Omphalomesenteric Duct Remnants

INTRODUCTION

The embryonic yolk sac communicates with the ali- mentary canal via the viteline duct, which normally regressed by the sixth or seventh week of gestation.

Incomplete regression results in various abnormal- ities which may be apparent in the newborn infant at birth. These include patency of the duct (omphalo- mesenteric or vitello-intestinal duct), persistence of the patent intestinal end of the duct as a Meckel’s di- verticulum, persistence of the omphalo-mesenteric duct as a fibrous cord (Meckel’s band), the presence of a cyst within a Meckel’s band, or an isolated rem- nant of intestinal mucosa at the umbilicus (umbilical polyp). Each of these may give rise to problems re- quiring operation to remove the anomaly in the new- born period or beyond.

The indications for resection of a Meckel’s diver- ticulum include bleeding, diverticulitis, intussuscep- tion, or Meckel’s band obstruction. The Meckel’s di- verticulum is lined by ileal mucosa. Islands of ectop- ic gastric tissue may also be present in a Meckel’s di- verticulum and secrete gastric acid, which may lead to ulceration of the adjacent ileal mucosa and blee- ding which at times is severe. This is a common cause of rectal bleeding in infancy. Ectopic gastric tissue may be identified by Technetium

scanning.

Diverticulitis: inflammation of a Meckel’s diver- ticulum produces symptoms identical to those of acute appendicitis, which is the usual pre-operative diagnosis. The true diagnosis is seldom made prior to laparotomy. Meckel’s diverticulitis may lead to for- mation of an inflammatory mass and occasionally is complicated by perforation.

Intussusception: a Meckel’s diverticulum may in- vert into the lumen of the ileum and be dragged along by peristaltic contractions. This leads to intus- susception, which will present with acute abdominal pain and evidence of intestinal obstruction. At oper- ation the intussusception is reduced as far as possible prior to resection of the diverticulum and adjacent il- eum.

Meckel’s band obstruction: loops of small intes- tine may become trapped around a Meckel’s band leading to intestinal obstruction with a high risk of strangulation. Division of the band and excision of the diverticulum are required.

Asymptomatic Meckel’s diverticulum: there is no sound evidence to support routine resection of an asymptomatic diverticulum encountered incidental- ly at operation.

Duct Remnants

David Lloyd

Figure 30.1

General anaesthesia is used. No pre-operative prep- aration is required other than routine withholding of feeds. A single dose of broad spectrum antibiotics is given on induction of anaesthesia to reduce the risk of wound infection.

When the diagnosis is known, a bleeding or in- flamed Meckel’s diverticulum may be approached through a right transverse abdominal incision situat- ed just below the level of umbilicus. For intestinal ob- struction, particularly when the cause is not known, a right transverse incision situated above the umbili- cus will provide good exposure and is easier to ex- tend across the abdomen should this be necessary.

The Meckel’s diverticulum may be folded over and adherent to the adjacent small bowel mesentery. It is mobilized easily by dividing these peritoneal adhe- sions.

Figure 30.2

In most cases the diverticulum is excised with the adjacent segment of ileum. This ensures a straight anastomosis of the ileum and ensures removal of any ectopic gastric tissue. The lines of resection are illus- trated. Note that the blood supply to the Meckel’s diverticulum runs from the small bowel mesentery across the ileum to the diverticulum; this vessel must be separately divided.

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Figure 30.3, 30.4

A narrow-based Meckel’s diverticulum may be ex- cised using a transverse elliptical incision as illustrat- ed. A stay suture is inserted on either side of the ile- um at the corners of the proposed excision. The di- verticulum is excised with a cuff of adjacent ileum.

The open ileum is inspected for islands of ectopic

gastric tissue, which must be excised if present, and

then is closed with interrupted inverting absorbable

sutures. The abdomen is closed in a routine manner.

Figure 30.1 Figure 30.2

Figure 30.3 Figure 30.4

Figure 30.5, 30.6

A patent omphalomesenteric duct presents with a fis- tula at the umbilicus through which small bowel con- tent is discharged. There may or may not be an asso- ciated mucosal remnant at the umbilicus. Surgical management is excision of the entire fistula, the in- testinal end of which usually widens into a Meckel’s diverticulum.

The umbilical end of the fistula is excised circum- ferentially. The omphalomesenteric duct is then ap- proached through a sub-umbilical incision. After in- cising the skin and subcutaneous tissues, these are retracted, and the patent omphalomesenteric duct is identified by blunt dissection. The abdominal wall

fascia is opened transversely on either side of the fis- tula, or a midline incision may be used. Both umbili- cal arteries, the single vein and the urachal remnant are ligated and divided. The umbilical end of the fis- tula is brought out through the sub-umbilical inci- sion. The omphalomesenteric duct is dissected into the peritoneal cavity and its insertion into the termi- nal ileum is identified, exteriorized through the sub- umbilical incision, and resected as described for exci- sion of a Meckel’s diverticulum. The ileum is repaired by end-to-end anastomosis. The umbilical incision is closed using a purse-string suture and the abdominal incision is closed in layers using absorbable sutures.

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Figure 30.5

Figure 30.6

CONCLUSION

Post-operative care includes nasogastric tube drain- age of the stomach and intravenous fluids are re- quired until normal gastrointestinal function is re- established. Post-operative antibiotics may be given for prophylaxis against wound infection if indicated.

Failure of the viteline duct to regress results in anomalies that may require resection to prevent or

treat complications. The risk of post-operative com- plications, notably wound infection, is low and the outcome of surgery is excellent. Successful use of a la- paroscopic approach for these anomalies has been reported.

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SELECTED BIBLIOGRAPHY

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Swaniker F, Soldes O, Hirschl RB (1999) The utility of techne- tium 99

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Teitlebaum DH, Polley TZ, Obeid F (1994) Laparoscopic diag- nosis and excision of Meckel’s diverticulum. J Pediatr Surg 29 : 495–497

St Vil D, Brandt ML, Panic S (1991) Meckel’s diverticulum in

children: a 20 year review. J Pediatr Surg 26 : 1289–1292