[CG] GTN Nitroglycerin (Glyceryl Trinitrate) for emergency cervico-uterine relaxation

Warning

exp date isn't null, but text field is

Please report any inaccuracies or issues with this guideline using our online form

Rapid and transient relaxation of the cervix and uterus is occasionally required to allow obstetric manoeuvres during emergencies.

A number of case reports and trials have shown nitroglycerin (Glyceryl Trinitrate) to provide rapid and transient cervico-uterine relaxation (albeit unlicensed).

The therapeutic effect is seen within 1-2 minutes of administration and lasts for 3-5 minutes.

Indications:

  • Fetal head entrapment during vaginal breech delivery.
  • When uterine relaxation is required during a difficult caesarean section.
  • Management of uterine inversion

Administration:

Maternal IV cannula requires to be sited prior to administration of GTN (the drug may cause profound drop in BP)

Sublingual via metered pump:

Nitrolingual pump spray should be primed before using it by pressing the nozzle once.

1-2 sprays (400-800 micrograms) administered as spray droplets beneath the tongue (do not inhale). Ask woman to close her mouth after spray administered.

Repeat after 5 minutes if hypertonus sustained.

Cautions:

  • Nitrates may increase intraocular pressure and so should be used with caution in glaucoma.

Contraindications:

  • Uncorrected hypovolaemia
  • Severe anaemia (Hb<60 g/L)
  • Increased intracranial pressure
  • Constrictive pericarditis / pericardial tamponade
  • Hypersensitivity to GTN. Nitrates, coconut oil, ethanol, glycerol monocaprylocaproate, peppermint oil

Side-effects:

Due to vasodilating effects –

Headache
Hypotension
Reflex tachycardia or bradycardia 
Rarely nausea, vomiting,flushing

(For complete list cautions,contraindications and side-effects see BNF)

Haemodynamic monitoring, a rapidly running I.V. infusion and immediately available ephedrine and phenylephidrine are mandatory prior to the use of Nitroglycerin (Glyceryl Trinitrate).

Once the third stage is complete, a Syntocinon infusion should be commenced. 

 

References

Smith GN & Brien JF. Use of nitroglycerin for uterine relaxation. Obstet Gynecol Survey 1998; 53:9:559-65.

Oxford Handbook Anaesthesia 2016

Last reviewed: 24 November 2021

Next review: 29 November 2026

Author(s): Dr Julie Murphy

Version: 4

Approved By: Dr Catrina Bain, Clinical Director, Obstetrics GGC; Obstetric Guideline Group

Document Id: 492