A Spigelian hernia is a very rare type of ventral abdominal wall hernia. They occur below the umbilicus in a specific area known as the Spieghel’s semilunar line, through the Spieghel’s fascia. This hernia is very difficult to diagnose since it works its way in between the muscle layers of the abdominal wall and does not surface just below the skin.
Hernias of the lower back, or posterior lumbar area, can be congenital (i.e. acquired since birth), spontaneous, or traumatic in nature. They can occur in two anatomic places in the lower back; the first is Grynfeltt’s lumbar triangle (superior/upper location) and the second is Petit’s lumbar triangle (inferior/lower location). These hernias will occur either: at the edge of the latissimus dorsi muscle (the main superficial back muscle) where it inserts with the external oblique muscle at the iliac crest bone; or just underneath this muscle where the 12th rib intersects with the deeper abdominal wall muscle known as the internal oblique muscle.
These types of hernias are very rare but can occur through one of three potential spaces in the pelvic floor (or perineum). These hernias usually occur in older malnourished women. The most well-known of these hernia types is the obturator hernia since it occurs through a space known as the obturator canal. When this hernia type occurs, it places pressure on the obturator nerve that runs in the same space causing pain in the region of the hip, knee and inner aspect of the thigh. This pain is known as the Howship-Romberg sign. This hernia can be diagnosed by noting a palpable mass on rectal or pelvic exam in the area of the medial thigh.
These types of hernias are rare and almost always present as a hernia through an incision from previous surgery. Operations, such as kidney removal (nephrectomy) or spinal stabilization surgery, that require large flank incisions can often result in the development of incisional hernias. These usually occur as a result of denervation injury which means that the muscle can become weak if the nerve that supplies it get cut or injured.