NORCET 1 - 2020
Obstetrics & Gynaecology
Medium

32 week pregnant woman hospitalized with vaginal discharge, and its

fibronectin test positive, what kind of labour does it indicate?

Appeared in: NORCET 1 - 2020

Explanation

  • Preterm labor is defined as labor that starts before the 37th completed week of gestation.
  • The patient in the scenario is at 32 weeks, which is clearly within the preterm period.
  • Fetal fibronectin (fFN) is a protein that acts as an adhesive, holding the fetal sac to the uterine wall. Its detection in vaginal fluid between 22 and 34 weeks is abnormal.
  • A positive fFN test indicates a disruption of this adhesive layer and is a strong predictor of impending preterm labor, often within the next one to two weeks.

Why Other Options Were Wrong

  • Option A: Post-term labor occurs after 42 completed weeks of gestation. The patient is at 32 weeks, which is preterm.
  • Option B: Prolonged labor refers to the duration of labor (e.g., lasting more than 12-20 hours), not the gestational age at which it begins. The fFN test does not predict the length of labor.
  • Option D: Precipitated labor is an extremely rapid labor and delivery, usually lasting less than three hours from the start of contractions. It is a disorder of uterine action and is not predicted by an fFN test.

Related Visual

Visual explanation — Related Visual
  • Visual 1: Diagram - An illustration showing the location of fetal fibronectin at the choriodecidual junction, highlighting its role as a 'glue' between the chorion and the decidua.
  • Visual 2: Chart - A timeline of pregnancy marking the preterm period (before 37 weeks), term period (37-42 weeks), and post-term period (after 42 weeks), with the 32-week mark clearly shown in the preterm zone.
Clinical Relevance
  • Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Identification of preterm labor based on gestational age and diagnostic tests as background academic context rather than a clinical decision trigger.
  • A positive fFN test is a critical finding that prompts nurses to initiate protocols for managing preterm labor. This includes administering tocolytics to slow contractions and corticosteroids (like Betamethasone) to accelerate fetal lung maturity, which is crucial for the baby's survival.
  • Nurses are responsible for the correct specimen collection for the fFN test. Contamination with blood, amniotic fluid, or lubricants can lead to inaccurate results, so meticulous technique is essential.
  • What if? If the fFN test were negative, it would have a high negative predictive value (over 99%). This means it's highly unlikely the woman would deliver in the next 1-2 weeks. This reassuring result would allow for less aggressive management and potentially discharging the patient with close follow-up instructions.
How to Approach the Question
  • First, identify the key clinical data in the stem: the gestational age (32 weeks) and the diagnostic test result (positive fibronectin test).
  • Recognize that 32 weeks is before the full-term mark of 37 weeks, which immediately points towards a 'preterm' condition.
  • Recall the purpose of the fetal fibronectin (fFN) test. A positive result indicates a breakdown of the 'glue' between the fetal sac and uterus, signaling a high risk of premature delivery.
  • Connect the positive test result at a preterm gestational age (32 weeks) to the definition of preterm labor.
  • Systematically evaluate and eliminate the other options based on their definitions. 'Post-term' relates to being overdue (>42 weeks). 'Prolonged' relates to the duration of labor. 'Precipitated' relates to the speed of labor. None of these are indicated by the patient's gestational age or fFN result.
Concept Tested & Keywords
  • Concept Tested: Identification of preterm labor based on gestational age and diagnostic tests.
  • Stem keywords: 32 week pregnant, vaginal discharge, fibronectin test positive
  • Lead-in keywords: what kind of labour
  • Clinical cues: 32 weeks gestation: This is a key indicator, as it falls before the 37-week threshold for full-term pregnancy.
  • Clinical cues: Positive fibronectin test: This is a specific biochemical marker indicating an increased risk of preterm delivery.

Question ID

QmzTuDGIy77NWq0vYb38sP

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