INTRODUCTION

Intestinal malrotation is the result of abnormal rotation of the intestinal tract and resultant abnormal fixation of the intestine. The normal embryologic process of intestinal lengthening begins at approximately 5 weeks of gestation when the gastrointestinal (GI) tract is essentially a short straight tube with vascular supply from the superior mesenteric artery (SMA) and the superior mesenteric vein (SMV) (Fig. 80-1). As the GI tract rapidly lengthens over the next 7 weeks, the duodenum makes its C-loop configuration posterior to the SMA, and the distal small bowel and cecum lengthen and reenter the abdomen anterior to the SMA, after a short time within the umbilical stalk, at about the 10th week of gestation. The cecum enters in the left upper quadrant and then rotates 270° counterclockwise to reach its final destination in the right lower quadrant. Once the rotation is completed, the intestine should be fixed in an inverted N arrangement with the ascending colon attached to the right retroperitoneal area, the small intestinal mesentery fixed at the terminal ileum in the right lower quadrant to the ligament of Treitz in the left upper quadrant, and finally, the descending colon attached to the left retroperitoneal area (Fig. 80-2). When this normal rotation and fixation do not occur, the cecum typically remains in the midabdomen or left upper quadrant, attempted cecal fixation results in band formation across the first and second portion of the duodenum (Ladd’s bands), and the entire midgut is attached by only a narrow band of tissue around the SMA, predisposing it to twisting (midgut volvulus) (Fig. 80-3). Certain patients, such as children with congenital heart disease and heterotaxia syndrome, are at increased risk for intestinal malrotation.¹ Other children with “nonrotation” of the intestine are those with congenital diaphragmatic hernia, gastroschisis, and omphalocele. However, these children rarely need operative intervention for the nonrotation because they are rarely symptomatic and volvulus almost never occurs in them.

Figure 80-1 Schematic ventrolateral view of a 5-mm embryo.

(Reprinted with permission from Smith SD. Disorders of intestinal rotation and fixation. In Grosfeld JL, O’Neill JA, Fonkalsrud EW, Coran AG (eds): Pediatric Surgery, 6th ed. Philadelphia: Mosby Elsevier, 2006; p 1343.)

Figure 80-2 Normal fixation of the midgut, shaped as an inverted N that prevents midgut volvulus.

(Reprinted with permission from Smith SD. Disorders of intestinal rotation and fixation. In Grosfeld JL, O’Neill JA, Fonkalsrud EW, Coran AG (eds): Pediatric Surgery, 6th ed. Philadelphia: Mosby Elsevier, 2006; p 1346.)

Figure 80-3 Pathophysiology of midgut volvulus with malrotation. The narrow mesenteric attachment in nonrotation (A) or incomplete rotation (B) predisposes the patient to midgut volvulus (C).

(A–C, Reprinted with permission from Smith SD. Disorders of intestinal rotation and fixation. In Grosfeld JL, O’Neill JA, Fonkalsrud EW, Coran AG (eds): Pediatric Surgery, 6th ed. Philadelphia: Mosby Elsevier, 2006; p 1347.)

It must be emphasized that, although the previous description of intestinal malrotation is the most common type, variations of the anomaly occur. Some patients with radiographic findings of malrotation may have normal fixation and little risk of volvulus, whereas ileal volvulus can occur with normal rotation, although that is rare.²

The classic clinical presentation of a child with intestinal malrotation is one with bilious vomiting. If the child also has midgut volvulus, hematemesis, hematochezia, and peritonitis may be present as late signs, but within the first hours of midgut volvulus, the abdominal examination may be deceptively benign. Approximately 60% of patients with intestinal malrotation present in the first week of life, 80% in the first month of life, and 90% in the first year of life, but the patient may be asymptomatic until adulthood.³

The diagnosis of intestinal malrotation is best made by emergent upper gastrointestinal (UGI) study when the diagnosis is considered. A normal examination, thus ruling out malrotation, requires that the fourth portion of the duodenum crosses the midline to the left of the vertebra and ascends to the level of the greater curvature of the stomach. Volvulus may be diagnosed by UGI if the contrast forms a sharp “beak” at the third portion of the duodenum without contrast passing distally, or rarely, a corkscrew appearance of the contrast is seen at the duodenal-jejunal junction⁴ (Fig. 80-4). Malrotation may also be diagnosed by abdominal ultrasound or computed tomography (CT) scan with intravenous contrast because of an abnormal relationship between the SMA and the SMV. However, UGI remains the most commonly used examination.

Figure 80-4 Lateral view of an upper gastrointestinal study shows intestinal malrotation with midgut volvulus. Note the “corkscrew” appearance of the contrast in the duodenum.

INDICATIONS

In the symptomatic patient with malrotation, urgent operation to correct the condition is indicated. In asymptomatic patients with malrotation, elective operation to prevent midgut volvulus is also indicated.

OPERATIVE STEPS (THE LADD PROCEDURE) (Fig. 80-5)

Figure 80-5 Operative correction of intestinal malrotation with midgut volvulus. A, The appearance of the viscera upon entering the abdomen. B, The intestinal mass is delivered out of the wound and pulled downward. C, The volvulus is corrected by untwisting the midgut in a counterclockwise direction. D, Ladd’s bands are lysed. E, The mesentery is widened, and the intestine is returned to the abdomen with the duodenum straightened and coming down the right side, and the cecum (after appendectomy) is placed into the left lower quadrant.

(A–E, Reprinted with permission from Smith SD. Disorders of intestinal rotation and fixation. In Grosfeld JL, O’Neill JA, Fonkalsrud EW, Coran AG (eds): Pediatric Surgery, 6th ed. Philadelphia: Mosby Elsevier, 2006; p 1355.)

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