Nursing The Laboring Family: Anatomy of the Pelvis and Fetal Monitoring

Nursing The Laboring Family Part 1

Anatomy of the Pelvis

  1. Pelvic Features
        - The pelvis is part of the birth "passage."
            - True Pelvis: This is the bony passageway through which the fetus must travel during birth.
            - False Pelvis: This comprises the upper flared parts of the two iliac bones, as well as the concavities and wings of the sacrum.
            - Linea Terminalis: An imaginary line that separates the false pelvis from the true pelvis.

Types of Pelvis Shapes

  1. Pelvic Types
        - Gynecoid: A round shape, most preferred for vaginal delivery as it is conducive to childbirth.
        - Android: Heart-shaped and resembles the male pelvis; not favorable for vaginal delivery.
        - Anthropoid: Oval in shape; usually adequate for vaginal delivery.
        - Platypelloid: Flat shape that is not favorable for vaginal delivery.

Fetal Skull Anatomy

  1. Fontanels (Soft Spots)
        - These are intersections of sutures on the fetal skull and are pivotal in identifying the position of the fetal head as well as assisting in molding during delivery.
            - Anterior Fontanel: Diamond-shaped; closes between 12-18 months of age.
            - Posterior Fontanel: Triangular shape; closes around 2 months of age.
        - Flexion: This is a presentation of the fetus where the smallest circumference of the fetal head is presented.
        - Sutures: These allow for overlapping, changes in shape = molding, and assist in identifying the position of the fetal head.

Fetal Presentation and Position

  1. Understanding Fetal Orientation
        - Attitude: Relationship of different body parts to one another.
            - Normal Attitude: Flexion.
        - Lie: The relationship of the fetal axis to the maternal axis.
            - Normal Lie: Longitudinal (the fetus is aligned with the mother).
        - Presentation: Refers to the part of the fetus that enters the inlet first.
            - Normal Presentation: Cephalic (head), vertex.
            - Abnormal Presentations: Breech (buttocks), brow, face, and shoulder.
        - Position: Refers to the presenting part in relation to the pelvis.
            - Normal Position: Occiput is either transverse or anterior.
            - Abnormal Position: Occiput posterior.

Fetal Station and Engagement

  1. Fetal Station
        - Ischial spines serve as anatomical landmarks for measuring. The station is given numerical values either above or below these spines, represented as plus (+1 to +4) or minus (-1 to -4).
        - Floating: When the fetus is not engaged in the pelvic inlet.
        - Engagement of the Fetus: Refers to the presenting part reaching the zero station, marking it as engaged in the birth canal.

Landmarks for Fetal Positioning

  1. Landmarks
        - A three-letter abbreviation is used to identify the position of the fetus.
            - Body Parts Abbreviation: Occiput (O), mentum (M), sacrum (S), and scapula (Sc).
            - The position is referenced in relation to the mother’s left (L) or right (R) side.

Clinical Assessment of Fetal Presentation

  1. Question on Fetal Presentation
       - Question: What presentation refers to a fetus whose head enters the pelvic inlet first? Select all that apply.
            - A. Cephalic
            - B. Mentum
            - C. Sacrum
            - D. Vertex
            - E. Anterior

   - Answer: A and D
        - Explanation: When the head of the fetus is the first part to enter the pelvic inlet, the fetus is said to be in cephalic/vertex presentation. Mentum refers to the chin (incorrect), sacrum refers to above the coccyx (incorrect), and anterior indicates position not presentation (incorrect).

Assessment Techniques for Fetal Orientation

  1. Leopold’s Maneuvers
        - A series of assessments designed to determine fetal orientation and position by:
            1. Determining if the fetal head is located in the fundus or if the fetus is in a breech position.
            2. Locating the fetal back in relation to the maternal right or left side.
            3. Assessing the descent and mobility of the fetal head.
            4. Evaluating flexion and descent of the fetal head during labor.

Review of Fetal Heart Rate (FHR) Monitoring

  1. FHR Transducer Placement
        - The transducer should be placed strategically to monitor the fetal heart rate (FHR).
        - Always check the maternal pulse rate to validate FHR readings, distinguishing it from the maternal heart rate.

External Fetal Monitoring Techniques

  1. External Mode FHR Monitoring
        - FHR is monitored using an ultrasound transducer that captures high-frequency sound waves reflecting the mechanical activity of the fetal heart.
        - The uterus can be monitored using a toco-transducer, which converts contraction pressure into a diagrammatic wave for interpretation.

Internal Fetal Monitoring Techniques

  1. Internal Mode FHR Monitoring
        - FHR can be assessed using a spiral electrode that converts fetal ECG signals; this requires membranes to be ruptured and the cervix to be somewhat dilated.
        - Uterine contractions can also be monitored using an intrauterine pressure catheter, which translates contraction pressure into mmHg for accurate measurements.

Protocol for Electronic Fetal Monitoring (EFM)

  1. EFM Assessment Protocol
        - During EFM, the following parameters should be assessed for uterine activity and fetal response:
            - Contractions
            - Baseline rate
            - Variability in heart rate
            - Presence of accelerations
            - Presence of decelerations

FHR Assessment Indicators

  1. Reassuring Indicators for FHR
        - A reassuring fetal heart rate is characterized by:
            - FHR between 110-170 bpm
            - Variability of 6-25 bpm
            - Presence of accelerations in FHR
            - Absence of decelerations in FHR.