Essentially are holes(defects) in the muscular fascial layer of the abdominal wall through which fat and intestines can protrude causing pain and eventually incarceration(getting stuck) and strangulation(so tight that blood cannot get into the intestines causing necrosis (gangrene).
Umbilical hernias are very common resulting in defects left from the umbilical vein not completely fibrosing after delivery. I generally repair these under local anesthesia with intravenous sedation. If the defect is smaller than 2 cm it is closed with sutures without mesh and if it is greater than 2 cm mesh should be used to prevent excessive tension and hernia recurrence. The intra-abdominal side of the mesh has a protective layer to prevent the intestines from adhering to it.
Inguinal hernias are common since the spermatic cord(round ligament in women) go through this area with the resulting hole which enlarges over time. Also the abdominal wall musculature in this area only has one layer as opposed to the 3 layers in other areas. No exercises or conservative approaches will repair these defects. Multiple repairs are available to treat this problem. I do not believe that one procedure is best for all patients, and choose the best repair for each patient. An open(surgical incision) repair can be performed using local anesthesia with intravenous sedation and I generally perform a mesh free inguinal hernia repair when performing this operation, using a relaxing incision in the anterior rectus sheath which allows mobilization of the transversalis fascia so that it can be sutured to Cooper's ligament(A ligament on the inside of the pelvis bone) without tension. Usually I can get healthy strong tissue for an excellent repair and if that tissue is not available, use a piece of mesh placed behind the abdominal wall therefore avoiding the location of the major sensory nerves. Mesh repairs have known complications including nerve entrapment and infection and therefore I only use it when necessary. I generally perform a laparoscopic repair on young healthy patient's, which is performed under general anesthesia and requires mesh placement behind the muscular layer that is tacked in place to Cooper's ligament. The mesh is therefore buttressed up against the abdominal wall and additionally held in place by intra-abdominal pressure. This physiologically makes more sense than placing the mesh on the outside of the abdominal wall. In patients with a hernia recurrence following open repairs, a laparoscopic approach is used and in patients with a recurrence following a laparoscopic repair, an open repair is then performed.
Ventral/incisional hernias are generally in the abdominal midline and can be repaired with sutures if the defect is small but mesh is generally used for larger defects. An open repair can be performed or a laparoscopic repair can be performed depending on the size of the defect and possible complicating intra-abdominal processes. For massive hernias a tissue advancement(component separation ) can be performed with a posterior mesh reinforcement.