most common cause of lower gastrointestinal hemorrhage ( lgib ) in elderly patient is diverticular disease   and mortality rate is very low 24% . a massive lgib from primary ilio - rectal fistula is rare and difficult to diagnosis but more common from secondary after previous vascular surgery
a variety of treatment options are available , such as in situ graft , closure of defect alone , endovascular stent graft , extra - anatomical bypass and embolic coiling .
exploration using laparotomy for ligation internal iliac aneurysm and rectal resection is a simple operative procedure which can be applied when emergency option is needed to save a life .
we describe successful emergency surgery in primary ilio - rectal fistula when patient presents a massive lgib and hypovolemic shock .
an 88-year - old man , his underlying diseases are hypertension , dyslipidemia , moderate aortic stenosis and mitral valve stenosis , chronic kidney disease and prostate cancer .
at emergency department , physical exam showed hypotension blood pressure 70/50 mmhg and per rectal exam showed blood clot with enlarged prostate .
after resuscitation until stable vital sign , he was sent for colonoscopy but can not be evaluated due to a lot of blood clots in the rectum .
he was admitted for observation and we planned to repeat colonoscopy again following day because he was stable and bleeding was stopped . following day after admitting , he had massive lower gastrointestinal bleeding again fresh blood ~1000 ml from his anus .
but the patient had a problem vascular access site and then send to computed tomography angiography ( cta ) for evaluate access site .
we found 3 cm aneurysm of right internal iliac artery with partial thrombus and attached to rectosigmoid colon with leakage of contrast into sigmoid lumen ( figs 12 ) .
he was sent to operating room during transferring we gave blood transfusion and then emergency explore laparotomy was performed , the operation performed by partial aneurysmectomy , ligated right internal iliac , wedge resection rectum wall and temporary abdominal closure with swab packing due to bowel distension and abdominal pressure was high .
he was sent to operating room for change swab packing on day 3 and permanent abdominal closure on day 5 . during postoperative period
primary aorto / ilio - enteric fistula ( paef ) is very rare , but secondary fistula is more common .
sir astley cooper was the first to describe a paef as a condition caused by spontaneous erosion of the aorta into the gastrointestinal tract .
etiology of paef are several causes , most causes are due to aneurysm , infection , tumor , radiotherapy and foreign body ingestion [ 59 ] .
the most common site of fistula located in duodenum 54% , esophagus 28% , small bowel and large bowel 15% .
the classical triad of symptoms associated with a fistula is gastrointestinal hemorrhage , abdominal pain and a pulsating abdominal mass .
most common sign and symptoms of fistula is gastrointestinal bleeding , but only 11% presented with classical triad .
the diagnosis of paef is difficult to make . because most of patients were send to endoscope due to gastrointestinal bleeding symptoms .
several diagnosis investigations were used when patients are clinically stable such as cta , angiography , colonoscopy , and red blood cell scan .
all of these do not constitute specific investigation . however , ct scan can diagnose specifically aorto / ilio - enteric fistula ( for example , air within aortic wall or contrast fill in bowel lumen ) that detection rate 61% when failure diagnosis from endoscopy .
such as , in situ graft , closure of defect alone , endovascular stent graft , extra - anatomical bypass and embolic coiling .
optional treatment depends on surgeon s experience , hospital facilities and the type of paef .
this case was send to the operating room after diagnosis right internal ilio - rectal fistula for emergency exploration with laparotomy because the patient s active bleeding and vital signs were not stable preventing adequate preparation time for intervention or stent graft in hospital .
we decided to ligate right internal iliac artery , wedge resection rectum with suture repair because this is a simple operation and can save patient s life .
other options could be done by endovascular therapy or embolic coiling if we had time to prepare and the patient was already stabilized in this hospital . in conclusion , paef is very rare .
the patient who has massive lower gastrointestinal bleeding with failure of endoscope may need to consider imaging to rule out paef .
there are several treatment options for paef but no conclusive specific treatment it depends on patient s situation and physician s experience . although endovascular or embolization is minimally invasive surgery and good for the patient who is a high operative risk but an emergency simple operation is an effective procedure not only saves patient s life but also can be done by a general surgeon ( fig .
figure 1:axial view iliac aneurysm with partially thrombose contact rectosigmoid colon and contrast leak.figure 2:coronal view iliac aneurysm.figure 3:cta after 1 year .
 abstractmassive lower gastrointestinal from primary isolated ilio - rectal fistula is a rare condition and difficult to diagnosis and emergency surgery for this situation has a high mortality rate . 
 this report describes a successful operation in an 88-year - old man at present with massive lower gastrointestinal hemorrhage from ilio - rectal fistula and hypovolemic shock . 
 underlying diseases are prostate cancer , hypertension , dyslipidemia , aortic stenosis , mitral valve stenosis and chronic renal disease . 
 operative treatment is to explore laparotomy with internal iliac artery ligation and rectal resection . during postoperative period patient developed acute cholecystitis and treated by cholecystectomy 
 1 month after operation the patient went home without morbidity and 1-year follow - up he had not any complications . 
INTRODUCTION
CASE REPORT
DISCUSSION
CONFLICT OF INTEREST STATEMENT