Podcast
Questions and Answers
What is the posterior sagittal diameter of the outlet during childbirth?
What is the posterior sagittal diameter of the outlet during childbirth?
The sub-pubic angle in females is acute.
The sub-pubic angle in females is acute.
False
What is the angle of inclination between the pelvic inlet and the horizontal?
What is the angle of inclination between the pelvic inlet and the horizontal?
55°
The posterior sagittal diameter of the mid-pelvis is at least _____ cm.
The posterior sagittal diameter of the mid-pelvis is at least _____ cm.
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Match the following angles with their corresponding gender:
Match the following angles with their corresponding gender:
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What is the station of the fetal head when it is engaged?
What is the station of the fetal head when it is engaged?
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Deep transverse arrest occurs at a station level above the ischial spine.
Deep transverse arrest occurs at a station level above the ischial spine.
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At what station level do the forceps and vacuum become applicable during delivery?
At what station level do the forceps and vacuum become applicable during delivery?
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The ischial spine serves as the landmark for the ______ nerve block.
The ischial spine serves as the landmark for the ______ nerve block.
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Match the following terms with their descriptions:
Match the following terms with their descriptions:
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Which diameter is the longest AP diameter of the fetal skull?
Which diameter is the longest AP diameter of the fetal skull?
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The bitemporal diameter is larger than the bimastoid diameter.
The bitemporal diameter is larger than the bimastoid diameter.
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What is the engaging diameter for a vertex that is fully flexed?
What is the engaging diameter for a vertex that is fully flexed?
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The diameter seen in brow presentation is the _____ diameter.
The diameter seen in brow presentation is the _____ diameter.
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Match the following head positions with their engaging diameters:
Match the following head positions with their engaging diameters:
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Which type of pelvis is the most common according to the Caldwell-Moloy classification?
Which type of pelvis is the most common according to the Caldwell-Moloy classification?
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CPD is an absolute indication for recurrent C-section.
CPD is an absolute indication for recurrent C-section.
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What is the anterior boundary of the pelvic outlet?
What is the anterior boundary of the pelvic outlet?
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What shape is the inlet of an android pelvis?
What shape is the inlet of an android pelvis?
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The mid-pelvis is said to be contracted if the interischial diameter is less than 10 cm.
The mid-pelvis is said to be contracted if the interischial diameter is less than 10 cm.
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The ______ partition of the pelvic inlet is typically vertical in an anthropoid pelvis.
The ______ partition of the pelvic inlet is typically vertical in an anthropoid pelvis.
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Match the following pelvic types with their characteristics:
Match the following pelvic types with their characteristics:
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What is the distance used to denote a contracted pelvis in clinical assessment?
What is the distance used to denote a contracted pelvis in clinical assessment?
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The ______ serves as the roof of the mid-pelvis.
The ______ serves as the roof of the mid-pelvis.
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Match the following pelvic terms with their definitions:
Match the following pelvic terms with their definitions:
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What is the maximum measurement for the obstetric conjugate to be considered contracted?
What is the maximum measurement for the obstetric conjugate to be considered contracted?
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The routine pelvimetry is recommended by WHO for the diagnosis of cephalopelvic disproportion.
The routine pelvimetry is recommended by WHO for the diagnosis of cephalopelvic disproportion.
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What is the best method for diagnosing cephalopelvic disproportion?
What is the best method for diagnosing cephalopelvic disproportion?
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A contracted inlet is defined as an obstetric conjugate less than _____ cm.
A contracted inlet is defined as an obstetric conjugate less than _____ cm.
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Match the types of pelvis with their characteristics:
Match the types of pelvis with their characteristics:
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Which type of fetal lie is characterized by the fetal axis being at an angle to the long axis of the uterus?
Which type of fetal lie is characterized by the fetal axis being at an angle to the long axis of the uterus?
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Cephalic presentation is considered a normal presentation during childbirth.
Cephalic presentation is considered a normal presentation during childbirth.
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What management technique may be used for a transverse lie in the antenatal period?
What management technique may be used for a transverse lie in the antenatal period?
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The part of the fetus presenting at the lower pole of the uterus is known as the ______.
The part of the fetus presenting at the lower pole of the uterus is known as the ______.
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Match the types of fetal presentation with their definitions:
Match the types of fetal presentation with their definitions:
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What is the method of delivery when a hand prolapse occurs?
What is the method of delivery when a hand prolapse occurs?
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The normal attitude of a fetus during delivery is complete extension.
The normal attitude of a fetus during delivery is complete extension.
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What is the presenting part of the fetus determined by?
What is the presenting part of the fetus determined by?
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In a vertex position, the reference point on the presenting part is the ______.
In a vertex position, the reference point on the presenting part is the ______.
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Match the following fetal positions with their descriptions:
Match the following fetal positions with their descriptions:
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Which part of the fetal skull is most commonly presented in anencephaly?
Which part of the fetal skull is most commonly presented in anencephaly?
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The anterior fontanelle is triangular in shape.
The anterior fontanelle is triangular in shape.
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What is the normal position of the fetus in utero?
What is the normal position of the fetus in utero?
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The _____ is the most common presenting part in a flexed fetal position.
The _____ is the most common presenting part in a flexed fetal position.
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Match the following parts of the skull with their correct description:
Match the following parts of the skull with their correct description:
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What is the most common cause of a free floating head without descent at term in a primigravida?
What is the most common cause of a free floating head without descent at term in a primigravida?
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Cephalhematoma is characterized by a collection of fluid above the periosteum.
Cephalhematoma is characterized by a collection of fluid above the periosteum.
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What is the grading system used for molding during labor?
What is the grading system used for molding during labor?
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In cases of prolonged labor with caput succedaneum, the condition may lead to __________ (CPD).
In cases of prolonged labor with caput succedaneum, the condition may lead to __________ (CPD).
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Match the type of head swelling with their characteristics:
Match the type of head swelling with their characteristics:
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Study Notes
Ischial Spine Significance
- The ischial spine is a crucial anatomical landmark during labor and delivery, playing a vital role in determining fetal head station, identifying the level of internal rotation, and serving as a reference for pudendal nerve block.
- Station 0 aligns with the ischial spine, indicating the fetal head is engaged in the pelvic inlet.
- Forceps and vacuum delivery are typically indicated at station ≥ +2.
- Internal rotation of the fetal head often occurs at the level of the ischial spine, influencing the fetus' descent through the birth canal.
- Deep transverse arrest, a potential complication in labor, can occur at the level of the ischial spines.
- The levator ani muscle, a crucial structure supporting the pelvic floor, originates from the ischial spine.
- For pudendal nerve block, the sacrospinous ligament is pierced to access the nerve.
Pelvic Dimensions & Angles
- Posterior sagittal diameter of the pelvic outlet: 7 to 7.5 cm
- Posterior sagittal diameter of the mid-pelvis: ≥ 5cm
- Sub-pubic angle is typically obtuse in females and acute in males.
- The angle between descending rami of pubic bones is a significant factor in childbirth.
- The angle of inclination, defining the angle between the pelvic inlet and the horizontal plane, is approximately 55°.
Fetal Skull Diameters
- Fetal skull diameters are crucial in understanding the relationship between the fetal head and the maternal pelvis during labor.
- The longest AP diameter of the fetal skull is the mento-vertical diameter (14 cm), typically seen in brow presentation.
- Transverse diameters range from the smallest bimastoid (7.5 cm) to the longest bitemporal (8 cm).
- The engaging diameter varies based on the fetal head position:
- Vertex (fully flexed): sub-occipital bregmatic diameter (9.5 cm)
- Brow (partially extended): occipito-frontal diameter (11.5 cm) or mento-vertical diameter (14 cm)
- Face (fully extended): sub-mento-vertical diameter (11.5 cm) or sub-mento-bregmatic diameter (9.5 cm)
Fetal Skull Presenting Parts
- The presenting part defines the fetal body part that occupies the lower pole of the uterus during labor.
- Vertex presentation, the most common, involves the fetal head presenting.
- Breech presentation, the most common malpresentation, involves the buttocks presenting.
- Shoulder presentation, common with transverse lie, involves the shoulder presenting.
Labor & Puerperium
- The active space, the space available for fetal descent, becomes available around 38 weeks in primigravida and at the onset of labor in multigravida.
- Molding describes the alteration in the fetal head shape as it passes through the birth canal.
- Caput succedaneum is an edematous swelling above the periosteum, occurring when the fetal head remains stationary for extended periods during labor.
- Cephalhematoma is a collection of blood beneath the periosteum, typically occurring due to traumatic instrumental delivery.
Pelvic Outlet & Mid-pelvis
- The pelvic outlet lies at the level of the ischial tuberosities.
- The AP diameter of the pelvic outlet is approximately 13 cm.
- The transverse diameter, also known as the bituberous diameter, is the distance between the ischial tuberosities (typically around 11 cm).
- A contracted outlet, defined by a bituberous diameter less than 8 cm, can make vaginal delivery challenging.
Contracted Pelvis & Cephalopelvic Disproportion (CPD)
- Contracted inlet is defined as an obstetric conjugate less than 10 cm or a diagonal conjugate less than 11.5 cm.
- Contracted mid-pelvis exists when the interischial diameter is less than 8 cm.
- A contracted outlet is diagnosed when the bituberous diameter is less than 8 cm.
- CPD is a relative finding where the fetal head is too large for the maternal pelvis, or the pelvis is too small for the fetal head, indicating the need for a C-section.
- Diagnosis of CPD is typically made during a trial of labor (vaginal delivery).
Types of Normal Pelvis (Caldwell-Moloy Classification)
- The Caldwell-Moloy classification categorizes pelvic types based on the shape of the pelvic inlet.
- Gynaecoid pelvis, the most common female pelvis, has a transverse oval inlet.
- Android pelvis, resembling a male pelvis, has a heart-shaped inlet.
- Anthropoid pelvis, resembling an ape pelvis, has a vertically oval inlet.
- Platypeloid pelvis, the least common, has a flat bowl-shaped inlet.
Note:
- There is no role for instrumental delivery in CPD.
- CPD is determined relative to the current fetus and should not be considered an indication for recurrent C-sections.
- CPD in the current pregnancy, regardless of severity, is a contraindication for vaginal birth after C-section (VBAC).
Lie, Presentation & Presenting Parts
- Lie describes the relationship between the fetal long axis and the maternal uterus' long axis.
- Longitudinal lie, the most common, aligns the fetal axis parallel to the maternal uterus.
- Oblique lie occurs when the fetal axis is at an angle to the maternal uterine axis.
- Transverse lie, when the fetal axis is perpendicular to the maternal uterine axis, increases the risk of hand and cord prolapse.
- Presentation defines the fetal part occupying the lower pole of the uterus.
- Cephalic presentation, the most common, describes the fetal head presenting, while breech presentation has the buttocks presenting.
Terminology of Labor
- The presenting part refers to the part of the presentation that lies over the internal os.
- Denominator is a reference point on the presenting part, like the occiput for vertex presentation.
- Attitude describes the relationship between fetal parts, with flexion being normal and extension leading to face or brow presentations.
- The image illustrates various fetal positions during labor.
- Hand prolapse, a common occurrence in transverse lie, necessitates a C-section, while head and hand prolapse during longitudinal lie can be managed vaginally
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Description
Discover the vital role of the ischial spine during labor and delivery. This quiz covers its importance in fetal head station, internal rotation, and as a reference point for procedures like pudendal nerve block. Learn about potential complications and pelvic dimensions as well.
