Lower GI - NMS Casebook

Question 1

The following clinical stem is relevant for the next few flashcards

A 45 year old woman has a 3 day history of nausea and crampy abdominal pain followed by vomiting and abdominal distention. She had no bowel movements in the past 3 days. She has no significant history except for a previous appendectomy.

On physical examination, mild tachycardia and mild orthostatic hypotension are present. The patient is otherwise normal except for the abdomen, which is distended, tympanitic and mildly tender throughout but without rebound or localised tenderness. The bowel sounds have a crescendo-decrescendo quality with periods of hyperactivity and periods of silence.

There is no stool in the rectum WBC is 14,000/mm3, and hematocrit is 44%.

What is the most likely diagnosis?

Answer 1

A small bowel obstruction is the most likely possibility, although a number of other problems such as ileus could have a similar picture.

Question 2

What is your next diagnostic move - what investigation would you order?

Answer 2

An abdominal radiograph - an obstructive series which includes an upright posterior-anterior and lateral chest radiograph (CXR) and a flat and upright abdominal radiograp is necessary.

Question 3

What is this patient’s predicted fluid and electrolyte status?

Answer 3

• Dehydration due to vomiting and poor oral intake is expected.
• In addition, the usual metabolic picture involvees contraction alkalosis with hypokalemia whicih develops as a result of a multistep process
  
  • When H+ is secreted into the stomach, HCO3- is secreted into the plasma.
  • To maintain neutrality, Cl- is also secreted into the stomach.
  • With vomiting, there is a loss of H+, Na+, Cl- and water which leads to alkalosis and volume contraction.
  • In response to this state, the kidney preferentially retains Na+ and H+ at the expense of K+ which is lost in the urine.

Question 4

How would you correct this metabolic problem?

Answer 4

Correction of this deficit requires rehydration with sodium and potassium-containing-intravenous fluids. The alkalosis usually corrects itself after rehydration.

Question 5

What is the overall management plan?

Answer 5

• Rehydration and assessment of the patient’s overall condition are necessary.
• It is usually safe to manage small bowel obstructions with nasogastric drainage and IV fluids.
• This management strategy, may last for several days in the majority of cases in the absence of marked leukocytosis, fever, acidosis or localised tenderness and no radiographic findings suggestive of ischemia closed loop obstruction or perforation.
• Serial physical examination, lab studies and abdominal radiography are important parts of the observation plan.

Question 6

The patient improves over the next several days. her pain and distention resolve - her appetite returns. What is your management plan at this point?

Answer 6

• Remove NG tube
• Feeding should begin
• If patient tolerates food - discharge them.
• No further radiographs or evaluation is necessary.

Question 7

What is your final diagnosis of this patient’s case?

Answer 7

• Adhesions secondary to prior appendectomy - this diagnosis is presumptive in that there is no way to prove this specific diagnosis except at laparotomy.
• The patient should return if symptoms recur

Question 8

Would your initial assessment and management change in any way as a result of a 1 day duration of present illness?

Answer 8

• Would be more suspcious of a more proximal obstruction in the gastrointestinal tract.
• Proximal obstructions tend to have less abdominal distention on physical examination.
• Management remains unchanged.

Question 9

Would your assessment and management change if had been no previous abdominal surgery?

Answer 9

• No change in management if adhesions still present
• But adhesions can develop with no prior surgery - but through other causes - such as:
  
  • Hernia
  • Small or large bowel tumours
  • Tumours metastatic to the bowel
  • Inflammatory process should be suspected

Question 10

Would your initial assessment and management change if there was heme-positive stool in the rectum?

Answer 10

• Increased suspicion of an obstructing tumour or ischaemic bowel is warranted.

Question 11

Would your initial assessment and management change if there were no bowel movements but still passage of flatus?

Answer 11

• If there are no bowel movements but flatus - this is termed as partial small bowel obstruction
• The radiographic picture may show usual findings but may also show air in the colon or rectum.
• Partial small bowel obstruction is more likely to resolve without surgery and is less likely to have a complication such as ischaemia or perforation.

Question 12

Would your initial assessment and management change if there had been a small amount of diarrhea?

Answer 12

• Finding is typical of a partial obstruction
• You should also suspect a fecal impaction and severe constipations as a cause of the diarrhea.
• Gastroenteritis is another possible explanation, although the overall picture is not typical of this diagnosis.
• Examination for fecal impaction is appropriate.
• You should otherwise manage the patient for a partial small bowel obstruction.

Question 13

Would your initial assessment and management change in the presence of an inguinal hernia?

Answer 13

• An inguinal hernia - a common cause of obstruction may go unrecognized preoperatively in patients who are overweight or have altered consciousness.
• If present the condition requires repair and relief of the bowel obstruction because of the risk of strangulation.
• Typically this is performed through a mid-line laparotomy incision to allow complete evaluation of the bowel and its viability.

Question 14

Would your initial assessment and management change if there had been a Clark level 4 melanoma was excised 2 years ago?

Answer 14

• Melanoma frequently manifests as a bowel obstruction and can present many years or even decades later.
• Tumour-related obstructions often do not resolve with nonoperative management, and surgery is indicated.
• Even so, the tumour is extensive and surgical resection is not possible.
• The patient should be explored to establish a diagnosis and to relieve the obstruction.
• Even a patient with known tumour may have an obstruction due to another cause such as adhesions.
• However, if it is an unresectable tumour - the prognosis is poor.
• Melanoma is the most common tumour that metastasizes to the intestine.

Question 15

Would your initial assessment and management change if the patient had metastatic breast cancer that had been treated with chemotherapy 1 year ago?

Answer 15

• Metastatic breast cancer can also manfiest as bowel obstruction.

Question 16

Would your initial assessment and management change if there had been localised abdominal tenderness with rebound?

Answer 16

• Localised tenderness with other signs and symptoms of bowel obstruction should alert the clinician that a potential serious complication such as a closed loop obstruction, perforation, ischaemia or an abscess is present.
• Localised tenderness is an indication that surgical exploration rather than observation is necessary.

Question 17

Would your initial assessment and management change if there was a WBC count of 24,000/mm3?

Answer 17

• Marked leukocytosis is another indicator of a serious complication and warrants exploration.

Question 18

Would your initial assessment and management change if there was moderate metabolic acidosis?

Answer 18

• Metabolic acidosis with no other obvious cause warrants suspicion of ischemic or necrotic bowel.
• Depending on the patient’s overall status and radiographic findings there are two options:
  
  • Urgent exploration
  • Mesenteric arteriography to check for an arterial occlusive lesion before exploraton

Question 19

Would your initial assessment and management change if there was a temperature of 103 degree farenheit?

Answer 19

• This degree of temperature which indicates a bowel perforation or ischemic process with sepsis, warrants exploration.

Question 20

You admit a 38 year old woman with abdominal findings similar to the patient in Case 8.1. You decide that your new patient has a small bowel obstruction and no evidence of complications. You should place an NG tube, correct fluid and electrolyte abnormalities and plan to follow the progress of the obstruction. With observation and serial examinations, you note that the woman has partial improvement with some flatus and one small bowel movement. You decide to remove the NG tube because she has made progress. When you do, she becomes nauseated and distended over the next 6 hours, and it appears that her obstruction has recurred.

What is the next step?

Answer 20

• The patient, who has failed nonoperative management, should got to the operating room for exploratory laparotomy.

Question 21

You decide to explore this patient. What is the most likely operative findings?

Answer 21

• The most likely finding is an adhesive band of scar tissue from the earlier procedure that is occluding a segment of bowel.
• This band can be single, affecting a small amount of bowel or multiple affecting a large amount of bowel.

Question 22

What operation would you perform?

Answer 22

• Lysis of adhesions to free up the entire section of involved bowel would be appropriate.
• Typically, you find one band that is highly obstructing, with distended bowel proximally and empy bowel distally.
• This definitively confirms the diagnosis of small bowel obstruction.

Question 23

What is your postoperative plan?

Answer 23

• The patient remains nill-by-mouth (NBM) with an NG tube for several days until bowel function returns.
• After she resumes eating, you may discharge her.
• Most patients who have undergone a lysis of adhesions are cured of obstruction in the short term.
• Follow up primarily consists of wound observation to check for any signs of infection.
• No currently known therapy prevents recurrence of adhesions or obstruction over the long term.

Question 24

You are asked to see a 46 year old woman in the emergency department who has the signs and symptoms of a small bowel obstruction. How would each of the following radiographs influence your decision making?

A closed loop obstruction

Answer 24

• Typically, an adhesive band occludes the inlet and outlet of a loop of bowel, allowing secretions and air to accumulate in the loop and distend it.
• The loop can become ischaemic due to blood flow obstruction from either twisting the blood supply or the adhesive band obstructing the blood supply.
• The loop can also perforate.
• The patient should be urgently explored after resuscitation.

EXTRA NOTES

• The primary issue is whether the bowel is viable. If observation does not provide a definitive indication, either resection and reanasomosis or a ‘‘second look’’ operation is necessary.
  
  • A second look op. is a planned reexploration 24 horus later to inspect the questionable bowel.
  • Resection of any ischaemic or necrotic bowel followed by anastomosis reestablishes bowel continuity.

Question 25

You are asked to see a 46 year old woman in the emergency department who has the signs and symptoms of a small bowel obstruction. How would each of the following radiographs influence your decision making?

Crampy abdominal pain and free air in the peritoneal cavity

Answer 25

• Exploration is necessary to resolve this problem.
• If the free air occurred during observation for a small bowel obstruction - it is most likely due to either an ischemic perforation or perforation due to overeexpansion of the bowel.
• Thus part of the process of observation includes monitoring the degree of intestinal distention on the radiographs

Question 26

You are asked to see a 46 year old woman in the emergency department who has the signs and symptoms of a small bowel obstruction. How would each of the following radiographs influence your decision making?

Crampy abdominal pain and an inguinal hernia

Answer 26

• This patient has evidence of a small bowel obstruction and bowel within a hernia sac.
• Urgent exploration is necessary after resuscitation

Question 27

You have decided to explore a patient with an incarcerated inguinal hernia and a small bowel obstruction. What are the options for operative management?

Answer 27

• Management may differ depending on how sick the patient appears.
  
  • In a relatively stable patient with no signs of systemic illness, exploration through a hernia incision in the groin is appropriate.
  • The surgeon can explore the hernia - inspect the bowel and return it to the peritoneal cavity if viable - and thus repair the hernia.
  • In a patient who is ill, exploration through a midline abdominal incision is preferred.
    
    • This allows a more thorough inspection of the entire bowel
    • If bowel is questionable or necrotic - either observation until it is viable or resection and reanastomosis are possible.
  • The surgeon may repair the hernia entirely or partially (to prevent immediate recurrence followed by formal repair at a later date when the patient has recovered)

Question 28

You are exploring a 60-year-old man with a smal l bowel obstruction that i nvolves particularly dense adhesions. In the process of lysing one, you enter the bowel lumen . What are the management options?

Answer 28

• An unplanned enterotomy is an undesirable event when it occurs during lysis of adhesions.
• If holes are small, primary repair is appropriate. If holes are large, multiple, or involve densely adherent bowel, the segment of affected bowel may require resection.

Question 29

What problems might you anticipate in the postoperative period?

Answer 29

The greatest risk of an enterotomy is a postoperative leak and development of a small bowel fistula.

Question 30

You are asked to see a 49-year-old man on the medical service who is recovering from pneumonia. Abdominal distention, nausea, and crampy abdominal pain have recently developed. What might be causing the distention?

Answer 30

• Inpatients with multiple other diseases such as:
  
  • heart failure
  • sepsis
  • chronic obstructive pulmonary disease
    
    • May look as if they have a bowel obstruction.
• This could be a small bowel obstruction - if this is present treatment is warranted.
• However, distention has additional causes:
  
  • paralytic ileus
    
    • A paralytic state in which the bowel fails to maintain peristalsis
  • air swallowing
  • constipation
• Nausea, vomiting and abdominal distention develop and from a functional standpoint - nothing can pass through the bowel.

Question 31

If you are uncertain of the diagnosis of bowel obstruction in a complex situation such as this, is there any way you can confirm the diagnosis of a small bowel obstruction without an operation?

Answer 31

• If you are uncertain of the diagnosis or if NG drainage leads to only partial improvement, an upper GI series with small bowel follow-through prior to the decision to explore the patient is warranted.
• If the bowel is obstructed, the barium stops at the obstruction, andthis establishes the diagnosis.
• Severe constipation should also be evident with this study, although a colon full of stool is usually visible on a plain radiograph of the abdomen.
• If the barium finds its way to the colon and eventually to the rectum, there is no mechanical bowel obstruction, and surgery will not help.
• Treatment of constipation involves enemas and disimpaction, not surgery.
• Paralytic ileus from many causes may also produce obstructive symptoms.
• It may lead to poor peristalsis and a slow transit time as seen on the small bowel follow through.

Question 32

A 70-year-old woman presents to the emergency department with a 1 -day history of nausea, vomiting, and increasingly severe abdominal pain.

She has a low-grade fever as well as mild distention of the abdomen, which is nontympanitic and mildly tender.

Her pain seems much more severe than her abdom inal findi ngs. Her abdominal radiograph shows a nonspecific ileus.

On initial evaluation, the patient is stable, with a blood pressure (BP) of 1 40/85 mm Hg (her baseline). She has a WBC count of 1 5,000/mm3 and no acidosis.

What is the next step?

Answer 32

• Based on the initial findings, a suspicion of ischaemic bowel is appropriate. Two approaches are possible:
  
  • Proceed to the operating room if you think the patient has necrotic bowel
  • Perform further evaluation prior to a management decision.
• In this case, because the patient appears stable and has no strong evidence for necrosis, further evaluation is most likely safe.
• After hydration, it is necessary to ensure that the patient is well oxygenated and perfused.
• Sigmoidoscopy to establish the diagnosis of colon ischaemic and the depth of ischaemia if present may be warrranted.
• A negative sigmoidoscopy does not rule out ischaemia, and evaluation should continue if ischaemia is suspected.
• The patient could then safely undergo a mesenteric angiogram to allow the clinician to diagnose a vascular problem and decide whether surgical revascularization was an option.

Question 33

Following from the previous case, the patient undergoes sigmoidoscopy, which reveals a segment of ischemic but not necrotic sigmoid colon, and an angiogram. Clinically, she improves after antibiotics and hydration.- what is the next step?

Answer 33

• She has most likely had an ischaemic event that has resolved for the time being but is likely to recur.
• The next episode could be worse, resulting in colonic necrosis.
• Establishing an anatomical abnormality on angiogram is key.
• Repair of this defect would mostlikely prevent a recurrence of ischaemia.
• She should undergo semielective revascularization of the mesenteric circulation.

Question 34

The patient opts for revascularization. The procedure is successful - what is your long term management plan?

Answer 34

• Most surgeons would place the patient on antiplatelet therapy with aspirin.
• In addition, evaluation for the presence of cardiac and peripheral vascular disease is warranted, because it is probably present and will affect her survival.

Question 35

What if a patient with suspected mesenteric ischaemia had significantly worsening pain over the next hour?

Answer 35

• Concern if patient has necrotic bowel should prompt you to proceed to the operating room.

Question 36

What if a patient with suspected mesenteric ischaemia had a WBC count of 24,000/mm(3)?

Answer 36

• Suspect:
  
  • Ischaemia
  • Necrosis
  • Perforation with infection
• Indication to proceed to operating room

Question 37

What if a patient with suspected mesenteric ischaemia had a WBC count of 2500/mm(3)?

Answer 37

• Elderly individuals, in particular, sometimes respond to overwhelming sepsis with leukopenia often with a marked left shift.

Question 38

What if a patient with suspected mesenteric ischaemia had a history of atrial fibrillation?

Answer 38

• Embolization to the bowel from a thrombus in the left atrium associated with AF should be suspected.
• Depending on the patient’s overall status, an angiogram of the mesenteric circulation before exploration is a possibility; exploration is most likely necessary.

Question 39

What if a patient with suspected mesenteric ischaemia had a history of abdominal bruits?

Answer 39

• A bruit may suggest stenosis of the coeliac and mesenteric vessels and consequent ischaemia.
• An angiogram preoperatively could be helpful in the operative planning.
• By itself, a bruit is not an indication for surgery.
• In addition, most patients with bowel ischaemia do not have bruits.

Question 40

What if a patient with suspected mesenteric ischaemia had an hematocrtic of 55%?

Answer 40

• Polycythemia is most likely to be secondary to severe dehydration, which could be corrected by rehydration.
• Treatment involves rehydration.
• Although polycythemia vera is less common in older patients, it may also occur.
• It is a hypercoagulable state, and like other hypercoagulable conditions - can cause:
  
  • stasis
  • low flow
  • thrombosis in the mesenteric vascular beds
• Treatment of primary polycythemia consists of phlebotomy and hydration.
• Angiography should still be performed for operative planning.
• Polycythemia as a secondary event may also be associated with COPD, and depending on the state of the patient, a pulmonary evaluation would be appropriate.

Question 41

What if a patient with suspected mesenteric ischaemia had a history of congestive heart failure?

Answer 41

• CHF can be associated with low flow states in the mesenteric circulation.
• An angiogram can confirm a low flow nonocclusive state in a suspected combination of congestive heart failure and mesenteric ischaemia.
• Treatment of this condition involves direct mesenteric infusion of a vasodilator such as papaverine and efforts to improve cardiac output.

Question 42

What if a patient with suspected mesenteric ischaemia had a history of thoracic aortic dissection?

Answer 42

• Aortic dissection can occlude any vessel orifice in the aorta.
• The combination of dissection and mesenteric ischaemia suggests an occlusion related to the dissection.
• Angiography allows for diagnosis and the planning of surgical correction.

Question 43

What if a patient with suspected mesenteric ischaemia had a BP of 90/60 mm Hg (in the emergency department)?

Answer 43

• The combination of suspected mesenteric ischaemia and hypotension may indicate:
  
  • Ischaemia
  • Sepsis
  • Hypotension
    
    • could also be due to nonocclusive ischaemia due to low flow
• Overall patient assessment, measurement of hemodynamics, angiography or surgery may be necessary to diagnose the problem correctly.

Question 44

What if a patient with suspected mesenteric ischaemia had bloody diarrhea?

Answer 44

• This suggests an ischaemic segment of colon with necrosis of at least the mucosa and subsequent sloughing.
• The next step in evaluation is sigmoidoscopy to assess the colon.
• If full-thickness necrosis is present - exploration and resection are necessary.
• If only mucosal ischaemia is present - it is possible to avoid resection by:
  
  • optimizing hemodynamics
  • antibiotic administration
  • close observation

Question 45

Laboratory studies reveal that the patient is acidotic, with a blood pH of 7.14, and a WBC count of 25,000/mm3. You decide that she may have necrotic bowel and that abdominal exploration is warranted. How would you manage necrosis of the left colon?

Answer 45

• Resection of the colon back to well perfused edges is necessary
• If the patient is stable and conditions are favourable, reanastomosis of the colon is appropriate.
• If not, a colostomy and Hartmann pouch operation (stapling the distal colon closed and placement back into the abdomen) are warranted

Question 46

Laboratory studies reveal that the patient is acidotic, with a blood pH of 7.14, and a WBC count of 25,000/mm3. You decide that she may have necrotic bowel and that abdominal exploration is warranted. How would you manage necrosis of the intestines from the ligament of Treitz to the transverse colon?

Answer 46

• In the majority of cases, this is a hopeless situation.
• Management should probably not involve resection, with closure of the abdomen, thus allowing patients to succumb to the illness.
• Surgical resection and reanastomosis may be appropriate in younger individuals with no other illnesses.
• Resection of the majority of bowel is appropriate, leaving patients with a short bowel syndrome and the need for chronic total parenteral nutrition (TPN) or small bowel transplantation.

Question 47

What if the same patient had necrosis of 2 feet of jejunum and ischaemia of the adjacent bowel?

Answer 47

• Resection of the necrotic bowel back to the healthy edge is necessary, with reanastomosis performed under favorable conditions.
• If there is doubt as to the viability of the reamining bowel, a ‘second look’ procedure should be performed the next day.
• In seriously ill patients, another alternative is ileostomy, which allows direct observation of the viability of the bowel.
• Because there is no intestinal anastomosis, there is no risk of anastomotic breakdown.
• Patients may also benefit from postoperative mesenteric angiography to allow assessment of the vasculature.

Question 48

What if a patient had ischaemia but no necrosis of the intestines and acute occlusion of the origin of the superior mesenteric artery?

Answer 48

• In this situation, it is desirable to revascularize the bowel.
• The superior mesenteric artery should be exposed and the occlusion either removed or bypassed.
• The bowel can then be inspected for viability and managed accordingly.
• In addition, these patients are ideal subjects for preoperative mesenteric angiography.

Question 49

What if a patient had ischemia of the intestines with multiple sma l l punctate areas of necrosis throughout the jejunum and ileum in a patient with a pulse
in the superior mesenteric artery and mild chronic congestive heart failure?

Answer 49

• This suggests either multiple small emboli or a low flow state. Obviously, necrotic areas warrant resection.
• Postoperative optimization of hemodynamics and a “second look” operation are a reasonable management scheme, although the outlook is poor.
• Angiography may demonstrate a low mesenteric flow rate.

Question 50

What if the patient had viable but ischaemic intestines in a patient with a pulse in the superior mesenteric artery but evidence of a low flow rate?

Answer 50

• The hemodynamic status of this patient should be optimized.
• Preoperative angiography and recognition of the low flow state would be better treated by optimizing vascular perfusion than with surgery.
• This would avoid an unnecessary operation.