Lower Gastrointestinal Disorders Flashcards
What is an “obstructive series”
Upright PA and lateral CXR, and flat and uptright abdominal radiograph
Why do patients with SBO typically present with contraction alkalosis and hypokalemia?
When patients have SBO they tend to vomit because of bowel back up. This results in loss of H2O, Na+, H+ and Cl- with an overall decrease in plasma volume from H20 loss and an increase in pH due to H+ loss…giving you alkalosis. Hypovolemia and alkalosis causes the kidneys to retain more Na+ and H+…thus giving you hypokalemia.
How do you correct a contraction alkalosis in a patient with SBO?
IVF containing Na and K usually does the job
When is it appropriate to d/c a patient w/SBO
Pain and distention resolution w/toleration of food after NG removal.
Differential diagnosis for SBO in a patient with no prior abdominal surgeries?
Adhesions can still form regardless of surgical history. Hernia, bowel tumors or inflammatory processes can also cause SBO.
A patient presents with nausea, vomiting, abdominal distention and tenderness to palpation of the abdomen. She says that she has had symptoms for the past 2 days and only has passed small amounts of diarrhea. What do you need to do in your assessment of this patient?
Typically complete SBO presents with no BMs. Small amounts of diarrhea can indicate constipation and you need to check for fecal impaction. Gastroenteritis and partial SBO should also be in your differential.
What is the most common tumor metastasis in the intestine?
Melanoma, it frequently manifests as SBO that does not resolve with nonoperative management. Even if the tumor is not resectable, surgical measures should be taken to relieve the obstruction.
A patient presents with SBO and a PHMx significant for ovarian cancer. What is at the top of your differential?
Recurrent ovarian cancer can happen locally or as peritoneal studding, resulting in obstruction.
How can breast cancer affect the bowel?
Breast cancer mets can manifest as SBO
What is a good physical exam finding that tells you this patient needs surgical exploration for SBO?
Localized tenderness, markedly elevated temperature, localized pain around hernia, free air under diaphragm on CXR and marked leukocytosis can indicate closed loop obstruction, perforation, ischemia or abscess. Metabolic acidosis is suspicious for ischemia or necrotic bowel and depending on the patients status and imaging mertis either urgent surgical exploraiton or mesenteric arteriography before exploration to check for arterial occlusion.
Post-op plan for pt that underwent LOA to correct SBO
NPO w/NG tube until bowel function returns. Once patient tolerates food d/c.
What is a second look operation in regards to surgery for SBO?
If the SBO was due to a closed loop obstruction and it was questionable if the bowel would still be viable, you re-explore the abdomen in 24 hours to assess for viability and resect any ischemic or necrotic bowel followed by anastamosis. Don’t just send the patient home because ischemic bowel will present several days later and make the patient much sicker.
Management of a patient with SBO due to hernia.
Exploration through hernia incision if patient is stable. Exploration through midline abdominal incision if patient appears ill to more thoroughly inspect the entire bowel for ischemia and necrosis. Repair the hernia and resect non-viable bowel.
Management of accidental enterotomy during intra-abdominal procedure
If small, primary repair is fine. If large, resection and anastomosis are required. Either way, the patient will be at risk for small bowel fistulas and leaks post-op.
A patient presents with heart failure, COPD and urinary sepsis. The sepsis is resolved in the hospital, but he has SBO now. After NG drainage and NPO treatment, the patient still cannot tolerate solids. You are unsure if the obstruction is mechanical or from paralytic ileus due to his many comorbidities. How do you determine if you need to do surgery or not?
Upper GI series w/small bowel follow through. Note that constipation can be seen on radiographs and in upper GI series the Barium will still find its way through the impacted stool.
Work up of a patient with possible mesenteric ischemia
Pain out of proportion to PE, nonspecific ileus on radiographs, hydrate/oxygenate/perfuse, sigmoidoscopy to check for ischemia, mesenteric angiogram if sigmoidoscopy is negative. If the patient looks really sick and you suspect necrotic bowel you can go straight to the OR.
This patient presents with 1 day hx of nausea, vomiting and sever abdominal pain. PE shows abdominal distention and tenderness. Her pain seems much more severe than her abdominal findings. Sigmoidoscopy shows ischemic bowel. Mesenteric angiogram is shown below. How do you tx this patient?
Revascularization of SMA due to risk of recurrence, necrosis and a much worse episode. Also put the patient on aspirin.
When can you go directly to the OR for a patient with suspected ischemic bowel?
Significantly worsening pain over acute time period, markedly elevated WBC/markedly decreased WBC in elderly or metabolic acidosis
When is an angiogram an acceptable next step before taking a patient with mesenteric ischemia to the OR?
Hx of a-fib, hx of abdominal bruit (looking for stenotic celiac/SMA) and hx of thoracic aortic dissection.
A patient presents with symptoms of mesenteric ischemia. His hct is 55%, how do you manage this patient?
Most common cause of polycythemia is dehydrate, so rehydrate the patient. If the patient has polycythemia vera the patient needs phlebotomy, rehydration, angiography and surgery if angiography indicates significant occlusion. If the patient has COPD, he needs a pulmonology consult to improve ventilation which will decrease RBC load.
A patient presents with sx of mesenteric ischemia and hx of CHF. How do you manage this patient?
Ischemia may be due to low flow nonocclusive state, confirmed by angiogram. Tx involves direct mesenteric infusion of papaverine (PED10A inhibitor) to vasodilate and meds to improve cardiac output. If necrosis is likely go to the OR, where you will likely see small punctate areas of necrosis, indicating a low flow state. Post-op hemodynamic optimization and second look is a reasonable approach without immediate resection.
Next step in a patient with suspect mesenteric ischemia and bloody diarrhea?
Sigmoidoscopy, if full-thickness necrosis is present then send for surgery. If only mucosal necrosis, optimize hemodynamics, give abx and admit for observation.
How do you treat a patient with mesenteric necrosis from the ligament of Treitz to the transverse colon?
Let the succumb to the disease and die. In younger individuals you may consider surgical resection and reanastaomosis followed by chronic TPN or small bowel transplant due to short bowel syndrome.
How do patients present if they develop short bowel syndrome from multiple bowel resections?
Deficiencies in vitamins A (night blindness, xerophthalmia, xerosis, Bitot spots and keratinization of the skin and mucous membranes), D (muscle aches, muscle weakness, bone pain, osteomalacia and hypocalcemia), E (mild hemolytic anemia and nonspecific neurologic deficits), K (easy bruisin/bleeding), B9 (macrocytic anemia), and B12 (macrocytic anemia + posterior column deficits), calcium,magnesium, iron, and zinc.
Management differences in relatively healthy patients with necrotic bowel resection vs. ill patients with necrotic bowel resection?
Healthy: direct anastomoses after resection w/second look if you’re really concerned about the viability of the bowel. Ill: ileostomy for direct visualization of the bowel and no concern for leak.
Ulcerative Colitis vs. Crohn’s disease
How are strictures and fistulas typically managed in patients with Crohn’s disease?
Get CT to r/o perforation or abscess. Tx nonop w/TMP, bowel rest and observation. Management is based on patient symptoms and active problems, not radiologic findings. Only if SBO from stricture does not resolve do you consider resection of stricture back to normal bowel and anastomosis or stricturoplasty (axial cut of stricture w/ transverse repair to dilate lumen).
What is the problem with resecting a stricture at the terminal ileum in a patient with Crohn’s disease?
The terminal ileum reabsorbs B12 and bile acids. B12 deficiency results in megaloblastic anemia posterior column sx. Bile acid deficiency results in diarrhea, malabsorption and oxalate stones.
Tx for patient w/perianal abscesses and fistulas?
Drain the abscess and open the fistula tract +/- seton if the tract is deeper. Rx metronidazole
Tx for Crohn’s colitis
Sulfasalazine (5-acetylsalicylic acid compound) if confine to colon. Colectomy +/- ileostomy is often necessary.
Risk for developing colorectal cancer in patients with UC? How do you account for this medically?
Low for 1st 10 years (2-3%). Increases 1-2% per year after 10 years. Consequently patients should have colonoscopy every 1-2 years 8-10 years after disease onset. Colonscopy should include biopsy of suspicious lesions (strictures, polyps and plaques) and random biopsies because UC colorectal cancer does not always follow the polyp to cancer sequence. Proctocolectomy (removal of mucosa w/ileal pouch and anal anastomosis) is indicated if severe dysplasia is present. Note that these types of surgeries have a high reoperative and failure rate, despite curing the cancer.
What is the blood supply to the colon
What is the blood supply to the rectum?
What type of surveillance do you need to do in a patient with UC after they have proctocolectomy?
If there is no rectal mucosa left, none. If rectal mucosa is left over, proctoscopy every 6-12 months.
A woman presents 6 months after proctocolectomy for UC with fever, blood-tinged diarrhea and pain w/defecation. How do you treat her?
She has pouchitis. Confirm the dx w/endoscopy looking for hemorrhagic mucosa with edema and small ulceration. Tx with metronidazole.
A patient presents to the ER with recurrent bloody diarrhea, abdominal pain and distention. T-101, HR-120, abdomen is distended and acutely tender. PMHx significant for UC. How do you evaluate and treat this patient?
PMHx significant for UC w/her sx is concerning for toxic megacolon. You should get CBC and an obstructive series to r/o perf. If toxic megacolon is confirmed, place NG, put pt as NPO, add TPN, IVFs, broad spectrum abx and high dose IV steroids. Then admit for close observation. This resolves 50% of cases. Indications for ileostomy with Hartmann pouch of rectum and total abdominal colectomy include no improvement over 3-6 days, no response to medical management, air in the colon wall (indicating impending perf) or perf (mortality rate of 27-44%).
A patient presents to the ED with RLQ pain exaccerbated by pain in the right pelvis on rectal exam. What might this indicate?
Possible retrocecal appendicitis, ovarian pathology or PID.
Work up for a patient with RLQ pain that could be appendicitis
NPO, Hydration, observation w/serial exams and CBC. Pain meds should be avoided so as not to mask sx. You may also order u/s to r/o gyn pathology or CT to dx appendicitis.
RLQ pain + hematuria
Severe UTI or kidney stone. Dx w/IV pyelogram or CT w/o contrast to check for stones.
RLQ pain + dysuria and high WBC
UTI or appendicitis. Continue to observe and follow patient.
RLQ pain + cervical motion tenderness
PID -> gyn consult
RLQ pain + adnexal tenderness
Appendicitis, PID or TOA
Initial tx for IBD
5-acetylsalicylic acid-containing compounds + steroids. Make sure to r/o appendicitis before giving steroids because it can obscure the correct dx due to decreased inflammation.
Epidemiology of appendicitis
Bimodal distribution with peaks at ages 25 and 65. Older adults typically present with non-classic sx of vague abdominal pain, sepsis, altered mentation and failure to thrive. Little kids more often present with ruptured appendix.
Where does appendicits present in pregnant women? How is it managed?
Presents in upper and lateral abdomen due to uterine enlargement. Appenectomy is safe during pregnancy and should be done to minimize risk of peritonitis.
A patient presents with appendicitis and you take her to the OR. In the OR the appendix has a 1cm yellow firm mass at its tip. How do you treat this?
This is most likely a small carcinoid tumor. If < 2cm w/no evidence of local spread routine appendectomy can be performed. If > 2cm or base of appendix/cecum is involved perform right colectomy and reanastomosis. Check 5-HIAA and serum serotonin levels to determine the malignancy of the tumor (not TNMG). If this may be a recurrent lesion CT abdomen and octreotide scan can help you localize neuroendocrine tumors.
What is the adenoma-carcinoma sequence?
It is the morning of the surgery for your patient having a colon resection for colon cancer. What is your plan for the patient?
Hopefully the patient completed bowel prep the day before (GoLYTELY, Mg-citrate + oral nonabsorbable abx). Before opening the patient give a single dose of cephalosporin. Once the patient is opened, explore the liver, diaphragm, small bowel and peritoneum for mets. Resect the appropriate side of the colon, regional LNs and then reanastomose bowel. Post-op the patient needs to be NPO of IVFs until bowel function returns.
How do you stage colon cancer?
Tx:Incomplete information.
Tis: CIS, involves only the mucosa, has not grown beyond the muscularis mucosa
T1: The cancer has grown through the muscularis mucosa and extends into the submucosa.
T2: The cancer has grown through the submucosa and extends into the muscularis propria
T3: The cancer has grown through the muscularis propria and into the serosa but not through it. It has not reached any nearby organs or tissues.
T4a: The cancer has grown through the serosa
T4b: The cancer has grown through the serosa and is attached to or invades into nearby tissues or organs.
Nx: Incomplete information.
N0: No cancer in nearby lymph nodes.
N1: 1-3 positive local LNs
N1a: 1 positive local LN
N1b: 2-3 positive local LNs
N1c: Positive perinodal fat, no cancer in actual LNs
N2: 4+ positive local LNs
N2a: 4-6 positive local LNs
N2b: 7+ local LNs
M0: No mets
M1a: 1 met to distant organ/LNs
M1b: > 1 met to distant organ/LN or distant part of peritoneum
Stage I (92% 5 year survival colon, 87% rectal, tx is polypectomy +/- partial colectomy w/LN dissection)
T1-T2, N0, M0
Stage IIA (87% 5 year survival colon, 80% rectal, tx is partial colectomy, chemorads is controversial, but if chemo is used it is 5-FU + leucovorin or capecitabine)
T3, N0, M0
Stage IIB (63% 5 year survival colon, 49% rectal)
T4a, N0, M0
Stage IIC
T4b, N0, M0
Stage IIIA (89% 5 year suvival colon, 84% rectal, tx is partial colectomy w/LN dissection + chemo w/5-FU, leucovorin, + oxaliplatin or chemo w/capecitabine + oxaliplatin. Rads is added case by case.)
T1-T2, N1, M0 or T1, N2a, M0
Stage IIIB (69% 5 year survival colon, 71% rectal)
T3-T4a, N1, M0 or T2-T3, N2a, M0 or T1-T2, N2b, M0
Stage IIIC (53% 5 year survival colon, 58% rectal)
T4a, N2a, M0 or T3-T4a, N2b, M0 or T4b, N1-N2, M0
Stage IVA (11% 5 year survival colon, 12% rectal, tx is partial colectomy w/LN dissection and mets resection + chemo or chemo alone +/- palliative colon resection to relieve obstruction)
Any T, Any N, M1a
Stage IVB (11% 5 year survival colon, 12% rectal)
Any T, Any N, M1b
Tx for apatient with rectal cancer confined to the bowel wall w/o LN spread or mets.
Abdominoperineal resection (takes the entire rectum w/permanent colostomy and excision of regional LNs).
How do rectal carcinomas metastasize?
Lymphatic spread via the internal iliac nodes, sacral nodes and inferior mesenteric nodes if > 5cm from anal verge. Inguinal nodes can also be involved if < 5cm from anal verge.
What are risks and complications of abdominoperineal resection?
Impotence (50% incidence to due proximity of sympathetic plexus), incontinence, massive bleeding from presacral space, ureter injury and colostomy complications.
What procedures can you do to resect rectal cancer while preserving continence?
Sphincter-preserving proctectomy or coloanal anastomosis.
Management of diverticulitis
Fluids only diet + broad spectrum abx 7-10 days in outpatient and increase dietary fiber. If clinical picture is more serious complete bowel rest, IVF, IV abx and meperidine for pain (decompresses bowel as opposed to morphine that can cause increased pressure). You should check obstructive series to r/o perf and consider CT to check for inflammation, abscess, diverticul and thickened sigmoid bowel wall…all of which would confirm diverticulitis.
Why are diverticula associated with heavy lower GI bleeding?
Vasa recta arteries that penetrate the diverticulum become eroded. Note that although left sided diverticula are more common, right sided diverticula bleed more.
What causes sigmoid volvulus and how do you treat it?
Clockwise twisting of the mobile sigmoid colon around the mesentery causes a closed loop obstruction. Confirm dx by barium enema, tx with rigid proctosigmoidoscopy and placement of rectal tube to untwist sigmoid colon.
Tx of cecal volvulus
Surgical detorsion, cecopexy or right colectomy. In stable patients with viable bowel the operation of choice is right colectomy with primary anastomosis due to risk of recurrence.
Tx options for patients with anal fissures
Conservative: sitz baths, stool softeners and bulk agents. Surgical: lateral sphincterotomy to divide a portion of the internal sphincter and decrease reflex spasm of the internal anal sphincter with stool passage. Also biopsy lesion to r/o anal cancer. 90% of fissures heal with lateral sphincterotomy.
How do you tx fistula in ano?
Unroof the sinus tract from the internal anal crypt to the external opening in the perianal skin, drain any undrained fluid and allow the tract to re-epithelialize. Note that if the tract traverses an anal sphinter a seton should be placed to retain continence.
What are the 4 types of perianal abscesses and how does management of each differ?
Perianal and ischiorectal can be drained through a perianal incision. intersphincteric requires drainage from inside the anal canal. Supralevator drainage depends on its origin and termination.
Tx for pilonidal abscesses
Unroof the cysts, remove all hair and leave open to heal by secondary intention.
When do you use permanent stomas?
After abdominoperineal resection w/end sigmoid colostomy, after total proctocolectomy for UC with ileostomy (undone by ileoanal pullthrough) or ileal conduit draining the urinary system to the skin.
