Volvulus overview

# Overview
A volvulus is a loop of the bowel that has twisted on itself or around the axis of the mesentery. The pathophysiology and treatment of volvulus were established in the 20th century, by William Ladd. However, evidence for cases of volvulus go as far back as 1550 BC in Egypt. Volvulus can happen at various parts of the gastrointestinal tract. Volvulus can also occur congenitally or acquired in a newborn, an infant or an adult. These include sigmoid volvulus, cecal volvulus, gastric volvulus and ileal volvulus. Regardless of cause, volvulus causes symptoms by two mechanisms. One is bowel obstruction, manifested as abdominal distension and vomiting.  The other is  ischemia (loss of blood flow) to the affected portion of intestine. This causes severe pain and progressive injury to the intestinal wall, with accumulation of gas and fluid in the portion of the bowel obstructed. Ultimately, this can result in necrosis of the affected intestinal wall, acidosis, and death. Acute volvulus therefore requires immediate surgical intervention to untwist the affected segment of bowel and possibly resect any unsalvageable portion. Midgut volvulus occurs in patients (usually in infants) that are predisposed because of congenital intestinal malrotation. Segmental volvulus occurs in patients of any age, usually with a predisposition because of abnormal intestinal contents (e.g. meconium ileus) or adhesions. Volvulus of the cecum, transverse colon, or sigmoid colon occurs, usually in adults, with only minor predisposing factors such as redundant (excess, inadequately supported) intestinal tissue and constipation. Volvulus must be distinguished from other diseases, as it may be a solitary finding or a feature of another disease. Differential diagnoses include:Crohn's disease, necrotizing enterocolitis, duodenal atresia, pyloric stenosis, toxic megacolon and pseudocolonic obstruction (Ogilvie syndrome). Acute mechanical small bowel obstruction is a common surgical emergency where volvulus is the cause in 10% of cases. It is estimated that over 300,000 laparotomies are performed per year in the United States for adhesion-related obstructions such as volvulus. Volvulus originating in the colon is the third most common cause of large bowel obstruction. Common risk factors in the development of volvulus include pregnancy, chronic constipation, age over 50, and long sigmoid colon and mesentery. There is insufficient evidence to recommend routine screening for volvulus. However, there are screening programs in place that utilize an ultrasound to seek out intestinal malrotation, which may be a cause of fatal midgut volvulus. If left untreated, the majority of patients with volvulus may progress to develop gangrene of the bowel, which can be fatal. Common complications of volvulus include bowel ischemia, gangrene, and necrosis. Prognosis is generally excellent, so long as the affected part of the bowel is resected or untwisted before ischemia occurs, usually within 48-72 hours. If necrosis of the affected bowel has already occurred then the prognosis is poor and may be fatal. There is no single diagnostic study of choice for the diagnosis of volvulus. Volvulus can be diagnosed based on clinical findings and on the findings on CT scan, plain x-ray or plain x-ray with contrast. The most common symptoms of volvulus include abdominal pain, abdominal distension, constipation and vomiting. Patients are usually elderly or institutionalized. Patients with volvulus usually appear in distress. Physical examination of patients with volvulus is usually remarkable for abdominal distention and abdominal tenderness. An x-ray (with or without contrast) may be helpful in the diagnosis of volvulus. Findings on an x-ray suggestive of sigmoid, cecal and ileal volvulus include; u-shaped, distended segment of colon seen as an ahaustral collection of gas volvulus. Findings on an x-ray suggestive of gastric volvulus includes a single, large, spherical gas bubble located in the upper abdomen or chest with an air-fluid level. It is important to rule out pneumoperitoneum before carrying out a barium enema. The initial investigation for volvulus can be a plain x-ray without contrast, or a CT scan. CT scan is useful in diagnosing volvulus when x-ray has been unfruitful. CT can also identify the level of obstruction and determine if bowel necrosis has occurred. Laparoscopy may be helpful in the diagnosis of complicated volvulus when diagnosis is equivocal by other imaging modalities. Surgery is the mainstay of treatment for volvulus. Endoscopic and nasogastric decompression may be used initially in an attempt to detorse the volvulus when feasible. Subsequently, an open procedure or laparotomy may follow to enter the abdomen, untwist the bowels and restore the blood supply. Necrotic bowel is either resected and re-anastomosed with the remaining bowel or is connected externally by colostomy or ileostomy.

# Historical Perspective
The pathophysiology and treatment of volvulus were established in the 20th century, by William Ladd. However, evidence for cases of volvulus go as far back as 1550 BC in Egypt.

# Classification
Volvulus can happen at various parts of the gastrointestinal tract. Volvulus can also occur congenitally or acquired in a newborn, an infant or an adult. These include sigmoid volvulus, cecal volvulus, gastric volvulus and ileal volvulus.

# Pathophysiology
Regardless of cause, volvulus causes symptoms by two mechanisms.  One is bowel obstruction, manifested as abdominal distension and vomiting.  The other is  ischemia (loss of blood flow) to the affected portion of intestine.  This causes severe pain and progressive injury to the intestinal wall, with accumulation of gas and fluid in the portion of the bowel obstructed. Ultimately, this can result in necrosis of the affected intestinal wall, acidosis, and death.  Acute volvulus therefore requires immediate surgical intervention to untwist the affected segment of bowel and possibly resect any unsalvageable portion.

# Causes
Midgut volvulus occurs in patients (usually in infants) that are predisposed because of congenital intestinal malrotation. Segmental volvulus occurs in patients of any age, usually with a predisposition because of abnormal intestinal contents (e.g. meconium ileus) or adhesions. Volvulus of the cecum, transverse colon, or sigmoid colon occurs, usually in adults, with only minor predisposing factors such as redundant (excess, inadequately supported) intestinal tissue and constipation.

# Differentiating Volvulus from other Diseases
Volvulus must be distinguished from other diseases, as it may be a solitary finding or a feature of another disease. Differential diagnoses include:Crohn's disease, necrotizing enterocolitis, duodenal atresia, pyloric stenosis, toxic megacolon and pseudocolonic obstruction (Ogilvie syndrome).

# Epidemiology and Demographics
Acute mechanical small bowel obstruction is a common surgical emergency where volvulus is the cause in 10% of cases. It is estimated that over 300,000 laparotomies are performed per year in the United States for adhesion-related obstructions such as volvulus. Volvulus originating in the colon is the third most common cause of large bowel obstruction.

# Risk Factors
Common risk factors in the development of volvulus include pregnancy, chronic constipation, age over 50, and long sigmoid colon and mesentery.

# Screening
There is insufficient evidence to recommend routine screening for volvulus. However, there are screening programs in place that utilize an ultrasound to seek out intestinal malrotation, which may be a cause of fatal midgut volvulus.

# Natural History, Complications, and Prognosis
If left untreated, the majority of patients with volvulus may progress to develop gangrene of the bowel, which can be fatal. Common complications of volvulus include bowel ischemia, gangrene, and necrosis. Prognosis is generally excellent, so long as the affected part of the bowel is resected or untwisted before ischemia occurs, usually within 48-72 hours. If necrosis of the affected bowel has already occurred then the prognosis is poor and may be fatal.

# Diagnosis

## Diagnostic Criteria
There is no single diagnostic study of choice for the diagnosis of volvulus. Volvulus can be diagnosed based on clinical findings and on the findings on CT scan, plain x-ray or plain x-ray with contrast.

## History and Symptoms
The most common symptoms of volvulus include abdominal pain, abdominal distension, constipation and vomiting. Patients are usually elderly or institutionalized.

## Physical Examination
Patients with volvulus usually appear in distress. Physical examination of patients with volvulus is usually remarkable for abdominal distention and abdominal tenderness.

## Laboratory Findings
Laboratory testing is carried out to rule out other causes of acute abdominal pain and to determine if bleeding is present. These tests may include, complete blood count, electrolytes and serum lactate levels.

## X-ray
An x-ray (with or without contrast) may be helpful in the diagnosis of volvulus. Findings on an x-ray suggestive of sigmoid, cecal
and ileal volvulus include; u-shaped, distended segment of colon seen as an ahaustral collection of gas volvulus. Findings on an x-ray suggestive of gastric volvulus includes a single, large, spherical gas bubble located in the upper abdomen or chest with an air-fluid level. It is important to rule out pneumoperitoneum before carrying out a barium enema.

## CT
The initial investigation for volvulus can be a plain x-ray without contrast, or a CT scan. CT scan is useful in diagnosing volvulus when x-ray has been unfruitful. CT can also identify the level of obstruction and determine if bowel necrosis has occurred.

## Other Diagnostic Studies
Laparoscopy may be helpful in the diagnosis of complicated volvulus when diagnosis is equivocal by other imaging modalities.

# Treatment

## Medical Therapy
There is no medical therapy for volvulus; the mainstay of therapy is surgical.

## Surgery
Surgery is the mainstay of treatment for volvulus. Endoscopic and nasogastric decompression may be used initially in an attempt to detorse the volvulus when feasible. Subsequently, an open procedure or laparotomy may follow to enter the abdomen, untwist the bowels and restore the blood supply. Necrotic bowel is either resected and re-anastomosed with the remaining bowel or is connected externally by colostomy or ileostomy.

## Prevention
There are no established measures for the primary prevention of volvulus. Volvulus cannot be prevented in the case of congenital intestinal malrotation. However, in adults care should be taken to consume a high fiber and potassium diet with conservative use of laxatives to avoid volvulus.