Table of Contents
Introduction to Pediatric Intestinal Malrotation
Normal embryonic development
During the 2nd month of embryonic life, intestinal loops rotate in the yolk stalk outside the abdomen around the axis of the superior mesenteric artery. The duodenojejunal loop grows faster than the distal loop which facilitates its rotation of 90 ° anti-clock wise. After the 2nd month, the duodenojejunal loop returns to the abdomen and rotates for additional 180 ° anti-clock wise. Fixation of the rotated bowel follows to the retroperitoneum. The fixation of the bowel loops with a mesentery extending from the upper left abdomen to the lower right abdomen.
Nonrotation results after the return of the bowel loops to the abdomen with no rotation which leads to the abnormal location of the colon to the left of the abdomen and the small bowel to the right. It is usually asymptomatic and discovered accidentally with imaging studies. Malrotation is more serious and patients are at increased risk of volvulus. During malrotation, the cecocolic loop rotates for 90 ° leading to fixation of the cecum in the mid-upper abdomen with bands of peritoneum than can cause intestinal obstruction.
Clinical Picture of Pediatric Intestinal Malrotation
Acute intestinal obstruction
Malrotation can present with acute intestinal obstruction or insidious onset of chronic symptoms in older children. Acute intestinal obstruction presents with bilious vomiting, abdominal pain and distension, hypovolemia and sometimes peritonitis. Chronic symptoms of malrotation include abdominal pain, vomiting, chronic diarrhea failure to thrive, biliary stones and pancreatitis.
Malrotation leads to twisting of the narrow based mesentery around the superior mesenteric artery leading to intestinal ischemia and necrosis. A process known as volvulus. Children present with acute episode of vomiting, abdominal pain, drawing up the legs, bleeding per rectum, tachycardia, tachypnea, hypovolemic shock and even sepsis. Volvulus can be self-limited leading to intermittent attacks of vomiting and abdominal pain.
Other forms of intestinal obstruction due to malrotation are duodenal atresia or duodenal obstruction with Ladd bands leading to vomiting with no abdominal distension.
Omphalocele is an abdominal wall defect at the midline covered only by amnion and peritoneum containing bowel loops. Warton’s jelly lies in between the two layers and the umbilical vessels run to insert the apex of the sac.
Pathogenesis occurs during the embryonic development, due to rapid growth of the intestine and abdominal contents more than the abdominal cavity leading to physiologic midgut herniation. It becomes smaller and the abdominal contents protrude into the extraembryonic coelom at the base of the umbilical cord. Physiologic midgut herniation is evident at the 9th to 11th week post menstrual which should be reduced into the abdominal cavity by the 12th week. It is associated with nonrotation of the intestine and considered rotational anomaly.
Omphalocele sac is not common with the liver protruded outside the abdomen and it is more common with aneuploidy. Ultrasonography is used to diagnose omphalocele prenatally and postnatally. Maternal alpha fetoprotein and genetic testing can be used to diagnose
Ultrasonography is used to diagnose omphalocele prenatally and postnatally. Maternal alpha fetoprotein and genetic testing can be used to diagnose fetus with aneuploidy. Following diagnosis, the fetus should be followed with serial ultrasonography, nonstress tests and biophysical profile to evaluate timing and mood of delivery. Cesarean section is only performed when indicated for specific cases with liver herniation inside the sac. After delivery; the defect should be covered with saline soaked dressings and covered with sterile plastic wrap until closure of the defect is feasible.
Investigations of Pediatric Intestinal Malrotation
Simple laboratory tests can be used according to the presentation but they are not used for final diagnosis. CBC with differential, stool guaiac and hemoglobin are helpful in general assessment. The first imaging modality of choice is plain abdominal radiographs. It is used in stable patients to exclude intestinal perforation and pneumoperitoneum. Gasless abdomen is common in infants with volvulus. Double bubble sign indicated duodenal obstruction while passage of a nasogastric tube to the abnormal position of the duodenum is diagnostic.
GI contrast series
Plain X-ray is followed by upper GI contrast series which is more accurate and sensitive. Upper GI contrast series is definitive in the diagnosis malrotation as misplaced duodenum, corkscrew duodenum, volvulus with beaking duodenum and duodenal atresia. Small bowel follow-through, barium enema and laparoscopy can be used in cases where the upper GI contrast series are not conclusive. Ultrasonography is also limited in the diagnosis but it can be used for screening with abnormal positions of the third part of the duodenum, superior mesenteric artery and vein.
Whirlpool sign and dilated duodenum also can be visualized in case of volvulus. CT scan is rarely used for the diagnosis of intestinal malrotation due to limited diagnostic value but in specific cases it can be beneficial e.g. whirlpool sign in case of volvulus due to twisting of the bowel mesentery around the superior mesenteric artery. MRI is useful with pregnant patients and in-utero diagnosis due to when the ionizing radiation is contraindicated. Flexible sigmoidoscopy is used in volvulus through the lower GI tract.
Differential diagnosis of Pediatric Intestinal Malrotation
Malrotation in infants and young children should be differentiated from other diseases with a similar presentation including; acute necrotizing enterocolitis in infants, intussusception and other causes of intestinal obstruction or peritonitis. Acute necrotizing enterocolitis presents early in infancy especially with premature babies. Plain radiographs show abdominal distension, pneumatosis intestinalsis and air in the portal vein or the peritoneal cavity. Intussusception presents with blood in stool and bilious vomiting. Ultrasound shows bull’s eye sign due to invagination of a bowel loop within another loop.
Management of Pediatric Intestinal Malrotation
Patients in shock
Patients presenting with acute intestinal obstruction should be evaluated for signs of shock, sepsis and peritonitis. First aid measures should be implemented to those in shock including; resuscitation with fluids, nasogastric tube decompression, broad spectrum antibiotics and exploratory laparotomy. There is no need for imaging diagnosis in these patients.
Imaging diagnosis and surgical intervention
In patients with no emergent symptoms, imaging diagnosis is conducted followed by surgical management to fix the bowel loops and prevent future malrotation. The surgical intervention consists of division of any bands or adhesions compressing the duodenum, widening of the mesenteric base, appendectomy, exclusion of duodenal obstruction and making adhesions to fix the bowel to the right and the colon to the left to prevent malrotation.
Complications of surgery include short gut syndrome due to resection of long segment of necrotic bowel, intestinal obstruction due to post-operative adhesions and recurrence of volvulus.