The Stages of Labor – USMLE Step 2 CK

by / Wednesday, 30 June 2010 / Published in OB/GYN

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It should be noted that both general and spinal anesthesia, as well as sedation may reduce uterine cavity activity if administered in the latent phase, prolonging this stage of labor.

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Consider prolonged phase if it exceeds >20h in a primipara and >14hr in multiparous.  Management includes waiting for the drug to wear off.  If the patient has hypocontraction, diluted infusion of oxytocin should be administered.

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STAGES OF LABOR:

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Stage 1:

Latent Phase – Begins at the onset of regular contractions (If this phase arrests, therapeutic rest is the protocol)

Active Phase – Begins with the onset of cervical dilation acceleration (usually around 3-4cm).  (If this phase arrests for 2hr or more, this is an indication for C-section).

Rate of dilation in active phase: Primipara (1.2cm/hr), Multipara (1.5cm/hr)

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Stage 2 :

Begins with complete cervical dilation and ends with delivery of fetus.  This may last up to 2hrs in primipara and 1hr in multipara.

Stage 3:

Begins with delivery of fetus and ends with expulsion of the placenta.  This phase may take up to 30 minutes.

  • This phase can be augmented with IV oxytocin infusion
  • Signs of stage 3 include – A gush of blood vaginally – Lengthening of the umbilical cord

Stage 4:

A 1hr-2hr period of close observation after delivery when vitals and vaginal bleeding are monitored for onset of pre-eclampsia and postpartum hemorrhage.

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It should be noted that an important cause of arrest disorder is midpelvic contraction which is indicated by a prominent ischial spine(s).

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