Gen Surg: Intestinal Obstruction and Hernia

Question 1

Gross anatomy of abdominal wall, inguinal/femoral canal and intra-abdominal viscera.

Answer 1

Inguinal ligament: made up of lower border of external olbique aponeurosis. Extends from asis to pubic tubercle.

Rectus sheath (superior to arcuate line): aponeurotic tendinous sheath enclosing rectus abdominus. Anterior = external oblique + 1/2 internal oblique. Posterior = transversus abdominus fascia + 1/2 internal oblique.

Lower 1/4 rectus sheath (inferior to arcuate line): anterior sheath only (ext + int obliques + transversus muscle fascia). Rectus abdominus muscles lie on transversalis fascia directly.

Inguinal canal: superficial ring made by external oblique aponeurosis. Deep ring = transversalis fascia. Canal passes through musculature of internal oblique but under fibers of transverse abdominis.

Question 2

Etiology SBO

Answer 2

Adhesions: main, 75%. Due to scarring from prior abdominal surgery with tethering of bowel.
Hernia
Neoplasms
Other: intrinsic (e.g. IBD, neoplasm), intraluminal (e.g. gallstone ileus, bezoar), extrinsic (e.g. adhesions, hernias)

Question 3

SBO SS

Answer 3

Colicky, periumbilical abdominal pain, abdominal distention/bloating, n/v (bilious possible), obstipation, ask about prior SBOs (recurrences common). Ask about prior abdo surgeries.

Question 4

SBO PEx

Answer 4

Inspection: look for prior surgical scars.
Distended abdomen: listen for hyperresonance.
Tenderness to percussion/palpation. Look for peritonitis (sign of dead bowels).
Look for hernias (erythematous, tender bulges).

Question 5

Types of SBO’s

Answer 5

Complete: no distal passage of stool or gas.
Partial: narrowing of lumen with some passage.
Open loop: proximal decompression achieved with gastric decompression.
Closed loop: both proximal and distal segments of bowel are obstructed, forming a loop. Pressure inside loop > BP thus get ischemic gut.

Question 6

SBO investigations

Answer 6

Blood: WBC, BUN, Cr, lytes, lactate.
Imaging: start with 3 view AXR (upright >3 air-fluid levels, supine caliber of SB >3cm, step-ladder appearance), on CXR or upright can also look for air under diaphragm.

CT: try to identify transition point.

Question 7

SBO mgmt

Answer 7

Non-operative mgmt: NPO, IVF, NG tube, serial AXR/exams. Good approach if partial SBO, post-op, due to adhesions. Stop once there is resolution of pain, distention, n/v, bm, flatus.

Operative indications: virgin abdomen/non-adhesive SBO, no improvement/worsening, unstable, strangulation, peritonitis, perforation, closed loop.

Question 8

Etiology LBO

Answer 8

Neoplasm: CRC, local non-colonic, mets.
Volvulus: cecal, sigmoid.
Inflammatory mediated: diverticulitis, Crohns, radiation.
Hernia, intussusception, adynamic, stricture, foreign body, fecal impaction.

Rare compared to SBO, same work up tho.
Considered closed-loop obstructions if ileocecal valve intact. Pressure builds up proximally from obstruction –> closed IC valve produces closed loop and cecum is at high risk for perforation.

Question 9

LBO mgmt

Answer 9

Conservative: Bowel rest, IVF, NG tube decompression, serial AXR for partial/subacute.
Emergent OR if: perforation, volvulus, complete obstruction or high grade obstruction.

Question 10

Adynamic bowel types:

Answer 10

Ileus:
may affect small or large bowel.
Often occurs POD4.
RF: bowel manipulation, meds (opioids, antiAChs), immobilization, lyte abnormalities (esp hypoK), urinary retention, infection.

Ogilvie’s syndrome: large bowel only!!
Acute colonic pseudo-obstruction. Disruption of colonic motility –> distension –> ischemia/perforation.
RF: trauma, severe infection, cardiac disease.

Symptoms Adynamic bowel: Distension, pain, n/v.
On imaging: enlarged bowel loops but no mechanical obstruction.
Mgmt: aggressive supportive care. Bowel rest, NG/rectal tube decompression, IVF, stop offending agents, mobilize, neostigmine (acetylcholinesterase inhibitor) for Ogilvie’s to stimulate bowel movement.

Question 11

RF hernia development

Answer 11

Male sex.

Acquired (increased abdo pressure): coughing/COPD, constipation, obesity, straining.

Congenital: weakened connective tissue/CTD, patent processus vaginalus (congenital opening between peritoneum and testes).

Question 12

Reducible vs incarcerated vs strangulated hernia.

Answer 12

Reducible: can manually reduce contents into abdo cavity.

Incarcerated: inability to reduce contents. Tender, swollen but can still hear bowel sounds.

Strangulated: incarcerated with signs of bowel compromise. Reduction of venous return to bowel due to restriction –> increased tissue edema –> compromised circulation and block of arterial blood supply. Pt will appear sick (vomiting, abdo distention, constipation/obstipation).

Question 13

Desribe direct inguinal hernia

Answer 13

Protrusion through weakened floor of inguinal canal due to weak abdominal muscles. Medial to the epigastric vessel’s (within Hasselbach’s triangle).

Question 14

Describe indirect inguinal hernia

Answer 14

secondary to patent processus vaginalis. Passes through the internal ring via inguinal canal with the spermatic cord. Is lateral to the epigastric vessels.

Question 15

Describe femoral hernia

Answer 15

passes through teh femoral canal (below the inguinal ligament). More common in elderly women. High risk for strangulation.

Question 16

Describe umbilical hernias

Answer 16

Passes through the fibromuscular ring at the umbilicus. Usually presents in kids. If in adult, should repair.

Question 17

Describe Richter’s hernia

Answer 17

Herniation of only a part of the bowel wall, not full circumference of lumen.

Usually umbilical hernias. Make up 10% of strangulated hernias (not obstructive but may progress to gangrene). Get herniation of antimesenteric wall without compromise of entire lumen. Most commonly involves the terminal ileum.

Question 18

Hernia Hx

Answer 18

Bulge/groin tenderness.
Symptoms worsen with physical activity, prolonged standing.
Ask about obstructive symptoms: bloating, n/v.

Question 19

Hernia PEx

Answer 19

Ask pt to do valsalva if no bulge is appreciated.
May be difficult to distinguish femoral from inguinal hernia on exam (femoral will be below inguinal ligament and medial to femoral vein).

Question 20

Hernia mgmt

Answer 20

Non-surgical: watchful waiting.
Manual reduction unless signs of bowel compromise.

OR indications: symptomatic, incarcerated or strangulated (emergent repair), all females with groin hernia (higher chance of femoral hernia), any femoral hernia (high risk incarceration/strangulation)