What is the significance of the golden hour in obstetrics and gynaecology (OB/GYN) emergencies?

The Golden Hour in Obstetrics and Gynecology Emergencies

The "golden hour" concept in obstetrics and gynecology refers to critical time-sensitive interventions where specific time windows directly impact maternal and fetal survival, most notably the 5-minute window for perimortem cesarean delivery during maternal cardiac arrest and the 3-hour window for tranexamic acid administration in postpartum hemorrhage. 1

Critical Time-Dependent Interventions

Maternal Cardiac Arrest: The 5-Minute Rule

If cardiopulmonary resuscitation does not restore effective cardiac activity within 4 minutes of arrest onset in a pregnant woman ≥20 weeks gestation, emergency cesarean delivery must be performed with the goal of delivering the fetus within 5 minutes of arrest onset. 1

The evidence demonstrates stark mortality thresholds:

• No maternal survival has been reported after 15 minutes of resuscitation 1
• No fetal survival has been reported after 30 minutes of resuscitation 1
• Maternal and fetal survival correlates directly with the time interval between cardiac arrest onset and fetal extraction 1

Critical technical considerations during resuscitation:

• A team member must continuously shift the gravid uterus leftward using two-handed traction to relieve aortocaval compression 1
• Without left uterine displacement, external cardiac massage yields only 10% of normal pregnancy cardiac output 1
• The left lateral position reduces chest compression efficacy and should not be used 1
• Do not transport the patient to an operating theater due to time constraints 1

Postpartum Hemorrhage: The 3-Hour Window

Administer tranexamic acid 1 g IV within 3 hours of bleeding onset to reduce maternal mortality from postpartum hemorrhage. 1, 2

The WOMAN trial demonstrated:

• Reduced bleeding-related mortality (RR 0.81,95% CI 0.65-1.00) when tranexamic acid was given within 3 hours 1
• A second 1 g dose can be administered if bleeding continues after 30 minutes or restarts within 24 hours 2
• Efficacy diminishes significantly after the 3-hour window 1

Immediate oxytocin administration:

• Give 5-10 IU oxytocin slow IV or IM at shoulder release or immediately postpartum to prevent postpartum hemorrhage 1
• This represents first-line prophylaxis in all deliveries, including those outside specialized structures 1

Time-Sensitive Assessment Windows

Imminent Delivery Recognition

In pregnant patients presenting in labor, assess for multiparity, previous rapid or non-hospital delivery, regular painful contractions, and urge to push to predict imminent delivery. 1

If qualified medical staff (physician or midwife) are present and imminent delivery is suspected, perform cervical examination before contacting the receiving obstetric team to determine whether transfer or on-site delivery is appropriate. 1

Severe Pre-eclampsia: The 15-Minute Rule

Administer antihypertensive treatment when systolic BP ≥160 mmHg and/or diastolic BP ≥110 mmHg persists for more than 15 minutes at rest to reduce severe maternal, fetal, and neonatal complications. 1, 3

Administer magnesium sulfate to women with severe pre-eclampsia and at least one clinical sign of severity to reduce eclampsia risk. 1, 3

The treatment decision and modalities should be discussed via phone call between emergency and receiving obstetric/anesthetic teams before initiating therapy 1

Common Pitfalls to Avoid

Do not attempt pre-hospital perimortem cesarean delivery. Time intervals between cardiac arrest and fetal extraction in non-hospital settings always exceed those in specialized structures, making maternal and especially fetal survival without neurological sequelae highly exceptional 1

Do not delay tranexamic acid administration beyond 3 hours of bleeding onset. The therapeutic window closes rapidly, and delayed administration loses efficacy 1, 2

Do not use visual estimation for blood loss measurement. Visual assessment consistently underestimates blood loss; use calibrated blood-collection drapes and volumetric/gravimetric measurement tools 2, 3

Do not perform manual placental removal outside specialized structures except in cases of severe uncontrollable postpartum hemorrhage. This increases infection and hemorrhage risk 1

Do not wait for laboratory results before initiating blood component therapy in severe bleeding. In massive hemorrhage, administer red blood cells, fibrinogen, and fresh frozen plasma empirically while using point-of-care testing when available 2, 3

Prognostic Indicators Requiring Immediate Action

Hypofibrinogenemia (fibrinogen <2 g/L) with ongoing bleeding predicts progression to massive obstetric hemorrhage. 2, 4

FIBTEM A5 value <12 mm on viscoelastic testing predicts progression to severe hemorrhage. 4

Platelet transfusion is rarely required unless blood loss exceeds 5000 mL or platelet count is <75 × 10⁹/L. 2

The "Golden Hour" Terminology

It bears noting that the term "golden hour" as a universal 60-minute window lacks definitive scientific support in the medical literature 5. In obstetrics and gynecology, the critical time windows are intervention-specific and range from 5 minutes (perimortem cesarean) to 3 hours (tranexamic acid), rather than a single "golden hour" 1, 2