Abdominal Trauma

Key Points
Unrecognised abdo injury continues to be an important cause of death.
Any pt with blunt/penetrating abdo injury should be considered.
Major trend in recent years has been toward less invasive diagnosis and management.

Anatomy
Mechanism
Assessment
Blunt trauma studies
Penetrating studies
Laparotomy indications
Special problems

Anatomy

External
Area from trans-nipple line superiorly to inguinal ligaments & symphysis pubis inferiorly, and anterior axillary lines laterally.
Flank is from ant to post axillary lines from 6th ICS to iliac crest.
- thick abdo muscles here, partially protective against penetrating wounds.
Back from posterior axillary lines, tip of scapulae to iliac crests, also protected by muscles.

Internal
Upper peritoneal cavity - (covered by lower aspect of bony thorax), includes diaphragm, liver, spleen, stomach, transverse colon.
Lower peritoneal cavity - contains small bowel, ascending & descending colon, sigmoid colon, female organs.
Pelvic cavity - surrounded by pelvic bones, lower retroperitoneal and intraperitoneal spaces, contains rectum, bladder, iliacs, female organs.
Retroperitoneal space - potential space posterior to peritoneal lining, containing aorta, IVC, duodenum, pacreas, kidneys, reters and asc/desc colon and some pelvic structures.
- difficult to recognise structures here, don't present with peritonitis & not accessable to lavage.

Mechanism

Blunt trauma
Direct blow compresses / crushes viscera.
Can rupture hollow organs (esp if distended eg pregnant uterus) with haemorrhage, peritonitis.
Shearing injuries from restraint devices improperly worn
Deceleration injuries affect sites of supporting ligaments; rate of deceleration key factor in severity.
Most frequent sites injured at laparotomy: spleen (40-55%, liver 35-45%, small bowel 5-10%, 15% retroperitoneal haematoma.
Blast injury can cause intraperitoneal injury without penetration

Penetrating trauma
Damage by lacerating or cutting
High-velocity gunshots also transfer much energy and cavitated, tumble or fragment.
Liver (40%), small bowel (30%), diaphragm (20%), colon (15%) injured in stabs.
Small bowel (50%), colon (40%), liver (30%), abdo vascular (25%) in gunshots

Assessment

Rapidly determine if abdo injury present
And if it is a cause of hypotension
- if haemodynamically stable can undertake a more detailed evaluation for specific injuries.

History
MVA: determine speed, impact, restraints, airbags, pt's position.
Penetrating: weapon, time of injury, distance, number of stabs/shots, amt of bleeding at scene.
Magnitude and location of abdo pain and if referred to shoulder.

Physical
Will miss 55%+ of significant abdominal injuries
Inspection
: Undress. Abrasions, contusions, lacerations, penetrating wounds, evisceration, pregnant state.  Logroll.
Auscultation: Bowel sounds (attenuated by free blood or GI contents, lost in ileus).
Percussion, Palpation
-
rebound is not usually present in early haemoperitoneum.
- note for a pregnant uterus.
Pelvis, perineal, rectal, genital: as for secondary survey
Gluteal: (iliac crests to gluteal folds) - penetrating injuries here have 50% incidence of significant intra-abdo injury: search.

Penetrating wounds
Most gunshots managed by exploratory laparotomy - significant injury 90%.
Stabs managed more selectively - 30% cause significant intraperitoneal injury.
- a surgeon may wish to explore locally to assess depth if not under ribs.
- if penetrating anterior fascia, higher risk of intraperitoneal injury, can be taken as indication for laparotomy
- if too difficult, may go straight to laparotomy

Tubes / Investigations
As for secondary survey

XRs
Haemodynamically abN pt with a penetrating wound does not require XR
Haemodynamically N may have an upright CXR to exclude chest life threat or intraperitoneal air.
- marker rings to entrance and exit wounds to track missiles.
Supine, upright or decubitus views for extraluminal air (prompts laparotomy).
Loss of psoas shadow suggests retroperitoneal injury.

Contrast special studies
Urethography
Before urethral catheter if urethra damage suspected.
- #8 Fr secured to meatal fossa by balloon inflation to 1.5-2ml.  15-20mL undiluted contrast instilled with gentle pressure. 
- radiograph with oblique projection and slight stretch on penis.
Cystography
For suspected bladder rupture
Bulb syringe attached to a catheter is held 40cm above pt, 300mL water-soluble contrast is instilled until flow stops / pt voids / discomfort.
AP, oblique, and postdrainage views exclude injury.
CT cystogram is alternative option, esp if suspicious of kidneys / pelvic bones.
CT/IVP (IV Pyelogram)
Best for haemodynamically N pts with haematuria and suspected urinary injury.
Contrast-enhanced CT defines renal injury presence. (or pyelogram if not available)
High-dose rapid injection of renal contrast allows kidney visualization.
- unilateral non-function indicates absent kidney, thrombosis, artery avulsion or massive parenchymal damage.
- warrants further evaluation with contrast CT or renal arteriogram or surgery.
GI
Retroperitoneal injury suspicion needs CT with contrast or specific GI studies.

Blunt Trauma Studies

DPL
Diagnostic Peritoneal Lavage
98% sensitive for intraperitoneal bleeding.
Done by surgical team caring for a haemodynamically abN pt with multiple blunt injuries, especially when:
- sensorium change
- sensation change (eg cord injury)
- areas adj to abdo injured
- equivocal physical exam
- for prolonged period of GA / investigations even if haemodynamically N
- lap-belt sign
Or for haemodynamically N pts where CT not available.
Contraindicated if existing indication for laparotomy
- relative contraindications for previous abdo ops, advanced cirrhosis, preexisting coagulopathy.
See technique

FAST
Focused Assessment Sonography in Trauma (bedside).
With an experienced operator - has sensitivity, specificity and accuracy comparable to DPL.
- 86-97% accurate
Compromised by obesity, subcutaneous air and previous abdo ops.
Scanned: pericardial sac, hepatorenal fossa, splenorenal fossa, pelvis/pouch of Douglas.
- second scan 30m later for progressive bleeding.

CT
Only for haemodynamically N pts with no need for laparotomy.
Provides specific information, 92-98% accurate
Contraindicated if delay, uncooperative pts, allery to contrast.
CT may miss GI, diaphragm, pancreatic injury.
- Free fluid suggests without liver, spleen injury suggests GI injury, can be an indication for early laparotomy.

Penetrating Trauma

Lower chest wounds
If asymptomatic: serial physical exam, Xrs, thoracoscopy, laparoscopy or CT
Late posttraumatic left-sided diaphragmitic hernia occurs after stab wounds so early exploration is also an option.
Straight to laparotomy for gunshot wounds.

Local exploration vs DPL for abdo stabs
55-60% of pts with anterior peritoneum penetrating stabs have hypotension, peritonitis or evisceration and require emergency laparotomy.
Half of the rest of such pts will need op eventually.
Therefore laparotomy is a reasonable option for all such pts.
Less invasive procedures include serial exams (sensitivity 94%), DPL (90% accuracy) or laparoscopy (sensitive but not specific).

Serial exams and CT in flank/back penetrations
Serial physical exam is very accurate for wounds posterior to the anterior axillary line
Double or triple contrast CT is recommended.
Rarely retroperitoneal injuries are missed by either route - early outpt follow-up is mandatory after a 24hr admission.


Laparotomy Indications

In general, if stable enough for CT, usually stable enough for trial of conservative management.

See guidelines
1. Hypotension in blunt abdo trauma with evidence of intraperitoneal bleeding.
2. Blunt abdo trauma and positive FAST, DPL and haemodynamically unstable
3. Hypotension and penetrating abdo wound.
4. Gunshot wound traversing peritoneal cavity or retroperitoneum.
5. Evisceration
6. Bleeding from stomach, rectum, or penetrating wound.
7. Peritonitis
8. Free air, retroperitoneal air or rupture of a hemidiaphragm.
9. Contrast-CT with ruptured GI tract, intraperitoneal bladder injury, renal pedicle injury or severe visceral parenchymal injury.

Special Problems

Diaphragm
See diaphragm trauma notes

Duodenum
Rupture classic in an unrestrained driver in frontal impact or in pt with direct abdo blow (eg bicycle handlebars).
Suspect by bloody gastric aspirate, retroperitoneal air on XR or CT.
Upper GI XRs or double contrast CT if high risk.

Pancreas
Direct epigastric blow crushes p. against spinal column.
Persistently elevated or rising serum amylase should raise suspicion (single amylase not sensitive or specific).
Double-contrast CT may not show significant trauma immediately - repeat at >8hrs if suspected.
Surgical exploration warranted if concern after an equivocal CT (or ERCP).

Genitourinary
Blows to back or flank with visible signs mark potential renal injury and warrant CT/IVP.
Also if gross haematuria or microscopy in a penetrating abdo wound or episode of hypotension or associated intraabdominal injuries.
CT is sensitive and specific.
95% can be treated non-operatively.
Renal artery thrombosis or pedicle disruption in deceleration is a rare and may present with no haematuria but much pain.
Ant pelvic #s usually accompany urethral injury.
- disruptions may be above (posterior) or below (anterior) to the UG diaphragm.
- posterior usually in the multi-injured pt with pelvic #s.
- anterior often from straddle impacts

Small bowel
Deceleration causes tearing near a fixed pt of attachment, especially if seat belt incorrectly applied.
Seat-belt sign or lumbar distraction # on XR should alert to this.
Signs may be frank or subtle (with minimal early bleeding).
US and CT are not diagnostic if suble, and DPL is a better choice when abdo wall ecchymosis present.

Solid organ injury
Liver, kidney, spleen injury cause shock and need urgent laparotomy.
Isolated solid organ injury may otherwise be managed non-operatively.
- admit and manage non-operatively with surgeon guidance.
- concomitant hollow viscus injury in 5% of these pts,

Pelvic #s & Associations
#/s disruptions suggest major force transmitted.
- often auto-accident, motor vehicle / motorcycle accidents.
Associated with intra/retro-peritoneal injury and vascular damage.
- hence hypotension may be due to: 1) # bone; 2) pelvic venous plexuses; 3) pelvic arteries; 4) extrapelvic.
Consider mechanism
i) AP compression: direct crush / fall from >12ft, symphysis pubis disruption relates to tearing of posterior ligaments, opening of pelvic ring and bleeding from posterior pelvic veins or int iliac branches.
ii) Lateral compression: involved hemipelvis internally rotates driving bones into lower GU system; heavy haemorrhage uncommon due to pelvic volume reduction.
iii) Vertical shear: disrupts sacrospinous and sacrotuberous ligaments with major pelvic instability.
iv) Combinations.
Assessment
Examine flank, scrotum and perianal area for blood at meatus, swelling, bruising, lacs to rectum/vagina, high-riding prostate.
Test instability once.
Leg-length or rotational deformity without a limb #.
AP pelvis XR.
Management
Splint an unstable pelvic #: close increased volume during resuscitation
i) wrap a sheet around the pelvis as a sling, internally rotating lower limbs.
ii) apply a vacuum-type long spine splinting device.
iii) pneumatic anti-shock garment.
iv) longitudinal splint for lower extremity #.

Restraint Patterns
Lap Belt
Compression
Mesentry tear, bowel rupture, vascular thrombosis
Hyperflexion
Lumbar chance #.
Shoulder Belt
Submarining
Innominate, carotid, subclavian, vertebral a. tear, C-spine #.
Compression
Subclavian a. tear, rib #, pulmonary contusion, upper abdo.
Airbag
Contact
Corneal abrasion, face, neck, chest abrasion.
Contact/deceleration
Cardiac rupture
Flexion (unrestrained)
C-spine/T-spine #
Hyperextension (unr.)
C-spine #.


References
ATLS