Volvulus and intestinal malrotation

Volvulus is defined as the twisting of a loop of bowel on its mesentery and is one of the most common causes of intestinal obstruction. The sigmoid colon, and less frequently, the cecum, are the common sites of volvulus in adults. Volvulus in a neonate or infant almost always presents as a midgut volvulus secondary to intestinal malrotation. Patients typically show features of bowel obstruction (abdominal pain, distension, bilious vomiting) or of bowel ischemia and gangrene (tachycardia, hypotension, hematochezia, peritonitis) in severe cases. The whirl sign and a grossly dilated loop of bowel on an abdominal CT scan establish the diagnosis of volvulus in adults. Upper GI series is the investigation of choice in infants with suspected midgut volvulus, which is seen as a cork-screw duodenum. Sigmoid volvulus without peritonitis is initially managed with endoscopic detorsion, followed by a semi-elective surgery (sigmoid colectomy). Sigmoid volvulus with peritonitis, and all cases of cecal volvulus, require emergency surgery. Endoscopic detorsion should not be attempted in a patient with cecal volvulus because of the high risk of perforation. The Ladd procedure (laparotomy and detorsion of the volvulus) is indicated in all patients with intestinal malrotation since it is impossible to predict if volvulus of the midgut will occur in an asymptomatic patient or not.

• Incidence
  • Volvulus: 3^rd most common cause (∼ 10–15%) of intestinal obstruction in the United States
    • Sigmoid volvulus (most common, 80%)
    • Cecal volvulus (15%)
    • Transverse colon volvulus (3%)
    • Splenic flexure volvulus (2%)
  • Intestinal malrotation: symptomatic malrotation (midgut volvulus) in 1:6000 live births in the United States
• Age and sex
  • Sigmoid volvulus: ∼ 70 years; ♂ > ♀
  • Cecal volvulus: 40–60 years; ♀ >♂
  • Intestinal malrotation and midgut volvulus: neonates and infants

References:^{[1][2][3][4][5][6][7][8][9][10][11]}

Epidemiological data refers to the US, unless otherwise specified.

• Long mesentery
  • Acquired (sigmoid volvulus): chronic constipation , high-fiber diet → chronic overloading of the sigmoid colon → lengthening of the sigmoid colon and its mesentery → increased risk of torsion
  • Congenital (cecal volvulus): abnormally mobile cecum → predisposition of the cecum to rotate on its axis (axial torsion) or fold upwards (cecal bascule)
• Intestinal malrotation: abnormal rotation of the bowel with abnormal fixation of mesentery to the posterior abdominal wall
• Megacolon (Hirschsprung's disease, Chaga's disease)
• Intestinal bands/adhesions
• Decreased pelvic space: pregnancy or pelvic mass
• Previous history of volvulus

References:^{[2][3][4][5][12][13][14][15][16]}

• Torsion of bowel on its axis
  • → Closed-loop mechanical bowel obstruction → accumulation of gas and feces within the loop → increased intraluminal pressure → impaired capillary perfusion of bowel → bowel strangulation, ischemia, and gangrene
  • → Torsion of the mesenteric vascular pedicle → occlusion/thrombosis of mesenteric vessels → bowel strangulation, ischemia, and gangrene

References:^[5][17]

Clinical features

• Previous episodes of abdominal pain, which decreased after explosive passage of stool/gas
• Slowly (most common) or rapidly progressive symptoms of bowel obstruction
• If bowel ischemia occurs → tachycardia, hypotension, peritonitis (rebound tenderness), hematochezia or blood on DRE may be present
• If bowel perforation occurs → obliteration of liver dullness on percussion

Differential diagnoses

• Acute megacolon
• Toxic megacolon
• Other causes of mechanical bowel obstruction (e.g., colon cancer, strictures, cecal volvulus)

Treatment

1. Initial resuscitation: IV fluids; acid-base and electrolyte imbalance correction; nil per oral; placement of a nasogastric tube
2. Evaluation
   • No signs of peritonitis: rigid/flexible sigmoidoscopic detorsion of the volvulus → inspection of the mucosa for signs of ischemia
     • No signs of mucosal ischemia → placement of a soft rectal tube (for bowel decompression) → semi-elective surgery within 72 hours of detorsion
     • Signs of mucosal ischemia → emergency surgery (see below)
   • Signs of peritonitis/unsuccessful endoscopic detorsion → broad-spectrum IV antibiotics and emergency surgery
3. Surgery
   • Sigmoid colectomy and primary anastomosis : indicated in hemodynamically stable patients with viable bowel
   • Hartmann's procedure: indicated in hemodynamically unstable patients or those with ischemic/gangrenous bowel

References:^{[18][1][3][4][5][17][19][20][21]}

Types

• Axial torsion of the cecum (90% of cases): the cecum rotates on its mesenteric axis → bowel obstruction with vascular compromise
• Cecal bascule (10%): the cecum folds upwards onto the ascending colon → bowel obstruction often without vascular compromise

Clinical features

• Acute presentation: features of small bowel obstruction
• Insidious onset: recurrent episodes of right lower abdominal pain

Differential diagnoses

• Sigmoid volvulus
• Small bowel obstruction (e.g., adhesions, tumors, intussusception)

Treatment

1. Initial resuscitation (See “Treatment” of sigmoid volvulus above.)
2. Surgery
   • Hemodynamically stable patients: ileocecal resection or right colectomy with ileocolic anastomosis
   • Hemodynamically unstable patients
     • Cecostomy
     • Detorsion with cecopexy

References:^{[1][5][12][19][22][23]}

Definition

• Intestinal malrotation: arrest in the normal rotation of the gut in utero, resulting in an abnormal orientation of the bowel and mesentery within the abdominal cavity
• Normal intestinal rotation: the midgut starts to elongate in utero (4^th week) → herniation of the midgut out of the umbilicus (6^th week) → 90° counter-clockwise rotation of the midgut → re-entry of the midgut into the abdominal cavity(10^th week) → 180° rotation inside the abdominal cavity (a total of 270°) → fixation of the duodenojejunal flexure and cecum to the posterior abdominal wall

Common types of intestinal malrotation
Nonrotation	Incomplete rotation
The entire colon is left-sided; the entire small bowel is right-sided	The cecum remains fixed in the RUQ by peritoneal bands (Ladd bands)
The mesenteric attachment has a wider base than in incomplete rotation	The mesenteric base is narrow

• Midgut volvulus: torsion of a malrotated midgut causing mechanical bowel obstruction, mostly in neonates and infants

Clinical presentation

• Malrotation: mostly asymptomatic
• Midgut volvulus
  • Bilious vomiting with abdominal distension in a neonate/infant
  • Signs of bowel ischemia: hematochezia, hematemesis, hypotension, and tachycardia
• Features of duodenal obstruction: bilious vomiting without abdominal distension
• Variable presentation in older children/adults: recurrent episodes of abdominal pain and vomiting; failure to gain weight; malabsorption Abdominal examination is unreliable
• Features of associated congenital anomalies
  • Commonly associated anomalies: congenital diaphragmatic hernia (∼ 100%) ; congenital heart defects (up to 90%); omphalocele (up to 45%)
  • Less commonly associates anomalies: gastroschisis; Meckel diverticulum; esophageal atresia; biliary atresia

Differential diagnoses

• In neonates/infants with recurrent vomiting: duodenal atresia and stenosis; , hypertrophic pyloric stenosis
• In neonates with features of bowel ischemia/gangrene: necrotizing enterocolitis (NEC)
• In older children with abdominal pain and vomiting: intussusception
• In older children/adults with nonspecific symptoms: GERD; chronic mesenteric ischemia; food allergy

Treatment

• Midgut volvulus with/without peritonitis
  • Initial resuscitation: nil per oral; nasogastric tube insertion; IV fluids; correction of electrolyte imbalance; broad-spectrum IV antibiotics
  • Emergency surgery (Ladd procedure)
• Incidentally detected/asymptomatic intestinal malrotation: elective surgery (Ladd procedure)

References:^{[6][7][24][25][26][27][28][29]}

Volvulus

• Work-up follows the same protocol as that for bowel obstruction.
• Abdominal x-ray (erect and supine)
  • Sigmoid volvulus: coffee bean sign (bent inner tube sign)
  • Cecal volvulus: kidney bean sign
  • Bowel perforation: air under diaphragm
• CT scan
  • Whirl sign: pathognomonic for volvulus
  • Specific features of sigmoid/cecal volvulus are similar to those seen in x-rays
  • Demonstrates bowel ischemia , or perforation , if present
• Barium enema: : bird's beak sign (tapering of the dye column at the site of the twist)
  • In cecal bascule, the end of the barium column is rounded, rather than tapered (tear drop sign).
  • Cecal volvulus: normal-sized colon with bird's beak sign at the cecum; dye does not enter the small bowel
  • Sigmoid volvulus: normal-sized rectum with bird's beak sign at the sigmoid; dye does not enter the sigmoid colon

Intestinal malrotation and midgut volvulus

• Laboratory studies: complete blood count; electrolyte levels; arterial blood gas analysis

Imaging in intestinal malrotation and midgut volvulus
	Intestinal malrotation	Midgut volvulus
Upper GI series (gold standard in hemodynamically stable patients)	Displaced duodenojejunal junction	Corkscrew duodenum
Barium enema (lower GI series)	Malpositioning of the cecum (left-sided cecum)	Bird's beak sign at the site of the twist
Abdominal ultrasound	Abnormal position of the superior mesenteric vessels and bowel	Whirlpool sign (on color doppler)
CECT scan (oral and IV contrast)	Findings similar to those seen on ultrasound	Findings similar to those seen on ultrasound Can demonstrate bowel ischemia , or perforation , if present

References:^{[3][6][7][8][11][23][26][28][30][31][32][33][34][35][36][37][38][39][40][41][42]}