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Macklers triad

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Mackler's triad Boerhaave syndrome spontaneous esophageal perforation

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Retching

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retching mechanism physiology dry heaving vs vomiting

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Here is a comprehensive answer on retching:

Retching (Dry Heaving)

Definition

Retching is the rhythmic, synchronous contraction of the diaphragm, abdominal muscles, and intercostal muscles against a closed glottis, without the expulsion of gastric contents. It is also called "dry heaving" and represents the second phase of the full emetic sequence.
  • Rosen's Emergency Medicine, p. 1222 | Sleisenger & Fordtran's GI and Liver Disease, p. 196 | Yamada's Textbook of Gastroenterology, p. 577

The Three-Phase Emetic Sequence

PhaseDescription
1. NauseaUnpleasant sensation of impending vomiting; increased tone in duodenum/jejunum, decreased gastric tone, reflux of intestinal contents into stomach; often with hypersalivation, repetitive swallowing, tachycardia
2. RetchingSpasmodic respiratory movements with glottis CLOSED; no oral discharge of gastric contents; associated with intense nausea; usually (but not always) culminates in vomiting
3. Vomiting (emesis)Forceful expulsion of gastric contents through the mouth; glottis closes to prevent aspiration
Each phase can occur independently - nausea can occur without retching, and retching can occur without vomiting.

Mechanism of Retching

  • The glottis remains closed throughout - this is the key distinction from vomiting
  • There is rhythmic, spasmodic, inspiratory-type effort against that closed glottis
  • Stomach and esophagus undergo retroperistalsis (reverse movement)
  • Gastric contents are churned and mixed with refluxed intestinal secretions, imparting an orad (upward) momentum to the bolus - this prepares the stomach contents for actual expulsion during vomiting
  • The act is coordinated by the vomiting center in the medulla (contains muscarinic receptors), which receives afferents from:
    1. GI tract visceral afferents (vagus nerve)
    2. Extra-GI visceral afferents (biliary system, heart, peritoneum, pharynx)
    3. CNS afferents (vestibular system, thalamus, cortex)
    4. The chemoreceptor trigger zone (CTZ) in the area postrema, floor of the 4th ventricle (outside blood-brain barrier)

Important Differentiations

FeatureRetchingVomitingRegurgitationRumination
GlottisClosedCloses at endOpenOpen
Gastric expulsionNoYes (forceful)Passive/effortlessEffortless
Abdominal muscle contractionYesYesNoNo
NauseaYesOftenUsually absentUsually absent

Clinical Relevance

Retching is clinically important because it can cause or contribute to several conditions:
  1. Mallory-Weiss tears - Retching and vomiting abruptly raise intra-abdominal pressure, causing mucosal tears at the gastroesophageal junction. However, a history of retching preceding hematemesis is present in only about one-third of Mallory-Weiss cases (a common misconception that it always precedes the tear).
  2. Boerhaave syndrome (Mackler's triad) - Violent retching/vomiting raises intra-esophageal pressure enough to cause full-thickness (transmural) rupture of the esophagus.
  3. Gastric volvulus - Presents with severe epigastric pain and distention followed by violent nonproductive retching (Borchardt's triad).
  4. Post-surgical complications - After fundoplication or hiatal hernia repair, postoperative retching can cause early anatomic failure; antiemetics and urgent esophagram are indicated if it occurs.
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