417 J Pak Med Assoc Case Report Spigelian Hernia: a rarity Kamran Ahmad Malik, Pradeep Chopra Department of General Surgery, Sultan Qaboos University Hospital, Muscat, Oman. Abstract Spigelian hernias are rare and generally difficult to diagnose because of their location and vague non-specific symptoms. They are situated between the muscular layers of the abdominal wall and can be easily overlooked because of abdominal obesity. The diagnosis has been considerably aided by the introduction of ultrasonography and computed tomography (CT). These hernias require surgical treatment. We report a 31 years old patient from the Sultan Qaboos University Hospital who presented with colicky lower abdominal pain associated with a tender swelling above and lateral to the inguinal canal. A diagnosis of Spigelian her- nia was made and confirmed on exploration. The hernia was reduced and the defect repaired. Her recovery was uneventful. Introduction Spigelian hernia is a protrusion of preperitoneal fat, a sac of peritoneum or an organ, through a congenital defect or weakness in the Spigelian fascia. It is essential to reca- pitulate the anatomy of the anterior abdominal wall to prop- erly understand Spigelian hernia. Adriaan Van der Spieghel was first to describe the semilunar line and hence the hernia got its name. Henry-Francis Le Dran described spontaneous rupture along the semilunar line in 1742, but Josef T.K. Linkosch was first to refer this condition as a her- nia in 1764. 1 Spigelian hernias are rare accounting for 1-2% of all hernias, with a slightly higher incidence in the female sex. Spigelian line marks the transition from muscle to aponeu- rosis in the transverses abdominis muscle of the abdomen. It is a lateral convex line between the costal arch and the pubic tubercle. The part of the aponeurosis that lies between the semilunar line and lateral border of the rectus muscle is called the spigelian fascia or zone. Anteriorly throughout its length, the semilunar line is reinforced by the aponeuro- sis of the external oblique. Posteriorly in the cephaled two thirds it is reinforced by the transversus abdominis muscle which is muscular almost to the midline in the upper abdomen. This support prevents herniation and hence very rare above the umbilicus. Spigelian hernia is defined as a protrusion of preperitoneal fat, a sac of peritoneum or an organ, through a congenital defect or weakness in the spigelian fascia. 1 It is usually located between the different muscle layers of the abdominal wall; therefore it is also called as interparietal, interstitial, intermuscular, intramuscular or intra-mural her- nia. The majority of spigelian hernias are found in a trans- verse band lying 0-6 cms cranial to a line running between both anterior superior iliac spines referred to as the spigelian hernia belt where the spigelian fascia is the widest. 2 Hernias that penetrate the spigelian fascia within the Hasselbach's triangle (bounded by rectus abdominis muscle medially, inferior epigastric artery laterally and by inguinal ligament inferiorly) caudal and medial to the infe- rior epigastric vessels are called low spigelian hernias. Most spigelian hernias occur below the level of the umbilicus close to the level of the arcuate line (inferior margin of pos- terior leaflet of rectus sheath within the abdomen), though they have being reported to occur above the level of the umbilicus. Incisional hernias through the spigelian fascia or line conventionally are not considered as spigelian hernia, though some authors have described them as spigelian her- nia. 3 We report this rare variety of hernia, found in one of our patients, with review of literature to discuss the diagno- sis and management, as such kind of hernias are clinically elusive with fatal outcome if ignored. Case Report A 31 years old lady presented with 5 hours history of colicky abdominal pain associated with nausea and a palpa- ble lump at the right lower quadrant of the abdomen. She denied any disturbances in her bowel habits. She had sim- ilar complaints 3 months back, which resolved sponta- neously and she was thoroughly investigated then. Abdominal ultrasonography, barium studies for both upper and lower gastrointestinal systems were all normal at that time. This time on examination a 6 x 4 cms well delineated swelling above and lateral to the right inguinal canal was palpable. It was sub-cutaneous, firm, tender and irreducible with absent cough impulse. Clinical impression of an irreducible Spigelian her- nia with high index of suspicion of strangulation was made on the basis of her past history of similar complaint, which was reduced on conservative treatment at that time, and the peculiar location of the lump. Her routine