TURP Syndrome

Definition

TURP syndrome describes a constellation of symptoms arising from systemic absorption of large volumes of hypotonic, nonelectrolyte irrigation fluid during transurethral resection of the prostate (or similar endoscopic procedures). It is essentially an iatrogenic form of water intoxication combining circulatory fluid overload, dilutional hyponatremia/hypoosmolality, and solute toxicity from the irrigant.

Incidence: mild-to-moderate cases 0.78-1.4%; overall <1%
Mortality: up to 25% in severe cases (serum Na⁺ <120 mEq/L)
Onset: 15 minutes to 24 hours after resection begins

Mechanism / Pathophysiology

Irrigation fluid is absorbed through opened prostatic venous sinuses. On average, 10-30 mL/min of fluid is absorbed per minute of resection, making prolonged procedures especially dangerous.

Factors governing absorption rate:

Height of irrigation bag above the table (hydrostatic pressure)
Degree of bladder distension
Extent of venous sinus opening
Duration of resection

Three interrelated pathophysiologic arms:

1. Hypervolemia

Acute volume expansion → hypertension + bradycardia initially
Ventricular failure + pulmonary edema in patients with reduced cardiac reserve
Hypertension + hyponatremia cause osmotic/hydrostatic water shift out of vasculature → pulmonary edema → hypovolemic shock (paradoxical late hypotension)
Regional anesthesia further aggravates hypotension

2. Hyponatremia / Hypoosmolality

Dilutional hyponatremia from hypotonic fluid absorption
Acute hypoosmolality drives free water into brain → cerebral edema
CNS symptoms correlate with rapidity of fall:
- <120 mEq/L: restlessness, confusion, hypotension, pulmonary edema, CHF
- <115 mEq/L: ECG changes (widened QRS, ventricular ectopy, ST elevation)
- <110 mEq/L: seizures, loss of consciousness
- ~100 mEq/L: respiratory and cardiac arrest

3. Solute toxicity (depends on irrigant used)

Irrigating Solutions and Their Toxicities

Solution	Osmolality	Toxicity
Glycine 1.5%	230 mOsm/L	Transient blindness (retinal inhibitory NT), hyperammonemia (glycine → ammonia), cardiac T-wave changes
Sorbitol 2.7% + Mannitol 0.54%	195 mOsm/L	Hyperglycemia (sorbitol), intravascular volume expansion (mannitol)
Distilled water	0 mOsm/L	Massive hemolysis - largely abandoned
Normal saline (bipolar TURP)	Isotonic	No hyponatremia; risk of volume overload only

Electrolyte solutions cannot be used in monopolar TURP as they disperse the diathermy current.

Glycine-Specific Toxicity

Glycine is an inhibitory neurotransmitter in the retina - causes transient blindness with sluggish/nonreactive pupils (vs. cerebral edema where pupillary reflexes are normal)
Acts on NMDA receptors (allosteric activation) - lowers seizure threshold
Metabolized hepatically to ammonia → encephalopathy, nausea/vomiting within 1 hour post-op
CNS toxicity appears when serum ammonia >100 μmol/L; coma possible at higher levels

Clinical Manifestations

Cardiovascular

Early: hypertension, bradycardia (volume overload)
Late: hypotension, pulmonary edema, congestive heart failure, cardiovascular collapse

CNS / Neurological

Headache, restlessness, confusion, agitation
Visual disturbances (transient blindness - glycine)
Seizures, coma
Encephalopathy (ammonia)

Respiratory

Dyspnea, cyanosis, pulmonary edema

Other

Nausea, vomiting
Arrhythmias
Hemolysis (if hypotonic solutions used)

Risk Factors

Large prostate (>45 g) requiring longer resection
Resection time >90 minutes
High irrigation bag pressure
High intravesical pressure
Extensive venous sinus opening
Large irrigation volumes used
Use of hypotonic irrigants

Diagnosis

TURP syndrome is a clinical diagnosis supported by:

Serum sodium (check if symptoms arise intraoperatively or postoperatively)
Serum osmolality
Serum ammonia (if glycine irrigant used)
ECG monitoring (QRS widening, ST changes)
Monitoring fluid balance: irrigant instilled vs. drained

Treatment

Treatment is guided by severity and intravascular volume status:

Severity	Management
Mild	Fluid restriction + IV furosemide (loop diuretic to excrete free water)
Severe hyponatremia with seizures/coma	Hypertonic saline (3% or 5% NaCl) - correct Na⁺ cautiously
Seizures	Midazolam 2-4 mg IV; Mg²⁺ (counteracts glycine's NMDA activation and dilutional hypomagnesemia)
Airway compromise	Endotracheal intubation to prevent aspiration
Normal/near-normal osmolality	Hemodialysis preferred over hypertonic saline
Hypoxemia/hypoperfusion	Treat supportively

Caution with hypertonic saline: Correct Na⁺ no faster than 8-10 mEq/L per 24 hours to avoid osmotic demyelination syndrome.

Prevention

Use bipolar TURP with isotonic saline irrigation (eliminates hyponatremic risk)
Monitor fluid balance continuously; stop surgery if >750-1000 mL absorbed (females) or >2000 mL (males)
Limit resection to <90-120 minutes
Keep intravesical pressure <15-25 mmHg
Use regional anesthesia (spinal/epidural) - the awake patient can report symptoms early, allowing earlier detection
Warm irrigation solutions (also prevents hypothermia)

Anesthetic Preference

Regional (spinal) anesthesia is preferred for TURP because:

Patient remains awake - early CNS symptoms (confusion, visual changes) can be reported
Sensory level can be monitored to detect significant fluid shifts
Associated with lower 30-day mortality vs. general anesthesia in large database studies
Neuraxial anesthesia does NOT affect blood loss or postoperative cognitive function vs. general anesthesia

Modern Context

Advances in surgical technique have markedly reduced TURP syndrome:

Bipolar TURP uses normal saline - eliminates hyponatremia risk (volume overload risk remains)
Laser ablation, radiofrequency ablation, photodynamic and thermal therapy, cryotherapy
These alternatives have reduced both incidence and severity of TURP syndrome significantly

Sources: Morgan & Mikhail's Clinical Anesthesiology, 7e, p. 1303-1304 | Miller's Anesthesia, 10e, pp. 8471-8476, 6372-6374

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