Malrotation

Malrotation is a structural anomaly of the GI tract resulting from improper sequence of events in the embryological development of the gut, which predisposes the bowel to twist around its mesentery resulting in a condition known as volvulus.

http://www.wikiradiography.net/page/Neonatal+Abdominal+Pathology

Epidemiology

1. Occurs between 1/200 – 1/500 live birth
2. Traditionally, considered primarily a disease of infancy
3. However, prevalence of malrotation in children over one year of age and adults may be higher than previously thought.

Embryology

• Between the 4th to 8th weeks of development expansion of the GI tract causes the primary intestinal loop to buckle into the area of the yolk stalk.
• As the primary intestinal loop buckles it twists 90 degrees counterclockwise.
• The primary loop returns to the abdomen during the 8th to 10th week of gestation with an additional 180 degrees counterclockwise rotation.
• The proximal portion of the bowel is fixed to the retroperitoneum early in gestation, at the ligament of Treitz, whereas fixation of the colon is gradual and usually completed near term.

Pathophysiology

1. Malrotation refers to impaired rotational process of the midgut as it returns from outside of the abdominal cavity (extracoelomic phase of development) to the abdominal cavity.
2. The impaired rotational process could be non-rotation or partial rotation and/or combination of both which results in abnormal fixation of the cecum to the right abdominal wall and obstruction of duodenum by bands of peritoneum called Ladd bands.
3. Ladd bands cross the duodenum and can cause extrinsic compression and obstruction of the duodenum.
4. Malrotation results in narrow and long base of mesentery which predisposes bowel to twist around it; this condition is known as volvulus.
5. Often volvulus occurs about the superior mesenteric artery axis, which results in ischemia of regions supplied by the artery, from duodenum to the splenic flexure. 

Differential Diagnosis

The differential diagnosis of intestinal malrotation should be guided by the age of the patient. In premature infants it is important to consider necrotizing enterocolitis as well, and in older infants, intussussception is also commonly associated with bilious vomiting. In older children one should consider any cause of intestinal obstruction, vomiting, and acute abdomen, including:

1. Trauma
2. Foreign body ingestion
3. Poisoning
4. Appendicitis
5. Incarcerated inguinal hernia
6. Peptic ulcer disease
7. Constipation
8. Gastroenteritis
9. Urinary tract infection
10. Pelvic inflammatory disease
11. Ectopic pregnancy

Presentation

• Signs of bowel obstruction
• Bilious vomiting in the neonate is an indication of malrotation until proven otherwise and is usually due to acute volvulus
• Chronic volvulus will involve recurrent abdominal pain and malabsorption, as well as diarrhea, constipation, and gastroesophageal reflux.
• Acute duodenal obstruction occurs mainly in infants and involves the compression of the duodenum by Ladd bands. Patients demonstrate forceful vomiting.
• Chronic duodenal obstruction may appear in older children (preschool-age).
  • Other less common presentations can include failure to thrive, solid food intolerance, malabsorption, chronic diarrhea

Evaluation

1. For children that are stable upon presentation, radiologic evaluation is indicated, including plain radiographs and an upper GI contrast series.
2. Diagnostic findings on a plain radiograph include an abnormally positioned duodenum as shown by placement of a nasogastric tube, and the “double-bubble” sign specific to duodenal obstruction.
3. Be aware that plain radiographs may be completely normal in individuals with malrotation as well.
4. Gold standard – upper GI study with contrast. These include visualization of a misplaced duodenum with a “corkscrew” appearance,  and duodenal obstruction.
5. Other imaging modalities that may be used include a lower GI series (contrast enema), ultrasound, and CT scanning.

Management

1. Volvulus is a surgical emergency, delay in untwisting bowel can lead to ischemic necrosis
2. Ladd procedure  - divide peritoneal (Ladd) bands which obstruct the duodenum, separate the duodenum and jejunum to the right side of the abdomen and the colon to the left side of the abdomen.
3. The goal is to minimize risk of future volvulus by widening base of mesentery.
4. Appendectomy is also always performed to eliminate appendicitis as a potential diagnosis in future episodes of abdominal pain
5. The most common complication of midgut volvulus is short-bowel syndrome. Patients should be monitored for malabsorption and may require very long-term parenteral nutrition.
6. In the absence of volvulus or bowel ischemia, as might be seen in the older child or adult, the Ladd procedure can be performed laparoscopically. In addition, for those patients who have asymptomatic malrotation, or malrotation incidentally discovered, laparoscopic correction is an option as well.
7. Most surgeons recommend surgery for malrotation, regardless of whether symptoms are present or not, due to the risk of volvulus.

References

1. El-Gohary Y, Alagtal M, Gillick J. Long-term complications following operative intervention for intestinal malrotation: a 10-year review. Pediatr Surg Int. 2010 Feb;26(2):203-6.
2. Hagendoorn J, Vieira-Travassos D, van der Zee D. Laparoscopic treatment of intestinal malrotation in neonates and infants: retrospective study. Surg Endosc. 2011 Jan;25(1):217-20.
3. Larsen, W. Essentials of Human Embryology. Churchill Livingstone. 1998. 160-171
4. Millar AJ, Rode H, Cywes S. Malrotation and volvulus in infancy and childhood. Semin Pediatr Surg 2003; 12:229.
5. Nehra D, Goldstein AM. Intestinal malrotation: varied clinical presentation from infancy through adulthood. Surgery 2011; 149:386.
6. Stevenson, R.,Ziegler, M. Abdominal pain unrelated to trauma. Pediatrics in Review. 1993;14;302.
7. Ross III, Arthur J., Intestinal Obstruction in the Newborn. Pediatrics in Review 1994; 15; 338.
8. Ross, A., LeLeiko, N. Acute Abdominal Pain. Pediatrics in Review. 2010;31;135