Colorectal Surgery Practice Questions

Q: A patient is planned for elective colon surgery. What is the ideal timing for administration of prophylactic parenteral antibiotics?

1 hour before skin incision. ***1 hour before skin incision*** - Administering prophylactic antibiotics within **60 minutes** prior to the initial incision ensures adequate **tissue concentration** at the time of potential bacterial contamination. - Giving the dose too early risks the drug level dropping before the surgery begins, while giving it too late fails to protect during the highest risk period. *30 minutes before surgery* - While this timing falls within the acceptable window, it is not the **optimal** or widely recommended target compared to the 60-minute benchmark. - Depending on the specific antibiotic (e.g., **vancomycin** or **fluoroquinolones**), 30 minutes may not be sufficient for full infusion prior to incision. *2 hours before surgery* - Administering antibiotics 2 hours preoperatively significantly increases the risk that peak **serum levels** will be missed during the critical window of contamination. - Prolonged time intervals prior to incision are associated with higher rates of **surgical site infections (SSIs)**. *4 hours before surgery* - This duration is far too early; the drug will likely be cleared or metabolized below the **minimum inhibitory concentration (MIC)** required to prevent infection by the time the incision is made. - Prolonged preoperative administration does not provide additional benefit and may contribute unnecessarily to **antibiotic resistance**.

Q: A 65-year-old male with diabetes mellitus presents with purulent rectal discharge and is diagnosed with fistula-in-ano. Surgical management is planned. Which of the following procedures is considered internal anal sphincter-preserving?

Fistulectomy. ***Fistulectomy*** - A **fistulectomy** involves the complete excision of the **fistula tract** from its internal to its external opening, sparing the surrounding healthy **anal sphincter complex** when performed correctly. - It is the traditional standard for simple, low-lying **fistulae-in-ano** where the sphincter muscle involvement is minimal or superficial, thus preserving continence. *LIFT (Ligation of Intersphincteric Fistula Tract)* - The **LIFT** procedure is specifically designed to isolate and ligate the fistula tract in the **intersphincteric plane**. - While it preserves the sphincter, it is distinct from a formal **fistulectomy** and is often used for complex or **transphincteric fistulas** to avoid sphincter division. *FiLaC (Fistula-tract Laser Closure)* - **FiLaC** is a minimally invasive, sphincter-sparing technique that uses a **radial laser probe** to destroy the epithelial lining of the fistula tract. - It promotes healing of the tract from the inside out without requiring the division or excision of the **anal sphincter** muscles. *VAAFT (Video-Assisted Anal Fistula Treatment)* - **VAAFT** utilizes an **endoscope** (fistuloscope) to visualize the tract and fulgurate it under direct vision. - This procedure allows for the identification of lateral tracts and abscess cavities while strictly preserving the **anal sphincter** integrity.

Q: According to the American Association for the Surgery of Trauma (AAST) colon injury grading scale, how is a colonic laceration involving more than 50% of the bowel wall circumference without complete transection classified?

Grade III. ***Grade III*** - According to the AAST colon injury scale, a Grade III injury is defined as a colonic laceration encompassing greater than 50% of the bowel wall circumference, but short of complete transection. - This categorization is critical in trauma surgery for determining the necessity of more aggressive management strategies, such as resection, compared to simpler primary repair. *Grade II* - A Grade II colon injury is defined as a laceration involving 50% or less of the bowel circumference. - These injuries are generally associated with lower morbidity and often amenable to simple primary repair or stricture considerations. *Grade IV* - Grade IV injuries involve full-thickness transection of the colon. - This injury grade represents a higher level of tissue destruction requiring more complex management, usually involving formal resection rather than simple repair. *Grade V* - A Grade V injury pertains to a colon injury associated with **tissue loss** and **devascularization** of a colonic segment. - This is the most severe classification in the AAST scale and necessitates significant surgical intervention due to the compromised blood supply.

Q: On defecography, a rectocele is considered clinically significant when there is anterior bulging of the rectal wall into the posterior vaginal wall measuring more than:

2 cm. ***2 cm*** - A rectocele is defined as an anterior bulging of the rectal wall into the posterior vaginal wall, and it is considered clinically significant on **defecography** when this protrusion exceeds **2 cm**. - While smaller protrusions may be seen on imaging, they are often asymptomatic and do not require surgical intervention unless the patient presents with specific symptoms like **obstructed defecation**. *1 cm* - A rectocele measuring **1 cm** is typically considered to be within the range of physiologic or normal findings on defecography. - Many asymptomatic women show minimal bulging of this size, so it does not meet the criteria for **clinical significance** or surgical correction. *3 cm* - Although a **3 cm** rectocele would certainly fit the criteria for a clinically significant finding, it is not the minimum threshold for that clinical diagnosis. - Using a higher threshold would result in missing diagnosis and potentially undertreating patients who have symptomatic outlet obstruction related to a **2 cm** rectocele. *4 cm* - A **4 cm** rectocele is a large defect, but setting the diagnostic threshold this high would be inaccurate. - Clinical guidelines use the **2 cm** cutoff to balance diagnostic sensitivity with the correlation of patient-reported symptoms like **rectal digitation**.

Question 1

A patient is planned for elective colon surgery. What is the ideal timing for administration of
prophylactic parenteral antibiotics?

Accepted Answer

1 hour before skin incision

Answer

30 minutes before surgery

Answer

2 hours before surgery

Answer

4 hours before surgery

Question 2

A 65-year-old male with diabetes mellitus presents with purulent rectal discharge and is
diagnosed with fistula-in-ano. Surgical management is planned. Which of the following procedures
is considered internal anal sphincter-preserving?

Accepted Answer

Fistulectomy

Answer

LIFT

Answer

FiLaC

Answer

VAAFT

Question 3

What is the fundamental surgical principle underlying TME in the operative management of
rectal cancer?

Accepted Answer

En bloc removal of the entire mesorectum as a single intact unit

Answer

Excision of only the peritumoral fat surrounding the tumor

Answer

Routine resection of the pelvic autonomic nerves

Answer

Ligation of the internal iliac artery

Question 4

According to the American Association for the Surgery of Trauma (AAST) colon injury grading
scale, how is a colonic laceration involving more than 50% of the bowel wall circumference without
complete transection classified?

Accepted Answer

Grade III

Answer

Grade II

Answer

Grade IV

Answer

Grade V

Question 5

On defecography, a rectocele is considered clinically significant when there is anterior bulging
of the rectal wall into the posterior vaginal wall measuring more than:

Accepted Answer

2 cm

Answer

1 cm

Answer

3 cm

Answer

4 cm

Colorectal Surgery — MCQs

Colorectal Surgery — MCQs

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