In gastroenterology, a diverticulum is defined as a bulging (or outpouching) of some part of the gastrointestinal tract. Because these bulges typically involve all three layers of the gastrointestinal wall (mucosa, muscle, and serosa), the diverticula becomes effectively a sac that can and does collect undigested or partially undigested materials that travel through the digestive system. Diverticula usually develop later in life and are often asymptomatic, but one type that is somewhat unique is Meckel’s diverticulum.
What is Meckel’s Diverticulum?
Meckel’s diverticula is named after Johann Friedrich Meckel, a German biologist who first classified the condition in 1809. As opposed to most other types of diverticula, Meckel’s diverticulum is a congenital condition that is present at birth. It is estimated that some 2%-4% of the population has the condition; as such, it is the most common type of congenital malformation of the digestive tract. Also, because it is present at birth, any adverse symptoms or complications of Meckel tend to be far more common in children rather than adults.
By the fourth week of a normal pregnancy, the embryo gets its blood supply from the vitelline duct (also known as the omphalomesenteric duct), a tube that connects the yolk sac (a structure that has multiple functions in embryonic development) to the developing fetus via the midgut lumen. Usually the vitelline duct narrows and is eventually absorbed into the fetus by the eighth week. In some pregnancies, however, the vitelline duct fails to narrow and disappear; the result is a vitelline fistula that remains attached to the fetus and becomes connected to the umbilical cord. Eventually, the ectopic tissue of this vestigial structure stays intact as Meckel’s diverticulum on the small intestine near the ileum and the ileocecal valve.
Meckel’s diverticulum is considered a “true diverticulum,” which means that it involves all layers of the intestinal wall and stems from the antimesenteric border of the small intestine (by contrast, a false diverticulum means that only some of the layers are involved). This type is different than other cysts and fistulae related to the vestigial vitelline duct because Meckel’s diverticulum doesn’t have attachments to other parts of the gastrointestinal system. Though it is clearly a congenital anomaly, it is still unknown why exactly this diverticulum occurs.
Symptoms of Meckel
Most people who develop Meckel’s diverticulum are actually asymptomatic (this is sometimes referred to as silent Meckel’s diverticulum). With the clinical presentation of symptoms, however, they typically present in children before they are two years old; symptoms are much rarer in adults. One of the reasons this condition can be difficult to diagnose is that the symptoms can sometimes mimic other gastrointestinal disorders like Crohn’s disease, peptic ulcer disease, and appendicitis. Below are some of the most common symptoms:
- Bleeding: Because the diverticulum is a sac open to the inside of the ileal small bowel, sometimes stomach acid and other gastric juices can enter the diverticulum and cause an ulcer to form. These ulcers, in turn, can cause gastrointestinal bleeding that is seen in the stool.
- Tenderness: The presence of a diverticulum can cause tenderness in the area around the belly button (umbilicus, or navel).
- Abdominal Pain: Abdominal pain in the right lower quadrant and cramping are possible due to a variety of factors related to the irritation caused by the diverticulum.
- Intestinal Obstruction: In some cases, the diverticulum can cause a segment of the small intestine to “telescope” into another segment (a condition known as intussusception), causing a bowel obstruction that can lead to a variety of other gastrointestinal problems. The diverticulum can also cause a volvulus to form, which is when a loop of intestine becomes twisted around itself.
- Diverticulitis: Though rare, sometimes Meckel’s diverticulum can actually lead to Meckel’s diverticulitis, an inflammation of the diverticula with symptoms that look very much like the symptoms of appendicitis. Additionally, the inflamed diverticula can become perforated and lead to yet another disease, peritonitis (an inflammation of the inner lining of the abdominal wall).
As noted above, the majority of patients who have Meckel’s diverticulum are asymptomatic, and this means that no treatment is needed. Most people can live a normal life without any disruption, and they may only discover they have it by accident during tests for other conditions or during surgery. Because the symptoms can look like a variety of other conditions, diagnosis of Meckel can be challenging. Currently, the preferred diagnostic tool is called a technetium-99m pertechnetate scan (also sometimes just referred to as Meckel’s scan). The purpose of the scan is to look at gastric mucosa and determine whether the diverticula contain telltale gastric or pancreatic cells in the ectopic mucosa surrounding the diverticulum.
Meckel’s diverticulum is already a fairly rare condition, but is also notable because the treatment options are limited. If there are no symptoms, or if the symptoms are very mild, no treatment is necessary. If the symptoms are severe (a sub-type known as complicated Meckel’s diverticulum), however, or if there is significant bleeding, the only option is surgery. The most common type of surgery is intestinal resection. This procedure is usually done using laparoscopic techniques (known as a laparotomy), and it involves removing the section of the small intestine that contains the diverticulum. Then, the two remaining ends of the intestine are stitched together with sutures.
Occasionally, a surgeon will discover the diverticulum while performing another type of surgery. If the patient is a child or a young adult, the surgeon will perform an incidental removal of the diverticulum there and then, out of an abundance of caution, even if the condition was asymptomatic. The same is true if discovered while operating on an elderly patient since allowing it to remain may lead to additional complications.
Because of how relatively rare it is for Meckel’s diverticulum to present with specific symptoms, most people won’t even know they have it nor even think to be aware of it. The symptoms can and do look like the symptoms for other conditions, though, so it is always beneficial to be aware of changes in one’s bowel habits or any discomfort that is experienced. If you (or your child) have bloody stool or any of the other symptoms listed above, you should make an appointment with a gastroenterologist. At Cary Gastroenterology Associates, we are dedicated to helping you stay proactive about your digestive health so you can catch any problems as soon as possible. If you would like to speak with one of our board-certified gastroenterologists, request an appointment today.