Obstetric Anatomy and Prenatal Care

Comprehensive practice flashcards featuring essential vocabulary and key concepts from the lecture on obstetric pelvic anatomy, fetal skull diameters, fetal presentation and positioning, and signs and physiology of pregnancy.

Linea Terminalis

An imaginary anatomical line that divides the superior false pelvis from the inferior true pelvis.

Coccyx

A caudal pelvic structure located just below the sacrum, composed of 5 small fused bones.

Pelvic Outlet

The inferior portion of the pelvis, where the greatest diameter is the anteroposterior diameter.

Pelvic Cavity

The curved passage situated between the pelvic inlet and pelvic outlet designed to slow and control the speed of birth.

Platypelloid Pelvis

A "flattened" pelvis type characterized by a smoothly curved oval inlet.

Anteroposterior Diameter (Pelvic Inlet)

The distance between the pubic symphysis and the sacral promontory, measuring approximately $11\,\text{cm}$.

Cranium

The uppermost portion of the fetal skull composed of eight bones, four of which are superior and clinically significant during delivery: the frontal, two parietal, and occipital bones.

Biparietal Diameter

The transverse diameter of the fetal skull, measuring $9.25\,\text{cm}$.

Suboccipitobregmatic Diameter

The smallest anteroposterior diameter of the fetal skull, measuring approximately $9.5\,\text{cm}$.

Occipitomental Diameter

The widest anteroposterior diameter of the fetal skull, measuring approximately $13.5\,\text{cm}$.

Occipitofrontal Diameter

An anteroposterior diameter of the fetal skull measuring $12\,\text{cm}$.

Submentobregmatic Diameter

An anteroposterior diameter of the fetal skull measuring $9.5\,\text{cm}$.

Suboccipitofrontal Diameter

An anteroposterior diameter of the fetal skull measuring $10.5\,\text{cm}$.

Fetal Presentation

The specific fetal body part that first contacts the cervix or is born first, determined by the fetal lie and attitude.

Cephalic Presentation

The most frequent fetal presentation where the head is the presenting part, classified into vertex, sinciput, brow, and face types.

Breech Presentation

A presentation in which the fetal buttocks or feet are the presenting part, categorized into complete, frank, or footling.

Shoulder Presentation

A fetal presentation occurring when the fetus lies horizontally in the maternal pelvis, presenting with the acromion process, iliac crest, hand, or elbow.

Fetal Attitude

The degree of flexion assumed by the fetus during labor or the anatomical relationship of the fetal parts to each other.

Military Position

A state of moderate fetal head flexion where the head is held straight without the chin touching the chest.

Caput Succedaneum

An edematous swelling of the presenting area of the fetal scalp caused by sustained cervical pressure during labor.

Engagement

The descent and settling of the fetal presenting part into the maternal pelvis to the level of the ischial spines.

Fetal Station

The relationship of the presenting fetal part to the maternal ischial spines, where station $0$ represents the ischial spine level, negative numbers indicate centimeters above, and positive numbers indicate centimeters below.

Crowning

The clinical milestone occurring at $+3$ or $+4$ station when the fetal presenting part reaches the perineum and remains visible through the separated vulva.

Presumptive Signs of Pregnancy

Subjective symptoms experienced and reported by the woman (such as amenorrhea, nausea, and breast tenderness) that cannot be verified by an examiner and do not definitively diagnose pregnancy.

Probable Signs of Pregnancy

Objective physical indicators detectable by an examiner (such as positive laboratory tests, uterine softening, and cervical changes) that strongly suggest but do not conclusively confirm pregnancy.

Positive Signs of Pregnancy

Definitive evidence of pregnancy demonstrated exclusively by fetal movement felt by an examiner, audible fetal heart tones, or sonographic identification of the fetal outline.

Goodell's Sign

Marked softening and increased vascularity of the cervix during pregnancy.

Chadwick's Sign

A bluish-violet discoloration of the vaginal mucosa and cervix caused by increased pelvic blood flow.

Hegar's Sign

Marked softening of the lower uterine segment detected during early gestation.

Operculum

A dense mucus plug that occludes the endocervical canal during pregnancy to prevent pathogenic ascent.

Carpal Tunnel Syndrome (Pregnancy)

Median nerve compression at the wrist brought on by fluid retention and relaxin-mediated joint laxity, often aggravated by repetitive manual actions.

Supine Hypotension Syndrome

A fall in maternal arterial pressure caused by compression of the inferior vena cava by the gravid uterus when the woman lies flat on her back.

Pyrosis

Esophageal reflux and burning (heartburn) precipitated by elevated progesterone levels, diminished gastric motility, and cephalad displacement of the stomach.

Cephalopelvic Disproportion (CPD)

A mismatch in size between the fetal presenting head and the maternal pelvic capacity that impedes vaginal delivery.

Pelvis

A bony ring formed by four united bones (two innominate bones, the sacrum, and the coccyx) that functions to support and protect pelvic organs.

Innominate Bone

The flaring hip bone of the pelvis, composed of three fused bones: the ilium, ischium, and pubis.

Coccyx

The triangular terminal portion of the vertebral column situated just below the sacrum, composed of 5 small bones fused together.

Linea Terminalis

The imaginary anatomical line across the pelvic brim that divides the false pelvis from the true pelvis.

False Pelvis

The superior half of the pelvis that supports the enlarging uterus during the late months of pregnancy and aids in directing the fetus into the true pelvis for birth.

Pelvic Outlet

The inferior portion of the pelvis where the greatest dimension is the anteroposterior diameter.

Pelvic Cavity

The curved passage located between the pelvic inlet and pelvic outlet designed to slow and control the speed of birth.

Anteroposterior Diameter (Pelvic Inlet)

The anatomical distance between the pubic symphysis and the sacral promontory, normally measuring approximately $11\,\text{cm}$.

Platypelloid Pelvis

A pelvis classification characterized as a "flattened" pelvis featuring a smoothly curved oval inlet.

Cephalopelvic Disproportion (CPD)

An obstetric complication in which the fetal head is too large or the maternal pelvis is too small or constricted to allow passage during labor.

Cranium

The uppermost portion of the skull composed of eight bones, four of which (frontal, two parietal, and occipital) play an important role during childbirth.

Biparietal Diameter

The transverse diameter of the fetal skull measuring approximately $9.25\,\text{cm}$.

Suboccipitobregmatic Diameter

The smallest anteroposterior diameter of the fetal head, measuring approximately $9.5\,\text{cm}$.

Occipitomental Diameter

The widest anteroposterior diameter of the fetal head, measuring approximately $13.5\,\text{cm}$.

Occipitofrontal Diameter

The anteroposterior diameter of the fetal skull measuring approximately $12\,\text{cm}$.

Submentobregmatic Diameter

An anteroposterior diameter of the fetal skull measuring approximately $9.5\,\text{cm}$.

Suboccipitofrontal Diameter

An anteroposterior diameter of the fetal skull measuring approximately $10.5\,\text{cm}$.

Fetal Presentation

The body part of the fetus that first contacts the cervix or is born first, determined by the combination of fetal lie and fetal attitude.

Cephalic Presentation

The most common fetal presentation where the fetal head is the presenting part; divided into vertex, sinciput, brow, and face types.

Vertex Presentation

The ideal cephalic presentation occurring with complete head flexion, which aids cervical dilatation and reduces the risk of cord prolapse.

Breech Presentation

A fetal presentation where the buttocks or lower extremities are the presenting part; classified into complete, frank, or footling.

Shoulder Presentation

A presentation occurring when the fetus lies horizontally in the pelvis, presenting with the acromion process, scapula, iliac crest, hand, or elbow.

Fetal Attitude

The degree of flexion assumed by the fetus during labor, describing the spatial relationship of the fetal parts to each other.

Military Position

A fetal attitude of moderate flexion in which the fetal head is straight with the chin not touching the chest.

Caput Succedaneum

Edema that forms on the presenting area of the fetal skull as a consequence of sustained pressure against the cervix during labor.

Fetal Position

The relationship of a designated fetal landmark (e.g., Occiput, Mentum, Sacrum, Acromion Process) to a specific quadrant and side of the maternal pelvis.

Engagement

The settling of the presenting part of the fetus into the pelvis to the level of the maternal ischial spines.

Fetal Station

The relationship of the presenting fetal part to the maternal ischial spines, designated as $0$ at the spines, negative numbers ($-1$ to $-4\,\text{cm}$) above, and positive numbers ($+1$ to $+4\,\text{cm}$) below.

Crowning

The point during labor when the presenting part reaches station $+3$ or $+4$ at the perineum and can be visualized when the vulva is separated.

Presumptive Signs of Pregnancy

Subjective symptoms experienced by the pregnant woman (such as amenorrhea, nausea/vomiting, fatigue, and breast tenderness) that cannot be verified by an examiner and do not confirm pregnancy.

Probable Signs of Pregnancy

Objective findings verified by an examiner (such as positive pregnancy tests, Goodell's sign, Chadwick's sign, and Hegar's sign) that indicate high likelihood but do not definitively diagnose pregnancy.

Positive Signs of Pregnancy

Objective clinical findings that definitively confirm pregnancy, consisting of examiner-felt fetal movement, audible fetal heart tones, and sonographic visualization of the fetus.

Goodell's Sign

Softening of the cervix caused by increased vascularity and edema during pregnancy.

Operculum

A thick mucus plug that forms within the cervical canal during pregnancy to block bacterial entry into the uterus.

Chadwick's Sign

Bluish or violet discoloration of the mucous membranes of the vagina and cervix resulting from increased vascularity.

Carpal Tunnel Syndrome

Compression of the median nerve in the wrist during pregnancy, influenced by repetitive motion, fluid retention, and the hormone relaxin.

Supine Hypotension

A fall in maternal blood pressure caused by compression of the vena cava by the heavy uterus when the woman rests flat on her back.

Left-Sided Sims Position

A recommended side-lying sleeping posture with the top leg flexed forward to optimize placental perfusion and avoid vena cava compression.