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Small Intestine, Appendix, and Colorectal

Elise Sienicki, MD¹, Vishal Bansal, MD², and Jay J. Doucet, MD, MSc³

¹ Naval Medical Center, San Diego, CA, USA

² Scripps Mercy Hospital, San Diego, CA, USA

³ Department of Surgery, University of California San Diego, San Diego, CA, USA

Colon, Small Bowel, and Appendix

A 21‐year‐old man is brought by ambulance to the trauma bay after sustaining a gunshot wound to the abdomen. He is alert and oriented with a heart rate of 130 beats/min and blood pressure 95/55 mm Hg. His FAST exam is positive and he is taken urgently for laparotomy. During surgery, there is extensive damage to the transverse colon. You notice an expanding hematoma at the base of the transverse mesocolon and suspect a superior mesenteric artery (SMA) injury. As you expose the SMA, you find a near‐complete transection of the SMA just distal to the middle colic artery. Which of the following is true about this injury?

Ligation at the point of injury would most likely result in loss of significant portions of small bowel.
This is a zone 3 injury, which carries a mortality rate of 40%.
The preferred method of repair involves temporary shunting with a second‐look operation.
This patient’s greatest mortality risk is due to infection.
Most SMA injuries can be managed successfully with angioembolization.

Injuries to the SMA carry significant morbidity and mortality. The incidence of these injuries is unknown; however, they generally account for less than 1% of cases at large trauma centers. Most laparotomy deaths for SMA injuries are due to exsanguination, not infection. Review of the literature reveals that those who undergo primary repair have a lower incidence of associated vascular and nonvascular injuries, and have improved survival, compared to those who undergo ligation (and have a higher number of associated injuries). The SMA zones of injury were first described in the 1970s.

Zone of injury	Anatomic location	Mortality (%)
Zone 1	Aorta to inferior pancreato‐duodenal artery	Close to 100
Zone 2	Inferior pancreato‐duodenal artery to middle colic artery	43
Zone 3	Trunk distal to middle colic artery	25
Zone 4	Segmental branches	25

There are no definitive published guidelines for management of these injuries; however, there are various options that have been extensively reviewed. Ligation should be considered in unstable patients when bowel ischemia is present. Ligation in zones 1 and 2 carries a significant risk of bowel ischemia, unless sufficient collaterals are present. Ligation in zones 3 and 4 carry a lower risk of ischemia, but the risk may be increased if the patient has significant atherosclerotic disease. In a damage‐control setting, shunting can be performed with a planned second‐look operation, with later reconstruction with a saphenous vein graft or PTFE. Angioembolization has been successful in managing these injuries recently, although there is significant risk of ischemia and it is advised to only perform angioembolization in hemodynamically stable patients.

Answer: A

Asensio JA, Britt LD, Borzotta A, et al. Multi‐institutional experience with the management of superior mesenteric artery injuries. J Am Coll Surg. 2001, 193(4):354–366. Erratum in Journal of the American College of Surgeons, 193 (6), 718.

Phillips B, Reiter S, Murray EP, et al. Trauma to the superior mesenteric artery and superior mesenteric vein: A narrative review of rare but lethal injuries. World J Surg. 2018; 42(3):713–726.

A 60‐year‐old woman presents to the trauma bay after a head‐on motor vehicle collision. She is alert, oriented, and complaining of abdominal pain. Her vitals are normal on initial assessment. Bruising is present across her low abdomen and she has tenderness without peritoneal findings. Initial CT scan of the abdomen shows no solid organ injury but a small amount of free fluid in the right paracolic gutter and some mild small bowel wall thickening. Her abdominal pain improves in the trauma bay and she is admitted for observation. Six hours later, you are called to reassess her because her pain has returned. Her vitals remain within normal limits. She is tender in the right hemi‐abdomen, but again without peritoneal signs. Her labs have since resulted and show a WBC count of 11 000. Which of the following is the next best course of action?
1. Repeat CT scan of the abdomen with IV contrast only
2. Repeat CT scan of the abdomen with IV and PO contrast
3. Continued observation until she develops peritonitis
4. Surgical exploration
5. Acute abdominal series
Answer: D
Which of the above patient’s signs or symptoms predict, with the greatest accuracy, the presence of blunt small bowel injury?
1. Tenderness on physical exam
2. Free fluid on CT scan
3. Bowel wall thickening
4. Lower abdominal bruising from seat belt
5. Elevated WBC count
Blunt small bowel perforation (SBP) remains a diagnostic challenge to this day, even though our diagnostic capabilities have improved. Rates of small bowel injury range from 5 to 15% of blunt abdominal trauma patients, and perforation occurring in 1%. These injuries are often found incidentally on laparotomy for other intra‐abdominal injuries. The presence of abdominal free fluid in the trauma patient, in the absence of solid organ injury or other obvious source of bleeding, should prompt evaluation for small bowel injury.

Another mechanism of small bowel injury in trauma is mesenteric injury resulting from shearing forces that can tear the small bowel loose from its blood supply, which may result in delayed perforation, stricture, and internal hernia from bowel being trapped in the new mesenteric defect.

Blunt abdominal trauma patients can present a diagnostic challenge. Many recommend additional diagnostic/therapeutic intervention by 8 hours after arrival in these patients, as the mortality from blunt SBP increases to 30.8% from 13% in those who receive surgical therapy greater than 8 hours from injury. Repeat CT scans may provide some useful information; however, in this patient who has reasonable signs of small bowel injury on her initial scan, will only delay operative intervention. Continued observation in this patient who is high risk is also not the best course of action.

Recent studies show that the most accurate indicator of blunt SBP is the presence of free fluid on abdominal CT. Other signs including tenderness on physical exam, bowel wall thickening, seat belt sign, and elevated WBC count are less reliable.

Answer: B

Fakhry SM, Allawi A, Ferguson PL, et al. Blunt small bowel perforation (SBP): An Eastern Association for the Surgery of Trauma multicenter update 15 years later. J Trauma Acute Care Surg. 2019; 86(4):642–650.
A 38‐year‐old woman is horseback riding when she is thrown from the horse and lands on a wood pile. She is brought to the hospital for evaluation of rectal pain. She is hemodynamically normal. There is blood present on digital rectal exam and a small external wound is noted that is not bleeding. A CT scan with IV contrast shows evidence of a rectal injury 8 cm above the anal verge that is confirmed on rigid proctoscopy. What procedure should this patient undergo?
1. Transanal repair without fecal diversion
2. Transanal repair with sigmoid loop colostomy
3. Transanal repair with end‐sigmoid colostomy
4. Primary repair, presacral drainage, and sigmoid loop colostomy
5. Primary repair, distal limb washout, and sigmoid end colostomy
In the 1970s, Vietnam‐era surgeons taking care of combat casualties published the 4 “Ds” of rectal trauma, and advocated for their regular use when dealing with penetrating rectal injuries: direct repair, diversion, distal rectal washout, and presacral drain. Over time, however, these data have been challenged, and current guidelines and the data do not support the use of presacral drainage or distal limb washout. In traumatic injury to the anus, the concern for severe fecal incontinence as well as pelvic sepsis is paramount; therefore, aggressive surgical management is still a surgical mainstay. Careful examination of the anus under anesthesia will help ascertain the continuity and of the internal and external sphincter, as well as the integrity of the anal canal and distal rectum. Immediate repair of the sphincter and transanal repair of the rectum should combined with diversion by loop colostomy in those with extraperitoneal injuries to avoid the development of pelvic sepsis. End‐colostomy is a surgical option, but the ease of colostomy takedown with a loop colostomy makes it preferred in this setting.

Answer: B

Brown CVR, Teixeira PG, Furay E, et al. The AAST contemporary management of rectal injuries study group contemporary management of rectal injuries at level I trauma centers: The results of an American Association for the Surgery of Trauma multi‐institutional study. J Trauma Acute Care Surg. 2018; 84(2):225–233
A 57‐year‐old man is brought to your trauma bay after sustaining multiple stab wounds to the abdomen. He has a history of asthma but is otherwise healthy. He is tachycardic and hypotensive and is given two units of whole blood in the trauma bay and is transferred urgently to the operating room for exploration. During surgery, you encounter a significant splenic laceration with active hemorrhage, a full‐thickness descending colon injury involving less than 50% of the circumference of the colon, as well as a serosal tear of the stomach. A splenectomy is successfully performed and the stomach thoroughly examined with no posterior injury identified and no pancreatic injury. At this point, the patient has received another two units of packed red blood cells, and is hemodynamically stable with an arterial pH of 7.34. How should the colon injury be addressed?
1. Resection, primary anastomosis, diverting transverse loop colostomy
2. Resection, primary anastomosis
3. Primary repair, diverting transverse loop colostomy
4. Primary repair
5. Transverse loop colostomy, drain placement
The grade of injury in adult civilian patients with penetrating colon injuries is less important for determining the management of colon injuries than is the risk factors for anastomotic breakdown. Even destructive injuries (>50% of circumference) may be managed without diversion in low‐risk patients. For high‐risk penetrating colon injuries (delay >12 hours, shock, associated injuries, transfusion > 6 units of blood, contamination, or left‐side colon injuries), colon repair or resection may be still be performed rather than mandatory colostomy. Colostomy may have a role in select patients with other injuries (pancreas). Low‐risk patients with penetrating colon injury without signs of shock, significant hemorrhage, severe contamination, or delay to surgical intervention should preferentially undergo colon repair or resection and anastomosis versus colostomy. In cases of damage‐control laparotomy, there is increased risk of anastomotic breakdown; however, colostomy is still not mandatory and clinical judgment is required.

Answer: D

Cullinane DC, Jawa RS, Como JJ, et al. Management of penetrating intraperitoneal colon injuries: A meta‐analysis and practice management guideline from the Eastern Association for the Surgery of Trauma. J Trauma Acute Care Surg. 2019; 86(3):505–515.
An 89‐year‐old woman is brought to the ED by ambulance from a skilled nursing facility, where she has been recovering from hip replacement surgery, with a chief complaint of constipation for 7 days. She has a past medical history that includes diabetes, dementia, and hypertension. On exam, she is quite distended but nontender to palpation in her abdomen. Plain radiographs of the abdomen are obtained which show significant dilation of the entire colon without air in the sigmoid or rectum, and without free air. In addition to admission, electrolyte replacement and cessation of narcotics, what is the next best step in management?
1. Rectal tube placement
2. Anoscopy
3. Placement of an NG tube
4. Laparotomy
5. Upper GI contrast study
Answer: C
The above patient is admitted for conservative medical management, cessation of narcotics, and an NG tube but has not had relief of symptoms after 72 hours. What is the next best step to relieve her symptoms?
1. Decompressive rectal tube placed at bedside
2. Subcutaneous neostigmine in a monitored setting
3. Colonoscopic decompression
4. Exploratory laparotomy and subtotal colectomy
5. Loop sigmoid ostomy for colonic pseudo‐obstruction
Acute colonic pseudo‐obstruction (ACPO), or Ogilvie’s syndrome, almost exclusively occurs in hospitalized or immobilized patients. Risk factors include older age, recent major orthopedic procedure, narcotic use, and electrolyte disturbances. Despite the dramatic appearance of the colon on imaging, these patients rarely need surgery. The most serious adverse events of ACPO are ischemia and perforation, with an increased risk in patients with cecal diameters greater than 10–12 cm and in those with abdominal distention greater than 6 days. When evaluating these patients, a mechanical obstruction must be ruled out first. This can be done with either rigid proctoscopy or CT scan. CT imaging is not only highly sensitive and specific for detecting mechanical obstruction, but it can also show evidence of ischemia, perforation, and evaluate for extrinsic or intrinsic compression. Water‐soluble contrast enema of the rectum and distal colon is another diagnostic option, although CT has largely replaced contrast enema studies. It is worth noting that mechanical obstruction rarely occurs in a patient admitted for unrelated illnesses (i.e., pneumonia, elective non‐GI surgery). Rectal tube placement at the bedside rarely is helpful because the right colon is frequently adynamic. After maximal medical management with narcotic avoidance, electrolyte correction, and NG decompression (if needed), the next step is neostigmine administration which is 85–94% effective. Male gender, younger age, postsurgical status, and having electrolyte imbalance are risk factors for nonresponse to neostigmine. Daily administration of polyethylene glycol via nasogastric tube has also been shown to decrease recurrence. Continuous infusion or subcutaneous administration of neostigmine may reduce cardiovascular effects while remaining effective. Traditionally, endoscopic decompression with colonoscopy is second‐line therapy after failure of medical management and neostigmine. There are no randomized controlled trials of pharmacologic versus endoscopic therapy for ACPO; however, two retrospective studies found colonoscopic decompression to be superior to neostigmine. The data are considered limited and the 2020 American Society for Gastrointestinal Endoscopy ACPO guidelines continue to recommend initial pharmacologic therapy.

Answer: B

Naveed M, Jamil LH, Fujii‐Lau LL, et al. American Society for Gastrointestinal Endoscopy guideline on the role of endoscopy in the management of acute colonic pseudo‐obstruction and colonic volvulus. Gastrointest Endosc. 2020; 91(2):228–235. doi: 10.1016/j.gie.2019.09.007. Epub 2019 Nov 30. Erratum in: Gastrointest Endosc. 2020 Mar;91(3):721.
A 65‐year‐old woman with a history of chronic constipation and rheumatoid arthritis, presents with a 12 hour history of severe right lower quadrant abdominal pain, nausea, and vomiting. She takes methotrexate for her arthritis as well as multiple laxatives for constipation. On examination, she is distended and has mild lower abdominal tenderness without peritoneal signs. Her labs are normal including WBC count and renal function. A coffee‐bean sign is seen on an abdominal plain film taken in the ED. She is taken to surgery, where patchy ischemic bowel is found at the involved segment. What is the best management strategy for this patient?
1. Detorsion and placement of a venting tube through the abdominal wall
2. Detorsion and pexy of the non‐ischemic portion of the involved bowel to the abdominal wall
3. Resection and diverting ileostomy
4. Resection and primary anastomosis
5. Detorsion and observing the involved portion of bowel with resection only if it does not appear viable
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