Sphincter of Oddi Dysfunction: An Overview
Guest: Dr. Joe Romagnuolo – Gastroenterology-Hepatology
Host: Dr. Linda Austin – Psychiatry
Dr. Linda Austin: I am Dr. Linda Austin and I am interviewing Dr. Joe Romagnuolo who is Associate Professor of Medicine at the Digestive Disease Center. We are going to be talking, today, about a very special interest of his in the area where we are going to be doing some very interesting clinical trials at the medical university. It is called Sphincter of dysfunction. Dr. Romagnuolo, what is the Sphincter of Oddi?
Dr. Joe Romagnuolo: The Sphincter of Oddi is a circular muscle that is at the bottom of the bile duct and pancreatic duct. Both of those ducts drain into part of the intestine that is just past the stomach. The fluids in the bile and pancreatic duct are used to help digest food, especially fats. That circular muscle, that sphincter, prevents food and other contents from going up into the duct and controls the amount and rate of fluid going into the intestine.
Dr. Linda Austin: So, when there is dysfunction, or poor function, of that sphincter, that little tightening, squeezing muscle, then, in that tube, what happens?
Dr. Joe Romagnuolo: Well, when that muscle clamps down, it can cause pain that is very similar to a gallbladder attack or to an attack of pancreatitis. Because it prevents the flow of juice from both of those systems, the bile and pancreatic duct get engorged and get full of fluid and that causes pain.
Dr. Linda Austin: Can that pain come and go?
Dr. Joe Romagnuolo: It can. Most commonly, it does come and go and it is worsened with meals because the flow of juice from those systems is increased when you have a meal.
Dr. Linda Austin: Now, why have I never heard of this before?
Dr. Joe Romagnuolo: Well, Sphincter of Oddi dysfunction is a difficult diagnosis to make. In some patients they will have dilation of the duct which you can see on an ultrasound, MRI or CT scan. Or, you might get an elevation of the liver test if the bile duct is obstructed because that is what drains the liver. Or, you may have an elevation in the pancreatic enzymes, in pancreatitis, if the pancreatic duct is blocked. Otherwise, if those two sets of tests are normal, then the diagnosis can be very difficult to make and you really need a specialized test, called an ERCP (Endoscopic Retrograde Cholangiopancreatography) with pressure measurements, or manometry, to diagnose that condition.
Dr. Linda Austin: So, then, would it be relatively unusual for a family doctor or even an internist to make this diagnosis?
Dr. Joe Romagnuolo: It would. I think if the blood tests are elevated or if the imaging tests are abnormal then there is something objective that at least points to the bile duct or the pancreas as a cause for the pain. But, if all those tests are normal then it may be a diagnosis that is not thought about.
Dr. Linda Austin: I see. So, the patient, then, might have gone to their family doctor or to their internist with unexplained abdominal pain, not gotten a diagnosis, and then they end up coming to the Digestive Disease Center for further evaluation, at which point you would do specialized tests? Do I have that right?
Dr. Joe Romagnuolo: That is right. In general, most patients who come to us for an assessment for Sphincter of Oddi dysfunction, or what we call SOD, have already had multiple investigations that are normal. They have had CT scans that are normal, endoscopies that are normal. They are often actually referred by other gastroenterologists who have already evaluated their pain to the extent that they can and have not found a cause.
Dr. Linda Austin: Is there anything characteristic about the pain? Can you just describe it a little bit more? Where in the belly is it? When does it come on? What is the relationship to food? Is it a burning pain, a stabbing pain, an ache? How do patients describe it?
Dr. Joe Romagnuolo: Well, you know, the classical description is that it is in the upper abdomen, what we call the epigastrium, just below the breast bone, or in the right upper quadrant of the abdomen where the gallbladder would be. Those pains last generally somewhere between 15 minutes to a couple of hours and will be intermittent. They can happen every day or they may happen once or twice a year, with severe attacks, that might bring you to the emergency department. Some people have discomfort that is there in between attacks, at a low level, and other people are completely pain free between attacks. In those patients who have pain that is there all the time, it generally gets worse when they eat.
Dr. Linda Austin: Just right after they eat?
Dr. Joe Romagnuolo: Usually right after they eat.
Dr. Linda Austin: Is there anything characteristic about the type of pain. Is it a knife-like pain, or a burning, or an ache, or a dull pain, or is it variable?
Dr. Joe Romagnuolo: It is variable. I think most people describe it as a sharp pain, or a stabbing pain, that is in the center of their upper abdomen and sometimes radiates into their back or radiates into the right upper quadrant. In some cases, it is a burning sensation, but usually a burning sensation makes us think that maybe heartburn or some type of indigestion is more likely the cause.
Dr. Linda Austin: What are some other entities, such as heartburn, maybe ulcer, that this could be confused with? What are the things you have to rule out as you go along?
Dr. Joe Romagnuolo: Well, because the ERCP with manometry that we do is somewhat dangerous, there are complications associated with it, we really want to make sure that we are doing it on the right group of patients, who have really had the simpler diagnoses ruled out. So, ulcers can feel like this. Heartburn can potentially feel like this, although it is a little bit lower than where you would normally feel heartburn, but certainly it can occur that low. Indigestion, or what we call functional dyspepsia, or non-ulcerative dyspepsia, meaning, you feel like you have an ulcer but you do not. In fact, pancreatitis, chronic and acute, can feel like a Sphincter of Oddi dysfunction attack.
Dr. Linda Austin: Is it only the ERCP test that could distinguish it, say, from pancreatitis? It sounds like in both, you could have elevation of the pancreatic enzymes.
Dr. Joe Romagnuolo: What we normally do is split patients who are suspected of having SOD into three categories. The Type 1 patients are patients who, it looks like the bile duct or pancreatic duct is the cause for their pain. There is dilation of the bile duct and there is elevation of the liver enzymes when they have attacks of pain. Those patients can generally just have an ERCP and have that sphincter cut.
Type 2 patients will have something objective, perhaps imaging, perhaps the enzymes, and those patients have a pretty high chance of being cured with cutting that sphincter with an ERCP.
The group that is the most controversial, and probably the hardest, and has the lowest chance of potential benefit is what we call Type 3 SOD patients. Those patients have normal imaging and normal labs. In those patients, it can be very difficult to know whether SOD is really the cause for their pain.
Dr. Linda Austin: Let’s talk some about ERCP. First of all, that stands for?
Dr. Joe Romagnuolo: ERCP stands for Endoscopic Retrograde Cholangiopancreatography. The endoscopic is because it is done with a scope. The retrograde is because the dye is injected in the opposite direction that it normally flows. Cholangio means bile duct, and pancreatography is the pancreatic duct dye injection.
Dr. Linda Austin: So, we are just going to call it ERCP, I think. How long does that procedure take?
Dr. Joe Romagnuolo: That can take anywhere from 15 minutes to an hour. On average, it takes about 30 to 45 minutes. It involves putting a flexible tube, a scope, into the stomach and then into the small intestine.
Dr. Linda Austin: Through the nose? Is that right?
Dr. Joe Romagnuolo: Through the mouth, under sedation. After we pass just beyond the stomach, we find a little hole, or nipple, where the ducts drain into the intestine. That little hole is cannulated with a little tube. So, we put a little tube inside that hole to inject dye to outline the bile and pancreatic duct. In the kind of ERCP that we do for SOD, we also take pressure measurements of the little muscle that is around that nipple, that is called the ampulla of Vater. We take pressure measurements of that sphincter with that pressure measurement catheter inside that little hole. That hole can be 1-2 mm in size, so it is usually a tight opening, and getting the catheter into the hole can be easy or quite difficult but we are successful more than 95 percent of the time.
Dr. Linda Austin: You mentioned that you only do the ERCP when you have a very high index of suspicion that you are going to be right? Is that correct? What percent of the time do you, in fact, find SOD in that patient?
Dr. Joe Romagnuolo: Depending on whether you look at patients who have Type 1 or Type 2, or Type 3, depending on how much objective evidence that the bile or pancreatic duct is the cause of the pain, it varies, but it is well over 50 percent. Overall, it is probably about two thirds of patients who will have an abnormal manometry that are sent for that specific test. We do ERCP for other reasons. We do it to look for bile duct stones, to evaluate for cancer, to drain the bile duct in patients who have jaundice from a narrowing that is benign or malignant. So, there are certainly other reasons why you might do an ERCP. But when we are doing it for unexplained abdominal pain and we are doing it with pressure measurements, or manometry, we tend to be very cautious about the patients we are doing this on.
Dr. Linda Austin: You mentioned earlier that you can, then, cut the sphincter in the process of doing the ERCP. So, in other words, the same ERCP, the same procedure, can actually be diagnostic and curative? Is that correct?
Dr. Joe Romagnuolo: That is right. So, if we found some type abnormality or pathology, we generally treat it at the same time, if it is possible. Certainly, in this case, with SOD, the treatment is cutting that muscle, cutting the sphincter, what is called a sphincterotomy. That is done with a cutting wire that is on the end of that catheter and it is done during the same procedure.
Dr. Linda Austin: What is your success rate on that?
Dr. Joe Romagnuolo: The success rate of getting into the duct that you want and being able to do the therapy that you want is almost 100 percent. We are well over 95 percent at being able to get what we want done at the time of the ERCP. What we are most concerned about, for ERCP, are the complications that may follow.
Dr. Linda Austin: What are those complications?
Dr. Joe Romagnuolo: The most common complication is pancreatitis. Pancreatitis, in our hands, looking back at our data base, is well under the reported literature at about two to three percent. But, it is a bit higher if you look at the subgroup of patients who go for manometry for evaluation of SOD, at about five percent. So, approximately 1 in 20 patients will get pancreatitis.
Dr. Linda Austin: What happens then? Is that an acute pancreatitis that then subsides, or can that ever cause chronic problems?
Dr. Joe Romagnuolo: Almost always it is just acute pancreatitis. Most patients will get abdominal pain that keeps them in the hospital for three to four days when they have an acute pancreatitis that follows an ERCP. That will happen in approximately 1 in 20 cases. A small percentage of patients who get post-ERCP pancreatitis will have to stay in the hospital over a week and sometimes, if you are very unlucky, you may get severe pancreatitis which may keep you in the hospital for months or even place you in the intensive care unit.
Dr. Linda Austin: But that , mercifully, is quite a rare event?
Dr. Joe Romagnuolo: It is quite a rare event. Because of that fear, we have to select people quite appropriately and they certainly have to understand the risks and benefits of that procedure when they are deciding to do it for unexplained abdominal pain. When there is almost certainly a pathology, such as a bile duct stone or a tumor, then the risks of post-ERCP pancreatitis are actually quite low, about two percent. In those cases where the chances of benefit are nearly 100 percent, it is a much easier decision to go ahead with the procedure.
Dr. Linda Austin: Is the ERCP with the incision the only way to treat SODs?
Dr. Joe Romagnuolo: It is the most common way of treating it and it is the safest way of treating it. But, you can have what is called the surgical sphincteroplasty which is the surgical version of the sphincterotomy where you have an operation where the actual muscle is cut by surgical means.
Dr. Linda Austin: So, in other words, you open up the abdomen with an incision? I would think that would be far more traumatic than what you are describing.
Dr. Joe Romagnuolo: It is far more traumatic and has a longer recovery time.
Dr. Linda Austin: Are there no medications that can treat this?
Dr. Joe Romagnuolo: In general, patients have already tried antispasmodics before they come to see us. They have generally tried that for presumed Sphincter of Oddi dysfunction or a suspicion of irritable bowel syndrome, antispasmodics are used for both conditions, and that has failed. Antispasmodics can be helpful in some patients with SOD.
Dr. Linda Austin: And then, if the ERCP is successful, will the patient remain symptom free indefinitely, or does it ever come back?
Dr. Joe Romagnuolo: It can come back. The sphincters can heal with a scar and that happens, luckily, in only a small percentage of patients. When the pancreas duct is cut, it can occur in up to 20 percent of patients. It will scar down, potentially, over time and have to be re-cut in the future if symptoms were to recur. For the bile duct sphincter, to have the sphincter scar back down again, what we call re-stenosis, is very uncommon.
Dr. Linda Austin: Dr. Joe Romagnuolo, thank you so much for talking with us today.
Dr. Joe Romagnuolo: Thank you.
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