 Now, let's move on to our next talk, which is by Dr. Anita Mandawa. She is Senior Consultant Radiologist at Department of Radiology, BIA Cancer Hospital and Research Institute, Hyderabad, Telangana. And Ma'am has several publications to her credit. She has a professional experience of over 20 years and her key areas of interest are pertaining to Onko imaging. Today's topic is a little unusual and uncommon topic. But it is very, very important because as people sitting in cancer hospital, we know that the patient's lifespan is limited in most of the cases because we are working in tertiary care cancer hospitals. And whatever little amount of life they have got to live, if they are having a fistula, they are going to have a very bad quality of life. So detection of fistula is extremely important in malignancies. So today, we'll just quickly look at the clinical background of these fistulas, most common etiology, role of various imaging modalities and what are the goals of imaging. So a fistula is defined as an abnormal communication between two epithelial surfaces. And the earliest case was reported in Egyptian mummy in 1935, which was a vasikovaginal fistula. And for a long time, the cause of fistula source prolonged obstructed labor with improved obstetric care, that's no longer a problem. Now the communist cause is either inflammatory diseases or malignancies. The communist fistulas we see in our practice are vasikovaginal fistulas and rectovaginal fistulas. In case of malignancies, even uterine and cervical fistulas are not that uncommon. So patients usually present to us with the symptoms of either hematuria and hematuria or pyuria or if elementary tract is involved, they'll come with features of fecaluria or diarrhea with incontinence or foul spelling, vaginal discharge and recurrent UTIs. This is one of the most common presentations. And a non-specific finding, but very important is weight loss. So patients with these symptoms, if they come to us for evaluation for something as we need to look for a fistula. So as I said, the common causes of pelvic fistulas, benign etiologies are inflammatory bowel diseases, infections and surgeries, but most common cause is post radiation or directly malignancies, cervical colorectal ovarian and bladder neoplasms, condensers present with fistulas or postoperative cases. Again, they can have acute phase or chronic phase, they can have fistulation at the site of anastomosis or due to the dehesives or due to the recurrence. So there are several investigations for evaluation of fistulas. So historically, a lot of IVUs or cystographies were used for diagnosis, histographies, vaginographies for uterine and vaginal fistula evaluation, fistula graphies for fistulas with external cutaneous openings and barium wheel follow through or barium enemas, which we still do in few cases. But all of these investigations have one severe limitation that is you cannot visualize any fistula beyond that system which it is examining. The second one is lack of mural and extraluminal visualization. For that, you need cross-sectional imaging. So here we have a barium enema in a known case of carcinoma of rectum. We are seeing barium inside the large bubble, rectum and something outside of the contour of rectum. So in an oblique view, we can very clearly see the communication between the rectum and vagina. This is a clear-cut case of recto-vaginal fistula. But now you just don't know what is happening outside of the bubble lumen or what is happening to the bubble lumen itself. So for that, we definitely need a cross-sectional imaging. So coming to the next imaging, commonest imaging modalities are resolved. And as far as fistulas are concerned, please do not take ultrasound lightly because I'm going to show what we can do with ultrasound in next few slides. So ultrasound is very important because it is a very easily available inexpensive imaging modality. Though it has got its own limitations in the evaluation of fistulas because small fistulas of less than 1 centimeter can be very easily missed. And in postoperative and post-RT cases, again, the anatomy is totally disturbed. So in those cases also we may miss fistulas. And most importantly, we don't have a good urinary bladder volume when whenever there is a suspected vesicle fistulas where they have continuous urinary leakage or in well-in-catheters. In those cases, again, we don't have a good field of view. So in these cases, suboptimal studies, in these cases also it is very difficult to visualize a fistula through USG. But I'll show you some clues today where you can see when you see that you'll be able to pick up a fistula. So what are the signs of fistula on ultrasound? The first one is sonographic air contrast sign. The second one is sonographic flap type sign. And the third one is presence of ring down artifacts. We look at each of these signs very clearly in the next few slides. Other than this on ultrasound, we should be able to pick up focal wall thickening of the organs involved or adherence of organs to each other in pelvis. It will again be indicative of a suspicion clue to f is underlying fistula. If whenever we see fluid adjacent to either a mass or in the cul-de-sac and the POD, again, we need to rule out the fistula. And whenever there is loss of neural stratification in the adjacent bubble wall, that also may point out to a fistula. Other than this, we can see bubble wall, omental thickening or abdominal lymphadenopathy, ascites or any secondary metastatic lesions in the liver or something. Again, we need to think of a malignancy and a malignant fistula. So the first one which I'm going to show you is the air contrast sign. So this air contrast sign, give me a second. I'm going to... Okay. This is the air contrast sign. So what is air contrast sign? Air contrast sign is a continuous hyperechoic fistula tract within a hypoechoic neoplastic mass extending between the organs. Here is a case of carcinoma of cervix which is invading the rectum. You see a partially distended urinary bladder. So behind it is the uterus and the cervix and behind it is the rectum. Once you see this, you see a continuous air tract going from the rectum into the vagina. So this appearance, when you are able to see this continuous air tract between the two orgis and organs which are adherent to each other, it will point out to an air contrast sign which is the earliest clue of fistula. So this is the case of recto vaginal fistula. So you are able to see this recto vaginal fistula with air contrast sign, very, very clear your ultrasound. So this same recto air contrast sign on a ultrasound image, you are able to see the air going from the rectum into the vagina behind the urinary bladder. This is an ultrasound image and this is the recto vaginal fistula. The same fistula I am going to demonstrate on CT in the same patient where you can see the rectal contrast passing into the vagina just behind the urinary bladder. So this exactly what you are seeing on CT are able to see on even the ultrasound. So this is the air contrast sign showing your recto vaginal fistula. The second sign is the flat type sign. Whenever you see air passing into the urinary bladder, in a known case of malignancy you have to think of a vesicle fistula. So this is very clearly demonstrating the passage of air into the urinary bladder from the rectal mass. This is a case of recto vesicle fistula. So whenever you have a vesicle fistula, you need to look for this flat type sign. The third is ring down artifacts. So what are ring down artifacts? Some gas containing fistulas, they show irregular tracks of discontinuous hypericoic cocaine with posterior ring down artifacts. So these are ring down artifacts. When you are seeing ring down artifacts between two adjacent masses with very, when the flat planes between them are not seen, the cleavage planes are not clearly seen, then you should suspect a fistula. So these are the ring down artifacts. This is a partially distended urinary bladder and uterus. Here is the vagina and posterior to them is a rectum. The same image we are confirming a recto vaginal fistula over with CT. So whenever you see again ring down artifacts, you need to think of a fistula. So this is a case of recto vaginal fistula showing ring down artifacts. A few other cases on ultrasound and corresponding CT images I will show you. Again, a contrast sign between rectum and vagina. The same thing confirmed on CT. You are seeing a very nice rectal contrast within the vagina, which it is not supposed to be in vagina. You are seeing a beautiful communication between rectum and posterior wall of the vagina. But the same thing you are able to see even on ultrasound. So this is a case of recto vaginal fistula. Similarly, here we have a case of carcinoma of cervix, large mass recurrence and a communication air contrast sign between the rectum and the uterus. So this is a recto uterine fistula. You can as well see the oral contrast in the bubble loops even into the rectum. And this contrast you are seeing it in the low part of cervix and vagina and in the uterus. So this is a case of recto vaginal fistula. Even complex fistulas, multiple fistulas can be appreciated in ultrasound if you know what to look for. Here is a case of again carcinoma of cervix, a large regular mass invading the rectum and adjacent bubble. So here you can see multiple air foci between this mass and in the rectum in the vagina and even in the bubble loop in the air focus in the adjacent ideal loop. So the same thing which we can see on ultrasound. So you are having a recto vaginal fistula between the vagina and rectum and contrast which is seen as air foci on ultrasound and contrast is seen in the mass as this contrast is coming from the bubble. So this is the bubble loop, ideal loop which is communicating with the rectum and the cervical mass. So here you have an entero vaginal fistula as well as a recto vaginal fistula together which you can in fact appreciate on ultrasound too when you compare both the images. So next is the CT and MR. Coming to the cross-sectional imaging, the biggest advantage of cross-sectional imaging is we are able to localize the fistula in three dimensions and identify the underlying etiology. So the most important thing is this identification of the location and the adjacent tissue will determine the surgical procedure and the approach. So when we are evaluating on CT or MRI, we need to see in all three planes because in sagittal planes and profiled planes we see the psycho vaginal and recto vaginal fistulas very well and we can even profile the fistula on the level or give the level of the fistula so that appropriate surgical approach can be taken whether it is amenable to open surgery or a lab surgery they can decide once we give them a proper level. And uretric and intravacycle or colovacycle fistula whenever there are ureters or bubble are involved we always need to evaluate fistulas in coronal sections. So what are the advantages? CT is the most important investigative modality for the evaluation of fistula because whenever we do a contrast-enhanced CT with multiplanar reconstruction the diagnostic accuracy is almost 100% for the evaluation of fistula. So unless there is contraindication for CT this is the imaging modality of choice except for few indications for MR otherwise I would generally say we prefer CT to investigate any pelvic fistula. So what are the imaging clues on CT? So when do you suspect that there is a fistula you do the routine CT of abdomen and when do you suspect whenever there is air in urinary bladder if there is no prior instrumentation or history of infection a air focus in urinary bladder directly points out to a fistulation process. Second is focal wall thickening whenever there is adjacent organ or the organ involved when there is wall thickening we should think of there is a malignant process going on and possibility of fistula. Third is when the organs are adherent to each other a large soft tissue mass is adherent to the organs again this presence of a large adherent soft tissue mass gives a clue to the presence of fistula. The fourth one is the most important one whenever we see presence of contrast in inappropriate locations this is a rectal compassion with the rectal contrast where it contrast is supposed to be in the rectum but now you are seeing the contrast everywhere in the vagina in the cervix and coming out through the vaginal and perineal soft tissue. So this is contrast in inappropriate location it directly indicates the presence of a fistula. So I am going to show you a few cases this is a rectal mass and you are seeing contrast abnormal communication with contrast between the two organs over here where you can see directly sorry this is a cervical mass this is a vesicovaginal fistula between the fistula between vagina and the urinary bladder. So you can see the fistula very well especially all vaginal fistulas have to be evaluated in sagittal plane. So once you see in welling catheter bulb is there once you see a communication between these two vagina and posterior wall of the urinary bladder directly on your sagittal plane there is no doubt about the presence of fistula. Even in plain CT this is a case of a 50-year-old female with rectal malignancy. So directly you are able to see air in the rectum and a linear tract going directly to the vagina. So this shows the presence of rectovaginal fistula on a direct plane CT itself. So once you do a rectal contrast you give it you can clearly demonstrate the fistula's tract between the rectum and vagina and the same tract you are able to see very well in sagittal planes. So this is a rectovaginal fistula. So coming to the rectovaginal fistula the biggest advantage of cross-sectional imaging is to locate the level of fistula. So the level of posterior vaginal wall involvement categorizes rectovaginal fistulas into three types. This is very important to know the etiology of the fistula, probable etiology of the fistula and for the approach. So low rectovaginal fistulas are usually located at the lower panther of the vagina they are most common due to vulval obstetric causes or some vulval or vaginal malignancies. So mid rectovaginal fistulas they communicate directly through the rectovaginal septum and they characteristically occur between the posterior fornics of the vagina and middle vanther of the rectum. These are the most important fistulas for us because all radiation induced fistulas are most commonly founded the mid rectovaginal are mostly mid rectovaginal fistulas. So RT fistulas which are the most common ones we see in practice we need to look at whenever we suspect we need to look at this location and high rectovaginal fistulas are seen between the sigmoid colon or rectum and the paternalized portion of the vagina. These are commonly due to pelvic procedures, neoplasms or inflammatory diseases. So I'm going to show a few examples. So the second thing is whenever you see a fistula in a malignant case or a post-radiation therapy case you once you find a fistula you need to go back and look for another one because post-radiation fistulas are always most of the time multiple and large. So this is a case of a 62 year old female of carcinoma urinary bladder post chemo and RT. Now you are seeing both sagittal sections and axial sections. So you see air in the urinary bladder. So this itself points out to probable fistula and then contrast you are seeing between the dome of the urinary bladder and the sigmoid colon high up. So this is a vesico sorry this is a sigmoid colob vesicle fistula and this is the you are seeing from the dome of the urinary bladder and the sigmoid colon. This is a sigmo vesicle fistula. So this is a colob vesicle fistula and vesicovaginal fistulas. You are seeing two fistulas in a single patient. So multiple fistulas are more common in post-RT cases. So another case of carcinoma cervix present post-radiation therapy there is no recurrence what you are seeing here is the contrast in the bubble loops and you are seeing a bubble loop which is interposed between the uterus and the urinary bladder because there gave a large four field radiation without countering the this was a conventional radiation field without countering the radiation field that given radiation and box field technique. So the bubble loop was also involved within the got included within the radiation field. After four years patient developed double fistulas you are able to see the bubble loop ideal loop between the urinary bladder and uterus. So here it is communicating with the cervix as well as a urinary bladder. So you have double fistulas in this case again air in the urinary bladder which is a clue. So what you have here is the communication between the bubble loop and the urinary bladder interop vesicle fistula and the communication between the bubble loop and the cervix. So this is a cervical fistula double fistulas as I said most commonly you see it post-artifistulas. Another case with multiple fistulas here you have a vesicovaginal fistula between the vagina and the urinary bladder at a lower level you are seeing a communication between the vagina as well as the rectum. So double fistulas vesicovaginal and rectovaginal fistulas in the same patient. Another case you are seeing at lower ends of both ureters carcinoma cervix again carcinoma cervix patient both lower uterus are communicating abnormally and contrast is seen on both sides of the vagina. So this is a case of as I said this is a case of bilateral fistulas bilateral ureteravaginal fistulas and to evaluate ureteric fistulas coronal views are better. So bilateral ureteravaginal fistulas again in this you are able to see the indirect clue air within the urinary bladder. So another case of a complex mass large mass invading the lower carcinoma cervix invading both the and even the bubble is involved in this you have an entero vesicle fistula between the collapsed urinary bladder you are able to see only the polys bulb over here. So this is the communication between the bubble and the urinary bladder and another vesicovaginal fistula posteriorly the same urinary bladder is communicating with the vagina so entero vesicle and vesicovaginal fistulas in the same case. Another case where you are able to see the uterus is having the contrast this is not the bubble this is the uterus so you are able to see the contrast in the bubble loops and contrast in the uterus. So here uterus is communicating at two points with the bubble looks one is with the sigmoid colon where you are able to see the sigmoid colon having a communication directly abnormal communication with the uterus which is a colloid uterine fistula on the left side and on the right side we have another communication between the ideal loop and the uterus so here is an entero uterine fistula. So these are abnormal unusual fistulas whenever you see this kind of fistulas you can be very sure that the underlying pathology is malignancy. So coming to the pet pet is recommended only for the staging of malignancy but it has poor anatomical resolution but few times accidentally when they do for staging we can discover a fistula itself here it is showing a nice rectovaginal fistula. So next is MR. MR is not advised for all because most of the patients they won't be able to hold the contrast for a long time and they are associated with artifacts and the imaging protocols are long but in few cases MR is advised. So on MR most of the fluid field tracts are hyper intense and all the gas field tracts are hyper intense and whenever we see the contrast enhancement of the fistula wall of the fistula we need to be suspecting a new plastic process or inflammatory or etiology non fibrous tracts will never enhance and whenever there is the contrast enhancement of the fistula tract is also highly suggestive of active disease. So this T1 weighted contrast and T2 weighted images they differentiate soft tissue masses especially if there is a soft tissue mass with fistula in radiation induced fibrosis it doesn't enhance if there is a residual recurrent malignancy it will enhance. So then MR is important and even diffusion weighted MR also is advantageous. Few studies have shown that it is advantageous for fistulas evaluation and the disadvantage small fistulas which are iso intense on T2 weighted images may be totally missed out to mark needing false negative results. So in future newer MR sequences with short imaging times sometimes they can differentiate the between viable and non viable tissues they could be useful in the but it needs lot of further studies. So a few MR cases this is a case of a large carcinoma cervix mass directly invading the urinary bladder this is pre-treatment and there is a fistula communication between the urinary bladder and the cervix so vesicobaginol fistula. Another case of vesicobaginol fistula fluid filled fistula we can see and complex fistula again you are able to see the fluid and contrast in a different case we are seeing two fistulas over here rectovaginol and vesicobaginol fistulas. So even in males they are not very uncommon carcinoma prostate this is a patient of carcinoma prostate post radiation he has developed their fistula over here so this is the rectovacycal fistula post RT case. So coming to the management of fistulas I have a couple of slides like benign fistulas it's always conservative approach and malignant fistulas mind you they always always need a curative or a palliative surgical intervention because the diagnosis of fistula itself says that in all fistulas it is T4 stage mostly urinary bladder uterus cervix vagina they are all T4a and rectum is T4b so whenever you see a fistula the best curative option is a n-block tumor fistula resection but most of the patients won't be amicable for surgical resection so large fistulas and active viable tumors presence of these tumors they are not candidates for surgical repair and post-article fistulas are again have high failure rates because of ischemic and non-vibals around in tissues and pool healing so these cases these patients they always require some other or otomies so diversion procedures or palliative procedures so in summary what do we look for in imaging we look to assess the location size number and course of the fistula strike always we need to assess adjacent areas and to rule out synchronous lesions and in malignant fistulas again we need to go back and restage the neoplasm and we should provide a pre-surgical roadmap because whether the surgeon is going to go for a curative resection or only a palliative bypass surgery or whether organs have to be removed or still preserved and how do they approach whether horoscopic or open and whenever you see a fistula whether is it an emergency procedure or whether it is elective or someric procedure so all this for a surgeon we need to give the answers to all these patients so again in portarty fistulas we need to describe the complete surrounding tissues so in confusion a comprehensive report should contain all details of all the things which have been described in the previous one and as I said ultrasound gives the earliest clue to the presence of fistulas and MDCT is the bold standard um best emerging modality bold standard imaging modality for the diagnosis and MRI in few situations especially when there are equivocal findings on CT or complex fistulas with the involvement of anorectal sphincter