4. appendicitis

appendix

• _{Most common position: Retrocecal (~65%)}

blind ended tube off the cecum

• _{Origin: arises from the posteromedial cecum, ~2–3 cm below the ileocecal valve}

RLQ

where the teniae coli converge

where to locate the base of the appendix

1/3 from ASIS → umbilicus

location of McBurney point

retrocecal

-results in less peritoneal irritation

most common position of the appendi

appendicular artery

(branch of ileocolic → from the SMA)

blood supply to the appendix

T10 // VAGUS

Sympathetic: T10 spinal level via the lesser splanchnic nerves → superior mesenteric plexus

Parasympathetic: Vagus nerve (CN X)

• High-yield: Visceral pain from early appendicitis refers to the periumbilical region (T10).

• → Once the parietal peritoneum becomes irritated, pain localizes to the RLQ/McBurney point via somatic nerves.

visceral inervation of appendix

_{(sympathetic and parasympathic)}

1. fecalith,

2. lymphoid hyperplasia,

3. tumor

causes of luminal obstruction of the appendix (3)

Luminal obstruction (fecalith, lymphoid hyperplasia, tumor)

↑ intraluminal pressure

Venous congestion → ischemia

Bacterial overgrowth

Perforation if untreated

pathophysiology of appendicitis

LLQ palpation → RLQ pain

retrocecal appendix

(most common position at 65%)

a positive psoas sign in appendicitis indicates what position of appendix?

pelvic appendix

a positive obturator sign indicates what position of the appendix

pain in the lower abdomen or inside of thigh when the hip is flexed and internally rotated; a sign of appendicitis

Rapid progression → early perforation

More diffuse pain, vomiting prominent

appendicitis complication associated with children

minimal symptoms

Higher risk of perforation

---

have lower threshold to dx

presentation of appendicitis more commonly seen in elderly

Appendicitis

Crohn's disease

Meckel diverticulum

Gynecologic causes

differential diagnosis of RLQ pain

Patient	Best/first imaging
Nonpregnant adult	CT abdomen/pelvis with IV contrast ⭐
Child	Ultrasound first
Pregnant	Ultrasound first → MRI if nondiagnostic
Unstable/peritonitis	Surgery consult — don't delay for imaging

best imaging & gold standard for appendicits

Enlarged appendix (>6 mm)

Wall thickening

Periappendiceal fat stranding

imaging findings associated with appendicitis (3)

fat stranding

---

_{On CT, normal fat looks dark/black. When inflamed, the fat develops streaky, hazy, whiter lines → fat stranding.}

_{For appendicitis:}

_{Enlarged appendix (>6 mm) + periappendiceal fat stranding = classic CT finding.}

_{Think: “The inflammation spills into the surrounding fat.”}

_{Other classic examples:}

• _{Diverticulitis → pericolic fat stranding}

• _{Pancreatitis → peripancreatic fat stranding}

• _{Cholecystitis → pericholecystic inflammatory changes}

Increased attenuation in fat from edema, inflammation, or hemorrhage

Alvarado score (MANTRELS)

for suspected acute appendicitis.

This scoring system combines findings to assist evaluation in patients with RLQ pain:

MANTRELS	Finding	Points
M	Migration of pain to RLQ	1
A	Anorexia	1
N	Nausea/vomiting	1
T	Tenderness in RLQ	2
R	Rebound tenderness	1
E	Elevated temperature	1
L	Leukocytosis	2
S	Shift to left (neutrophilia)	1
	Total	10

• ≤4 → appendicitis unlikely; high value for ruling out

• 5–6 → possible → further evaluation/imaging

• ≥7 → high probability of appendicitis

_{High-yield: The two 2-point findings are RLQ tenderness + leukocytosis → everything else is 1 point.}

Laparoscopic appendectomy

standard treatment of uncomplicated appendicitis

NPO

IV fluids

Antibiotics (broad-spectrum)

Situation	Common regimen
Uncomplicated appendicitis	Ceftriaxone + metronidazole
Alternative	Cefoxitin alone
Perforated/complicated	Piperacillin-tazobactam OR ceftriaxone + metronidazole

pre-op care of appendicitis

Sudden relief of pain → then worsening diffuse pain

Signs of peritonitis

Fever, tachycardia

signs of a perforated appendix

perforated appendix

sudden relief of pain----> then worsening diffuse pain

palpable mass in RLQ

signs of a appendiceal abscess

emergency surgery

management of perforation with peritonitis

Contained abscess → ABX + drain → cool it down

vs.

Free perforation/generalized peritonitis → surgery now.

management of appendix abscess

recurrent appendicitis

-multiple episodes of RLQ pain -> resolved after appendectomy

-sx proven to be result of inflamed appendix by histology

chronic appendicitis

An inflammatory process with increasing pain

(other symptoms may be present or absent)

Minimal pain

No fever

No leukocytosis

Delayed presentation → high perforation rate

describe the atypical presentation of appendicitis in the elderly

appendicitis in the elderly

Vague abdominal pain

Altered mental status

Late signs of peritonitis

neuroendocrine (carcinoid)

• _{Usually found incidentally after appendectomy}

• _{Most commonly at the tip of the appendix}

• _{Usually small and low-grade}

• _{<2 cm → appendectomy alone usually sufficient}

• _{>2 cm → generally consider right hemicolectomy based on pathologic risk factors}

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Feature	Board pearl
Location	Tip of appendix ⭐
Presentation	Usually incidental after appendectomy
Histology	“Salt-and-pepper” chromatin ⭐
Markers	Chromogranin A+, synaptophysin+
Hormone	Can produce serotonin (5-HT)
Carcinoid syndrome	Rare with appendiceal NET; usually requires significant metastatic disease — must mets to liver, otherwise liver will filter and prevent symptoms
Carcinoid syndrome symptoms	Flushing, diarrhea, bronchospasm, right-sided valvular disease
Urine test	↑ 5-HIAA
Small tumor	Appendectomy generally sufficient
Large/high-risk tumor	May require right hemicolectomy

most common type of appendix cancer

Type	High-yield feature
Neuroendocrine tumor (carcinoid) ⭐	Most common appendiceal tumor; usually at tip, incidental
Low-grade appendiceal mucinous neoplasm (LAMN)	Produces mucin; rupture → pseudomyxoma peritonei (jelly belly)
Adenocarcinoma	Malignant epithelial tumor; resembles colorectal adenocarcinoma
Mucinous adenocarcinoma	Mucin-producing invasive adenocarcinoma; can cause pseudomyxoma peritonei
Goblet cell adenocarcinoma	Has both goblet/mucinous + neuroendocrine-like features; more aggressive than classic NET
Signet-ring cell adenocarcinoma	Rare, very aggressive, poor prognosis

name the types of appendiceal cancer

(know highlighted)

abdominal distension

---

_because…

_{Pseudomyxoma peritonei = accumulation of mucin (“jelly”) throughout the peritoneal cavity, usually from a ruptured appendiceal mucinous neoplasm (especially LAMN).}

_High-yield

_{Appendiceal mucinous tumor → ruptures → mucin-producing cells seed peritoneum → progressive mucinous ascites}

_{Typical presentation:}

• _{Increasing abdominal girth/distention ⭐}

• _{Abdominal discomfort}

• _{Mucinous/gelatinous ascites}

• _{Can eventually cause bowel obstruction}

_{Classic CT: Scalloping of the liver/spleen surfaces from mucinous deposits.}

_{Treatment: Cytoreductive surgery + HIPEC (heated intraperitoneal chemotherapy) in appropriately selected patients.}

most common physial exam finding of mucinous appendix tumor

<2cm: appendectomy

>2 cm: right hemicolectomy

treatment of carcinoid appendix tumor

(tumor markers: chromogranin A and 5-HIAA)

right hemicolectomy

tx of adenocarcinoma of the appendix

(tumor markers: CEA, ca-19-9, ±ca 125)

Cytoreduction ± HIPEC

treatment of mucinous tumor of the appendix

(tumor marker: CEA, CA 19-9, CA-125.)

• CEA → usually used to monitor

• CA 19-9 → GI/mucinous tumor marker

• CA-125 → can reflect peritoneal involvement, including pseudomyxoma peritonei

CEA, CA 19-9, CA-125.

highlights:

Can you treat with antibiotics alone?

• Yes—in selected patients.

• Imaging-confirmed uncomplicated appendicitis can sometimes be treated nonoperatively with antibiotics after discussing risks and benefits.

• Benefits: avoids immediate operation/anesthesia.

• Downside: significant risk of treatment failure or recurrent appendicitis, meaning appendectomy may eventually be required.

Appendicolith = higher risk of failure/complications with antibiotic-only management → surgery is generally favored.

Board answer:

• Uncomplicated appendicitis → NPO + IV fluids + analgesia + preoperative antibiotics → laparoscopic appendectomy.                                  

• Key distinction:
  

• Uncomplicated → appendectomy
  

• Free perforation/peritonitis → urgent source control
  

• Contained abscess/phlegmon → antibiotics ± percutaneous drainage, with operative timing individualized.

  • dont drained if not contained