Volvulus

Overview

Definition

A volvulus is the twisting of a segment of bowel on its mesentery, which results in bowel obstruction.

Epidemiology

• 3rd most common cause of large bowel obstruction after cancer and diverticulitis
• Types of colonic volvulus:
  • Sigmoid (80%; most common)
  • Cecal (15%)
  • Transverse colon (3%)
  • Splenic flexure (2%)
• Sigmoid volvulus: 
  • Older men (mean age 70-years-old)
  • Sometimes affects younger patients with colonic dysmotility
• Cecal volvulus: common in middle-aged women

Etiology

Sigmoid volvulus:

• Long mesentery with a narrow base to allow twisting
• Redundant elongated colon usually from chronic constipation
• Risk factors:
  • Age (50% of patients > 70-years-old)
  • Institutionalized/nursing home residents
  • Neurologic disorders (e.g., Parkinson’s disease, multiple sclerosis)
  • Previous history of volvulus
  • High-fiber diet 
  • Chronic constipation and laxative abuse
  • Megacolon (Hirschsprung’s disease, Chagas disease)
  • Pregnancy

Cecal volvulus:

• Usually congenital
• Incomplete dorsal mesenteric fixation of the cecum 
• Elongated mesentery

Pathophysiology

• Torsion of bowel on its axis leads to closed-loop mechanical bowel obstruction.
• Accumulation of gas, water, and feces within the loop → increased intraluminal pressure
• Bacterial fermentation contributes to distention; increased intraluminal pressure impairs capillary perfusion.
• Impaired capillary perfusion of bowel → strangulation and ischemia
• Vascular occlusion in the mesentery if torsion is tight enough (> 360° torsion)
• Torsion of the mesenteric vascular pedicle → occlusion/thrombosis of mesenteric vessels → ischemia
• 3 types of cecal volvulus:
  • Type 1: clockwise twisting of the cecum along the long axis (cecum in right lower quadrant)
  • Type 2: counterclockwise twisting of the cecum and terminal ileum (cecum in left upper quadrant)
  • Type 3: cecal bascule (upward folding of cecum rather than twisting)

Clinical Presentation

Sigmoid volvulus

• Onset is usually slow and insidious.
• Abdominal pain with gradual distention
• Constant pain with superimposed colicky episodes
• Nausea, constipation
• Typically vomiting a few days after the onset of pain

Cecal volvulus

• Presentation is variable:
  • Insidious onset of intermittent abdominal pain and cramping
  • Acute sudden onset of abdominal pain
  • Symptoms last from hours to days
  • Severe, constant pain may indicate ischemia or perforation.
• Accompanying symptoms:
  • Nausea and bilious vomiting
  • Constipation
  • Obstipation (inability to pass flatus or stool)

Diagnosis

History

• Chronic constipation
• Long-term laxative use
• Neurologic disorders (e.g., Parkinson’s disease)
• Medications affecting bowel motility (psychotropics, opiates)

Physical exam

• Distended tympanitic abdomen
• Can be asymmetrically distended with emptiness on the right or left side
• Tenderness to palpation
• Signs of ischemia or perforation: 
  • Abdominal pain out of proportion to physical exam
  • Peritoneal signs (guarding, rigidity, rebound tenderness)
  • Tachycardia
  • Hypotension
  • Fever
  • Hematochezia or blood on a digital rectal exam

Laboratory studies

• Complete blood cell count:
  • Frequently normal
  • Significant leukocytosis may indicate ischemia/perforation.
• Chemistry:
  • Frequently normal
  • Hypokalemia/metabolic alkalosis with protracted vomiting
  • Metabolic acidosis/elevated lactic acid with ischemia/perforation
• Pregnancy test: obtained in all women of child-bearing age

Imaging

• Upright abdominal X-ray:
  • Sigmoid volvulus: coffee bean sign (dilated sigmoid colon projecting to the right upper quadrant)
  • Cecal volvulus: 
    • Kidney bean sign (dilated colon loop extending from right side to mid-abdomen)
    • Signs of small bowel obstruction (SBO): distended loops, air-fluid levels
  • Pneumoperitoneum: indicates perforation
• Abdominal CT scan:
  • Confirmatory test
  • Whirl sign: 
    • Pathognomonic for volvulus 
    • Indicates twisting of the mesentery
  • Small bowel dilatation (especially cecal volvulus)
  • Significant colon dilatation with distal decompression and paucity of gas in the rectum
  • Signs of ischemia: 
    • Pneumatosis intestinalis (air in the bowel wall) and portal venous gas
    • Thickened bowel wall (due to loss of venous/lymphatic drainage)
    • Free intraperitoneal fluid 
    • Mesenteric fat stranding
    • Differential wall enhancements (poor uptake of intravenous (IV) contrast into the wall of the affected bowel)
    • Free air indicates perforation.
• Contrast enema: 
  • Rarely needed for diagnosis
  • Sigmoid volvulus: 
    • Bird’s beak sign is seen at the sigmoid.
    • Dye does not pass the twist point in the sigmoid colon.
  • Cecal volvulus: bird’s beak sign, dye does not enter the small bowel

Management

Initial supportive management

• IV fluid and correction of electrolyte imbalance
• Nil per os (NPO) 
• Nasogastric decompression if vomiting/signs of SBO
• IV antibiotics for suspected ischemia/perforation/signs of sepsis

Sigmoid volvulus

Sigmoidoscopy with detorsion:

• For stable patients with no suspicion of ischemia or perforation
• Flexible or rigid
• Rectal tube should be left in place for decompression and prevention of immediate recurrence.
• Success rate: 75%–95%
• Recurrence: up to 84%
• Definitive surgery is recommended unless a very high surgical risk patient.
• Decompression should be attempted if feasible prior to surgery:
  • Converts emergent surgery into elective surgery and allows preoperative planning
  • Allows for successful primary anastomosis (helps avoid colostomy)

Surgery:

• Indications:
  • Peritonitis, signs of ischemia/perforation
  • Unsuccessful endoscopic detorsion
  • Successful detorsion in patients who are acceptable surgical candidates
• Procedures:
  • Sigmoid colectomy with primary anastomosis: stable patients with viable colon
  • Sigmoid colectomy with end colostomy (Hartmann’s procedure): unstable patients, perforation, ischemia

Cecal volvulus

• Direct surgical intervention after stabilization
• Colonoscopic decompression increases the risk of perforation and is not performed.
• Procedures:
  • Hemodynamically stable patients: ileocecal resection or right colectomy with ileocolic anastomosis 
  • Unstable patients: 
    • Detorsion and cecopexy (for viable bowel) +/- cecostomy tube for decompression
    • Right colectomy with ileostomy (for ischemic/necrotic bowel)

Prognosis

Overall mortality:

• Cecal volvulus: 6.64%
• Sigmoid volvulus: 9.44%

Predictors of mortality:

• Bowel gangrene/peritonitis
• Advanced age
• Coagulopathy
• Chronic kidney disease
• Stoma creation during surgery

Differential Diagnosis

• Acute megacolon/colonic pseudo-obstruction: massive dilation of the entire colon secondary to a functional problem rather than a mechanical obstruction; usually diagnosed by a combination of clinical history and imaging. Treatment is typically medical management with surgery reserved for advanced cases associated with ischemia and sepsis.
• Toxic megacolon: a complication of infectious or inflammatory colitis. Presentation includes tachycardia, hypotension, and massive abdominal distention. Diagnosis is based on several symptoms such as a history of bloody diarrhea, fever/infection, and CT findings characteristic of toxic megacolon. Management depends on the underlying cause with surgery reserved for failure of medical management.
• Mechanical large bowel obstruction (LBO): interruption of the flow of contents through the colon. Presentation is similar to the clinical picture and X-ray findings (dilation of the colon) of sigmoid volvulus. Definitive diagnosis is established with a CT scan and sometimes colonoscopy. Management usually involves surgical resection to address the cause of the obstruction.
• Mechanical small bowel obstruction (SBO): interruption of the flow of contents through the small bowel. Presentation similar to the clinical picture and some X-ray findings (small bowel dilation) of cecal volvulus. A definitive diagnosis is established with a CT scan. Nonoperative management is frequently successful. Surgery is reserved for severe clinical presentation and failure of medical management.