Meconium Ileus: Presentation, Workup, Diagnosis & Treatment Options

Hi, everyone. Welcome back to Stay Current Podcasts. I'm M Tom Bash, a research fellow at Cincinnati Children's Hospital Medical Center. With Stay Current, we share knowledge to improve child health around the globe. In this podcast, we are going to talk about meconium ileus presentation, diagnosis criteria, treatment options, and post-op care with Dr. Beth Romesky. My name is Beth Romesky. I'm a pediatric surgeon at Cincinnati Children's. We have a lot to cover today. So if you're looking for a specific part like diagnosis or treatment options, make sure to check out timestamps in the description. They'll take you wherever you need. Meconium ileus is a problem that affects some newborns where the thick meconium stool, which is present in the colon at birth, is unable to pass. And the majority of patients with meconium ileus do have cystic fibrosis. So the incidence of meconium ileus varies by race and ethnicity. So in the Caucasian population, in about one to every 1100 to 2500 live births, much less prevalent in black populations with one in every 17,000 live births and even more rare in Asian populations where it's one in every 90,000. And we know that about one in five babies with cystic fibrosis is born with meconium ileus. Oftentimes, these are actually picked up ahead of time, either through genetic screening tests or identification of dilated bowel or something that prompts a workup of the parents cystic fibrosis carrier status. So the gene in question with cystic fibrosis patients is the CFTR gene, which codes for protein that forms the cyclic AMP induced chloride channels. Those chloride channels regulate ion flow across the surface of epithelial cells. So when you have a mutated CFTR gene, the secretions, including the meconium are very thick and what we call inspissated, meaning they're just like devoid of enough moisture to allow things to move through. So that altered chemical makeup results in the bowel becoming filled with this thick inspissated meconium that does not move through the bowel normally and causes an obstruction. If you have an infant who either does not pass meconium in a typical fashion, or is distended at birth or has prenatal concerns for meconium ileus, then typically the first thing you're going to do is check an abdominal X-ray and just look at the bowel gas pattern. You're also looking for calcifications. There's simple meconium ileus and more complicated or complex meconium ileus. And the complicated meconium ileus patients, they can actually perforate in utero. So if on that initial X-ray of the infant calcification could mean that there was already complication in utero and a perforation and and healing took place. Otherwise, you're looking for a distension of the bowel. You're looking for signs that this could potentially be an obstruction at some level. In many of these cases, there is already a suspicion prior to birth that there could potentially be an issue with meconium ileus. There are some infants that either have poor prenatal care or did not show signs of it that it's a surprise. So there can be infants that come out with a normal, soft, flat abdomen and seem fine and just need to be observed. Many of these children will be born with a fairly distended abdomen and that along with prenatal diagnosis or concern, or if it's already known from previous pregnancies or because one of the parents has cystic fibrosis that CF is a consideration, then meconium ileus definitely moves up the ladder in terms of the differential. Particularly, differentiating meconium plugs from meconium ileus can be very challenging. You also need to consider causes of distal intestinal obstruction, like Hirschsprung's disease, or small left colon, or just delayed passage of meconium plug does in premature babies or sometimes we see that in term infants, but that's more common in premature babies. At least in the United States, cystic fibrosis testing is part of the standard newborn panel. If the newborn screen comes back positive, which you know, can take a week or more, then additional genetic testing is sent off to determine exactly which genetic mutation the patient has. But, of course, you're not going to be sitting around waiting for a week or more for that test to come back if you have an infant with a bowel obstruction. So if the child is stable and does not have signs of peritonitis, then it's appropriate to do more studies. And that study is going to be some sort of a contrast enema. Some people will just do a water soluble contrast enema, which will both provide diagnostic images and then also could potentially be therapeutic with its effect of drawing water into the colon to help try to clear some of that meconium. Other people will combine a contrast enema with Mucomyst mixed in. Mucomyst or acetylcysteine helps break up some of those chemical bonds and solubilize that inspissated stool. The contrast enema can be done on a repetitive basis and progressively see if you can get further and further up in the bowel. So the most common site of obstruction will be somewhere in the mid to distal ileum. It's usually not the colon that's obstructed. So sometimes the first contrast enema can clear out some of the colonic meconium. And then as you progress and repeat the study, you may be able to progress higher and higher. In some patients that might resolve the issue. So there are a certain number of babies with meconium ileus who never need an operation and with serial contrast enema administration, you can solubilize and relieve the obstruction. If the infant had peritonitis, then that's a different story, right? Baby needs to be taken to the operating room to be explored or if at any point during this process of doing the enemas, if you're worried that the abdominal exam has worsened, if there is concern for perforation, then those infants then need to be switched to surgical patients. If the patient either made some progress and stopped or never showed any signs of progress, then in the operating room you're going to explore. Most surgeons would do an open exploration since manipulation of the bowel is needed. What you want to try to figure out is where is the problem? Is there also some sort of acquired atresia that you need to deal with, the viability of all of the bowel? And then once you've assessed that, then you get to decide what's the most appropriate thing. Some people will just make a small enterotomy, place a catheter directly into the bowel in the area, either directly above or directly below where the obstruction is, and try to use that to loosen things up. There are reports taking off the tip of the appendix, putting a catheter retrograde through the appendix into the terminal ileum and using that as a mechanism of flush and sometimes bringing an appendicostomy up to the skin as a means of continuing to allow for irrigation of the bowel after surgery. There are many cases in which by time you get in there, the bowel may be severely dilated and not very healthy. So you may need to resect and you might need to create a stoma, usually an ileostomy in this situation. Some people will do that routinely, others will do that only if they feel like they can't get everything out and then plus or minus creation of a mucus fistula again for continued access to irrigate the bowel out. There are also some complicated meconium ileus patients that might not need an operation. So if on that initial X-ray you see calcifications and you're tipped off that this could have been a complicated process, then you might even try to feed first and see because they could have had something that perforated and healed over or something happened. So if they're not obstructed, then they don't necessarily need an exploration. And I would say if you're operating for a complicated meconium ileus, you're most likely going to be coming out of that with a stoma because you may not even be able to tell ultimately if the bowel is really in continuity and those can be a little tough. So, those infants I think can go either way. Some of them are very sick right after birth and need a more immediate intervention. Some of them can be stable for a while and then show their true colors. And there are a certain number of those patients that, you know, could potentially have completely healed and not obstructed their GI tract and not need an operation. There are different ways that you can put the bowel back together that still allow for decompression and or access to the bowel to do irrigations. The appendix is actually a reasonable solution to that problem because you can easily bring it up to the abdominal wall and then when you don't need it anymore, you can take it out. You just have to remember that the appendix is sutured to the abdominal wall. So that way if the patient presented later on with signs and symptoms of appendicitis, you just need to remember where it is. Post-op it's pretty common to run some of the mucomyst in from the top because these kids are very susceptible recreating this thickened meconium. So you do have to try to get on top of feedings and get things going. Because they have seen patients who had a delayed restart to feed who then obstructed again and had to be taken back to the OR or needed a lot of irrigation and enemas to try to unclog. I think most people will try to restart feedings as soon as is safe, also in combination with instilling the mucomyst through the NG tube or by mouth. And then once they're tolerating some sort of enteral diet, then usually the cystic fibrosis team and the dietitians will get involved with trying to get the pancreatic enzyme replacements going because that will also help prevent this from happening again. If you had to remove the bowel or if you have a proximal stoma, then you need to watch those babies very carefully for growth. Make sure they're absorbing nutrients well and achieving their goals in that sense before going home. Peroperative antibiotics are indicated in the sense that it's a class two or a class three operation, but additional antibiotics beyond the perioperative course are not necessarily indicated unless there is some other concomitant infection like a pneumonia or a wound infection or something else you would be treating. These babies all need an aggressive pulmonary toilet. So once you get them extubated, working on chest PT, making sure they're clearing their secretions and again, if your hospital has a cystic fibrosis team or cystic fibrosis experts, who are typically pulmonologist, get them involved in the care of these infants early on. If there is some question that this is not really cystic fibrosis or not really meconium ileus, then suction rectal biopsy at the bedside would be appropriate next step to look at that. But it's not routinely required in every patient who has a meconium ileus. I would say just if there's something about the patient's presentation that does not seem to fit, then you need to bring Hirschsprung's back into the list of potential diagnosis. A few tips are coming on our way from Dr. Romesky regarding post-op care during NiICU stay. Within that NiICU stay, making sure that they don't re-obstruct, again monitoring their growth really carefully, making sure that they're absorbing adequately, making sure that they're getting adequate pulmonary clearance, that we're replacing the needed enzymes and providing the family with the education and equipment they're going to need to take care of this child after discharge. In the long term, we'll often see patients back in early childhood or in teenage years where they present with something that's been listed as DIOS or distal intestinal obstructive syndrome. Since they're older kids, they might get a CAT scan and the comment on the CAT scan is that there's extensive fecalization of the distal ileum. And this is just a slow process of that really thick stool building back up. So in those patients, it may be that they need their enzymes ultimately altered. It may be that they've become non-compliant with their medication and led to something like this. Many CF patients and particularly those that had meconium ileus as a child, do have issues with chronic constipation and Miralax or some sort of PEG solution are often utilized to maintain the more thin stool and keep things moving. Most patients that present with this DIOS can be salvaged without an operation, which is the good news. We start with a contrast enema plus or minus Mucomyst, just sending it to try to loosen things up and get things going. And it would be rare that they would need to have an operation, but obviously if it's been a really delayed presentation or if you're unable to resolve the obstruction, then surgical intervention would be appropriate at that time. Even in a busy NiICU like they have here at Cincinnati Children's, they don't expect to see more than a few cases a year. And that's going to depend also on the community that you're serving. So if you work in a predominantly black or Asian population, then you're almost never going to see this. Over time, people have probably tried harder to keep babies out of the operating room. I think people are now more open to not always creating a stoma, trying other things to clear the meconium. We as surgeons tend to think of stomas as oh, it's not a big deal. It isn't a big deal if the baby does well with it. But stomas can prolapse, they get strictured. Also kids can have major electrolyte disturbances when they have an ileostomy. I think if you can try to avoid that safely, then that might be appropriate. Let's say we had to create a stoma. How long should we leave it? And should we discharge them with a stoma or not? I think for most surgeons, adults or pediatric or otherwise tend to not want to go back in the abdomen at interval less than four to six weeks. So I think that's fair to say that it would probably be at least six weeks of diversion. And at that point, reassessing mostly depends on their growth. And we want to see if they're having any complications with the stoma. There are some people that try to get infants home from the NiICU and then bring them back to close the stoma. There are other situations where you might want to do it before they go home. A lot of that's going to depend on growth. Some of that may really depend on the family situation or the resources in the community to deal with a child that has an ileostomy. Some places in the country and in the world where discharging a child with an ileostomy is not safe. They're going to get dehydrated, they're going to have significant issues. So they may need to stay in the hospital until that can be reversed. That was all regarding the diagnosis and treatment of meconium ileus. In conclusion, we need to look for distension of the bowel and for signs that this could potentially be an obstruction in order to diagnose meconium ileus. If the child is stable and does not have signs of peritonitis, we can do a contrast enema using Mucomyst or acetylcysteine, which will help solubilize that stool. If the infant has peritonitis, then that baby needs to be taken to the operating room to be explored. In many cases, by the time we get in there, the bowel may be severely dilated and not very healthy. So we might need to resect and create a stoma, usually an ileostomy. And as soon as it's safe, we should try to restart feedings to prevent reobstruction. Lastly, we mentioned some important topics like peri-op antibiotic use, how to care for a child with a stoma, and long-term follow-up. Thank you for listening to this podcast. Follow us on social media, subscribe to our YouTube channel, and download the Stay Current app for more content including videos, podcasts, and infographics. Cincinnati Children's Hospital and Stay Current, share knowledge to improve child health around the globe.