Introduction

 

Paraduodenal hernia is a rare congenital internal hernia which arises from an error of rotation of the midgut with entrapment of the small intestine beneath the developing colon. It is important as it usually presents as intestinal obstruction, and before laparotomy is often misdiagnosed. Mortality increases significantly with delays in surgical treatment.

 

Paraduodenal hernia, also referred to as internal, congenital, retroperitoneal, or meso-colonic hernia, is a herniation resulting from anomalies of rotation and reduction of the midgut loop in the embryo. This hernia occurs when the small intestine becomes trapped beneath the colon because of anomalous rotation of the mesentery of the developing colon. The duodenum and small intestine become trapped in a sac lined by peritoneum, behind the mesentery of the colon, either to the left or to the right of the midline.[1]

 

Case report

 

A 60 year old man, hailing from Nowgam village, was admitted in the emergency department with a history of severe abdominal pain of 8 hours duration. Pain was sudden in onset, colicky and more severe in the right upper abdomen to begin with. Subsequently the pain became constant and generalized. He had vomited once and passed no flatus. He had been keeping well except a few episodes of upper abdominal colic in recent years, which had resolved spontaneously. There was no significant past surgical history.

 

On examination the patient appeared to be in distress and was dehydrated with a pulse rate of 96 beats/min. He was afebrile and his blood pressure was normal. Abdominal examination revealed fullness in right upper quadrant with a palpable tender lump of approximately 9 × 6 cm size. There was overlying muscle guarding and bowel sounds were sluggish. White cell count was 13,000/mm3 with 82% neutrophils.  Electrolytes were normal and amylase was not raised. Abdominal X-rays (Figure 1) showed slightly distended gut loops in rightupper abdomen with no free gas under the diaphragm. Ultrasonography (USG) revealed a gut mass in right upper quadrant and free fluid in Morrison’s pouch.

 

A provisional diagnosis of acute intestinal obstruction due to a primary or, more likely, a secondary intussusception was made and after initial resuscitation, laparotomy was planned. Laparotomy showed small bowel obstruction because of a right paraduodenal hernia at the duodenal-jejunal flexure. The palpable lump, and the gut mass visualised on USG was actually the small gut entrapped in the hernia and not the intussusception, as presumed initially. The sac was inferolateral to the third (transverse) part of duodenum and extended behind the ascending mesocolon and right half of transverse mesocolon. The superior mesenteric artery and the right colic vein were in the free edge of the hernia. The small bowel was reduced from the hernial sac after widening the neck. Due to the tight neck the bowel trapped in the hernia was strangulated and had patchy gangrenous areas. About 30% of proximal small bowel had to be resected, and an end to end hand sewn anastomosis fashioned. The neck of the sac was obliterated by suturing the posterior peritoneum (Figures 2,3).

 

The patient showed rapid improvement post operatively and was discharged on 7^th post operative day, after he had tolerated soft orals and moved bowels.

 

Discussion

 

This case illustrates the typical onset of bowel obstruction caused by paraduodenal hernia, with rapidly progressing acute  abdominal pain from ischaemic bowel. As it is a closed loop obstruction, damage to the bowel occurs early, accounting for the high mortality rate in this condition. Presentation is dramatic, often with hypovolaemic shock and peritonism. Paraduodenal hernia can be divided into two types: left and right. A left sided hernia is produced by malrotation of the umbilical loop. As the small intestine is reduced into the  abdominal cavity, it is caught beneath the mesentery of the descending colon. The caecum is completely rotated and lies in the normal position in the right iliac fossa. The sac points downward and to the left towards the descending colon. The free edge of the sac contains the inferior mesenteric artery and vein and the left colic artery, and their branches are integral part of the hernia sac. The anterior wall of the sac is made up of the mesocolon of descending colon.[1,2,3,4]

 

A right paraduodenal hernia is produced when the umbilical loop fails to rotate completely and is caught beneath the caecum. The small intestine becomes imprisoned behind its mesentery. The major portion of the small intestine remains to the right of the superior mesenteric artery. The anterior wall of sac is made up of the mesentery of the ascending colon and transverse colon. Right sided paraduodenal hernias contain the superior mesenteric artery and iliocolic artery in the free edge of the sac.

 

The hernial orifice is to the right of midline and the peritoneal sac directed downward and to the right.[1,2,3,4] Internal hernias account for 0.5% of all cases of intestinal obstruction.[5] Paraduodenal hernia is the most common type, accounting for 53% of cases.[5,6,7,8] Paraduodenal hernia can present at any age but is typically seen between the fourth and sixth decades of life.[9] It is more common in men than women, with a ratio of 3:1,[8] and is more frequent on the left than right, with a ratio of 3: 1.[1] Fifty per cent of paraduodenal hernias cause obstruction, the remainder are diagnosed incidentally at exploratory laparotomy or at necropsy.[8,9]

 

The mortality of obstructed internal hernia exceeds 50%,[6,8] reflecting the large proportion of patients who present with intestinal obstruction and ischaemia requiring emergency surgery.[6,10,11] Consequently, all paraduodenal hernias, even those diagnosed incidentally, should be repaired.1,6,11 Internal hernias account for 0.5% of all cases of intestinal obstruction.[5] Paraduodenal hernia is the most common type, accounting for 53% of cases.[5,6,7,8] Paraduodenal hernia can present at any age but is typically seen between the fourth and sixth decades of life.[9] It is more common in men than women, with a ratio of 3:1,[8] and is more frequent on the left than right, with a ratio of 3: 1.[1] Fifty per cent of paraduodenal hernias cause obstruction, the remainder are diagnosed incidentally at exploratory laparotomy or at necropsy.[8,9]

 

The mortality of obstructed internal hernia exceeds 50%,[6,8] reflecting the large proportion of patients who present with intestinal obstruction and ischaemia requiring emergency surgery.[6,10,11] Consequently, all paraduodenal hernias, even those diagnosed incidentally, should be repaired.[1,6,11]

 

References

1.     Bartlett MK, Wang C, Williams WH. The surgical management of paraduodenal hernia. Ann Surg. 1968;168:249–54.

2.     Tireli M. Left paraduodenal hernia. Br J Surg. 1982;69:114.

3.     Filtzer H, Sedgwick CE. Strangulated paraduodenal hernia. Report of a case. Surg Clin North Am. 1973;53:371–4.

4.     Willwerth BM, Zollinger RM, Jr., Izant RJ, Jr. Congenital mesocolic (paraduodenal) hernia. Embryologic basis of repair. Am J Surg. 1974;128:358–61.

5.     Lee TK, Voon FC, Chow KW, Teo NH. Unusual variant of right paraduodenal hernia. Aust N Z J Surg. 1990;60:483–5.

6.     Freund H, Berlatzky Y. Small paraduodenal hernias. Arch Surg. 1977;112:1180–3.

7.     Ghahremani GG. Internal abdominal hernias. Surg Clin North Am. 1984;64:393–406.

8.     Newsom BD, Kukora JS. Congenital and acquired internal hernias: unusual causes of small bowel obstruction. Am J Surg. 1986;152:279–85.

9.     Brigham RA, Fallon WF, Saunders JR, Harmon JW, d’Avis JC. Paraduodenal hernia: diagnosis and surgical management. Surgery. 1984;96:498–502.

10.    Turley K. Right paraduodenal hernia: a source of chronicabdominal pain in the adult. Arch Surg. 1979;114:1072–4.

11.   Dengler WC, Reddy PP. Right paraduodenal hernia in childhood: a case report. J Pediatr Surg. 1989;24:1153–4.