strangulated. During inguinal herniorrhaphy, an unsuspected stage II femoral hernia was found in 12 instances, and a stage I precursor was present in 80. Flexibility in management is important. The choice of the low, inguinal or preperitoneal approach is determined by the mode of presentation of the hernia.