Endoscopic ultrasonography, or EUS, provides an important bridge between a suspected diagnosis and appropriate therapy. The procedure uses a thin, flexible endoscope containing a tiny ultrasound probe to examine the upper and lower gastrointestinal tract as well as nearby organs such as the pancreas, gall bladder and liver.
EUS enables gastroenterologists specially trained in its use to identify, evaluate and stage a wide range of benign and malignant conditions. Although its therapeutic applications have been expanding recently, EUS still might best be described as an intermediary diagnostic procedure that provides accurate diagnoses that can lead to the appropriate endoscopic, surgical or medical treatments.
Those capabilities have advanced dramatically since endoscopic ultrasound first was developed to evaluate the difficult-to-examine pancreas. Today, through EUS, patients are able to be assessed for bile duct blockages, chronic pancreatitis, staging of esophageal, stomach or rectal cancers, enlarged lymph nodes in the chest or abdomen, pancreatic cysts, submucosal gastrointestinal lesions, bile duct stones and more.
At Abington Memorial Hospital, one of the few non-academic centers in the region with EUS services, patients are referred for the procedure due to both presenting symptoms, such as unexplained abdominal pain or jaundice, and disorders that are detected only incidentally during other tests.
For example, we recently saw a patient who had undergone magnetic resonance imaging (MRI) for back problems. That test had incidentally noticed a one-centimeter pancreatic cyst. Such incidental findings are happening more and more frequently as computed tomography (CT) and MRI technologies improve.
When I examined the cyst with EUS, I discovered a nodule within it. Since endoscopic ultrasound also enables me to do fine-needle aspiration, we were able to determine that the nodule was pre-cancerous or cancerous based on cytology. This condition was detected in a patient who had no pancreatic cancer symptoms and only a very small lesion (less than half-an-inch). Because EUS identified that the nodule was suspicious for malignancy, the patient could have it surgically removed instead of having a deadly lesion grow silently over the next few years until it might be too late for surgery.
This is not an isolated example. At one time, pancreatic cysts were thought to be only the result of previous attacks of pancreatitis. Advanced technology now is showing us many instances in which patients have such cysts without having had pancreatitis. Currently, about 30 to 40 percent of the EUS patients I see—the largest patient category in my experience—are being evaluated for pancreatic cystic lesions, many of which are discovered incidentally.
EUS also provides excellent differentiation of the characteristics of submucosal lesions throughout the gastrointestinal tract. Patients being evaluated for these lesions comprise my second-largest EUS patient category. By investigating with EUS, we can determine which layer of the intestinal wall a lesion is arising from as well as its imaging characteristics. We are also able to sample it through fine-needle aspiration or core biopsy. Through this evaluation, we are often able to determine the character of the lesion and whether it can be watched or needs to be removed. The types of submucosal lesions commonly seen are lipomas, leiomyomas, carcinoid tumors and gastrointestinal stromal tumors.
Endoscopic ultrasound has proven to be a highly accurate adjunct for local and regional tumor staging in addition to CT or positron emission tomography (PET) scans. With EUS, we are able to pick up cancer spread to even very small lymph nodes—spread that may not be detected on CT or PET—and sample nodes for malignancy. By avoiding under-staging, we may spare the patient having to undergo a treatment that would not have brought any benefit.
As a therapeutic endoscopist, I use EUS and endoscopic retrograde pancreatography (ECRP) for therapeutic procedures including the placement of stents to drain blocked bile ducts and the extraction of bile duct stones or sludge. EUS is a less-invasive procedure that can help guide the treatment of patients with disorders of the bile ducts and pancreas. EUS may also be used to drain pancreatic pseudocysts that are symptomatic or not resolving on their own.
It can also be used to help manage pain that has not responded well to medication by injecting medication adjacent to the celiac plexus, a group of nerves that supplies sensation to the pancreas and other abdominal organs. This medication can be delivered as a celiac plexus block (temporary) in patients with non-malignant pain or as a neurolysis (permanent) in patients with cancer-related pain.
The only patient preparation needed for EUS is fasting after midnight, although rectal EUS usually requires enema to clean out the lower colon. Patients on blood thinners, aspirin or non-steroidal anti-inflammatory medications should discontinue such use for a week beforehand, to minimize the risk of bleeding if fine-needle aspiration is used. For aspirating a cyst, patients may receive an antibiotic before and after the procedure.
Endoscopic ultrasound is very safe, with risks similar to routine endoscopy. EUS procedures take longer than routine endoscopy—an upper EUS might last 60 to 75 minutes, compared with 10 to 15 minutes for the routine version—so prolonged sedation is an issue. An anesthesiologist usually manages the sedation. In the more than 550 EUS procedures I’ve performed, there have been very few complications.
With more than half of our EUS cases related to cancer evaluation, we know that patients may be anxious going into these procedures. We would always like to give them good news after EUS. When that isn’t possible, we are usually able to give them some hope, through accurate staging that gets them to the correct therapy they need as quickly as possible.
Daniel A. Ringold, MD, is a gastroenterologist and therapeutic endoscopist with Gastrointestinal Associates, Inc., and consulting physician at Abington Memorial Hospital (www.amh.org).