Abdominal Surgery: Small and Large Intestine Part I Lecture/Onlinemeded/amboss Flashcards
Many things can cause small bowel obstruction (SBO), but they are most commonly caused by…
adhesion and hernias of the abdomen
What will you see on Xray for SBO?
Abdominal X-rays(lying and standing) will show distended loops of bowel (lying) and air-fluid levels (standing).
A diagnostic procedure in which _______, a nontoxic, water-soluble contrast agent, is ingested and visualized on fluoroscopy to evaluate the integrity of the esophagus or eval SBOs.
gastrografin test
With increased demand comes ischemia. The intestines work harder to absorb food. Thus, patients will present with pain after eating and avoid eating (to avoid the pain), resulting in weight loss. They will have the typical risk factors—hypertension, diabetes, dyslipidemia, cigarettes, age—and maybe even evidence of vascular disease elsewhere (CVA, CAD, PLI).
Chronic mesentery ischemia
presents with pain out of proportion to the physical exam, elevated lactic acid,and, if allowed to go on long enough, bloody diarrhea because the mucosa is farthest from the blood supply, so it infarcts first and sloughs off. By the time there are peritoneal findings,
Acute mesenteric ischemia
How do we work up transmural infarct of the mesentery?
Diagnose with CT angiography and treat by relieving the blockage (stent or bypass) or removing the infarcted bowel
t are other etiologies of mesenteric ischamia aside from thrombus/embolus?
Acute mesenteric ischemia can also occur unrelated to atherosclerosis if the blood vessels become compressed, such as in volvulus, intussusception, or strangulated hernia. In these cases the underlying pathology needs to be corrected.
Chronic mesentery ischemia
acute mesenteric ischemia
Bowel that herniates through the inguinal ring will be within the spermatic cord along with the testicular blood vessels, lymphatics, and nerves. The inguinal ring is lateral to the epigastric blood vessels and superior to the inguinal ligament.
indirect hernia
maleadult hernia subtype, caused by increased intra-abdominal pressure (straining, lifting heavy things) and the area of weakened abdominal wall known as the inguinal triangle. This is a region where no abdominal muscle supports the abdominal wall, only the fascia of the transversalis muscle. The inguinal triangle is medial to the epigastric vessels and superior to the inguinal ligament. Entering the inguinal canal without going through the inguinal ring results an inguinal hernia that is outside the spermatic cord.
direct hernia
Femoral hernia
If bowel herniates under the inguinal ligament, it will exit into the anterior thigh, within the femoral triangle where the femoral nerve, artery, vein, some space, and lymphatics are found (NAVEL). Women get this type of hernia often because there is no inguinal canal or spermatic cord to herniate through. Pain and a bulge are elicited in the anterior thigh.
If bowel herniates under the inguinal ligament, it will exit into the anterior thigh, within the femoral triangle where the femoral nerve, artery, vein, some space, and lymphatics are found (NAVEL). Women get this type of hernia often because there is no inguinal canal or spermatic cord to herniate through. Pain and a bulge are elicited in the anterior thigh.
Femoral hernia
are herniations anywhere other than the groin or femoral triangle, anywhere there is an anterior abdominal wall. Most are iatrogenic, a consequence of surgery, called incisional hernias (caused by skin and fascia closing and healing well, but not the abdominal muscles).
ventral hernias
What kind of hernia is not reducible?
Incarcerated
An incarcerated hernia is not reducible, and the bowel cannot be pushed back in through the defect. As long as there are no signs of obstruction or ischemia, even an incarcerated hernia can be managed electively. But the symptom to watch out for is small bowel obstruction, escalating the severity to urgent.
small bowel perf shows as what on XR?
Free air under diaphragm
Perf of retroperitoneal organs/ascending and descening colon will show what on XR?
Air outlining the retroperitoneal organs (especially the kidney and blood vessels) indicates that there has been a retroperitoneal perforation (ascending and descending colon).
A radiographic finding of gas within the wall of the intestine. The etiology varies from benign conditions to life-threatening gastrointestinal diseases. In newborns, the finding is considered diagnostic for necrotizing enterocolitis (NEC), resulting from intramural gas-producing bacteria.
Pneumatosis intestinalis
Pneumatosis intestinalis
are small, slow-growing neuroendocrine tumors. They are most commonly located in the gastrointestinal tract and can synthesize a variety of hormones (especially serotonin).
Carcinoid tumors
Elevated 5-HIAA in the urine helps to establish the diagnosis.
Carcinoid tumor, we use 5-HIAA b/c its a serotonin metabolite and carcinoid tumors tend to produce serotonin
Why do many carcinoid tumors go asymptomatic?
They are most commonly located in the gastrointestinal tract and can synthesize a variety of hormones (especially serotonin). Most carcinoids are asymptomatic because most of the hormones they produce are metabolized by the first-pass effect in the liver.
What does carcinoid symdrome present with and when do we see it?
Carcinoid syndrome – characterized by diarrhea, flushing, dyspnea, and wheezing – may occur if a serotonin-producing tumor has metastasized to the liver, bypassing first-pass metabolism.
What heart problems can arise from carcinoid tumors?
Endocardial fibrosis that especially affects the right heart
Tricuspid insufficiency and/or pulmonary stenosis
Symptoms of right-sided heart failure
How may you be able to discern strangulated versus incarcertaed inguinal hernia on presentation?
Strangulated= sick as shit
When dealing with a SBO question, when do you pick NG tube over CT w/contrast?
If not peritoneal or refractory shock, when managing a small bowel obstruction a diagnosis should be confirmed with a CT scan with IV contrast, then treated conservatively with NG tube, IV fluids, and serial abdominal exams. An NG tube decompression may come before the CT scan, but not when the NG tube is part of an answer choice that represents conservative management only.
What does the red arrow hilight on this CT view?
This hilights a thrombus in the superiror mesenteric artery
Where the arrow is, what is this sign called and what is it indicative of?
Its called pneumonatosis intestinitis, this tells you that there is are in the bowel wall (you have black air surround grey fluid in the intestin), this can be from a number of etiolofies from necrotizing enterocolitis, acute mesenteric ischemia/perforation, or from an obstruction of other causes.
most common congenital gastrointestinal tract anomaly
Meckel diverticulum
Incomplete obliteration of the omphalomesenteric duct → persistence of the proximal (intestinal) segment of the duct → _____________________
Meckel diverticulum
omphalomesenteric duct is also called the vitelline or vitellointestinal duct
How does meckel diverticulum present?
Male more common than female, can be asymptomatic. Symptomatic one would present with:
Lower gastrointestinal bleeding (most common feature)
Presence of ectopic gastric mucosa or pancreatic tissue → acid or enzyme secretion within the diverticulum → ileal ulceration → bleeding
Can manifest as:
Hematochezia
Tarry stools
Abdominal pain (typically in the right lower quadrant)
What test to we do to dx meckel diverticulum?
Meckel scintigraphy scan (Meckel scan): a noninvasive nuclear medicine imaging technique using radiolabelled technetium (99mTc), which is preferentially absorbed by the gastric mucosa and can identify ectopic gastric mucosa
________________________ is a temporary disturbance of peristalsis in the absence of mechanical obstruction
Functional bowel obstruction, or paralytic ileus, is a temporary disturbance of peristalsis in the absence of mechanical obstruction
_____________________- is the most common cause of SBO and _____________ is the most common cause of LBO.
Postoperative bowel adhesion is the most common cause of SBO and malignancy is the most common cause of LBO.
Regardless of the cause, bowel obstruction typically manifests with
Regardless of the cause, bowel obstruction typically manifests with nausea, vomiting, abdominal pain, abdominal distention, and constipation or obstipation.
A type of mechanical bowel obstruction in which the proximal and distal ends of the obstructed loop are closed (e.g., volvulus, obstructed inguinal hernia, obstructing colon cancer with a competent ileocecal valve).
Closed-loop bowel obstruction which can rapidly lead to ischemia and perforation and typically necessitates surgical intervention.
List some causes of small bowel obstruction
adhesions
meckel diverticulum
strictures (crohn disease)
tumors
gallstone ileus
SMA syndrome
Hernia
Kiddos:
Congenital intestinal atresia (e.g., duodenal atresia, jejunal atresia)
Intussusception (e.g., secondary to Meckel diverticulum)
Congenital strictures and bands (e.g., Ladd bands in intestinal malrotation)
What are some causes of large bowel obstruction?
Tumors
diverticulitis
volvulus
adhesions
strictures
fecal impaction
in kiddos
Hirschsprung disease
Congenital strictures and bands (e.g., Ladd bands in intestinal malrotation)
Meconium ileus
Rectal atresia
How does intraluminal air appear in a complete bowel obstruction?
Complete bowel obstruction: minimal or no air distal to the obstruction
Small bowel dilatation
SBO mechanical
X-ray abdomen (AP view; supine position) of a patient with a history of distal colonic obstruction
Distal large bowel obstruction (1/2)
X-ray abdomen (AP view; supine position)
Bird beak sign: in volvulus
this is a barrium enema or water coluable enema
Apple core sign: in colonic malignancy
Temporary impairment of peristalsis in the absence of a mechanical obstruction
Paralytic ileus
What are the risk factors for Paralytic ileus?
Recent abdominal surgery
Atherosclerotic disease
Abdominal infections or inflammatory conditions
Certain medications (opioids, anticholinergics, antiparkinsonian agents)
What are some findings that can help differentiate a mechanical bowel obstruction from a paralytic ileus?
mechanical:
High-pitched, tinkling bowel sounds (early)
Absent bowel sounds (late)
PAralytic ileus:
Absent bowel sounds
Diagnosis is based primarily on characteristic endoscopic features (ulcerations, skip lesions, cobblestone appearance) and evidence of intestinal inflammation on imaging.
Crohn
What would you see on endoscopy for crohn disease?
ulcerations, skip lesions, cobblestone appearance
age of onset for crohn
Typical age of onset: bimodal distribution with one peak at 15–35 years and another one at 55–70 years
Risk factors for crohn
Familial aggregation
Genetic predisposition (e.g., mutation of the NOD2 gene, HLA-B27 association)
Tobacco smoke
Smoking tobacco is the primary modifiable risk factor for CD. Therefore, smoking cessation is especially important in patients with CD.
________________ most commonly affects the terminal ileum and colon, but involvement of any part of the GI tract (from mouth to anus) is possible.
CD most commonly affects the terminal ileum and colon, but involvement of any part of the GI tract (from mouth to anus) is possible.
________________________most commonly affects the terminal ileum and colon, but involvement of any part of the GI tract (from mouth to anus) is possible. In contrast to ___________________, rectal involvement is uncommon.
CD most commonly affects the terminal ileum and colon, but involvement of any part of the GI tract (from mouth to anus) is possible. In contrast to ulcerative colitis, rectal involvement is uncommon.
What are often the first signs of Crohn?
Perianal fistulas and abscesses are often the first signs of CD.
What are some extraintestinal symptoms of crohn?
Joint involvment: Enteropathic arthritis
e.g., sacroiliitis, spondylitis, inflammation of peripheral joints
Uveitis
Cholethiasis
Urolithiasis (remember increased risk of calcium oxalate stones)
Erythema nodosum
pyoderma gangrenosum
A rare oral condition strongly associated with inflammatory bowel disease (especially ulcerative colitis). Manifests with slightly elevated, yellow-white, round mucosal lesions with a characteristic snail-track appearance. Most commonly affects the labial and buccal mucosae, gingivae, and palate.
Pyostomatitis vegetans
A rare oral condition strongly associated with inflammatory bowel disease (especially ulcerative colitis). Manifests with slightly elevated, yellow-white, round mucosal lesions with a characteristic snail-track appearance. Most commonly affects the labial and buccal mucosae, gingivae, and palate.
What serologic marker is elevated in CD more than in UC?
↑ Anti-Saccharomyces cerevisiae antibodies (ASCA): more commonly elevated in CD than in UC
pANCA: more commonly elevated in UC than in CD
Treatments for CD
steroids
Thiopurine analogs (azathioprine, 6-mercaptopurine)
Anti-p40 antibodies (e.g., ustekinumab)
Alpha 4 integrase inhibitors (e.g., natalizumab, vedolizumab)
Anti-TNF-α antibodies: e.g., adalimumab, infliximab, certolizumab
Crypt abscesses are seen in
ulcerative colitis
UC or CD: primary sclerosing cholangitis
UC
UC or CD: transmural inflammation
CD
macrocytic, megaloblastic anemia in a pt with crohn is concerning for…
vitamin B12 deficiency
This patient with chronic abdominal pain, bloody diarrhea, significant weight loss, proctitis (evidenced by pain on defecation with an unremarkable rectal examination), anemia, and positive p-ANCA most likely has
ulcerative colitis (UC)
Confluent inflammation of the colonic mucosa with edema, fibrin-covered ulcers, and loss of vascular pattern
ulcerative colitis (UC)
Five days after undergoing open distal pancreatectomy and splenectomy for a complex pancreatic cyst, a 65-year-old man notes a gush of salmon-colored fluid from his wound while getting out of bed. What is the most likely problem?
Dehiscence
The drainage of clear pink fluid from this patient’s incision a few days after open abdominal surgery is most likely peritoneal fluid tinged with blood, which is consistent with fascial dehiscence.
What may predispose a pt to poor wound healing and subsequently wound/fascial dehiscence?
history of type 2 diabetes mellitus and smoking are big ones
CT scan of the abdomen shows an edematous appendix with a 5-cm periappendiceal fluid collection. The patient is placed on bowel rest and started on IV fluids. In addition to administering intravenous antibiotics, what is the most appropriate next step in management?
Percutaneous drainage.
Patients with large (> 4 cm) periappendiceal abscesses should be managed with nonoperative measures (i.e., IV antibiotics, fluids, and bowel rest) and percutaneous drainage of the abscess. Although appendectomy can be considered in patients whose appendiceal abscess is not eligible for percutaneous drainage and in patients with small abscesses, emergency appendectomy should generally be avoided in patients with appendiceal abscesses because of the high risk of surgical complications due to acute inflammatory reaction in the area around the abscess.
What is considered a large periappendiceal abscess?
over 4 cm
uniform distribution of gas in small bowel, colon, and rectum suggest paralytic ileus.
uniform distribution of gas) suggest paralytic ileus.
This is the most common cause of acute abdomen in pregnancy.
appendicitis
How does appendicits present in pregnancy?
presents with dull abdominal pain, vomiting, fever, leukocytosis, and mild pyuria. Pregnant patients may present with pain in the upper quadrants/RUQ because appendix is displaced/
Although appendicitis pain classically localizes to the RLQ (McBurney point), in pregnant patients the gravid uterus can displace the appendix towards the right upper quadrant or the flank. Sterile pyuria is a common finding in appendicitis and can occur if part of the urinary tract (usually the right ureter) is within close proximity of the inflamed appendix, causing ureteric irritation and/or inflammation. Graded compression abdominal ultrasound is the best initial imaging modality for suspected appendicitis in pregnancy.
Biopsy results showing granulomatous inflammation/noncaseating granulomas of the colonic mucosa are diagnostic of _____________
Crohn disease
findings of ulcers and polyps (likely inflammatory pseudopolyps) with crypt abscesses on biopsy are characteristic features of ___________________
ulcerative colitis (UC)
UC or CD: colonic granulomas
CD
