IFEMED Journal of the Obafemi Awolowo University Medical Students’ Association J. Ifemed | vol 14| issue 1|2008 Ifemedjc.com.ng Ifemed Journal of Medicine May be reproduced with permission and acknowledgement Copyright © 2008 Obafemi Awolowo University Medical Students’ Association. All rights reserved. Inguinal Hernia: An Overview E.A Agbakwuru 1 , A.O Adisa 2 , A.R.K Adesunkanmi 3 1,2,3 Professor/Consultant General Surgeons Department of Surgery, O.A.U.T.H.C Ile-Ife ABSTRACT A hernia is the protrusion of a viscus or a part of it though a defect in the walls of its containing cavity. [1] A hernia may be internal when the protrusion is not seen on the body wall or external when the protrusion may be seen on the body wall. External hernias, including inguinal, femoral, epigastric, incisional, umbilical, paraumbilical, lumbar, spigelian, obturator and sciatic hernias are commoner than internal hernias. [1,2] Inguinal hernias, i.e. hernia occurring through the inguinal canals, are the commonest type of all hernias. [1,2,3] It may account for 75-90% of al external hernias. All over the world, surgeries for inguinal hernias remain one of the most common elective operations performed by general surgeons. [4,5,6] In developing countries such as Nigeria, many patients present first with complications of inguinal hernias. [7,8] Inguinal hernias are commoner in males and may occur in all age groups. [3-6,9] SURGICAL ANATOMY The inguinal canal is an oblique intermuscular slit lying above the medial half of the inguinal ligament. It is not well formed in children but is about 4cm long in adults. [10,11] The canal transmits the ilioinguinal nerve and the genital branch of the genitofemoral nerve in both sexes along with the spermatic cord in males and the round ligament of the uterus in females. It begins at the internal (deep) ring and ends in the external (superficial) ring. The internal ring is a V-shaped opening in the transversalis fascia and lies about 1.25cm above the midpoint of the inguinal ligament. An indirect hernia passes through this ring to enter the canal and large hernia sacs may hence dilate this narrow opening. The external ring is a triangular aperture in the external oblique aponeurosis. It is situated above and medial to the pubic tubercle and through it an inguinal hernia, commonly the indirect type, may descend into the scrotum. The anterior wall of the canal is formed by the external oblique aponeurosis, reinforced laterally by the internal oblique muscles. [10,11] The posterior wall is formed by the strong conjoint tendon medially and the weak transversalis fascia throughout. This is why increased intra-abdominal pressure may lead to a defect in the posterior wall through which a direct hernia enters the canal. Such herniations commonly occur through the Hasselbach’s triangle which is bounded laterally by the inferior epigastric vessels, medially by the lateral border of the rectus sheath and inferiorly by the inguinal ligament. [10] The roof of the canal is formed by the arching fibers of the internal oblique and transversus abdominis muscle while the floor of the canal is formed by the inguinal ligament (Poupart’s ligament). A hernia sac is a diverticulum of peritoneum. It consists of a mouth, neck, body and fundus. The neck, when narrow can predispose to strangulation of the contents of the sac which may be omentum (omentocele), intestine (enterocele), or Merkel’s diverticulum (Littre’s hernia). [11,12] When only a portion of the circumference of the intestine is included, the hernia is called Richter’s hernia, and when part of a bowel (e.g bladder wall) forms part of the hernia sac, it is called a sliding hernia. [1,2,13] AETIOLOGY The testes descend from the posterior abdominal wall into the scrotum through the inguinal canal with a pouch of the peritoneum, the processus vaginalis, attached to it. The portion of the processus vaginals above the external ring usually obliterates at or soon after birth. Failure of its obliterations may lead to an indirect hernia in infancy, childhood or later in adult life. Congenital anomalies, prematurity, low birth weight, pelvic floor deformities, bladder atrophy and cystic fibrosis are all associated with increased incidence of inguinal hernia in childhood. [9,16] Weakness of the wall of the inguinal canal may be acquired with ageing or following nerve injury (e.g after a gridiron incision). Obesity causes stretching of the abdominal musculature just as fat accumulation may separate muscle fibers, weaken aponeurosis and thereby favours appearance of direct hernias. [13] Raised intra-abdominal pressure from chronic cough, bladder outlet obstruction, chronic constipation, weight lifting, heavy manual work, intra-abdominal masses, ascites or frequent pregnancies may lead to the formation of inguinal hernias. CLASSIFICATION Inguinal hernias are classified in different ways. (a) Based on the site of entry of the sac into the canal  Indirect- the sac enters the canal through the internal ring  Direct- the sac herniates through the posterior wall  Pantaloon hernia contains both direct and indirect hernias in the same canal (b) Based on the completeness of descent through the canal  Bubonocele- a sac limited to the canal  Funicular- one that is out of the canal with the fundus just above the pubic tubercle.  Complete (inguinoscrotal) hernia- the sac has descended into the scrotum. (c) Based on the state of the contents of the hernia sac.