Malrotation Flashcards
A previously well 3-week-old infant exhibits a sudden onset of bilious vomiting. Which of the following is the most likely diagnosis?
A. Pyloric stenosis B. Duodenal atresia C. Malrotation of the midgut D. Intussusception E. Tracheoesophageal fistula (TEF), H type
ANSWER: C
For a patient with bilious emesis, which would be the most appropriate initial diagnostic test?
A. Upper GI contrast study B. Abdominal ultrasound C. Barium enema D. Abdominal radiograph E. CT scan
ANSWER: A
COMMENTS: Infants with intestinal obstruction distal to the ampulla of Vater exhibit bilious emesis.
Fifty percent of children with malrotation have bilious emesis during the first few weeks of life.
Infants with malrotation are at a risk for midgut volvulus and possible ischemia.
Infants with a previous history of normal feedings in whom a sudden onset of bilious vomiting develops should be immediately evaluated for midgut volvulus.
Midgut volvulus is best demonstrated by an upper GI series showing an abrupt cutoff from failure of contrast material to pass beyond the distal duodenum or a corkscrew pattern of a partial obstruction from the torsed intestines (or both), whereas malrotation is demonstrated by an aberrant course of the duodenum and duodenal–jejunal junction.
A barium enema can be misleading in the diagnosis of malrotation because the position of the cecum cannot be relied on to rule in or rule out malrotation.
As soon as a diagnosis is made, the infant should be taken immediately to surgery. If for some reason the patient is unable to get an upper GI series in a timely fashion, he or she should proceed to the operating room for immediate exploration to avoid complications from volvulus.
Pyloric stenosis or TEF is not accompanied by bilious vomiting.
The symptoms of infants with H-type TEF are usually feeding difficulties and recurrent pneumonia.
The main symptoms associated with intussusception are colicky abdominal pain and bloody stools.
Duodenal atresia may mimic malrotation in the first 24 to 48 h of life, but at 3 weeks of age, duodenal atresia should already have been diagnosed and treated.
Importantly, malrotation of the midgut is frequently associated with duodenal atresia and should be searched for at the time of repair of duodenal atresia.
A 2-month-old otherwise healthy male presents with a 10-h history of bilious vomiting. An upper GI shows a corkscrew appearance of the duodenum that does not cross back over to the left side of the abdomen. Which of the following is correct regarding the management of this patient?
A. Orogastric tube should be placed, and the patient should have serial abdominal examinations over the next 24 h.
B. If intestinal volvulus is found at operation, the bowel should be rotated clockwise to reduce the volvulus.
C. Appendectomy should never be performed during surgery for this problem.
D. There is a high risk that this could recur even after surgery.
E. Surgery includes lysis of Ladd’s bands and positioning the duodenum along the right abdominal gutter.
ANSWER: E
COMMENTS: The radiologic finding described in combination with the clinical presentation of bilious emesis in an otherwise normally growing infant is diagnostic of intestinal malrotation.
Although malrotation itself does not cause significant morbidity, midgut volvulus, the most feared complication, does.
This can be catastrophic, resulting in complete necrosis of the intestine if not treated promptly.
Once the diagnosis of malrotation is made, an emergent laparotomy and correction should be performed.
If intestinal volvulus is found, the intestine should be rotated counterclockwise until the mesentery is straightened (“turn back the hands of time”).
Bowel viability should be determined, and any ischemic and necrotic areas have to be resected.
If areas that appear ischemic and do not pink up after the reduction of the volvulus are present, either resection should be performed or a second-look procedure in 24 h should be planned.
Ladd’s bands, which are peritoneal bands that extend across the duodenum causing an obstruction, are transected.
An appendectomy is performed since the cecum will usually be positioned in the left abdomen, making the diagnosis of acute appendicitis difficult.
The duodenum and small intestine are positioned in the right abdominal gutter; the colon is placed on the left.
Surgical fixation of the cecum and small bowel to attempt to prevent future volvulus is actually associated with an increased risk of obstruction and internal hernia.
The risk of revolvulus after a Ladd’s procedure is exceedingly low.
The laparoscopic approach to this procedure is being investigated.
Theoretically, there is less adhesion formation with laparoscopy; therefore there is a concern for inadequate postoperative fixation of the bowel and a higher risk of recurrence.
Further outcome studies with good follow-up are needed.
Discuss malrotation.
Disorders of intestinal rotation arise during gestation and represent the failure of normal 270-degree counterclockwise rotation of the intestines around the superior mesenteric artery (SMA).
Malrotation is associated with a narrow mesenteric base and intestines that are not fixed to the abdominal sidewall or retroperitoneum.
This anatomy predisposes the gastrointestinal (GI) tract to volvulus, in which the bowel twists around the SMA, forming a closed loop obstruction of the entire small bowel with interruption of arterial inflow and venous drainage.
Bilious emesis in an infant is the clinical finding that signals this life-threatening complication, and must be addressed with expedient operative exploration if the patient is in extremis versus rapid upper GI contrast study.
The definitive surgical management of malrotation with midgut volvulus is Ladd’s procedure, which includes reduction of volvulus, lysis of adhesive bands, and placement of the small bowel in the right abdomen and large bowel in the left abdomen.
What defines normal intestinal rotation and fixation?
Normal rotation is defined as a 270-degree counterclockwise rotation of the intestines around the superior mesenteric artery (SMA) axis.
The stomach resides above and anterior to the SMA.
Progressing along the intestinal tract, the second part of the duodenum lies to the right of the SMA, while the third part of the duodenum is posterior to the SMA.
The duodenum again crosses the midline, with the fourth portion to the left of the SMA.
Finally, the cecum and ascending colon lie to the right of the SMA.
Peritoneal attachments hold the duodenojejunal flexure in fixation at the ligament of Treitz, and the ascending and descending colon are likewise fixed to the retroperitoneum.
The normal axis of the mesentery thus lies between the ligament of Treitz and ileocecal fold; this wide fixation prevents twisting of the intestines.
What is the normal embryologic process of intestinal rotation?
Intestinal development begins in the fourth to eighth week of gestation, in which the intestinal tract is a straight tube.
The jejunum, ileum, cecum, right colon and part of the transverse colon enter into the umbilical cord, while the stomach remains in its position.
The duodenojejunal loop begins to curve downward and to the right of the super mesenteric artery (SMA) forming a 90-degree arc, then continues to rotate below the SMA to complete a 180-degree movement.
Finally, the duodenojejunal loop continues to the left of the SMA to achieve a full 270-degree rotation, which coincides with return of the rest of the intestines from the cord during the tenth week of gestation.
The return of the small bowel to the abdominal cavity pushes the fourth portion of the duodenum and the jejunum to the left of the SMA.
Finally, the cecum and right colon return to the abdomen and are fixed on the right side of the abdomen.
What is the incidence of intestinal malrotation and midgut volvulus?
Autopsy series suggest that 1:200–500 live births harbor some variant of intestinal malrotation.
The incidence of midgut volvulus is significantly lower, estimated to occur in 1:6,000 live births.
The majority of patients (58%) who develop symptoms from rotational abnormalities present during the first year of life, with 30% presenting in the first month of life.
What conditions are associated with intestinal malrotation?
Malrotation is most commonly associated with congenital diaphragmatic hernia, congenital heart disease, and omphalocele.
Up to 62% of patients present with some associated anomaly, including intestinal atresia, intussusception, anorectal malformations and Hirschsprung’s disease.
Gastroschisis patients all have malrotation.
What are the classifications of various disorders of intestinal rotation and fixation?
While any rotation less than 270 degrees is considered malrotation, there are several distinct categories of malrotation. Complications and risks associated with each category of malrotation vary.
a. Incomplete rotation is any degree of counterclockwise rotation less than 270 degrees about the SMA axis. Because of the broad definition, the position of the bowel and its attachments are highly variable.
b. Nonrotation occurs when the bowel returns to the abdominal cavity without any additional rotation and the cecum resides in the left upper quadrant of the abdomen. It occurs in 0.5–2% of patients and is not typically pathologic.
c. Reverse rotation is an abnormal clockwise rotation of the midgut, resulting in an anterior duodenum to the right of midline. The underlying transverse colon is often obstructed.
d. Paraduodenal (mesocolic) hernias are a result of incomplete fixation of either the ascending or descending colon in the retroperitoneum. Small bowel can herniate into that paraduodenal space and cause obstructive symptoms.
e. Mobile cecum describes a proximal colon that is not appropriately fixed in the right lower quadrant; however, the more proximal midgut (jejunum) is fixed in the left upper quadrant. These patients are still at a risk for volvulus.
How does malrotation lead to midgut volvulus?
Midgut volvulus is the most common and potentially devastating complication of malrotation, defined as a twisting of the bowel around its mesenteric base.
Risk of midgut volvulus is related to length of the mesenteric base; a narrower based malrotation has a higher risk of volvulus. Malrotation has a higher risk of volvulus than any of the variants.
What are the presenting features of midgut volvulus?
Bilious emesis in an infant is assumed to represent malrotation with midgut volvulus until proven otherwise.
This symptom alone should prompt surgical consultation with high index of suspicion for midgut volvulus.
Midgut volvulus can rapidly progress to severe systemic illness and hemodynamic compromise.
Other presenting features may include scaphoid abdomen. This results from initial proximal intestinal obstruction followed by proximal and distal intestinal emptying.
Crampy abdominal pain and blood per rectum may be encountered, though these can be late features of the disease process.
Because the obstruction is proximal, there may be no abdominal distension.
What is the worst-case scenario for patients with midgut volvulus and how can this be prevented?
The midgut volvulus can compromise blood supply to large portions of the small and large intestines.
The bowel can quickly become necrotic and cause severe metabolic derangements.
Mortality from a midgut volvulus ranges from 2–24%, with worse prognosis in patients with necrotic bowel, younger age, or associated anomalies.
Preventing bowel necrosis is best achieved by rapid diagnosis with an upper GI, aggressive resuscitation and broad-spectrum antibiotics, and early operative intervention to reduce the volvulus.
What is the differential diagnosis of infants who present with bilious vomiting?
Bilious emesis in a newborn infant is malrotation until proven otherwise by an upper GI study that shows normal rotation.
The differential for bilious emesis in a newborn includes duodenal atresia beyond the Ampulla of Vater.
Bilious emesis can also be caused by a functional or mechanical obstruction such as Hirschsprung’s disease, intussusception, or intestinal atresia.
Other etiologies like gastroenteritis or neonatal sepsis can also cause bilious emesis but have additional clinical features (profuse diarrhea, fever, etc.) that distinguish them from midgut volvulus.
How is midgut volvulus diagnosed?
A thorough history and physical exam should be performed on all patients suspected of a midgut volvulus secondary to malrotation. Most infants (93%) present with bilious emesis that is otherwise unexplained.
If a plain film radiograph has been obtained, it may show gastric outlet obstruction, a large stomach bubble, duodenal obstruction (“double bubble”), or may be without any focal abnormalities.
A normal plain film radiograph cannot rule out malrotation or a midgut volvulus, again because of a proximal obstruction there aren’t distended loops.
Most pediatric surgeons prefer an upper GI to diagnose malrotation, though contrast may not pass beyond the point of obstruction.
For a patient in extremis, rapid resuscitation and operative exploration without contrast studies may be indicated.
Abdominal ultrasound can diagnose midgut volvulus based on abnormal positioning of the superior mesenteric artery (SMA) and vein (SMV).
CT scans are generally not recommended for the diagnosis of malrotation or midgut volvulus.
What radiologic findings define normal rotation and rule out malrotation?
Contrast leaves the stomach and crosses the patient’s midline from left to right on anteroposterior view.
The patient is turned to the accommodate a lateral view, and contrast will flow posterior to the stomach through the retroperitoneal second portion of the duodenum.
The patient is transitioned back to an anteroposterior view, where contrast will then cross the midline from right to left of the spine while ascending towards the ligament of Treitz.
Finally, the duodenojejunal junction should be located at the same level as the gastric pylorus.
If all of these features are present, malrotation is ruled out. On ultrasound with doppler, normal rotation is defined by location of the SMV on the right and SMA on the left.
What radiologic findings are associated with malrotation and/or midgut volvulus?
On upper GI contrast study, the duodenojejunal junction will fail to cross midline to the left, and will lie inferior to the duodenal bulb.
Additionally, the second and third portion of the jejunum will not be located in the normal retroperitoneal location.
On ultrasound with doppler, reversal of the normal orientation of the mesenteric vessels is diagnostic of malrotation.
With abnormal rotation, the SMA will appear on the right, and the SMV will appear on the left. Specific radiologic findings associated with midgut volvulus include a corkscrew appearance of the duodenum and proximal jejunum.
Additionally, “whirlpool” appearance of the SMV and mesentery around the SMA may be seen on ultrasound in association with midgut volvulus.
What is the initial management of midgut volvulus?
Midgut volvulus should be managed with rapid diagnosis (upper GI), resuscitation and expedited operative exploration, with the goal of restoring blood flow to the bowel.
Resuscitation is best achieved with two large-bore IVs and 20 cc/kg bolus of normal saline or lactated ringer’s solution.
A nasogastric tube should be placed on suction to decompress the obstructed bowel proximally.
Broad spectrum antibiotic should be administered to cover translocation of enteric bacteria and possible perforation.
What is the surgical management of midgut volvulus?
Midgut volvulus is managed by the Ladd procedure, which begins with detorsion of the bowel in a counterclockwise fashion (as the volvulus is always in a clockwise direction).
“Turn back the hands of time” is a useful device to remember the counterclockwise direction of small bowel detorsion (Fig. 24.3).
Additionally, the abnormal peritoneal attachments (Ladd’s bands) between the duodenum and the right colon must be divided and the bowel should be repositioned a non-rotated position (see below).
How is a Ladd procedure performed?
The traditional Ladd procedure is performed through an upper transverse incision, though midline and laparoscopic approaches are commonly used.
After entering the abdomen, the bowel must be rotated in a counterclockwise direction, typically 720 degrees. The degree of detorsion can vary from one to multiple 360 degree turns.
As the bowel can appear initially dusky, purple, or black, sufficient time must be given for the reperfusion and recovery of the bowel.
The procedure then begins by identifying and dividing the abnormal peritoneal attachments to the duodenum, right colon and cecum (Ladd’s bands).
Division of these bands allows for the bowel to be placed in a position that maximizes the distance between the duodenum and the cecum.
The bowel is then returned to the abdomen with the small bowel on the right side of the abdomen and the large bowel on the left, with the cecum situated in the left upper quadrant.
The procedure is completed with an appendectomy, as the abnormal position of the appendix will obscure a possible acute appendicitis diagnosis in the future.
Bowel resection and diversion may have to be performed if there is frankly necrotic bowel or perforated bowel identified after untwisting the bowel and after sufficient time has passed to allow for bowel recovery intraoperatively.
What is the role of laparoscopic surgery in the surgical management of midgut volvulus?
Laparoscopic surgery can be useful in diagnosing malrotation when imaging find- ings are equivocal [7].
Laparoscopic Ladd’s procedure for malrotation is widely accepted. Some centers also advocate for a laparoscopic Ladd procedure in symptomatic patients without suspected volvulus, with conversion rates to open between 8 and 30% [8, 9].
Laparoscopy should not be used in a decompensated patient; patients with suspected midgut volvulus typically undergo an open Ladd procedure [10].
What is the postoperative care of a patient with midgut volvulus?
Broad spectrum antibiotics should be started preoperatively in patients with midgut volvulus and continued until the child appears well.
Antibiotics are targeted against bacterial translocation from compromised bowel.
Postoperative antibiotics for an uncomplicated Ladd procedure without midgut volvulus are not indicated.
Feeding postoperatively is dependent upon the degree and length of compromised bowel, as well as the return of bowel function.
Most surgeons opt to leave a decompressive nasogastric tube and await resolution of bilious output as an indication to begin to advance the diet.
Alternative means for providing nutrition parenterally should be considered in patients who may have delayed enteral intake.
What is are the potential complications of surgery for midgut volvulus and how are they managed?
Complications following a Ladd procedure are relatively rare if no bowel resection is performed.
A ten-year follow up study determined an overall complication rate of 9%, with the most common complications being bowel obstruction, incisional hernias and recurrent volvulus.
If compromised bowel does need to be resected, patients are at risk for short bowel syndrome.
While laparoscopic procedures may reduce the risk for adhesive small bowel obstructions, they may increase the risk for recurrent volvulus.
Overall, risk of recurrent volvulus is around 2%.
Additionally, patients who have undergone a Ladd procedure have risks for intussusception and prolonged postoperative ileus.
What is chronic midgut volvulus and how is it managed?
Though the majority of infants are diagnosed within hours of developing symptoms, older children and adults may have chronic symptoms of intermittent midgut volvulus that fail to be recognized.
Patients with undiagnosed malrotation may experience intermittent abdominal pain with or without emesis.
Most surgeons recommend a Ladd procedure in symptomatic patients, particularly in younger patients.
What is the treatment of asymptomatic or subclinical intestinal malrotation?
Treatment of asymptomatic malrotation or malrotation identified incidentally is somewhat controversial.
While most individuals present early in life, the risk of midgut volvulus does not completely disappear with age.
Determining the risk of volvulus by imaging is also limited, as no study can reliably identify a narrow-based mesentery.
Most surgeons advocate for elective surgery when malrotation is encountered incidentally in children.
However, the benefit of prophylactic Ladd’s surgery dwindles after childhood, so adults over the age of 20 may defer surgery if truly asymptomatic.
Laparoscopy can also be used to evaluate the mesentery width and mobility of the bowel.
It is important to note that upper GIs carry a false-positive rate that can be as high as 15%.
Which radiological finding is the most accurate in diagnosis of malrotation?
A caecum in the right upper quadrant
B duodenojejunal junction is below the pylorus, and to the right of the left vertebral pedicle
C partial duodenal obstruction
D inverted superior mesenteric artery (SMA) and vein (SMV)
E proximal jejunal loops on the left of the abdomen
B
The most helpful feature in the radiological diagnosis of malrotation is a duodenojejunal junction below the pylorus, and to the right of the left vertebral pedicle.
Care must be taken to decompress a distended stomach.
Seventy percent with this finding had malrotation confirmed at operation.
misleading anatomical variations in the position of the mesenteric vessels exist in patients with no abnormality.
Although inversion of the vessels suggest malrotation, a normal relationship between the SMA and the SMV does not exclude malrotation.
SPSE 1
*Photo from Sherif
