Chapter 48 Anomalies of Intestinal Rotation

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1 Chapter 48 Anomalies of Intestinal Rotation François I. Luks Rotational anomalies of the intestinal tract refer to the failure of the primitive midgut to establish its normal anatomical relationships and attachments as it develops into duodenum, small bowel, and proximal colon. The incidence of isolated malrotation in the general population is estimated at 1 in 500 live births, but it is much more common in a number of genetic, chromosomal, and congenital disorders. The term malrotation is most commonly used to describe nonrotation, whereby the duodenum fails to form its characteristic C-loop and instead runs in a straight cephalocaudal line into the proximal jejunum. Other rotational anomalies include incomplete rotation, where the normal rotational process of the midgut has been interrupted, reverse rotation, and errors of intestinal fixation, typically of the cecum and the ascending and descending colon. Embryology The final anatomic arrangement of the midgut follows a complex series of events that starts around the fourth week of gestation, when the straight intestinal tube rapidly elongates and the embryo develops left right differentiation. Midgut rotation has been artificially divided into three stages, representing the various positions of the distal duodenum and the cecum as they follow a 270 counter-clockwise path. The exact understanding of this intricate four-dimensional process is less important than the final anatomic relationships between the various components of the midgut, the mesentery and the vascular pedicle of the superior mesenteric artery. The key features of normal intestinal rotation include: (1) the duodenum describes a C-loop with concavity to the F.I. Luks (*) Warren Halpert Medical School of Brown University, Providence, RI, USA and Division of Pediatric Surgery, Hasbro Children s Hospital, 2, Dudley Street, Suite 180, Providence, RI 02905, USA francois_luks@brown.eduv patient s left and the third portion of the duodenum (at the ligament of Treitz) to the left of the midline; (2) the superior mesenteric artery runs in front of the third portion of the duodenum, which is in a retroperitoneal position; (3) the mesentery is attached posteriorly along a broad line that runs from the ligament of Treitz in the left upper quadrant to the cecum in the right lower quadrant, thereby preventing torsion of the mesentery on its axis (Fig. 48.1), and (4) the colon describes a frame with the cecum and ascending colon fixed along the right side of the abdomen and the descending colon fixed along the left side. The initial mechanisms of normal intestinal rotation are still poorly understood, but likely involve the same genes that are responsible for other aspects of asymmetrical development, the most important of which is the infolding of the primitive heart to form a four-chamber structure with clear separation between systemic and pulmonary circulations. Several disorders of left right differentiation, such as the heterotaxia syndromes, are therefore often associated with some form of anomalous intestinal rotation, abnormal budding of the endodermal appendages (polysplenia or asplenia, biliary anomalies, preduodenal portal vein), and varying degrees of cardiac anomalies. In immotile cilia disorders such as Kartagener syndrome, 50% of patients have situs inversus/ambiguus or anomalous intestinal rotation. All these disorders may be related to abnormal expression or differential signaling of the Hedgehog genes, transforming growth factor (TGF) b, and tyrosine kinase receptor pathways, all of which play a crucial role in establishing left right asymmetry in the early embryo. As the intestinal tract rapidly elongates around the fourth week of gestation, it temporarily leaves the abdominal cavity through a wide umbilical ring, while it also undergoes its rotational changes: both the duodenum and the colon rotate 270 counter-clockwise to lie in their final configuration. The last stage of intestinal rotation is completed as the midgut returns to the abdominal cavity. Any event that interferes with this process can result in incomplete rotation or nonrotation of the midgut. Thus, congenital diaphragmatic hernia and abdominal wall defects are associated with malrotation. It should be noted that while the visual image of moving and rotating intestinal loops can be illustrative, the process is P. Mattei (ed.), Fundamentals of Pediatric Surgery, DOI / _48, Springer Science+Business Media, LLC

2 374 F.I. Luks Fig Cut-out view of the mesentery in normal rotation (left) and non-rotation (right). Normally, the posterior attachment of the mesentery stretches from the ligament of Treitz to the ileocecal valve (ICV), preventing torsion of the mesenteric vessels. In non-rotation, the posterior mesenteric attachment (between duodenum and ICV) is narrow, placing it at risk of volvulus around the superior mesenteric artery more likely one of differential growth and proliferation of specific portions of the primitive intestinal tube, as elegantly demonstrated by Kluth and Lambrecht in their scanning electron microscopy studies of the fetal rat. In the absence of normal intestinal rotation, the duodenum fails to cross the midline and its third portion lies to the right of the spine. The SMA never crosses the duodenum and lies within a narrow mesenteric base that connects the duodenojejunal junction with the cecum (Fig. 48.1). The cecum is in a left paramedian location and congenital bands between duodenum and cecum keep the mesenteric root attached in a single narrow pedicle rather than the broad base seen in normal rotation. This configuration places the mesentery at risk for complete volvulus, which results in vascular cut-off at the root of the SMA and ischemic necrosis of the entire midgut from duodenum to proximal transverse colon. Two other features of nonrotation or incomplete rotation can become clinically significant. The cecum is normally fixed to the right lateral abdominal wall by peritoneal folds. These bands (Ladd s bands) are frequently present in malrotation and cause varying degrees of duodenal or proximal jejunal obstruction as they cross from the cecum to the right peritoneal wall. In addition, the anomalous location of the appendix can create diagnostic uncertainty in patients presenting with acute appendicitis and left-sided abdominal pain. There are other, less common forms of rotational anomalies. These include reverse rotation, whereby the duodenum comes to lie in front of the colon, and fixation anomalies of the colon. When either the ascending or the descending colon fail to adhere to the posterior abdominal wall, small bowel loops can herniate through these mesocolic gaps and cause an intestinal obstruction. These conditions are not only rare, but very difficult to accurately diagnose preoperatively. Diagnosis The majority of children with malrotation present in infancy, but since abnormal intestinal rotation is often asymptomatic, its true incidence is unknown. The most dramatic presentation of malrotation is midgut volvulus. This must be suspected in any infant who presents with bilious vomiting, and prompt diagnosis is important to avoid ischemic loss of intestine. Midgut volvulus and other intestinal catastrophes are easily differentiated from hypertrophic pyloric stenosis, where vomiting is non-bilious and occurs in an otherwise well and hungry child. Bilious vomiting is seen in half of the infants and one third of those older than 1 month who present with malrotation or midgut volvulus. Bilious vomiting is not pathognomonic for malrotation and is seen with other forms of intestinal obstruction, such as duodenal atresia, annular pancreas, small bowel atresia, meconium ileus, and Hirschsprung disease. While these conditions are all surgical, they do not require immediate surgical exploration. Initial treatment consists of bowel rest, intravenous hydration, and nasogastric decompression. Midgut volvulus, on the other hand, demands rapid operative correction, as it is associated with extensive intestinal ischemia. Initially, the infant with midgut volvulus has a scaphoid abdomen, since the point of

3 48 Anomalies of Intestinal Rotation obstruction is so proximal. However, gastric distention can obscure this clinical finding. As venous and lymphatic congestion progress toward ischemia, the intestinal loops become thickened and fluid-filled, and abdominal distention develops. By then, the child appears sick, with significant hypovolemia from third-space fluid losses and vomiting. Sloughing of intestinal mucosa can occur, leading to bloody stools. Clinical features include tachycardia, oligo- or anuria, poor capillary refill, metabolic acidosis and, ultimately, vascular collapse. Imaging plays a central role in the diagnosis of malrotation. A plain abdominal radiograph is non-specific, but may sometimes suggest the diagnosis. In the presence of tight Ladd s bands, duodenal obstruction may be seen as a double bubble, similar to that seen in patients with duodenal atresia. Unlike the usual situation with duodenal atresia., there is usually some distal intestinal gas, unless a complete midgut volvulus is present. In that case, the abdomen is gasless, save for the gastric and duodenal bubbles. In advanced volvulus, intestinal ischemia may result in breaches in the mucosal barrier, and the clinical and radiographic signs may be indistinguishable from those of necrotizing enterocolitis. These include intestinal pneumatosis and portal vein gas. It is important to realize that more than one cause of proximal intestinal obstruction may be present in the same infant: duodenal atresia and duodenal web can be associated with malrotation, as can jejunal atresia. If the child s condition permits, malrotation is most reliably diagnosed with an upper gastrointestinal contrast study. As contrast leaves the stomach, the duodenum and proximal jej unal loops opacify to the right of the midline (Fig. 48.2). Normal rotation of the midgut includes a duodenal C-loop that crosses the midline and the ligament of Treitz (duodenojejunal Fig Upper gastrointestinal contrast study (UGI) in an infant with malrotation: the duodenum does not cross the midline (enhanced vertebral bodies) and the duodenojejunal junction lies to the right of the spine 375 junction) that is located to the left of the spine and at least as high as the pylorus. These are important landmarks, because even a nonrotated duodenum may be tortuous (particularly if Ladd s bands partially occlude the duodenal outlet). This may give the impression of a C-loop, but an incomplete one, whereby the duodenojejunal junction does not quite reach the level of the gastric outlet. Other features of malrotation on UGI include right-sided position of the majority of small bowel loops and absence of a typical colonic frame. Instead, ascending and transverse colon are all located to the left of the spine (Fig. 48.3). A contrast enema may show the colonic anatomy better, but this is a less reliable test even a partially or completely rotated colon does not rule out malrotation or, more importantly, a narrow-based mesenteric attachment and its associated risk of volvulus. In recent years, ultrasound has been increasingly accurate in detecting abnormal rotation. If the duodenum is clearly seen, it can be followed as it is supposed to cross the spine. The relationship of the superior mesenteric vessels is the most typical ultrasonographic feature of malrotation. Normally, the SMA is posterior and to the left of the vein. In malrotation, the SMA lies to the right of the vein. In midgut volvulus, the further torsion of the vessels can be clearly seen as a swirl, or whirlpool pattern, on Doppler ultrasound (Fig. 48.4). The duodenal obstruction may be clearly visible Fig UGI in an older child with malrotation. Note duodenum and small bowel on the right and colon on the left

4 376 F.I. Luks Fig Ultrasonographic signs of midgut volvulus. Top: swirling pattern of the superior mesenteric vessels due to volvulus of the mesentery. Bottom: beak-like obstruction of the duodenum (arrow) and the torsion may give it a bird s beak appearance (Fig. 48.4). Other ultrasonographic signs of advanced midgut volvulus include free peritoneal fluid, intestinal wall edema, pneumatosis, and portal vein gas. While often accurate, ultrasonography is not as reliable as UGI in the diagnosis of malrotation. The right-sided course of the duodenum and the mesenteric vessel inversion may be missed, and false-positive results may be seen with any process that pushes the root of the mesentery to the right, such as acute gastric distention, splenomegaly or a splenic hematoma. The whirlpool sign and duodenal obstruction can also be seen on abdominal CT, however CT is not the diagnostic procedure of choice for either malrotation or midgut volvulus. While it is the diagnostic cornerstone of malrotation, one should forgo the UGI study if midgut volvulus is suspected, particularly in the very young infant. Any delay in surgical intervention can result in irreversible ischemic damage to the entire midgut, which in turn may lead to short bowel syndrome or death. The combination of bilious emesis, a scaphoid abdomen (after gastric decompression), and shock require prompt exploration. If the presentation is less dramatic, it may be reasonable to obtain an UGI, as long as surgical delay is kept to a minimum. The typical appearance of midgut volvulus on UGI is a corkscrew or apple-peel appearance of the first jejunal loops, best seen in a lateral view (Fig. 48.5). The management of asymptomatic malrotation is the subject of some debate. In the past, many have argued that malrotation is never asymptomatic, since its discovery follows an imaging study that was obtained for a reason. However, the symptoms ascribed to malrotation are often vague and nonspecific, including gastroesophageal reflux, chronic emesis, colicky abdominal pain, malabsorption, chronic diarrhea, or failure to thrive. Moreover, the presence of certain pathologies (heterotaxia syndromes) will often lead to a search for Fig Midgut volvulus (lateral view of an UGI): note corkscrew appearance of the duodenum and proximal jejunum associated malrotation and the increased use of medical imaging has led to the incidental finding of malrotation in patients who truly have minimal to no symptoms. The diagnostic criteria for malrotation in older or asymptomatic patients are the same as in infants. Malabsorption and failure to thrive may be a result of chronic or intermittent volvulus and lymphatic congestion; vomiting and reflux symptoms may be secondary to partial duodenal obstruction by Ladd s bands.

5 48 Anomalies of Intestinal Rotation Treatment Midgut volvulus is a surgical emergency. Aggressive intravenous hydration is important to counteract the hypovolemia due to vomiting and third spacing, but this should not delay intervention. Antibiotics are administered prophylactically. A laparotomy is performed through a right transverse incision above the level of the umbilicus. Viscera are gently exteriorized and examined. Because of the volvulus, the colon (which now lies posteriorly) is obscured by the small bowel loops. While maintaining the intestinal loops moist and warm, the volvulus is untwisted by turning the intestinal mass in a counter-clockwise fashion. The torsion may be more than 360, and the intestinal mass must be gently and methodically untwisted until the colon comes into view. This should release vascular constriction and allow the ischemia to improve. In reality, a midgut volvulus is often confusing at first and care must be taken not to cause additional bowel damage during detorsion. In some patients, further confusion may be caused by the presence of situs ambiguus or situs inversus, whereby the stomach may be on the right and the liver midline or on the left. In these cases, the duodenum may be on the left and the colon on the right. Once the intestinal torsion is corrected, viability of the loops is assessed. A period of observation, during which tension on the mesenteric root is alleviated and the viscera are kept warm, may allow some return of perfusion. If necessary, a hand-held Doppler probe or fluorescein may be used to assess vascular status. Only if bowel loops are frankly necrotic should they be resected in some cases, it may be better to preserve borderline viable intestine and perform a second-look operation in h. Overly aggressive resection can result in short bowel syndrome. After the volvulus has been corrected, the malrotation itself needs to be addressed. It is also important to confirm the patency of the intestinal tract, particularly in very young infants: a newborn who presents acutely with midgut volvulus may also have a duodenal web. This is best ruled out by passing the nasogastric tube through the duodenum. As the duodenum is straight, this is easier than with normal rotation. Surgical correction of malrotation without midgut volvulus is not an emergency, and may even be unnecessary in some cases. The main purpose of intervention is to prevent future midgut volvulus. This implies that the anatomic condition of the patient predisposes to torsion. While most patients with malrotation have a very narrow mesenteric pedicle caused by the close proximity of the duodenum and the ascending colon, the mesenteric attachment in some patients may be wide enough so as to be essentially normal. In congenital diaphragmatic hernia, for example, the intrathoracic migration of small and large intestinal loops allows the posterior mesenteric attachment to stretch sufficiently to prevent 377 future volvulus. The same probably holds true for abdominal wall defects as well, although cases of midgut volvulus have been described in these patients. It has been speculated that the presence of intra-abdominal adhesions (particularly in gastroschisis) may limit the risk of volvulus, but objective evidence is lacking. Some surgeons will contemplate a Ladd procedure during laparotomy for the repair of congenital diaphragmatic hernia if the patient s condition warrants additional operative time. In all other patients with malrotation, surgical exploration should be considered. The classic surgical treatment of malrotation is the Ladd procedure. Its goals are to relieve any duodenal or jejunal obstruction and decrease the risk of future midgut volvulus by widening the mesenteric base. The viscera are carefully examined, and any bands crossing anteriorly to the duodenojejunal junction are divided (Fig. 48.6). These Ladd s bands are avascular, but care must be taken not to damage the underlying mesentery. The root of the mesentery is then exposed, and the avascular connections between the duodenum and the ascending colon are carefully dissected with Metzenbaum scissors. Cautery should be kept to a minimum as mesenteric injury is a real risk (particularly at the level of the SMA takeoff). The duodenum is then gently teased toward the patient s right side of the abdomen, while the cecum and ascending colon are pushed to the left. This fully exposes the superior Fig Laparoscopic take-down of Ladd s bands between cecum and right lateral abdominal wall (from Lessin MS and Luks FI. Laparoscopic appendectomy and duodenocolonic dissociation (LADD) procedure for malrotation. Pediatr Surg Int 1998, Springer. Used by permission)

6 378 F.I. Luks asymptomatic patient. Placement of the trocars is straightforward: a 5-mm telescope is introduced through the umbilicus. Instrument cannulas may be placed in the inguinal regions, which is cosmetically superior. Because the area of interest lies in the mid-abdomen, it is not easy to establish a classic diamond-shaped configuration between telescope, instruments and target. This lack of adequate triangulation and the short distance between telescope and target introduce a degree of difficulty to the laparoscopic procedure. Performing the operation with only two instruments may be challenging as well, since sharp division of the congenital bands requires adequate tension between duodenum and colon. If necessary, a third instrument port should be placed. The appendix lies in a periumbilical location and can be easily exteriorized through the trocar incision for open removal at the end of the laparoscopic procedure. Postoperative Care Fig Laparoscopic division of duodenocolonic bands to expose the root of the superior mesenteric artery and widen the posterior attachment of the mesentery (from Lessin MS and Luks FI. Laparoscopic appendectomy and duodenocolonic dissociation (LADD) procedure for malrotation. Pediatr Surg Int 1998, Springer. Used by permission) mesenteric vessels and their proximal branches (Fig. 48.7). The separation of duodeno-colic bands is all that is needed to widen the mesenteric base: duodenal fixation and cecopexy in their respective location is unnecessary. Again, in some patients the base of the mesentery is already wide enough. If the root of the SMA is clearly splayed between the duodenum and the cecum, no further dissection is required. Appendectomy completes the Ladd procedure as the appendix lies in an abnormal location, making diagnosis of acute appendicitis difficult. Some surgeons prefer to perform an inversion appendectomy, citing a lower risk of infection, since the intestinal tract is not opened: the mesoappendix is divided, and the appendix is inverted into the colon. An absorbable tie is used to ligate the appendix at its base. Now devascularized, the appendix will auto-amputate within days and be eliminated in the stool. Of course, classic appendectomy is simpler, fast, and actually very safe. All the steps of the Ladd procedure, except detorsion of a midgut volvulus, can be safely performed laparoscopically as well (Figs and 48.7). An increasing number of surgeons are now choosing this approach, particularly in the older, The postoperative course primarily depends on the intraoperative findings. In cases with volvulus and significant intestinal ischemia, a prolonged ileus is typically seen. If bowel resection was performed, parenteral nutrition might be required and the chronic treatment of short bowel syndrome may be difficult. If the operation was performed electively for malrotation alone, prompt recovery can be anticipated. The long-term results of Ladd s procedure are believed to be excellent. However, postoperative small bowel obstruction occurs in up to 14% of patients, similar to the cumulative risk of small bowel obstruction after laparotomy for other indications. Moreover, recurrent midgut volvulus has been described. Its true incidence is not known but probably occurs in less than 2% of patients. The laparoscopic approach is too new to provide reliable recurrence rates, but the minimally invasive approach appears to be at least as efficient as the classic operation. While operative treatment of midgut volvulus is very effective, it is important to note that chronic symptoms believed to be associated with malrotation (malabsorption, failure to thrive, vague abdominal complaints) are less often corrected. Thus, patients and parents must be warned preoperatively that the operation is mainly aimed at preventing future midgut volvulus, and that some or all symptoms may still be present postoperatively.

7 48 Anomalies of Intestinal Rotation 379 Summary Points Bilious vomiting in the newborn is a surgical emergency and suggests intestinal obstruction or midgut volvulus until proven otherwise. If the infant s condition allows it, a diagnostic upper gastrointestinal series (UGI) may be obtained, but one should be ready to perform a rapid surgical exploration without imaging. Initially, infants with midgut volvulus have a scaphoid abdomen (if the stomach is decompressed). Delay in recognition and treatment of midgut volvulus may lead to necrosis of the entire small bowel and part of the colon. Malrotation carries the risk of midgut volvulus at any age therefore, surgical exploration and a Ladd procedure is recommended even in the older and asymptomatic patient. The main goals of the Ladd procedure are to widen the basis of the mesentery to avoid torsion of the mesenteric vessels, relief of duodenal obstruction by congenital bands and appendectomy, to avoid future confusion if appendicitis were to develop. Editor s Comment Many people confuse the terms malrotation and volvulus; they are not interchangeable. Malrotation describes a specific anatomy that is in and of itself harmless and usually asymptomatic; however, patients with malrotation are at risk for midgut volvulus, which is potentially catastrophic. In addition to signifying that the duodenum does not pass behind the SMA, malrotation also implies that the cecum and jejunum are adjacent to each other and that the entire midgut is based on a narrow mesenteric pedicle. Nonrotation also indicates that the duodenum does not pass behind the SMA, but it suggests that the mesentery is sufficiently broad that the risk of volvulus is minimal it is the anatomic configuration that remains after a properly performed Ladd procedure and occurs naturally in most patients with congenital diaphragmatic hernia and other anomalies that associated with rotational abnormalities. Infants and children with bilious emesis (and no prior abdominal surgical history) should be presumed to have malrotation with volvulus until proven otherwise. If they are septic or have peritonitis, they should be prepared for immediate laparotomy. Time is of the essence. If the patient is stable, an upper GI contrast study should be performed urgently it cannot wait until morning! If the findings are consistent with volvulus, the patient goes to the OR immediately. If there is malrotation without volvulus, most pediatric surgeons make plans to operate within 24 h but this can wait until the light of day. It is important to note that the picture of a wellappearing child and a totally benign abdomen (even if laboratory values and radiographs are within normal limits) does not rule out the possibility of volvulus with ischemic bowel. The Ladd procedure can be performed laparoscopically or open. Most useful when the procedure is being performed non-emergently, the laparoscopic approach is often quite difficult and there is a significant rate of conversion to open even for experienced laparoscopists. Regardless of the approach, the steps are the same: (1) detorse the bowel in a counter-clockwise direction ( turn back the hands of time ): if bowel is frankly necrotic it should be excised, which places the child at risk for short gut syndrome and intestinal failure, but if the bowel is of questionable viability, a second-look operation should be planned for h; (2) divide Ladd s bands; (3) straighten the duodenum (lyse all adhesions and undo its typical accordion configuration); (4) broaden the mesentery separate the colon and duodenum, open the anterior mesenteric peritoneum, and fan out the vessels of the mesentery; (5) remove the appendix; (6) establish a nonrotation configuration: place the small bowel on the right side of the abdomen with the duodenum along the right lateral side wall, and place the colon on the left side with the cecum in the left lower quadrant. Cecopexy and duodenal fixation sutures are unnecessary and create sites around which a volvulus could occur. When it comes the Ladd procedure, novices always place undue importance on the lysis of the Ladd bands; but the most important steps are the broadening of the mesentery, which is what prevents volvulus, and the straightening of the duodenum, which relieves many of the GI symptoms patients with malrotation have (emesis, reflux, failure to thrive). Turbid fluid at operation is almost always chylous ascites due to lymphatic congestion from partial volvulus and not evidence of bowel perforation. Postoperatively, many patients have a prolonged ileus. Some will have protracted symptoms of duodenal dysmotility or pseudo-obstruction. There are many variants of malrotation, including partial rotation, and right and left paraduodenal hernia. All are treated by trying to establish the nonrotation configuration the steps of the Ladd procedure are modified as necessary but the final anatomy should be the same. The exception is reverse rotation, which often requires that a portion of the bowel be divided to relieve entrapment. The rotational

8 380 F.I. Luks a nomalies displayed by patients with heterotaxy are also often quite challenging to deal with. The goal in these cases is to do whatever you have to do to leave the patient with a mesentery that is as broad as possible and therefore unlikely to volvulize. The upper GI is the gold standard for the diagnosis of malrotation but in clinical practice is frustratingly imprecise. To avoid missing a single case of malrotation, pediatric radiologists adhere to very strict criteria to define normal. Any variation, no matter how clinically insignificant, will be read out as the dreaded cannot rule out malrotation. Exploratory surgery has historically been the only way to decide if the intestine was truly malrotated; however, newer imaging modalities (US, MR) are becoming increasingly useful ways to confirm the retroperitoneal sweep of the duodenum and the absence of a narrow root of the mesentery. The ligament of Treitz can also be displaced by gastric or colonic distension and simply repeating the upper GI after a few weeks might yield a different result. Because 15% of patients with duodenal malrotation have normal colonic anatomy, contrast enema is not an accurate test for malrotation. Finally, there are some children who have an abnormally low ligament of Treitz. If the duodenum passes behind the SMA and the mesentery is sufficiently broad, these children are at minimal risk of volvulus and can be safely observed. Differential Diagnosis Pyloric stenosis Duodenal atresia Annular pancreas Small bowel atresia Meconium ileus Hirschsprung disease Avoid delays Intravenous hydration Prophylactic antibiotics Type & screen Informed consent Technical Points Right upper quadrant transverse incision Careful exteriorization and examination of the bowel Detorsion of the midgut volvulus in a counterclockwise fashion Assess and reassess viability of the bowel If bowel resection is unavoidable, limit its extent if necessary, re-explore after h Divide Ladd s bands (crossing duodenum), if present Widen mesenteric base by dividing avascular duodenocolonic bands Fully expose root of superior mesenteric artery and its first branches Adequate peri- and postoperative hydration to reverse third-spacing and fluid losses Suggested Reading Diagnostic Studies Plain radiograph Upper gastrointestinal (UGI) ( diagnostic test of choice) Contrast enema Ultrasonography Preoperative Preparation contrast series Parental Preparation Possible extensive bowel necrosis, bowel resection Possible short bowel syndrome Possible stoma Ladd WE. Congenital obstruction of the duodenum in children. N Engl J Med. 1932;206: Kluth D, Kaestner M, Tibboel D, Lambrecht W. Rotation of the gut: fact or fantasy? J Pediatr Surg. 1995;30: van den Brink GR. Hedgehog signaling in development and homeostasis of the gastrointestinal tract. Physiol Rev Surg Int. 2007;87: Seashore JH, Touloukian RJ. Midgut volvulus: an ever-present threat. Arch Pediatr Adolesc Med. 1994;148:43 6. Patino MO, Munden MM. Utility of the sonographic whirlpool sign in diagnosing midgut volvulus in patients with atypical clinical presentations. J Ultrasound Med. 2004;23: Spigland N, Brandt ML, Yazbeck S. Malrotation presenting beyond the neonatal period. J Pediatr Surg. 1990;25: Lessin MS, Luks FI. Laparoscopic appendectomy and duodenocolonic dissociation (LADD) procedure for malrotation. Pediatr Surg Int. 1998;13:184 5.

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