GI

GI System & Bowel Elimination Nursing Exam Study Guide

1. Anatomy & Physiology Overview

GI Tract Basics

  • The gastrointestinal (GI) tract runs from the MOUTH to the ANUS.

  • The major organ involved in bowel elimination is the LARGE INTESTINE.

Small Intestine

  • Length: 18–20 feet.

  • Components:

    • Duodenum

    • Jejunum

    • Ileum

  • Function:

    • Absorbs NUTRIENTS into the bloodstream.

    • Receives bile from the liver to aid in fat digestion.

    • Partially digested food in the small intestine is referred to as CHYME.

Large Intestine (Colon)

  • Length: Approximately 6 feet (about as tall as a person).

  • Also referred to as the COLON.

  • Primary Function: Absorbs WATER.

  • Also involved in the formation and expulsion of feces.

Parts of the Colon:

Colon Part

Location/Directions

Stool Consistency

Ascending Colon

Extends upward toward the liver

Very liquid/watery

Transverse Colon

Crosses horizontally

Semifluid

Descending Colon

Travels downward

Semisolid

Sigmoid Colon

Near rectum — distal end

Solid/formed feces

  • ⚠ Important for Exams: 'What stool consistency to expect from each colon part?' - Sigmoid = solid/formed. Know this!

Rectum & Sphincters

  • The rectum has vertical folds containing arteries and veins.

  • Hemorrhoids are enlarged/engorged veins in the rectum.

Sphincter

Control Type

Clinical Note

Internal Sphincter

INVOLUNTARY — not under your control

Stool may pass without control

External Sphincter

VOLUNTARY — under your control

Can consciously tighten the sphincter

  • ⚠ Exam Favorite: Which sphincter is voluntary vs. involuntary? External = voluntary. Internal = involuntary.

2. Key Physiology Concepts

Peristalsis

  • Definition: Contractions of circular and longitudinal intestinal muscles that move waste through the intestines.

  • Initiation: Controlled by the BRAIN — occurs automatically throughout the day.

  • Mass peristaltic sweep: Happens several times daily, moving fecal mass forward.

  • ⚠ Peristalsis STOPS due to:

    • Opioids (the #1 cause).

    • Anesthesia or surgery.

    • Certain medications.

Bearing Down (Valsalva Maneuver)

  • Definition: Voluntary contraction of abdominal muscles while holding the breath to assist in expelling feces.

  • Effect: Increases intra-abdominal pressure by approximately 4–5 times normal.

  • Uses: Also utilized during childbirth due to engagement of the same muscle group.

Physiological Effects During Bearing Down:

  • Blood flow to the heart: DECREASES while bearing down.

  • After bearing down: Blood rushes back, often exceeding normal flow, which can SLOW the heart rate leading to vagal response and potential syncope (fainting).

  • ⚠ Caution: Never permit a cardiac patient to bear down, as it may result in fatal vagal response (historically linked to heart attacks occurring on toilets).

3. Factors Affecting Bowel Elimination

Surgery & Anesthesia

  • Effects: Both surgery and anesthesia can stop peristalsis for 3–5 days.

  • Reason: Direct manipulation of the bowel during abdominal surgery inhibits peristalsis, contributing to postoperative constipation.

Medications

  • Opioids: Recognized as the #1 cause of halted peristalsis and constipation.

    • Recommendation: Always administer a stool softener alongside opioid pain medications.

    • Caution: The combination of opioids and surgery presents a heightened risk for constipation and bowel obstruction.

  • Anesthesia’s Impact: As mentioned, halts peristalsis.

  • Reasons against administering anti-diarrheal medications (e.g., Imodium):

    • Diarrhea from food poisoning must be allowed to exit.

    • Diarrhea resulting from antibiotics indicates irritation of intestinal lining; it should not be retained longer than necessary.

Psychological Variables

  • Influence of Stress/Anxiety: Can lead to 'nervous poops' due to increased peristalsis.

  • Emotional Factors: Chronic stress and repression of emotions often correlate with constipation.

    • Instructor Note: "Let your feelings out so your poop can come out!".

Diet & Fluid Intake

  • Diet, fluid intake, and activity level directly affect bowel habits.

  • At-Risk Patients: Sedentary individuals (hospitalized, elderly, postoperative) are at a HIGH RISK for constipation.

4. Developmental Considerations

Age Group

Key Bowel Facts

Breastfed Infants

2–10 stools/day; softer, less foul-smelling due to easier digestion of breast milk.

Formula-fed Infants

1–2 stools/day; typically smell worse due to harder protein breakdown.

Toddlers (18–30 months)

External sphincter begins to become voluntary; readiness for potty training varies; no punishment for accidents.

Adults

Habitual patterns vary widely; there exist cultural differences in bowel privacy norms.

Older Adults

Aging contributes to decreased GI motility; constipation often correlates with lifestyle factors rather than age itself.

  • ⚠ Caution for Toddler Potty Training: Physiological immaturity is genuine; the external sphincter may not yet be voluntary. Never shame or punish a child for accidents.

5. Stool Characteristics — Know & Ask Your Patients

Normal Stool

  • Color: Brown.

  • Consistency: Formed, soft.

Abnormal Findings - ⚠ Know These Findings

Finding

Possible Meaning

Ribbon-like/Narrow Stool

Indicative of obstruction in the bowel (possible tumor or cancer). Should consider blockage!

Black/Tarry Stool (melena)

Suggests GI bleeding (upper GI — indicates blood digested prior to exiting).

Bright Red Blood in Stool

Signals lower GI bleed (near rectum) — could indicate hemorrhoids or more severe conditions.

Watery/Liquid Stool

Expected from ascending colon ostomy; diarrhea if observed from sigmoid colon.

Clay-colored Stool

Suggestive of bile duct obstruction (lack of bile results in no brown color).

  • ⚠ Critical Note: Ribbon-like stool — think obstruction/tumor. Must flag this immediately!

6. Abdominal Assessment — Order Matters!

GI Assessment Order Different from Other Systems

Step

Action

Reason

1.

INSPECT

Visual inspection for clues before any physical examination.

2.

AUSCULTATE

Listen with a stethoscope to bowel sounds; palpation can alter initial sounds if done first.

3.

PERCUSS

Tap to evaluate tone/density and assess for air, fluid, masses.

4.

PALPATE

Perform this last to avoid influences on bowel sounds.

  • ⚠ Order must be: INSPECT → AUSCULTATE → PERCUSS → PALPATE. This differs from examinations of other body systems. Avoid auscultation after palpation.

  • Familiarize with the four abdominal quadrants and their landmarks.

  • During assessment, keep an eye out for hemorrhoids: look for enlarged rectal veins.

7. Nursing Diagnoses & Outcomes

Common Nursing Diagnoses

  • Constipation

  • Risk for Constipation (noting that almost all hospitalized patients fall into this category due to factors like being sedentary, postoperative, on opioids, or poor diet).

  • Bowel Incontinence

  • Diarrhea

Outcomes

  • Outcomes must be Specific + Time-Measurable:

    • ⚠ A crucial detail: If the outcome lacks a time component, it is considered incorrect. Always include a timeframe (e.g., "patient will have a bowel movement within 24 hours").

    • When opting for outcomes on NCLEX, select the one with a specific, quantifiable timeframe.

    • Practice Tip: On ATI/NCLEX practice, focus on the timed option since it tends to be the accurate choice.

After Midterm — Upgrade Your Nursing Diagnoses

  • Move away from using 'Pain' as your sole nursing diagnosis.

  • Utilize diagnoses such as: Constipation, Risk for Constipation, or Bowel Incontinence.

    • Nearly every hospitalized patient is at a risk for constipation.

8. Medications & Treatments

Common GI Medications

Medication

Use

Key Notes

Stool Softeners (e.g., Colace)

Used for post-operative, opioid administration, or constipation

Administer routinely with opioids

Laxatives

Prescribed for constipation

Administer as prescribed; avoid habitual daily use.

Zofran (Ondansetron)

For nausea/vomiting

An anti-emetic — abbreviated as ‘Zo-fran’ for vomiting.

Anti-diarrheals (e.g., Imodium)

Used for diarrhea

Do NOT utilize if diarrhea stems from food poisoning or antibiotics.

K-Exalate Enema

Treats hyperkalemia (high potassium)

Promotes potassium expulsion via stool. ⚠ Caution: Do NOT give to patients with LOW potassium. Potassium dysrhythmias are always priority!

Enemas

Varieties exist — consult Dr. Hodges' lab notes for detail

Digital Removal of Stool

Considered a LAST RESORT after unsuccessful enema

Requires physician order; manual (?) removal of stool with fingers.

  • ⚠ Risk During Digital Removal: Similar to Valsalva maneuver; can induce vagal response leading to syncope, particularly perilous in cardiac patients.

9. NG Tubes & Feeding Tubes

Verifying Placement — KNOW THIS

  • Correct Method: Utilize X-ray (gold standard) combined with checking the pH of aspirate.

  • pH Scale: Stomach acid is acidic (pH < 5 validates gastric placement).

  • ⚠ Caution: Never inject air and auscultate (listen for air); this practice is common in hospitals but is considered incorrect by nursing standards and should not featured in exams.

Feeding Position

  • ⚠ IMPORTANT: NEVER feed a patient while lying flat — the head of bed (HOB) must be elevated (at least 30–45 degrees) to avert aspiration/reflux.

J-Tube vs. G-Tube

  • J-tube (Jejunostomy Tube): Inserted into the JEJUNUM (small intestine).

  • G-tube (Gastrostomy Tube): Inserted into the STOMACH.

10. Ostomies

Stool Output by Ostomy Location

Ostomy Location

Expected Stool Output

Ileostomy (ileum)

Very liquid/watery — constant drainage.

Ascending Colostomy

Liquid to semi-liquid.

Transverse Colostomy

Semi-liquid to semi-formed.

Descending Colostomy

Semi-formed to formed.

Sigmoid Colostomy

Formed / solid (like normal stool).

  • ⚠ IMPORTANT for EXAMS: If the sigmoid ostomy produces watery output, this is ABNORMAL; do not provide anti-diarrheal without investigation.

Ostomy Care Priorities

  • Primary Concern: Maintain skin integrity around the stoma; ensure that feces do not come into contact with the skin to reduce the risk of breakdown, excoriation, and infection.

  • Psychological Impact: Patients may experience significant grief, alterations in body image, and social isolation (e.g., reluctance to participate in swimming, dating, or social activities).

    • Some patients may find empowerment over time through the use of ostomy covers and social media communities.

  • Note: Ostomies may be temporary or permanent; always assess the patient's understanding of their condition and needs.

11. Diagnostic Tests

  • X-ray: Useful for confirming NG tube placement and identifying obstructions.

  • Endoscopy / Esophagoscopy: Refers to GI scope; any procedure ending in '-oscopy' relates to GI procedures.

  • Colonoscopy: Visualizes the colon and is used for polyp and cancer detection.

  • Lab Studies: Includes stool culture, guaiac (fecal occult blood test), and blood labs.

  • Residuals: Checking residuals in tube feeding is common hospital practice, but current nursing standards advocate checking pH instead.

12. Quick Exam Review — High-Yield Points

HIGH-YIELD CHECKLIST — Know All of These!

Topic

The Answer

GI tract runs from…

Mouth to anus.

Major organ of bowel elimination

Large intestine (colon).

Small intestine length

18–20 feet.

Small intestine function

Absorb nutrients.

Large intestine function

Absorb water, form/expel feces.

Partially digested food = ?

Chyme.

Peristalsis = ?

Brain-controlled intestinal muscle contractions that move stool.

#1 medication that stops peristalsis

Opioids.

Surgery stops peristalsis for how long?

3–5 days.

Voluntary sphincter

EXTERNAL sphincter.

Involuntary sphincter

INTERNAL sphincter.

Bearing down = ?

Valsalva maneuver.

Valsalva risk in cardiac patients

Vagal response → bradycardia → syncope → possible death.

Sigmoid colon stool

Solid / formed.

Ribbon-like stool = suspect

Obstruction / tumor.

GI assessment order

Inspect → Auscultate → Percuss → Palpate.

How to verify NG tube placement

X-ray + pH (NOT air injection + auscultation).

K-Exalate enema treats…

Hyperkalemia (high potassium).

Digital removal = ?

Last resort after enema fails; risk = vagal response.

Outcome must always include…

A specific TIMEFRAME.

Potassium = always priority because…

Dysrhythmias can be lethal.

HOB during tube feeding

Elevated (30–45 degrees) — never flat.