Appendix, Rectum & Anal Canal Lecture Flashcards

This set of 100 flashcards covers carcinoma of the rectum, anal pathologies (fistula, fissure, pilonidal sinus), colonoscopy, and management of right iliac fossa masses based on lecture notes.

At what anatomical level does the rectum begin?

The rectosigmoid junction, at the level of the $S3$ vertebra.

What is the approximate length of the rectum from the anal verge?

Approximately $15\,cm$.

Which histological type accounts for more than $95\%$ of rectal cancers?

Adenocarcinomas.

What are the two primary molecular pathways for the development of rectal cancer?

The adenoma-carcinoma sequence ($APC/\beta$-catenin pathway) and the mismatch repair (microsatellite instability) pathway.

What is the peak incidence age range for carcinoma of the rectum?

Between $60-70$ years.

Which inflammatory bowel disease carries a higher risk for rectal cancer?

Ulcerative Colitis (especially with pancolitis lasting > 10 years).

Which type of adenomatous polyp has the highest malignant potential?

Villous adenomas.

What characterizes the inheritance of Familial Adenomatous Polyposis (FAP)?

An autosomal dominant mutation of the $APC$ gene with a $100\%$ lifetime risk of colorectal cancer.

Which genes are typically mutated in HNPCC (Lynch Syndrome)?

DNA mismatch repair genes ($MLH1$, $MSH2$).

What is the most common macroscopic appearance of rectal carcinoma?

Ulcerative, presenting with a raised, everted, rolled-out edge and a necrotic base.

Describe the clinical characteristic of polypoid/fungating rectal tumors.

A cauliflower-like mass that projects into the lumen and commonly bleeds but causes obstruction late.

Which macroscopic form of rectal cancer is less common in the rectum than in the left colon?

Annular/Stricturing.

What are two aggressive microscopic variants of rectal adenocarcinoma?

Mucinous and Signet-ring cell carcinomas.

To which organs can rectal cancer invade anteriorly?

Prostate, seminal vesicles, or vagina.

What is the initial site of lymphatic spread for rectal cancer nodes?

Perirectal nodes within the mesorectum.

What is the most common site for haematogenous spread of rectal cancer?

The Liver, via the portal venous system.

How do lower rectal tumors typically spread haematogenously to the lungs?

Via the inferior rectal veins to the systemic circulation.

What is the most common early symptom of rectal cancer?

Bleeding per Rectum (typically dark red and mixed with or coating the stool).

Define 'spurious diarrhoea' in the context of rectal cancer.

Passing a mixture of blood, mucus, and flatus without much actual stool, often occurring in the early morning.

What term describes the persistent feeling of incomplete evacuation?

Tenesmus.

What does severe pain radiating down the legs (sciatica) indicate in rectal cancer?

Advanced disease with sacral plexus involvement.

What information can a Digital Rectal Examination (DRE) provide about a rectal tumor?

Distance from the anal verge, size, mobility (fixation), and ulceration.

Which procedure is considered the gold standard for obtaining a tissue biopsy for rectal cancer?

Proctoscopy or Rigid Sigmoidoscopy.

Why is a full colonoscopy mandatory in patients with rectal cancer?

To rule out synchronous tumors, which are present in $5\%$ of patients.

What is the gold standard for local staging of rectal cancer?

$MRI$ Pelvis.

What does the acronym CRM stand for in rectal cancer staging?

Circumferential Resection Margin.

Which investigation is highly accurate for distinguishing between early $T1$ and $T2$ tumors?

Endorectal Ultrasound (ERUS).

What tumor marker is used for baseline prognostication and postoperative follow-up in rectal cancer?

$CEA$ (Carcinoembryonic Antigen).

What are the two main modalities for neoadjuvant therapy in rectal cancer?

Long-course chemoradiotherapy (LCRT) or Short-course radiotherapy (SCRT).

What is the core principle of rectal cancer surgery?

Total Mesorectal Excision (TME).

Define Total Mesorectal Excision (TME).

Sharp dissection in the avascular embryonic plane to remove the rectum along with its intact fatty mesorectal envelope containing lymph nodes.

What is the required distal clearance margin for upper and middle rectal tumors?

At least $2\,cm$.

What is the minimum distal clearance margin for lower rectal tumors post-radiation?

$1\,cm$.

What is the primary difference between a Low Anterior Resection (LAR) and an Abdominoperineal Resection (APR)?

LAR restores gastrointestinal continuity via anastomosis, while APR involves permanent removal of the anal canal and a permanent end colostomy.

Who is an Abdominoperineal Resection (APR / Miles' Operation) indicated for?

Patients with lower third rectal tumors that invade the anal sphincters or where distal margins cannot be achieved.

What is the function of a temporary covering loop ileostomy?

To protect a low anastomosis from faecal flow while it heals and mitigate the consequences of a leak.

Where is a permanent end colostomy placed following a Miles' operation?

In the left iliac fossa.

Which minimally invasive local excision techniques are reserved for early $T1N0$ rectal tumors?

$TEMS$ (Transanal Endoscopic Microsurgery) or $TAMIS$ (Transanal Minimally Invasive Surgery).

What chemotherapy regimens are used as adjuvant therapy for Stage III rectal cancer?

$FOLFOX$ or $CAPOX$.

What is a fistula in ano?

An abnormal, chronically inflamed hollow tract connecting a primary internal opening in the anal canal to a secondary external opening on the perianal skin.

What is the Cryptoglandular Hypothesis?

The theory that > 90\% of anal fistulas originate from infection of the anal glands in the intersphincteric space.

What are the characteristics of a fistula caused by Tuberculosis?

Watery discharge and undermined edges.

How is an Intersphincteric fistula classified in the Parks' system?

The tract travels through the intersphincteric space and opens onto the perianal skin; it is the most common type ($\approx 70\%$).

Describe a Transsphincteric fistula.

The tract crosses through both internal and external anal sphincters into the ischioanal fossa ($\approx 25\%$).

Which rare fistula type loops over the top of the puborectalis muscle?

Suprasphincteric ($\approx 4\%$).

What is an Extrasphincteric fistula?

A rare ($\approx 1\%$) tract connecting the high rectum directly to the perianal skin, bypassing the sphincter mechanism.

What are common clinical features of a fistula in ano?

Intermittent purulent/feculent discharge and pruritus ani (perianal itching).

What does the presence of an everted edge on a fistula opening suggest?

Malignancy.

What is Goodsall's Rule for an external opening anterior to the transverse line?

It connects via a short, straight, radial tract to an internal opening on the same radial axis.

What is Goodsall's Rule for an external opening posterior to the transverse line?

It connects via a curved (horseshoe) tract to a single internal opening in the posterior midline.

What is the exception to Goodsall's Rule?

Anterior external openings located > 3\,cm from the anal margin may track to the posterior midline.

Which investigation is the gold standard for mapping complex anal fistula tracts?

$MRI$ Pelvis/Perineum.

What is a Fistulotomy ('Laying open')?

The treatment of choice for low fistulas where the tract is divided and left open to heal by secondary intention.

When is a Seton placement indicated?

For complex or high fistulas where a simple fistulotomy would cause incontinence.

What is the purpose of a Cutting Seton?

It is tightened sequentially to slowly cut through the sphincter while fibrosis heals the muscle behind it.

What does the LIFT procedure stand for?

Ligation of Intersphincteric Fistula Tract.

What is a Fissure in Ano?

A linear tear or ulceration in the squamous epithelium (anoderm) of the lower anal canal distal to the dentate line.

Where do $90\%$ of anal fissures occur?

In the posterior midline.

Why is the posterior midline more susceptible to fissures?

It has a poor blood supply and lacks support from the decussating fibers of the external anal sphincter.

What does an atypical (lateral) fissure location suggest?

Secondary causes like Crohn's disease, Tuberculosis, Syphilis, $HIV/AIDS$, or Anal Carcinoma.

Explain the 'cycle of pain' in anal fissures.

Trauma $\rightarrow$ internal sphincter spasm $\rightarrow$ ischemia $\rightarrow$ non-healing $\rightarrow$ further pain.

Define the Chronic Fissure Triad.

A deep ulcer with indurated edges, a Sentinel Tag (distal), and a Hypertrophied Anal Papilla (proximal).

What is the hallmark symptom of an anal fissure?

Excruciating, sharp, tearing pain during and after defecation.

Why are DRE and Proctoscopy contraindicated in conscious patients with acute fissures?

Due to severe sphincter spasm and excruciating pain.

What is 'chemical sphincterotomy'?

Using medications like topical nitrates or calcium channel blockers to relax the internal sphincter and restore blood flow.

Name a side effect of topical $0.2\%$ Glyceryl Trinitrate ($GTN$).

Severe throbbing headaches.

Which topical agent is currently preferred over $GTN$ for fissures due to fewer side effects?

Topical Calcium Channel Blockers ($2\%$ Diltiazem or Nifedipine).

How does Botulinum Toxin (Botox) treat an anal fissure?

It causes temporary muscle paralysis of the internal anal sphincter ($2-3$ months) to allow healing.

What is the gold standard surgical procedure for chronic, refractory anal fissures?

Lateral Internal Sphincterotomy (LIS).

What anatomical structure is divided during a Lateral Internal Sphincterotomy (LIS)?

The lower third of the internal anal sphincter.

What is a Colonoscopy?

A visual examination of the entire mucosal lining of the large intestine from the rectum to the caecum.

List three absolute contraindications for colonoscopy.

Known colonic perforation, acute severe fulminant colitis/toxic megacolon, and acute diverticulitis.

What is the standard bowel preparation regimen using Polyethylene Glycol (PEG)?

A $4-liter$ split-dose regimen.

What position is a patient typically placed in for a colonoscopy?

Left lateral decubitus position.

Why is $CO_2$ preferred over air for insufflation during colonoscopy?

It is rapidly absorbed, causing less post-procedural cramping.

What is the reported incidence risk of perforation during colonoscopy?

$\approx 0.1\%$.

Describe Post-Polypectomy Coagulation Syndrome.

A transmural thermal injury to the bowel wall causing localized peritonitis (fever, pain) without frank perforation.

Define Pilonidal Sinus.

A blind-ending tracking sinus tract containing a 'nest' of hairs, usually in the sacrococcygeal region.

What is Bascom's Theory regarding pilonidal sinus?

It is an acquired condition where friction causes shed hairs to penetrate skin, leading to micro-abscesses and sinus tracts.

What was pilonidal sinus historically called during WWII?

Jeep Disease.

What is the Male-to-Female ratio for pilonidal sinus?

$3:1$.

How does an acute pilonidal abscess present?

As a sudden, painful, fluctuant, and erythematous swelling in the sacrococcygeal region.

Which surgical flap involves a rhomboid excision?

Limberg Flap.

What is the goal of the Karydakis Flap and Bascom's Cleft Lift?

To flatten the natal cleft and shift the healing scar away from the midline.

What does EPSiT stand for?

Endoscopic Pilonidal Sinus Treatment.

Categorize the differential diagnosis for a Right Iliac Fossa (RIF) mass based on origin.

Appendicular, Ileocecal, Gynaecological, Retroperitoneal, Urological, Vascular, and Lymphatic.

What is Signe de Dance?

An 'empty' Right Iliac Fossa found in patients with intussusception.

Which infection presents as a 'woody-hard' mass with sulfur granules?

Actinomycosis.

What components form an appendicular mass?

The inflamed appendix, the greater omentum, and adjacent loops of ileum and caecum.

When does an appendicular mass typically develop following acute appendicitis?

On the $3rd$ to $5th$ day.

Why is the greater omentum called the 'policeman of the abdomen'?

It migrates to and wraps around inflamed organs to wall off infection and prevent generalized peritonitis.

On percussion, what is the characteristic sound over an appendicular mass?

Resonant (due to overlying gas-filled bowel).

What is the 'Golden Rule' of surgery for an uncomplicated appendicular mass?

Never operate immediately.

What are the risks of early surgery on an appendicular mass?

Catastrophic fecal fistula, uncontrollable bleeding, and generalized peritonitis.

What is the name of the conservative management regimen for appendicular mass?

The Ochsner-Sherren Regimen.

List the core monitoring parameters in the Ochsner-Sherren Regimen.

Vital signs ($4$-hourly), mass size (marked on skin daily), abdominal girth, and clinical signs of peritonitis.

What is the earliest indicator of conservative failure in the Ochsner-Sherren Regimen?

A rising pulse rate.

When should the Ochsner-Sherren Regimen be abandoned for immediate surgery?

If there is a rising pulse, spiked fever, increasing mass size, or signs of generalized peritonitis.

What is an Interval Appendicectomy?

Surgical removal of the appendix performed $6-8$ weeks after the resolution of an appendicular mass.

What percentage of appendicular mass cases typically resolve with conservative management?

> 80\%.