Normal rotation of fetal intestine. (a) Orientation of the bowel in the umbilical cord before rotation starts. (b) Initial 90° anticlockwise rotation (stage I). (c) Further 180° anticlockwise rotation (stage II), which brings the duodenojejunal loop below and to the left of the superior mesenteric artery and cecocolic loop above and to the right of the superior mesenteric artery (From Lister J (1990) Malrotation and volvulus of the intestine. In: Lister J, Irving IM (eds) Neonatal surgery, 3rd edn. Butterworth & Co, London)
Normal intestinal rotation includes a 270° anticlockwise rotation of both the duodenojejunal loop and the cecocolic loop around the axis of the superior mesenteric artery. As a result, the duodenojejunal loop passes from a position above the superior mesenteric artery to a position below and finally to the left side of the artery, while the cecocolic loop passes from a position below the superior mesenteric artery to a position above and finally to the right of the artery (Fig. 17.1a–c).
The process of intestinal rotation has been traditionally divided in three stages. Stage I includes the initial 90° anticlockwise rotation, which will result in positioning of the duodenojejunal loop to the right of the superior mesenteric artery and the positioning of the cecocolic loop to the left of the artery (Fig. 17.1b). This stage occurs during the extracelomic phase of intestinal development. Stage II corresponds to the next 180° anticlockwise rotation, which takes place while the intestine returns into the abdomen and is completed by the end of the 12th week. These further 180° will complete the total 270° rotation, which will finally position the duodenum below the superior mesenteric artery and the duodenojejunal junction to the left of the superior mesenteric artery, as well as the colon above the superior mesenteric artery and the cecocolic loop to the right of the artery (Fig. 17.1c). Stage III constitutes the final 90° anticlockwise rotation of the cecocolic loop, which is usually completed until birth and results in the descent of the cecum from the right hypochondrium below the liver to its final position in the right iliac fossa. Stage III is attributed to differential growth. It must be highlighted that the staging of intestinal rotation serves only for understanding purposes, while the intestinal rotation is, in reality, a continuous process and should be conceived as such.
After normal rotation and fixation will be completed, the normal mesenteric attachment will extend from the ligament of Treitz, at the level of the pylorus, to the cecum. The second and third portion of the duodenum, as well as the ascending and the descending colon, will be fixed retroperitoneally [1–5].
17.1.2 Disorders of Intestinal Rotation and Fixation
22.214.171.124 Complete Non-rotation
The term refers to the absence of any intestinal rotation. It is characterized by a small and large bowel coursing vertically and a common longitudinal mesentery.
126.96.36.199 Incomplete Rotation
The term refers to the absence of stage II and III rotation, i.e., after the initial 90° anticlockwise rotation of the duodenojejunal and cecocolic loop around the superior mesenteric artery axis, no further rotation has occurred. As a result, the duodenum and small bowel are located on the right side of the artery and the cecum and colon on the left. Congenital adhesive bands between the bowel loops and the parietal peritoneum are often encountered.
The term refers to abnormalities occurring during stage II rotation and might include several different types based on the degree of rotation accomplished. In the commonest type, the intestinal rotation has stopped at some point just before the 180°, and, thus, the duodenojejunal loop has failed to cross the midline and lies to the right of the superior mesenteric artery (Fig. 17.2). Similarly, the cecocolic loop has rotated for almost 180° but no further and lies anterior to the duodenum and to the superior mesenteric artery or slightly to the left. Congenital adhesive bands, traditionally known as Ladd’s bands, course from the cecum to the parietal peritoneum usually obstructing the second part of the duodenum.
Commonest type of malrotation. Anticlockwise rotation of duodenojejunal and cecocolic loops has stopped at 180° (From Lister J (1990) Malrotation and volvulus of the intestine. In: Lister J, Irving IM (eds) Neonatal surgery, 3rd edn. Butterworth & Co, London)
188.8.131.52 Reverse Rotation
It refers to less common types of malrotation, in which the first 90° anticlockwise rotation (stage I) is followed by further 90–180° in the clockwise direction. As a result, the duodenum lies anterior to the superior mesenteric artery. The position of the cecum varies, based on the degree of its rotation. It might descend in the lower abdomen behind the small bowel mesentery, after a 90° clockwise rotation (Fig. 17.3), or it might cross the midline behind the superior mesenteric vessels and reach the right iliac fossa—after a 180° clockwise rotation (Fig. 17.4).
Reverse rotation following the initial anticlockwise 90° rotation of stage I. The 90° clockwise intestinal rotation (From Lister J (1990) Malrotation and volvulus of the intestine. In: Lister J, Irving IM (eds) Neonatal surgery, 3rd edn. Butterworth & Co, London)
Reverse rotation following the initial anticlockwise 90° rotation of stage I. Complete clockwise intestinal rotation through 180° (From Lister J (1990) Malrotation and volvulus of the intestine. In: Lister J, Irving IM (eds) Neonatal surgery, 3rd edn. Butterworth & Co, London)
184.108.40.206 Atypical Malrotation or Malrotation Variant
The intestinal rotation has been interrupted at some point between 180 and 270°. As a result, the ligament of Treitz is to the left of the midline but lower than the level of the pylorus.
In most cases of abnormal intestinal rotation and fixation, the small intestine has a narrow mesenteric base and, therefore, is prone to twist around the mesenteric vessels on a clockwise direction causing midgut volvulus. Other causes of intestinal obstruction in malrotation are the kinks and compression of the lumen caused by the congenital bands.
The lack of normal fixation of the right or left colon might result in the formation of potential spaces within the mesocolon, like hernial sacs, in which the small intestine might be entrapped causing right or left mesocolic hernias (Fig. 17.5) . These internal hernias might cause recurrent partial obstruction of the small bowel or might eventually result in complete obstruction and strangulation [7–16].
Right (a) and left (b, c) mesocolic hernias. The interrupted line in (a) shows the surgical incision at the area of the lateral peritoneal reflection used to reduce the herniated small bowel from the mesocolon. Note that the inferior mesenteric vein delineates the right margin of the left mesocolic hernias in (b) and (c) (From Willwerth BM et al. (1974) Congenital mesocolic (paraduodenal) hernia: embryologic basis of repair. Am J Surg 128:358)
17.2 Epidemiology and Associated Malformations
Intestinal malrotation is seen in up to 1:6000 live births. Most patients with volvulus (52–64 %) present in the first month of life and the majority of them (70 %) within the first week of life. Sporadic cases occur throughout life. Associated anomalies are found in 30–60 % of cases of malrotation. These include diaphragmatic hernias, exomphalos and gastroschisis, complete duodenal atresia or duodenal webs, jejunal atresia, Hirschsprung’s disease, anorectal malformations, and mesenteric cysts. Rotation and fixation abnormalities are also known to coexist with heterotaxy, with 70 % of these patients having malrotation [9, 10, 17, 18].
17.3 Clinical Manifestations
The primary symptom is the sudden onset of forceful vomiting, usually bilious and less commonly yellowish, in a previously healthy infant. Vomiting might be due to duodenal obstruction caused by Ladd’s bands, in the absence of volvulus, or might be the result of an acute obstruction caused by midgut volvulus. Crampy abdominal pain is also common. The obstruction might not be complete, so meconium and stool may be passing. Blood-stained emesis and passage of blood per rectum suggest bowel strangulation and are ominous signs.
Abdominal distention may or may not be present. Sometimes, the upper abdomen might appear distended and the lower abdomen scaphoid. Generalized distention is usually indicative of gangrenous volvulus and is a late sign. Tenderness on palpation is not a constant finding and, like abdominal distention, might be a late sign. Dehydration secondary to vomiting and/or intestinal ischemia, metabolic acidosis, and sepsis develop rapidly.
Intermittent or partial chronic midgut volvulus usually presents in children older than 2 years with symptoms of chronic vomiting, usually bilious, intermittent colicky abdominal pain, hematemesis, diarrhea, constipation, failure to thrive, and protein-calorie malnutrition.
17.4 Radiologic Diagnosis
A plain abdominal film showing gaseous distention of the stomach (Fig. 17.6a), and sometimes of the proximal duodenum as well (Fig. 17.6b), and a relatively gasless pattern in the rest of the abdomen is typical of midgut volvulus. Such a film might be all what is required to make the diagnosis in an infant with bilious vomiting, who is not stable enough to undergo an upper GI contrast study. However, plain abdominal radiography may not always be diagnostic, and, thus, an upper GI contrast study should always be considered in a bilious vomiter with a normal abdominal film.
Plain radiographs of infants with midgut volvulus, showing gaseous distention of the (a) stomach and of the (b) stomach and duodenum, with a paucity of gas distally
The upper GI contrast study is the investigation of choice for the evaluation of a patient with suspected abnormalities of intestinal rotation. In normal intestinal rotation, the duodenum descends to the right of the midline, courses transversely to the left, and then ascends to the left of the midline up to duodenojejunal junction at the level of the pylorus; the loops of the proximal jejunum are subsequently seen on the left of the midline.
In malrotation, the duodenum descends to the right of the midline and fails to course transversely to the left of the midline (Fig. 17.7a). Instead of crossing the midline, the contrast medium is seen to fill the jejunal loops on the right of the midline (Fig. 17.7b). Delay in the passage of the contrast into the jejunal loops and the characteristic spiral configuration of the proximal jejunum, known as “corkscrew” sign, indicate obstruction because of midgut volvulus (Fig. 17.8). In atypical malrotation, the duodenojejunal junction is demonstrated at the midline or to the left of the midline but lower than the level of the pylorus (Fig. 17.9).