Abdominal Surgery: Small and Large Intestine Part II Flashcards
the formation of abnormal outpouchings of the colonic mucosa
Diverticula
These can develop due to a combination of chronically elevated intraluminal pressures due to chronic constipation (e.g., due to low-fiber diets, lack of physical exercise) and age-related weakening of connective tissue.
Diverticula
What contributes to the formation of diverticula?
These can develop due to a combination of chronically elevated intraluminal pressures due to chronic constipation (e.g., due to low-fiber diets, lack of physical exercise) and age-related weakening of connective tissue.
What part of the GI tract is most involved in the formation of diverticula?
The sigmoid colon is most commonly involved.
When is colonoscopy warranted in the evaluation of diverticula?
Colonoscopy is the diagnostic modality of choice for symptomatic diverticulosis but is contraindicated if acute inflammation of the diverticula (i.e., diverticulitis) is suspected.
type of diverticulum that involves only the mucosa and submucosa and does not contain muscular layer or adventitia.
False diverticulum
Most common type of gastrointestinal diverticula
Typically acquired
particularly in the sigmoid colon
The presence of multiple colonic diverticula without evidence of infection
Diverticulosis
Contributing factors to diverticulosis
Diet (low-fiber, rich in fat and red meat)
Obesity
Low physical activity
Is the most common cause of lower GI bleeding in adults.
Diverticulosis is the most common cause of lower GI bleeding in adults.
________________is defined as the twisting of a loop of bowel on its mesentery and is one of the most common causes of intestinal obstruction but not the most common cause.
Volvulus
How do patients with a volvulus typically present?
Patients typically show features of bowel obstruction (abdominal pain, distension, bilious vomiting) or of bowel ischemia and gangrene (tachycardia, hypotension, hematochezia, peritonitis) in severe cases
__________________ is the investigation of choice in infants with suspected midgut volvulus
Upper GI series
A diagnostic imaging test which can be used to diagnose anatomic and/or functional abnormalities (e.g., strictures, dilatation) in the esophagus, stomach, and small intestines. A radiopaque fluid (e.g., barium or gastrografin) is swallowed and radiographs are taken to visualize the lumen of the alimentary tract.
Ladd procedure
Surgical procedure to treat intestinal malrotation, consisting of division of Ladd’s bands, widening of the small intestinal mesentery, appendectomy, and correcting the location of cecum and colon.
Surgical procedure to treat intestinal malrotation, consisting of division of Ladd’s bands, widening of the small intestinal mesentery, appendectomy, and correcting the location of cecum and colon.
Ladd procedure
Volvulus of the ________________ is more common in infants while in __________________ is more common in adults
infants–> midgut
adults–> sigmoid
What is the difference between intestinal alroation and a midgut volvulus?
Intestinal malrotation: arrest in the normal rotation of the gut in utero, resulting in an abnormal orientation of the bowel and mesentery within the abdominal cavity
Midgut volvulus: torsion of a malrotated midgut causing mechanical bowel obstruction, mostly in neonates and infants
Pathophys of volvulus
Closed-loop mechanical bowel obstruction → accumulation of gas and feces within the loop → increased intraluminal pressure → impaired capillary perfusion of bowel → bowel strangulation, ischemia, and gangrene
an abnormal rotation of the stomach of more than 180° → closed-loop obstruction → possible incarceration and strangulation → intestinal ischemia and perforation
Intestinal malrotation
Intestinal malrotation
Gastric volvulus
Features of gastric volvulus
severe abdominal pain, retching, and inability to pass a nasogastric tube
Signs of a midgut volvulus
Bilious vomiting with abdominal distension in a neonate/infant
Signs of bowel ischemia: hematochezia
Corkscrew duodenum
Midgut volvulus on an upper GI series
Upper GI Series=A diagnostic imaging test which can be used to diagnose anatomic and/or functional abnormalities (e.g., strictures, dilatation) in the esophagus, stomach, and small intestines. A radiopaque fluid (e.g., barium or gastrografin) is swallowed and radiographs are taken to visualize the lumen of the alimentary tract.
A radiologic sign characterized by a whorled appearance created by the twisting of one structure around another (e.g., from cecal volvulus, malrotation with midgut volvulus, ovarian torsion, testicular torsion). Can be seen on ultrasonography and CT scan.
Whirlpool sign, abdominal ultrasound will show this in a midgut volvulus
What might we see with a brium enema in a midgut volvulus?
Bird’s beak sign at the site of the twist
is the dilation of the colon in the absence of a mechanical obstruction (e.g., colonic tumor/stricture). There are three etiological types.
Megacolon
The 3 types: acute, chronic, and toxic megacolon
Chronic megacolon is often caused by…
colonic dysmotility due to neuropathic or myopathic etiology
Chronic megacolon is the permanent dilation of the colon caused by chronic colonic dysmotility due to an underlying neuropathic (Hirschsprung’s disease, chronic Chagas disease) or myopathic (Duchenne’s muscular dystrophy) disorder.
Acute megacolon is seen in/caused by…
characteristically seen in severely medically/surgically ill patients, probably secondary to an electrolyte/metabolic imbalance
How do we treat megacolon?
Patients with acute/chronic megacolon can often be treated conservatively with bowel rest, dietary modifications, prokinetic drugs, and/or neostigmine.
When is surgical intervention warranted in acute/chronic megacolon?
Surgical intervention for acute/chronic megacolon (colectomy and ileorectal anastomosis) is indicated if conservative treatment fails.
When is surgery indicated in toxic megacolon?
Conservative management of toxic megacolon includes bowel rest, IV antibiotics (for infectious colitis), IV steroids (for inflammatory bowel disease). There is a high risk of colonic perforation in patients with toxic megacolon. Hence, no improvement to medical therapy within 24–72 hours is an indication to perform surgery (subtotal colectomy and end ileostomy).
Etiology of chronic megacolon
Congenital (e.g., Hirschsprung disease)
Acquired:
diabetic neuropathy
Duchenne’s muscular dystrophy
Chronic Chagas disease
Etiology of toxic megacolon?
Infectious colitis
Bacterial: C. difficile (pseudomembranous colitis), Salmonella, Shigella, Campylobacter infections
Ulcerative colitis, Crohn disease
In which megacolon do we get loss of haustration observed on xray
Loss of haustration
What are some differences in the clinical features of the megacolons?
Acute: constipation/diarrhea
Chronic: constipation
Toxic: bloody diarrhea
How do patients with colonic polyps typically present?
Affected individuals are typically asymptomatic but may present with gastrointestinal (GI) bleeding, iron deficiency anemia, and/or mechanical bowel obstruction (e.g., due to intussusception)
Colonic polyps are classified histologically as adenomatous (most common), hyperplastic, inflammatory, serrated, or hamartomatous. Which ones have the highest malignancy potential?
Adenomas (e.g., adenoma-carcinoma sequence) have the highest malignancy potential (∼ 5%).
What subtype of adenomas have the highest malignant potential?
villous
An autosomal dominant syndrome characterized by > 10 hamartomatous polyps throughout the gastrointestinal tract. Typically manifests within the first 2 decades of life with hematochezia. Patients have an increased risk of developing colorectal and/or gastric malignancies.
Juvenile polyposis syndrome
An autosomal dominant, hamartomatous polyposis syndrome characterized by the presence of polyps (typically < 20) throughout the gastrointestinal tract (mainly the jejunum). Associated with mutation of the STK11 gene on chromosome 19p13.3. Manifests with hematochezia, constipation, diarrhea, mucocutaneous hyperpigmentation, and an increased risk of colorectal, ovarian, breast, and pancreatic cancer.
Peutz-Jeghers syndrome
Polyps tend to be asymptomatic. If a patient has polyps, what might you expect to observe clinically?
Hematochezia
Change in bowel habits
Mucus in stool
Pallor
Hamartomatous polyposis syndromes
A subtype of hereditary polyposis syndrome. Characterized by hamartomatous polyps. Includes Peutz-Jeghers Syndrome (PJS), Juvenile polyposis syndrome (JPS), and PTEN-Hamartoma Tumor syndromes (PHTS).
A subtype of hereditary polyposis syndromes. Characterized by numerous adenomatous polyps and an increased risk of colon cancer and other intestinal and extraintestinal tumors. Comprises classic familial adenomatous polyposis (FAP), FAP subtypes (e.g., Gardner syndrome, Turcot syndrome, attenuated FAP), and MUTYH-associated polyposis.
Adenomatous polyposis syndromes
For pts with recurrent intussusception, what should we evaluate them for?
A pathologic lead point like a meckel diverticulum, a tumor, a polyp. The most common lead point is a Meckel Diverticulum so be astute if you see a patient with recurrent intussusception with iron deficiency/anemia (a sign of occult bleeding possible due to meckels).
What are complications of diverticulitis?
a 99m technetium scan/nuclear scintigraphy is the modality we use to evaluate…
meckel diverticulum
What is the difference in approach for pts with asynmptomatic femoral hernias versus inguinal hernias?
What are the different kinds of ascitic fluid characteristics?
What is the typical appearance of ascitic fluid?
Straw-colored&clear
What does bloody ascitic fluid indicate?
suggests trauma or malignancy
What does cloudy ascitic fluid mean?
infection
What does milky ascitic fluid indicate?
lymphatic disruption
How could ordering a cell count and differential of ascitic fluid be helpful in dx?
Cell count can help narrow down somethings…
Lymphocyte predominance indicates malignancy or tuberculosis while neutrophil predominance suggests spontaneous bacterial peritonitis
Major risk factors for hepatocellular carcinoma
cirrhosis
chronic hep B
Elevated alpha fetoprotein in an adult male who has cirrhosis should raise concern for…
hepatocellular carcinoma
What is severe acute pancreatitis?
defined as pancreatitis that causes failure of greater than or equal to one organ system lasting more than 48 hours.
What are important clinical predictors of severe acute pancreatitis (associated with a worse prognosis)?
SIRS criteria, elevated BUN/signs of volume depletion due to third spacing, and radiologic signs of third spacing
What is emphysematous cholecystitis?
A lifethreatening form of acute cholecystitis that occurs more commonly in patients with immunosuppression or vascular disease. It arises due to infection of gallbladder wall with gas-forming bacteria and requires emergency cystectomy.
How is dx confirmed for emphysematous cholecystitis?
imaging demonstrating air fluid levels in the gall bladder, gas in the gall bladder wall, and occasionally pneumobilia.
What is the next step in managment of a biliary cyst dx’d w/MRCP?
Surgery!
There is a 30x increase in chance of malignancy so take that sucker out.
What lab values should you look for in acute pancreatitis?
amylase/lipase levels >3 times the upper limit of normal
55 yo m presenting with a year of progressive gatigue and frequenct loose stools. He describes voluminous foul smelling stools that are difficult to flush. He has lost about 20 pounds without trying this past year. On multiple occastions, he has been hospitalized for epigastric pain radiating to the back.
What is this describing most likely?
Pancreatic insufficiency due to pancreatitis.
Chronic pancreatitis can be due to alcohol abuse, cystic fibrosis, or autoimmune.
Pancreatic cancer can also cause pancreatic insufficiency.
What is the most likely caused of small bowel intestinal bleeding in a 10 yo boy?
meckel diverticulum, dx with t 99m scan
Ischemic colitis commonly affects what watershed areas?
the splenic flexure and rectosigmoid junction
How do we dx toxic megacolon?
ab ct, showing colonic dialation of greater than 6 cm
How does the presentation of left vs right sided colon adenocarcinoma present?
Left: obstruction of the outflow of stool leading to altered bowel habits, hematochezia
Right: bleeding is NOT likely visible so it has OCCULT bleeding and iron deficiency anemia
Right is more insidious
What do we mean by loss of haustrations on abdominal xray in the setting of toxic megacolon?
Systemic toxicity presenting as fever, tachycardia, hypotension as well as ab pain and distention following a diarrheal illness or in suspected IBD is concerning for…
Toxic megacolon
How do we treat toxic megacolon in an IBD pt?
Methyprednisolone!
Fluids, electrolyte repletion, bowel rest and decompression (NG tube) and broad spec abx.
What is the difference in presentation of a small bowel obstruction vs an ileus?
How do we manage c. diff?
DRE with bright red blood inthe rectum, colonoscopy with muscosal pallow, friability, and multiple telangienctasias in the setting of a pt with a hx of rdjuvant radiation therapy for cervical cancer is concerning for…
Radiation proctitis
How might a SBO develop in a pt with crohn?
Severe uncontrolled inflammation can lead to fibrotic strictures
How does abdominal compartment syndrome impact preload?
DECREASED preload (abdominal pressure decreases venous return to the heart)
Abdominal distention, colonic dialation, in the setting of electrolyte derrangements or medications…
Acute colonic pseudo obstruction (ogilvie syndrome) arises from autonomic dysruption of the colon
is the dilation of the colon in the absence of a mechanical obstruction (e.g., colonic tumor/stricture).
Megacolon
etiological factors → impairment/destruction of the autonomic nervous system → imbalance between sympathetic and parasympathetic control of intestinal motility–> megacolon
Pathophysiology of acute megacolon (ogilvie’s syndrome)
What can contribute to acute megacolon? (acute colonic pseudoobstruction, ogilvie’s syndrome)
Its idiopathic but can happen in the setting of very ill patients who recently underwent a surgical procedure, have electrolyte imbalances, or are on anticholinergic drugs, opioid analgesics, antipsychotics, calcium channel blockers
What are the risk factors for toxic megacolon?
infections colitis as seen in c diff, UC, Crohns
How may colonic polyps lead to bowel obstruction?
The polyps can cause intussusception
Most common type of nonneoplastic polyp among those with low malignant potential, common in the distal colon
hyperplastic polyp
red flags for CRC
change in bowel habits, lower GI bleeding, and weight loss. These features as well as iron deficiency anemia in men older than 50 years of age and postmenopausal women
What labratory marker do we track in colorectal cancer?
CEA, which is a prognostic marker and should not be used to screen for colorectal cancer. Think of it as the CA125 of CRC.
Lynch syndrome (hereditary nonpolyposis colorecta cancer) increases risk for what other kinds of cancer?
endometrial, gastric, and ovarian cancer.
What criteria do we use to ID individuals at increased risk for lynch syndrome?
Amsterdam II criteria
When is screening recommended for patients with family members who have lynch?
Preventative screening for colorectal cancer and associated tumors is recommended in individuals with family members known to have a Lynch syndrome gene mutation; it should occur every 1–2 years, starting at 20–25 years of age, or 2–5 years before the earliest recorded case of a tumor in the family.
presence of Lynch syndrome-related CRC and brain tumors (especially gliomas)
Turcot syndrome
What is the 3-2-1 rule with lynch syndrome?
3-2-1 rule: (3 affected family members, 2 generations, 1 relative under 50 years of age).
How does the manifestation of familial adenmatous polyposis differ from lynch?
Lynch syndrome typically manifests with colorectal cancer of the proximal colon, with only a few adenomatous polyps, in contrast to familial adenomatous polyposis, in which hundreds of adenomatous polyps are present.
painless rectal mass that protrudes through the anus
Fecal incontinence
Pruritus ani
Rectal bleeding
rectal prolapse
The main risk factors for developing anal cancer are …
The main risk factors for developing anal cancer are immunosuppression and human papillomavirus (HPV) infection.
This condition is the most common cause of lower gastrointestinal bleeding in adults.
Diverticulosis
Tx of choice for anal SCC
The combination of chemotherapy and radiation is the treatment of choice for patients with anal canal SCC; it has been shown to be superior to surgery, with a 5-year survival rate of ∼ 80%. Subsequent surgery is only indicated if a residual tumor is confirmed with biopsy after the completion of radiochemotherapy.
How does prophylaxis differ in pts with FAP versus lynch?
Patients with Lynch syndrome are at high risk of gastrointestinal malignancies and should receive an annual colonoscopy beginning at 20–25 years of age to screen for colorectal cancer, but prophylactic proctocolectomy is not recommended.
Prophylactic subtotal or total proctocolectomy with ileoanal anastomosis is recommended in patients with familial adenomatous polyposis (FAP). A family history of gastrointestinal malignancy is also seen in FAP. However, patients with FAP would have numerous polyps on colonoscopy by adolescence, and germline testing would show a mutation in the adenomatous polyposis coli (APC) gene rather than in MLH1 and MSH2.
Prophylactic proctocolectomy with ileoanal anastomosis is for…
Familial Adenomatous Polyposis
Which is worse: villous or tubular adenomatous polyp
villous; A villous adenomatous polyp has the highest risk (∼ 50%) of malignant transformation of the three types of adenomatous polyps.
An autosomal dominant, hamartomatous polyposis syndrome characterized by the presence of polyps (typically < 20) throughout the gastrointestinal tract (mainly the jejunum). Associated with mutation of the STK11 gene on chromosome 19p13.3. Manifests with hematochezia, constipation, diarrhea, mucocutaneous hyperpigmentation, and an increased risk of colorectal, ovarian, breast, and pancreatic cancer.
Peutz-Jeghers syndrome
This patient presents with a protruding rectal polyp and multiple hamartomatous polyps. In combination with mucocutaneous hyperpigmentation, what is the most likely dx?
Peutz-Jeghers syndrome
is a variant of familial adenomatous polyposis that manifests with multiple colonic polyps and may cause hematochezia together with extracolonic bone and/or soft tissue lesions, such as osteomas, epidermal cysts, and congenital hypertrophy of the retinal pigment epithelium, all of which are seen here. A family history of colon cancer at a young age furthermore supports this diagnosis.
Gardner Syndrome
Conservative measures such as sitz baths and topical therapy with calcium channel blockers (e.g., nifedipine, diltiazem) are recommended as the initial treatment for most…
anal fissures
What are the firstline Conservative measures for anal fissures?
Conservative measures such as sitz baths and topical therapy with calcium channel blockers (e.g., nifedipine, diltiazem) are recommended as the initial treatment for most anal fissures. These measures reduce anal sphincter tone and promote mucosal healing by increasing blood flow to the anal mucosa.
Frank blood in stool and DRE shows no masses is concerning for…
likely diverticulosis
