Intestinal malrotation in adults

INTRODUCTION — Intestinal malrotation occurs when the normal rotation of the embryonic gut is arrested or disturbed during in utero development.

While most cases of intestinal malrotation present during the neonatal period or the first year of life, some present as older children or adults [1-3]. The prevalence of malrotation in adults is unknown, but colorectal screening by computed tomography (CT) colonography has suggested a prevalence of 0.17 percent [4]. Because of its rarity, the diagnosis of intestinal malrotation in adult patients is often delayed and therefore associated with increased morbidity [5,6].

The clinical manifestations, diagnosis, and treatment of intestinal malrotation in adults will be discussed in this topic. Intestinal malrotation in children is discussed separately. (See "Intestinal malrotation in children".)

PATHOGENESIS — Intestinal malrotation occurs as a result of arrested normal rotation of the embryonic gut (see "Overview of the development of the gastrointestinal tract"). As a result, two anatomic variations develop (Ladd bands (picture 1) and a narrow mesenteric base (figure 1)), which predispose to symptoms of gastrointestinal obstruction. It should be differentiated from intestinal nonrotation, where most of the small intestine is on the right side while the colon is on the left side of the abdomen [7].

The pathogenesis of intestinal malrotation is discussed in detail separately. (See "Intestinal malrotation in children", section on 'Embryology and pathogenesis'.)

CLINICAL PRESENTATION — In neonates, intestinal malrotation almost always presents with acute obstruction or volvulus. However, the clinical presentation of intestinal malrotation in adults is more variable [5,7-9], and some adults are asymptomatic. In asymptomatic patients, malrotation is incidentally discovered by imaging studies obtained for other purposes.

Chronic clinical presentation — Approximately 88 percent of adults with intestinal malrotation present insidiously with one or more of the following features that usually occur during the postprandial period [9,10]:

●Intermittent abdominal pain is the most common symptom (approximately 40 percent)

●Intermittent vomiting (bilious or nonbilious) (12 to 30 percent)

●Failure to thrive/weight loss due to poor oral intake

●Food intolerance

●Malabsorption

●Chronic diarrhea

●Pancreatitis

●Peritonitis

●Motility disorders

●Chylous ascites

Many of these features are chronic and may be present for more than six months before the diagnosis of malrotation is made. Some adult patients report a chronic pattern of episodic vomiting and abdominal pain, which may be due to intermittent, self-limited volvulus. Occasionally, patients describe performing postprandial maneuvers for pain relief, such as lying on their right side and pushing on their abdomen.

Acute clinical presentation — Only 10 to 15 percent of adult patients with malrotation present with acute midgut volvulus, a potentially life-threatening condition [11]. This has even been reported in octogenarians [12,13]. Patients with acute midgut volvulus typically present with:

●Severe abdominal pain

●Nausea and vomiting

●Hematemesis or hematochezia

●Hemodynamic instability

Physical examination may reveal mild distension of the abdomen and diffuse tenderness with or without signs of peritonitis. Hematemesis and hematochezia are worrisome signs as they suggest bowel ischemia and possible necrosis [14].

DIAGNOSIS — The diagnosis of intestinal malrotation should be suspected in adults who present with the clinical features described above or who have abnormal findings on imaging studies performed for other reasons.

Except in patients who have an acute clinical presentation, an upper gastrointestinal series or a computed tomography (CT) scan with oral contrast should be performed to confirm the diagnosis. Patients with an acute clinical presentation with concern for bowel ischemia may be urgently taken to surgery without further imaging, and the diagnosis is made intraoperatively.

Diagnostic evaluation — Findings of the following imaging studies can be suggestive but are usually not diagnostic of intestinal malrotation in adult patients.

Plain films — The following findings on abdominal plain films in adult patients may suggest intestinal malrotation:

●Gasless abdomen

●Duodenal obstruction

●Bowel wall thickening and thumbprinting

●Free air (typically from intestinal perforation as a result of acute intestinal ischemia)

Contrast enema — A contrast enema can diagnose midgut volvulus associated with malrotation if it shows complete obstruction of the transverse colon (figure 2). The level of obstruction, which is revealed by a beaked (or tapered) contour of the barium, is located more proximally than what would be expected with a sigmoid volvulus (image 1).

Normal visualization of the cecum on contrast enema, however, does not rule out intestinal malrotation, because up to 20 percent of patients with malrotation have the cecum located in the right lower quadrant [15].

Abdominal CT — Abdominal CT is commonly used in the evaluation of abdominal pain and is the modality that most often identifies malrotation presenting in adults [9]. In an oral contrast-enhanced abdominal CT, malrotation is suggested when [16]:

●The course of the duodenum is abnormal (normally, the duodenum descends on the right, crosses the midline, and ascends to the level of the pylorus).

●The cecum is not located in the right lower quadrant but rather in the left upper or lower quadrant.

●A vertically oriented or reversed relative position of the superior mesenteric vein and superior mesenteric artery (the vein is normally located to the right of the artery).

●Extraintestinal anomalies such as the absence of pancreatic uncinate process or polysplenia syndrome (multiple spleens, congenital short pancreas, and left-sided inferior vena cava).

●Appendicitis with appendix in an abnormal location.

Volvulus associated with malrotation can be diagnosed on abdominal CT by the "whirlpool" sign (image 2). Detailed CT assessments of the anatomic variations in malrotation are accruing to attempt to determine clinical predictive factors of symptoms, including volvulus, to help guide clinical management [17].

Abdominal ultrasound — Ultrasound (US) is not supported for diagnosing malrotation; a normal abdominal US does not exclude malrotation [18]. However, malrotation may be identified incidentally given the frequency with which abdominal US is obtained in adults with chronic upper abdominal symptoms to rule out gallstone disease. US findings that are suggestive of malrotation include:

●A reversed relative position of the superior mesenteric vein and superior mesenteric artery (the vein is normally located to the right of the artery) [19]

●A US "whirlpool" sign of volvulus [20]

Confirmatory imaging study — An upper gastrointestinal (UGI) series is the best examination to visualize the duodenum and is therefore the "gold standard" for diagnosing intestinal malrotation in adults.

Upper gastrointestinal series — Normally, the duodenum should descend, cross the midline, and then ascend to the level of the pylorus, a course that is best visualized on the UGI series. Any deviation from this normal course is termed malrotation or nonrotation. Examples of malrotation include:

●A clearly misplaced duodenum with the ligament of Treitz on the right side of the abdomen

●A duodenum with a "corkscrew" appearance suggesting volvulus (image 3)

●A duodenal obstruction with a "beaked" appearance when volvulus with obstruction is present

The false-negative and false-positive rates of a UGI series in the diagnosis of malrotation are 6 to 14 percent and 7 to 15 percent, respectively [21]. If the UGI series is equivocal in diagnosing intestinal malrotation, it may be helpful to obtain a small bowel follow-through series, repeat the UGI series when the patient is symptomatic, or evaluate the colon with a contrast enema. (See 'Contrast enema' above.)

DIFFERENTIAL DIAGNOSIS — The differential diagnosis of intestinal malrotation depends upon its presentation. Intestinal malrotation can be distinguished from each of the following conditions by an upper gastrointestinal series. (See 'Confirmatory imaging study' above.)

Differential diagnosis of chronic presentation — The differential diagnosis of intestinal malrotation in adults with a chronic presentation includes (see 'Chronic clinical presentation' above):

●Gastroesophageal reflux disease (see "Clinical manifestations and diagnosis of gastroesophageal reflux in adults")

●Food allergy (see "Food intolerance and food allergy in adults: An overview")

●Irritable bowel syndrome (see "Clinical manifestations and diagnosis of irritable bowel syndrome in adults")

●Abdominal migraines (see "Causes of abdominal pain in adults", section on 'Less common causes')

●Petersen's hernia in patients who have undergone gastric bypass for morbid obesity (See "Bariatric operations: Late complications with acute presentations", section on 'Small bowel obstruction'.)

●Chronic mesenteric ischemia (see "Chronic mesenteric ischemia")

●Volitional curtailment of food intake in order to avoid symptoms (eg, abdominal pain or vomiting)

Differential diagnosis of acute presentation — The differential diagnosis of intestinal malrotation in adults with an acute presentation includes (see 'Acute clinical presentation' above):

●Acute superior mesenteric arterial thrombosis or embolic mesenteric ischemia (see "Overview of intestinal ischemia in adults")

●Perforated viscus (see "Overview of gastrointestinal tract perforation")

●Appendicitis (see "Acute appendicitis in adults: Clinical manifestations and differential diagnosis")

●Other causes of peritonitis

TREATMENT — The treatment of intestinal malrotation in adults depends upon its presentation. (See 'Clinical presentation' above.)

Treatment of patients with chronic presentation — Adult patients who have intestinal malrotation without volvulus are typically treated with an elective Ladd procedure. The Ladd procedure can be performed either open or laparoscopically, with most surgeons performing the open Ladd procedure because of its rarity in adult patients [22-24]. (See 'Surgical options' below.)

Treatment of patients with acute presentation — Adult patients who have intestinal malrotation with acute volvulus require emergency laparotomy with detorsion of the volvulus to avert midgut bowel ischemia or necrosis. In patients with diagnosed or strongly suspected midgut volvulus, preoperative preparation includes:

●Volume resuscitation

●Nasogastric decompression

●Broad-spectrum antibiotics

With appropriate resuscitation, the patient should be taken to the operating room for immediate laparotomy. Surgery should not be delayed for the purpose of fully resuscitating the patient, because metabolic derangements, such as hyperkalemia and acidosis, may persist in the presence of ischemic bowel.

At surgery, the volvulus is untwisted in a counterclockwise direction, and unequivocally necrotic bowel segments should be removed. Bowel segments with questionable viability should be preserved in order to avoid short bowel syndrome, and a second-look operation can be performed 24 to 36 hours later (after ongoing resuscitation in the intensive care unit), with resection of these segments if they become necrotic. The anesthetic and surgical team should be actively monitoring signs for ischemia and reperfusion injury. (See 'Surgical options' below and "Overview of intestinal ischemia in adults", section on 'Abdominal exploration'.)

Treatment of incidental or asymptomatic malrotation — In adult patients, intestinal malrotation can be found incidentally during evaluation or treatment of another disease, most commonly appendicitis.

When appendicitis occurs in patients with malrotation, the appendix will not likely be located in the right lower quadrant [25]. Such patients have a history and physical examination that are atypical for appendicitis and, as a result, have a higher rate of perforation. Thus, when abdominal computed tomography (CT) shows focal inflammation anywhere in the abdomen, along with an abnormal mesenteric vessel relationship, the position of the cecum must be ascertained and acute appendicitis excluded [26]. (See 'Abdominal CT' above.)

When appendicitis is diagnosed on abdominal CT with the appendix in an aberrant position, malrotation should be suspected. If malrotation is confirmed intraoperatively, a Ladd procedure can be added to the appendectomy, particularly if the patient has a history of chronic gastrointestinal complaints. (See 'Chronic clinical presentation' above.)

Prior to surgery, the patient should be informed that adding a Ladd procedure may convert a laparoscopic appendectomy to an open procedure if the surgeon is not facile with the laparoscopic Ladd procedure, and that the postoperative recovery may be prolonged because of an ileus, but the complication rate is not higher. (See 'Laparoscopic Ladd procedure' below.)

For asymptomatic adult patients diagnosed with malrotation by imaging studies alone, the choice between operative correction or continued watchful waiting is controversial [27]. While some authorities advocate close observation in those with minimal (eg, acid reflux) or no symptoms [28], the majority of experts favor operative correction with a Ladd procedure in such patients due to the potential risk of bowel ischemia [5].

SURGICAL OPTIONS — The Ladd procedure is the standard surgical treatment for intestinal malrotation. Although it does not complete the arrested gut rotation, the Ladd procedure minimizes potential risks of volvulus by widening the base of the mesentery and placing the bowel in a position of nonrotation. In addition, the Ladd procedure also divides all the Ladd bands and removes the appendix. The Ladd procedure can be performed open or laparoscopically.

By contrast, the Kareem procedure is a novel procedure that completes the duodenal rotation and establishes all mesenteric attachments in the anatomical positions [29]. The Kareem procedure has not been compared with the Ladd procedure in any trials or even non-randomized comparative series.

Open Ladd procedure — The five steps of a standard open Ladd procedure are (movie 1):

●Assessment for volvulus – In open surgery, most surgeons eviscerate the bowel as a unit in order to assess for any twist in mesentery and/or any signs of intestinal ischemia. When volvulus is present, the bowel is untwisted counterclockwise and any unequivocally necrotic segment is resected. (See 'Treatment of patients with acute presentation' above.)

●Ladd band division – Ladd bands are fibrous bands that run between the cecum and duodenum, occasionally to the right peritoneal side wall. Because Ladd bands can cause duodenal obstruction, they should be completely divided. When dividing the Ladd bands, the duodenum should be straightened with a Kocher maneuver to prevent incomplete division of the Ladd bands. Unlike in neonates, Ladd bands in adults are quite thick and vascular and therefore should be divided with cautery (image 2).

●Intermesenteric band division – Intermesenteric bands are fibrous bands between bowel loops other than the cecum and duodenum. Because they constrict the mesenteric base, intermesenteric bands are also divided as a part of the Ladd procedure. When dividing the intermesenteric bands, the entire bowel should be manually inspected (ie, "run") several times to ensure that all bands have been divided.

●Appendectomy – The appendix is frequently in an aberrant position in patients with malrotation. In such patients who develop appendicitis, the diagnosis is often delayed, leading to a higher complication rate. Thus, appendectomy is an integral part of the standard Ladd procedure. An inversion appendectomy may be performed at the surgeon's discretion to avoid opening the bowel. An analysis of the American College of Surgeons National Surgical Quality Improvement Program database studied 220 patients from 2015 to 2018 with a postoperative diagnosis of malrotation; half underwent an appendectomy and half did not. Comorbidities and perioperative variables were clinically similar, and there was no statistical difference in 30 day mortality (1.36 percent), length of stay (4.79±6.21 days), readmission rate (13.64 percent), or wound infection (2.27 percent) between groups [30].

●Placement of the bowel in the corrected position of nonrotation – At the conclusion of the Ladd procedure, the bowel is placed back in the abdomen in the position of nonrotation with the small bowel on the right, the colon on the left, and the cecum in the left upper quadrant. A suture pexy of the bowel loops is not supported.

Laparoscopic Ladd procedure — The Ladd procedure for malrotation can be performed laparoscopically following the same five steps outlined above. (See 'Open Ladd procedure' above.)

Studies of adult patients showed that patients who had the laparoscopic Ladd procedure had a longer operative time but a shorter hospital stay compared with those who had the open procedure [22,31]. Complication rates were comparable.

Although it has been suggested that the laparoscopic Ladd procedure may lead to more recurrent volvulus due to fewer adhesions, there have been no prospective studies comparing the two procedures. In most centers, the open Ladd procedure remains the gold standard for treating intestinal malrotation, especially when volvulus or bowel ischemia is suspected. Selected patients without volvulus may be treated laparoscopically by experienced surgeons [32-34].

Kareem procedure — The Kareem procedure involves liberation of the duodenum with completion of the 270 degree counterclockwise rotation and establishment of all mesenteric attachments [29]. The aim is to alleviate gastrointestinal symptoms and prevent volvulus. Resection of the convoluted colon is performed in patients with distorted or shortened mesocolon and colonic dysmotility. The current version of the Kareem procedure is only performed via laparotomy.

FOLLOW-UP — Routine imaging is not required following an uncomplicated operation. However, the patient should be counseled that:

●The Ladd procedure does not recreate normal rotation, and any subsequent imaging will still show "corrected" malrotation.

●The risk of acute volvulus still persists but is much lower following a Ladd procedure. Any acute abdominal symptoms should prompt an emergency upper gastrointestinal (UGI) series to rule out acute volvulus. The patient should be educated to advocate for such an imaging study when seeking medical attention.

●The provision of an operative note and pathology report from the indicated appendectomy can be offered to the patient for their personal medical records.

OUTCOMES

Mortality — Operative mortality for intestinal malrotation ranges from 0 to 25 percent in adult patients depending upon the presentation [5,35,36]. Patients who present with acute midgut volvulus have the highest mortality rate. In addition, age greater than 50 years, peritonitis, acute vascular insufficiency, coagulopathy, and nonoperative management have also been associated with an increased mortality rate [6].

Morbidity — In adults, the morbidity rate associated with surgery can be high (up to 60 percent) when surgery is performed for volvulus [5,36,37]. Patients with intestinal necrosis from volvulus have even higher complication rates [35]. Specific complications include:

●Anastomotic leak presenting as a contained leak with abscess or generalized peritonitis.

●Ileus – A prolonged ileus should be anticipated following the Ladd procedure and is often observed [23].

●Small bowel obstruction – Following laparotomy, patients have a lifetime risk of developing adhesive small bowel obstruction, reportedly up to 15 percent in some series [38]. The use of laparoscopy in select cases has reduced that risk. (See 'Laparoscopic Ladd procedure' above and "Etiologies, clinical manifestations, and diagnosis of mechanical small bowel obstruction in adults".)

●Recurrent volvulus – Surgery for malrotation reduces, but does not eliminate, the risk of volvulus. The risk of recurrent volvulus after a Ladd procedure is between 1.8 and 8 percent [39]. (See 'Acute clinical presentation' above.)

●Short gut syndrome – Short gut syndrome will develop after resection of the midgut (entire small bowel and ascending colon). This complication can only be prevented by prompt recognition and management of volvulus prior to the onset of irreversible bowel ischemia.

Patient-generated registry — A national (United States-based) online patient-generated registry supported by the NIH, Intestinal Malrotation Patient Outcomes and Wellness Registry (IMPOWER), was established in 2021 to capture both pediatric and adult patients, collecting their presenting symptoms, testing, diagnosis, treatment, and follow-up at six-month intervals. This database reports up to 82 percent of adult patients have ongoing gastrointestinal symptoms after the Ladd procedure, including abdominal pain, constipation, and feeding intolerance. Recognizing the limitations of a self-reported PGR, this registry has promise in providing critical data regarding the presentation, treatment, and long-term follow-up in patients with malrotations [40].

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Bowel obstruction".)

SUMMARY AND RECOMMENDATIONS

●Pathogenesis – Intestinal malrotation occurs as a result of arrested normal rotation of the embryonic gut. Although most commonly diagnosed in neonates and children, malrotation can have an initial presentation in adults. (See 'Introduction' above.)

●Clinical presentations – In adult patients, intestinal malrotation can present with chronic symptoms or acutely with life-threatening volvulus.

•Chronic presentation – Intestinal malrotation can present with chronic symptoms such as intermittent vomiting or abdominal pain. Once diagnosed radiologically, symptomatic malrotation without volvulus is treated surgically with an open or laparoscopic Ladd procedure. (See 'Chronic clinical presentation' above and 'Treatment of patients with chronic presentation' above and 'Surgical options' above.)

•Acute presentation – Volvulus associated with malrotation is a life-threatening condition that requires emergency evaluation, resuscitation, and surgical treatment. Patients often present acutely with severe abdominal pain, nausea, vomiting, hematemesis, hematochezia, or hemodynamic instability.

●Diagnosis – The diagnosis of intestinal malrotation in adults is suspected based upon clinical features or as a result of imaging studies performed for other reasons (eg, plain films, contrast enema, computed tomography, ultrasound). Such patients should undergo an upper gastrointestinal (UGI) series or a computed tomography (CT) with oral contrast to confirm the diagnosis. Patients with an acute clinical presentation with concern for bowel ischemia may be urgently taken to surgery without further imaging, and the diagnosis is made intraoperatively. (See 'Diagnosis' above.)

●Treatment – Treatment of intestinal malrotation in adults depends on the acuity of the presentation.

•Acute volvulus – Such patients should receive rapid resuscitation while being brought to the operating room for immediate laparotomy. At surgery, the bowel is detorsed counterclockwise and resected if frankly necrotic. If the bowel is not necrotic but its viability is questioned, it is preserved and reinspected at a second-look operation 24 to 36 hours later. (See 'Acute clinical presentation' above and 'Treatment of patients with acute presentation' above.)

•Chronic symptoms or incidental finding – When malrotation is identified either pre- or intraoperatively during an unrelated surgery (eg, appendectomy), a Ladd procedure may be performed synchronously with the index procedure. In asymptomatic adult patients with malrotation incidentally found on imaging studies obtained for other purposes, a Ladd procedure is suggested to lower the risk of volvulus. However, observation is a reasonable option for well-informed patients who choose to defer surgery. (See 'Treatment of incidental or asymptomatic malrotation' above and 'Surgical options' above.)

●Outcomes – The devastating complications of midgut bowel necrosis and/or short bowel syndrome can only be minimized by the prompt recognition and surgical treatment of intestinal malrotation. Postoperative complications such as ileus and bowel obstruction are common in adults following surgery for malrotation. (See 'Outcomes' above.)