The human gut, also referred to as the alimentary tract, is a long hollow organ that extends from the mouth to the anus. The longest part of the alimentary tract lies between the stomach and anus – it is known as the intestines or bowel. Broadly, the intestines are made up of the small intestine and large intestine which are responsible for digestion, absorption and waste expulsion from the body. The small intestine is about 6 meters long while the large intestine is about 1.5 meters in length. Of the two intestines, the small intestine is the narrower segment.
Some parts of the intestines are fixed to the abdominal wall, while others are free or suspended by supporting ligaments. The intestines are contained in the peritoneal cavity, a hollow space within the abdominal cavity that is lined by the peritoneum and in which peritoneal fluid lubricates the outer surfaces of various abdominal organs. This allows the different organs some degree of movement with sufficient lubrication to prevent abrasion. The intestines without further support would simply sink to the bottom of the peritoneal cavity with gravity.
However, certain parts of the intestines are suspended within the cavity by a double layer of peritoneum known as the mesentery. This allows for movement yet sufficient support. The intestines, however, given its length are able to move more freely and in the process prone to displacement or tangling. This can upset the functioning of the intestines but may also block its lumen or cut off the blood supply to its wall with life-threatening consequences.
What is a Volvulus?
Volvulus is the medical term for a complete twisting of the bowels around the mesentery attachment supporting it. It is a rare condition that can affect the stomach, small intestine or parts of the large intestine and is mainly seen in infants or children although certain types may occur in adults. Commonly it is referred to as a twisted bowel.
The two main aspects that contribute to the development of signs and symptoms as well as lead to possible complicates are obstruction and strangulation. With the twisting seen in a volvulus, the intestinal lumen may become obstructed to various degrees. Complete obstruction prevents food, chyme and waste from traveling further and causes it to back up in the gut. The twisting also strangulates the bowel wall so that blood vessels may become obstructed. This may reduce the blood flow through it and starve the intestinal tissue of oxygen. Eventually this will lead to ischemia, injury associated with reduced blood flow, or continue further to the point that the tissue of the intestinal wall dies and can even become gangrenous.
Types of Vovulus
There are several different types of volvulus. Some occur exclusively in infants or early childhood while other types may occur at any age. The different types include volvulus in newborns, and of the stomach (gastric), small intestine, cecum and sigmoid colon. The more common types of volvulus are discussed further.
Also known as volvulus neonatarum, this type of volvulus is seen in newborns. It is a consequence of malrotation during fetal development. The gut is initially a straight tube in the fetus and as its grows in length, it gradually rotates. This is only a partial rotation to house the very long intestines within the small spaces of the abdominal cavity. Sometimes this rotation may not occur (non-rotation) or may be abnormal (malrotation). With the latter, malrotation, there is a risk of a complete twisting that strangulates the bowels. This more often presents as a midgut volvulus where the midgut twists about the axis of the superior mesenteric artery (SMA).
The sigmoid colon is the last part of the large intestine which leads to the rectum. It is attached to the abdominal wall but with certain anatomic abnormalities, it may be free or be twisted around the base of narrow mesentery. In other cases, however, a volvulus of the sigmoid colon may arise with no anatomic abnormalities.
The cecum is the juncture between the last part of the small intestine, known as the ileum, and the first part of the colon of the large intestine, known as the ascending colon. As with the sigmoid colon, it is attached to the abdominal wall along with the ascending colon. Anatomic abnormalities where this part of the large intestine is free is likely to lead to a twisting (volvulus).
This is a twisting of the stomach which may affect the cardia (first part of the stomach attached to the esophagus) or the entire stomach. A significant number of cases arise with a hiatal hernia, a condition where part of the stomach protrudes up into the chest cavity through the diaphragmatic opening.
Causes of a Volvulus
A volvulus is more likely to occur with an anatomic abnormality even in the absence of any other disease. The different parts of the intestine, if not suspended or secured in the usual manner, can easily become entangled. However, a volvulus may arise with certain diseases despite the absence of any anatomic abnormality. The causative disease may depend on the part of the intestine that is involved.
- Hirschsprung disease
- Intestinal pseudo-obstruction
- Diaphragmatic hernia
- Meckel diverticulum
- Atresia or stenosis
- Cystic fibrosis
- Meconium ileus
Signs and Symptoms of a Volvulus
The clinical features largely depends on two factors – the extent of the obstruction of the gut lumen and/or the degree of reduced blood flow to the intestinal wall leading to ischemia.
- Vomiting – non-bilious and bilious vomiting (bile vomiting)
- Recurrent abdominal pain
- Lack of appetite
- Bloody stools (hematochezia)
As ischemia develops, abdominal distension and peritonitis will become evident. Once there is death of tissue in the intestinal wall, signs of septic shock will arise.
Diagnosis and Treatment
A volvulus is rare and its initial presentation is non-specific. Many other gastrointestinal disorders that are more common present in a similar manner. Radiological studies, particularly with the use of contrast dyes like in a barium meal, will help to identify the twisting of the bowels. Initial investigation may commence with an ultrasound study but should be followed by a CT scan as soon as possible.
Treatment is dependent on whether the condition is symptomatic or not. In asymptomatic cases, the treatment can be delayed if the patient so wishes but the patient should be monitored constantly. The presence of any intestinal obstruction warrants immediate surgery. The surgical approach known as Ladd’s procedure can be done with open surgery or as a laparoscopic procedure.