Ob-gyne: The Bony Pelvis

The most prevalent pelvic type is gynecoid. This type of pelvis is commonly found in women and is considered the most favorable for childbirth. The gynecoid pelvis has a round shape with a wide pelvic inlet and a generous pelvic outlet, allowing for easy passage of the baby during delivery. This pelvic type is associated with a lower risk of complications during childbirth compared to other types such as anthropoid, android, or platypelloid pelvis.

If the diagonal conjugate, which is a measurement of the distance between the sacral promontory and the lower border of the symphysis pubis, is greater than 11.5 cm, it suggests that the pelvic inlet is large enough to allow for a normal-sized fetus to pass through during vaginal delivery. This measurement is commonly used to assess the adequacy of the pelvis for childbirth. Therefore, the statement is true.

The saccrovertebral joint is not a joint of the pelvis. The pelvis consists of the sacroiliac joints, saccrococcygeal joint, and symphysis pubis. The saccrovertebral joint refers to the joint between the sacrum and the vertebrae of the spine, which is not part of the pelvis.

The boundaries of the pelvic inlet include the sacral promontory, iliopectinate lines, and pubic symphysis. These structures define the upper opening of the pelvis and help to separate the pelvic cavity from the abdominal cavity. The sacral promontory is a bony ridge on the sacrum, the iliopectinate lines are the junctions between the ilium and pubis bones, and the pubic symphysis is the joint between the two pubic bones. Together, these boundaries form the complete outline of the pelvic inlet.

The innominate bone, also known as the hip bone, is composed of three parts: the ilium, ischium, and pubis. These three parts come together to form the acetabulum, which is the socket that connects the hip joint. The ileum, on the other hand, is a part of the pelvis but is not a component of the innominate bone. Therefore, the correct answer is Ileum.

The ischial spines are used as a landmark to assess the level to which the presenting part of the fetus has descended into the true pelvis. These bony projections can be felt during a vaginal examination and provide information about the progress of labor and the position of the baby. By determining the position of the ischial spines, healthcare providers can gauge how far the baby's head has descended and make decisions regarding the management of labor.

The shortest AP diameter of the pelvic inlet is referred to as the obstetric conjugate. This measurement is important in obstetrics as it determines the size of the pelvic inlet and whether a baby can pass through during childbirth. The obstetric conjugate is measured from the sacral promontory to the lower border of the pubic symphysis and is typically shorter than the true conjugate, which is measured from the sacral promontory to the upper border of the pubic symphysis. The anatomic conjugate is measured from the sacral promontory to the posterior surface of the pubic symphysis, while the diagonal conjugate is measured from the sacral promontory to the lower border of the pubic symphysis, but it is not the shortest AP diameter of the pelvic inlet.

The obstetrical conjugate refers to the distance between the sacral promontory and the back of the pubic symphysis. It is an important measurement in obstetrics as it determines the size of the pelvic inlet. In this case, the correct answer states that the obstetrical conjugate is the shortest AP (anteroposterior) diameter. This means that it is the shortest distance from the front to the back of the pelvic inlet.

The AP diameter of the pelvic outlet refers to the measurement from the front to the back of the pelvic outlet. The correct answer range of 9.5-11.5 cm indicates that this measurement can vary within this range. This range allows for individual variation in pelvic size and shape, accommodating for the passage of the baby during childbirth.

The interspinous diameter refers to the distance between the spinous processes of the vertebrae in the spine. The correct answer is "10 cm or more" because it indicates that the interspinous diameter should be equal to or greater than 10 cm. This suggests that the space between the spinous processes is wide enough, which is important for proper spinal alignment and movement.

The average length of the true conjugate is 11 cm.

The average length of the diagonal conjugate is 12 cm. This means that when you take the length of all the diagonal conjugates and add them together, and then divide that sum by the number of diagonal conjugates, the result is 12 cm.

If midpelvic contraction is suspected, the ischial spines would be more prominent rather than less prominent. This is because midpelvic contraction refers to a narrowing of the pelvic outlet, which would cause the ischial spines to become more prominent as they are pushed closer together. Therefore, the statement "ischial spines are less prominent" is not true if midpelvic contraction is suspected.

It is the diameter of the pelvic outlet that is increased. This is most likely the reason that McRoberts maneuver is often successful in releasing an obstructed shoulder in shoulder dystocia.

The plane of the midpelvis is the correct answer because it represents the middle section of the pelvis, which typically has smaller dimensions compared to the pelvic inlet and outlet. The pelvic inlet is the upper opening of the pelvis, while the pelvic outlet is the lower opening. These two planes usually have larger dimensions to accommodate childbirth. The plane of greatest pelvic dimension is not the correct answer because it implies the largest dimensions, which is not true for the midpelvis.

The correct answer is 4.5 cm. The posterior sagittal diameter refers to the measurement of the distance from the back of the head to the sacrum, which is the triangular bone at the base of the spine. On average, this measurement is 4.5 cm.

The average length of the obstetric conjugate is 10 cm. The obstetric conjugate is the smallest diameter of the pelvic inlet, and it is measured from the promontory of the sacrum to the upper border of the pubic symphysis. This measurement is important in obstetrics as it helps determine if the pelvis is adequate for vaginal delivery. A length of 10 cm suggests a relatively smaller pelvis, which may require further assessment to ensure a safe delivery.

The diagonal conjugate diameter is the distance from the sacral promontory to the lower border of the symphysis pubis. The true conjugate is the distance from the sacral promontory to the upper border of the symphysis pubis, while the obstetric conjugate is the distance from the sacral promontory to the midpoint of the symphysis pubis. In this case, the diagonal conjugate diameter is 13 cm, so the true conjugate would be slightly longer than that, around 11.8 cm. The obstetric conjugate would be slightly shorter, around 11-11.5 cm. Therefore, the answer is 11.8 cm and 11-11.5 cm.

The diagonal conjugate is measured during a pelvic examination. It is the distance between the lower border of the symphysis pubis and the sacral promontory. This measurement is important in obstetrics as it helps determine the adequacy of the pelvic inlet for childbirth. It provides an estimation of the true conjugate, which is the narrowest diameter of the pelvic inlet. The diagonal conjugate measurement is commonly used in clinical practice to assess the pelvic dimensions and plan for a safe delivery.

The plane of greatest pelvic dimension refers to the widest part of the pelvis, which allows for the most spacious area within the pelvis. This plane is important for childbirth as it provides enough room for the baby to pass through the birth canal. It is also relevant for surgical procedures involving the pelvis, as it allows for easier access and maneuverability.

The given answer lists the four basic types of pelvis: gynecoid, andthropoid, android, and platypelloid. These types refer to different shapes and structures of the pelvis, which can have implications for childbirth and overall pelvic health. The gynecoid pelvis is the most common and ideal type for childbirth, while the andthropoid, android, and platypelloid pelvises have their own unique characteristics and potential challenges during childbirth.