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Patient Presentation

A 26-year-old woman in labor is admitted to the hospital birthing center. She requests an "epidural" for pain management.

Relevant Clinical Findings History

The patient has no history of chronic illness, and has had appropriate prenatal care. The pregnancy is full term.

Physical Examination

Noteworthy vital signs of the fetus:

  • Weight: 7.5 lb

  • Pulse: 145 bpm (adult resting rate: 60–100 bpm)

Results of physical examination:

  • Uterine cervix dilated to 4 cm

  • Contractions 3 minutes apart, each lasting 40-60 seconds

Clinical Problems to Consider Clinical Notes

There are three stages of childbirth:

  1. Stage 1 is characterized by the onset of uterine contractions and ends when the uterine cervix is dilated completely (10 cm). This stage can last up to 20 hours and is divided into three phases:

    1. Latent phase: cervix dilated 1–4 cm

    2. Active phase: cervix dilated 4–8 cm

    3. Transition phase: cervix dilated 8–10 cm

  2. During this stage, contractions typically increase in frequency, duration, and intensity. It is important to distinguish labor contractions from Braxton–Hicks (“false labor”) contractions, which are irregular, do not increase in frequency, and may change with body position and activity.

  3. Stage 2 begins when the cervix is dilated completely and ends with delivery. Delivery may last from 20 minutes to 2 hours.

  4. Stage 3 involves delivery of the placenta and lasts between 5 and 30 minutes.


  1. Describe the anatomy of the lumbosacral region of the vertebral column and the hip bone.

  2. Describe the anatomy of the lumbosacral region of the spinal cord and spinal nerves.

  3. Describe the anatomy of the spinal meninges and associated spaces.

  4. Describe the sensory innervation from the uterus, vagina, and female perineum.

  5. Explain the anatomical basis for the signs and symptoms associated with this case.


Lumbosacral Region of the Vertebral Column and Hip Bone

The five lumbar vertebrae and the sacrum form the skeleton of the inferior vertebral region (Fig. 8.1.1). The lumbar spinous processes are connected by supraspinous and interspinous ligaments. Adjacent laminae are connected by ligamenta flava (singular, ligamentum flavum). On the sacrum, the posterior median crest represents the spinous processes and extends inferiorly to the sacral hiatus.

Figure 8.1.1

Posterior view of the lumbosacral region showing (A) the intact vertebrae with supraspinous ligament and ligamentum flavum, and (B) the opened vertebral canal and contents.

The hip bone is formed by the fusion of the ischium, ilium, and pubic bones. The ischium has two prominent projections that are relevant to obstetrics and gynecology (Fig. 8.1.2):

  • The ischial tuberosity is a roughened area for attachment of muscles of the pelvic floor (urogenital diaphragm) and lower limb. It is ...

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