Mr. T is a 66-year-old man who arrives at the emergency department with bloody stools and dizziness. His symptoms started 2 hours ago.
|What is the differential diagnosis of GI bleeding. How would you frame the differential?|
The approach to GI bleeding is similar to the approach to other potentially life-threatening illnesses. Patient stabilization, specifically, hemodynamic stabilization is the first step in management. In a patient with GI bleeding, management precedes diagnosis, usually made by colonoscopy or esophagogastroduodenoscopy (EGD).
Initial management takes a very regimented course. The patient must be hemodynamically stabilized, preparation must be made in case of further bleeding, and initial diagnostic tests must be completed.
Clinically assess volume status.
Signs of shock may be seen with 30–40% volume depletion.
Orthostasis can be seen with 20–25% volume depletion.
Tachycardia may be present with 15% volume depletion.
Calculate necessary replacement (weight in kg × 0.6 (lean body weight made up of water) × % volume depletion).
Replace fluid losses initially with normal saline or Ringers solution.
Administer typed (or O−) blood if there has been a large degree of blood loss.
Preparation for further bleeding
All patients should have their blood typed and be cross-matched for at least 2 units.
Patients may initially have normal Hcts that drop only with fluid replacement.
It is common for a patient with a significant GI bleed to have a normal Hct at presentation.
Remember that the physical exam is insensitive for anemia (see Chapter 6, Anemia).
Two large bore IVs
IVs should be 16 gauge or greater.
Flow = ΔP (πr4/8μ) where ΔP is the pressure differential, r is the radius of the IV, μ is the viscosity of the fluid, and L is the length of the IV.
Flow can therefore be maximized by
Increasing the pressure behind the fluid being infused (squeezing the bag).
Decreasing the length of the IV.
Increasing the gauge of the IV (the most effective as the flow goes up by the fourth power of any increase).
Large gauge IVs (16 and larger) are much more effective than central lines for volume resuscitation.
Always make sure your patient has 2 usable large bore IVs, so you do not have to worry about IV access should life-threatening bleeding develop.
In large bleeds, a Foley catheter can help monitor fluid status.
Initial diagnostic tests
CBC and platelet count
Basic metabolic panel (chem-7)
Liver function tests (LFTs) (Abnormal LFTs raise the risk of underlying severe liver disease and thus coagulopathy and varices.)
Prothrombin time and partial thromboplastin time
Upright chest radiograph
Can diagnose perforated viscus
May provide clues to other diagnoses
Possibly nasogastric (NG) tube placement, which may help localize the source and acuity of blood loss
The differential diagnosis of GI bleeding is based on an anatomic framework. Upper GI bleeds originate proximal to the ligament of Treitz, ...