Answer:

• 1. Placenta Previa:The placenta implants partially or completely over the cervix (the lower part of the uterus that opens into the vagina). This can cause severe bleeding during pregnancy or delivery. > Types: Marginal, partial, complete/total.
• 2. Placental Abruption (Abruptio Placentae):Premature separation of a normally implanted placenta from the uterine wall before delivery of the baby. Can cause vaginal bleeding (revealed or concealed), uterine tenderness, and fetal distress.
• 3. Placenta Accreta / Increta / Percreta (Morbidly Adherent Placenta): Abnormal attachment of the placenta to the uterine wall. Accreta: Placental villi attach too deeply into the myometrium (uterine muscle) but do not penetrate the muscle. Increta: Villi invade into the myometrium. Percreta: Villi penetrate through the entire uterine wall, sometimes into adjacent organs like the bladder. These conditions can lead to severe postpartum hemorrhage because the placenta does not separate easily after delivery.
• 4. Succenturiate Lobe of the Placenta:An accessory lobe (or lobes) of placental tissue that develops separately from the main placental disc but is connected to it by blood vessels running through the membranes. Risk of retained placental tissue or ruptured vessels during delivery. (PDF point)
• 5. Placenta Marginata / Circummarginate Placenta:The fetal membranes (chorion and amnion) insert inwards from the placental edge, creating a raised, whitish ring around the periphery on the fetal surface. Usually of little clinical significance. (PDF point: "Here a ring is located at the edge of the placenta and is raised by a degenerated deciduas" - slightly different description but related concept).
• 6. Circumvallate Placenta:A more significant version of marginata where the membranes fold back upon themselves on the fetal surface, creating a thick, opaque ring around the periphery. Associated with increased risk of antepartum bleeding, preterm birth, and IUGR.
• 7. Bipartite Placenta (Bilobed Placenta):The placenta consists of two (or more - multilobed) roughly equal-sized lobes, separated by membranes. The umbilical cord may insert into either lobe or between them. Risk of retained lobe after delivery. (PDF point: "This when there are separate complete lobes and present with cords leaving them and then join one bipartite cord.")
• 8. Velamentous Cord Insertion:Umbilical cord blood vessels insert into the fetal membranes rather than directly into the placental disc. These vessels run unprotected within the membranes before reaching the placenta, making them vulnerable to rupture, especially if they cross the cervix (vasa previa).
• 9. Placental Infarcts:Areas of dead placental tissue due to interruption of blood supply. Small infarcts are common and usually harmless, but large or multiple infarcts can lead to placental insufficiency and IUGR.
• 10. Placental Tumors (e.g., Chorioangioma):Rare benign tumors of placental blood vessels. Large ones can cause complications like polyhydramnios or fetal anemia.

Placenta formation is a complex process involving both fetal (trophoblast) and maternal (decidua) tissues, beginning shortly after implantation of the blastocyst.

• 1. Implantation:Around 6-7 days after fertilization, the blastocyst (early embryo) attaches to and embeds within the uterine lining (endometrium), which has been prepared by hormones (estrogen and progesterone) and is now called the decidua.
• 2. Trophoblast Differentiation:The outer layer of the blastocyst, the trophoblast, differentiates into two layers: > Cytotrophoblast (inner layer): Actively dividing cells. > Syncytiotrophoblast (outer layer): A multinucleated, invasive layer formed by fusion of cytotrophoblast cells. It does not divide but expands rapidly.
• 3. Invasion and Erosion:The syncytiotrophoblast invades the maternal decidua, eroding maternal tissues, including endometrial glands and spiral arteries (small maternal blood vessels). This creates spaces called lacunae within the syncytiotrophoblast.
• 4. Formation of Chorionic Villi: Primary Villi: Around day 11-13, columns of cytotrophoblast cells proliferate and push into the syncytiotrophoblast, forming finger-like projections called primary chorionic villi. Secondary Villi: Mesoderm (embryonic connective tissue) from the developing embryo then grows into the core of these primary villi, transforming them into secondary chorionic villi. Tertiary Villi: Around day 21 (3 weeks post-fertilization), fetal blood vessels develop within the mesodermal core of the secondary villi, establishing a fetal circulation within the villi. These are now tertiary chorionic villi. These villi are the functional units of the placenta for exchange. (PDF: "The ovum appears with a fine hair with projections from the thromboplastic layer which grows after 3 weeks of gestation forming the chorion villi.")
• 5. Development of Intervillous Spaces:As the syncytiotrophoblast erodes maternal spiral arteries, maternal blood flows into and fills the lacunae, which coalesce to form large, continuous spaces called intervillous spaces. The chorionic villi float within these spaces, bathed in maternal blood. (PDF: "The villi will erode the maternal heart vessel then penetrate to the deciduas opening up a lake of maternal blood...")
• 6. Formation of Decidua Basalis and Chorion Frondosum: Decidua Basalis: The part of the maternal decidua underlying the implantation site, which forms the maternal component of the placenta. Chorion Frondosum: The part of the fetal chorion (derived from trophoblast and mesoderm) that has actively proliferating villi and is in contact with the decidua basalis. This forms the fetal component of the placenta. (PDF: "The part of the thromboplastic where the villi is profuse is known as ‘chorion frondosum’.") Chorion Laeve: The villi on the rest of the chorionic sac (not in contact with decidua basalis) degenerate and become smooth, forming the chorion laeve (smooth chorion). (PDF: "The villi after the capsular deciduas being less nourished, degenerates and form a chorion bulb which is the origin of the chorion membrane.")
• 7. Establishment of Fetoplacental Circulation:Fetal blood flows from the fetus through the two umbilical arteries into capillaries within the chorionic villi, exchanges gases/nutrients/wastes with maternal blood in the intervillous space, and then returns to the fetus via the single umbilical vein. (PDF: "A few villi attached to the deciduas deep arise from one stem which consists of the mesoderm, fetal blood vessel, branches of the umbilical arteries and veins.") Maternal and fetal blood do not mix directly, separated by the placental barrier (layers of the villus). (PDF: "These vessels are covered with a basingle layer of cytotrophoblast and external layer of the syncytiotrophoblast making impossible two circulation mix.")
• 8. Maturation:The placenta continues to grow and mature throughout pregnancy, becoming fully developed and functional around 10-12 weeks of gestation, although it continues to develop and change until term. (PDF: "Placental circulation is established by 17 days." "Therefore the placenta is fully/ completely developed and functioning from the 10th week of gestation and matures between 12-20 weeks of gestation.")

• 1. Respiration (Gas Exchange):Facilitates the transfer of oxygen from maternal blood to fetal blood, and carbon dioxide from fetal blood to maternal blood, via diffusion across the placental barrier. The placenta acts as the "fetal lungs."
• 2. Nutrition:Transports essential nutrients (glucose, amino acids, fatty acids, vitamins, minerals) from the mother to the fetus to support growth and development.
• 3. Excretion:Removes metabolic waste products (e.g., urea, uric acid, creatinine, bilirubin) from fetal blood and transfers them to maternal blood for excretion by the mother's kidneys and liver.
• 4. Endocrine Function (Hormone Production):Produces several vital hormones that maintain pregnancy and support fetal development: > Human Chorionic Gonadotropin (hCG): Maintains the corpus luteum in early pregnancy (which produces progesterone). Basis of pregnancy tests. > Progesterone: Essential for maintaining pregnancy (e.g., keeps uterus quiescent, supports endometrial lining). > Estrogens (e.g., Estradiol, Estriol): Promote uterine growth, breast development, and fetal organ development. > Human Placental Lactogen (hPL) / Human Chorionic Somatomammotropin (hCS): Modifies maternal metabolism to ensure adequate glucose and protein for the fetus; promotes breast development. > Other hormones like relaxin, CRH.
• 5. Protection (Barrier Function and Immunity): Barrier: Provides a selective barrier between maternal and fetal circulations, preventing passage of some harmful substances (though many drugs, viruses, and some bacteria can cross). Immunity: Transfers maternal IgG antibodies to the fetus, providing passive immunity against certain infections for the first few months after birth.
• 6. Storage:Can store some nutrients like glycogen, iron, and calcium, releasing them to the fetus as needed. (PDF point)
• 7. Detoxification (Limited):The placenta has some capacity to metabolize or detoxify certain drugs or substances, though this is limited compared to the maternal liver.

Answer: (Researched)

The fetal skull is a crucial structure in obstetrics as its size and mouldability significantly influence the progress and outcome of labor. Understanding its diameters is essential for assessing fetopelvic relationships.

These diameters present to the maternal pelvis depending on the degree of flexion or extension of the fetal head (attitude).

• 1. Suboccipitobregmatic (SOB) Diameter: Extends from the nape of the neck (below the occipital protuberance) to the center of the anterior fontanelle (bregma). Approximate Measurement: 9.5 cm. Presentation: Presents when the head is well-flexed (vertex presentation). This is the smallest and most favorable anteroposterior diameter for vaginal delivery.
• 2. Occipitofrontal (OF) Diameter: Extends from the occipital protuberance (most prominent point at the back of the head) to the glabella (most prominent point on the frontal bone, between the eyebrows). Approximate Measurement: 11.0 - 12.0 cm. Presentation: Presents when the head is partially deflexed or in a military attitude (neither flexed nor extended).
• 3. Submentobregmatic (SMB) Diameter: Extends from the junction of the neck and lower jaw (submentum) to the center of the anterior fontanelle (bregma). Approximate Measurement: 9.5 cm. Presentation: Presents in a face presentation when the head is fully extended and the chin (mentum) is anterior. This diameter (along with the bitemporal) allows for vaginal delivery in mento-anterior face presentations.
• 4. Mentovertical (MV) Diameter / Verticomental (VM) Diameter: Extends from the point of the chin (mentum) to the highest point of the vertex (center of the sagittal suture). Approximate Measurement: 13.5 - 14.0 cm. Presentation: Presents in a brow presentation (head is partially extended). This is the largest anteroposterior diameter of the fetal skull and usually makes vaginal delivery impossible unless the fetus is very small or the head flexes or extends further.
• 5. Submento-Vertical Diameter: Extends from the junction of the neck and lower jaw (submentum) to the highest point of the vertex. Approximate Measurement: 11.5 cm. Presentation: Presents in an incompletely extended face presentation or when the head converts from a brow to a face presentation.
• 6. Suboccipitofrontal (SOF) Diameter (less commonly emphasized than OF for deflexed states): Extends from the nape of the neck (below the occiput) to the center of the frontal suture (forehead). Approximate Measurement: 10.0 - 10.5 cm. Presentation: Can present if the head is slightly deflexed from a fully flexed vertex.

• 1. To Assess Fetopelvic Relationships and Predict Labor Outcome:Understanding fetal skull diameters, sutures, and fontanelles allows the midwife to assess how well the fetal head is likely to fit through the maternal pelvis during labor. This helps in anticipating potential difficulties (e.g., cephalopelvic disproportion) and planning appropriate care.
• 2. To Determine Fetal Presentation, Position, and Attitude During Labour:By identifying specific landmarks (sutures, fontanelles) on vaginal examination, the midwife can determine the presentation (e.g., vertex, face, brow), the position of the presenting part (e.g., LOA, ROP), and the degree of flexion or extension (attitude) of the fetal head. This is crucial for monitoring labor progress.
• 3. To Monitor Labor Progress and Detect Abnormalities:Knowledge of how the fetal head normally descends and rotates through the pelvis (mechanisms of labor) allows the midwife to identify deviations from normal progress (e.g., failure to descend, deep transverse arrest, malpositions) that may require intervention.
• 4. To Understand and Assess Molding and Caput Succedaneum:The midwife needs to understand that the fetal skull bones can overlap (molding) due to pressure during labor, which is a normal adaptive process. They also need to differentiate this from caput succedaneum (scalp edema). Excessive molding or caput can indicate fetopelvic disproportion or prolonged labor.
• 5. To Anticipate and Manage Potential Complications During Delivery:Knowledge of different presenting diameters helps the midwife understand why certain presentations (e.g., brow) are associated with obstructed labor. It also informs techniques for controlled delivery of the head to minimize perineal trauma.
• 6. To Perform Neonatal Assessment:After birth, examining the newborn's head, including palpating sutures and fontanelles, is part of the routine neonatal assessment to check for abnormalities, molding, or signs of birth trauma.
• 7. To Provide Accurate Health Education to Mothers:Being able to explain basic aspects of fetal skull anatomy can help mothers understand the labor process and the importance of certain maternal positions or interventions.

Answer: (Researched)

Fetal circulation has unique structures that allow the fetus to receive oxygen and nutrients from the placenta and bypass the non-functional fetal lungs and liver. These structures close or transform shortly after birth.

• 1. Umbilical Vein (1): Carries oxygenated, nutrient-rich blood from the placenta to the fetus. Postnatal Remnant: Becomes the Ligamentum Teres Hepatis (round ligament of the liver), found in the free edge of the falciform ligament.
• 2. Ductus Venosus: A shunt that allows a significant portion of oxygenated blood from the umbilical vein to bypass the fetal liver sinusoids and flow directly into the inferior vena cava (IVC). Postnatal Remnant: Closes shortly after birth and becomes the Ligamentum Venosum, a fibrous cord on the inferior surface of the liver.
• 3. Foramen Ovale: An opening between the right atrium and the left atrium of the fetal heart. It shunts most of the oxygenated blood entering the right atrium (from the IVC) directly into the left atrium, bypassing the pulmonary circulation (non-functional fetal lungs). Postnatal Remnant: Closes functionally soon after birth due to increased left atrial pressure (as pulmonary circulation starts). Anatomical closure occurs later, forming the Fossa Ovalis in the interatrial septum.
• 4. Ductus Arteriosus: A blood vessel connecting the pulmonary artery to the aortic arch. It shunts most of the blood pumped by the right ventricle away from the high-resistance fetal lungs directly into the aorta for systemic circulation. Postnatal Remnant: Constricts and closes shortly after birth (due to increased oxygen tension and decreased prostaglandins) and becomes the Ligamentum Arteriosum, a fibrous cord connecting the pulmonary trunk to the aorta.
• 5. Umbilical Arteries (2): Carry deoxygenated blood and waste products from the fetus back to the placenta. They arise from the internal iliac arteries. Postnatal Remnants: The proximal (closer to origin) parts remain patent as the superior vesical arteries (supplying the upper bladder). The distal parts constrict and obliterate, becoming the Medial Umbilical Ligaments, found on the anterior abdominal wall.
• 6. Placenta:The temporary organ of exchange between mother and fetus. It is expelled after birth.

Fetal circulation is adapted to the intrauterine environment where the placenta, not the lungs, is the site of gas exchange.

1. Oxygenated Blood from Placenta:Highly oxygenated and nutrient-rich blood flows from the placenta to the fetus through the single umbilical vein, which runs in the umbilical cord.
2. Bypass of Liver (Ductus Venosus):Upon entering the fetus, about half of the umbilical vein blood flows through the fetal liver sinusoids. The other half is shunted directly into the inferior vena cava (IVC) via the ductus venosus, thus bypassing much of the liver circulation. This allows highly oxygenated blood to reach the heart and brain more quickly.
3. Entry into Right Atrium and Shunt to Left Atrium (Foramen Ovale):The oxygenated blood from the ductus venosus mixes with deoxygenated blood returning from the lower body in the IVC. This mixed, but still relatively well-oxygenated, blood enters the right atrium. Most of this blood is shunted directly from the right atrium to the left atrium through the foramen ovale, an opening in the interatrial septum. This bypasses the right ventricle and pulmonary circulation.
4. Blood Flow from Left Atrium to Systemic Circulation:From the left atrium, the oxygenated blood passes into the left ventricle and is then pumped into the aorta. The branches of the aortic arch supply the heart muscle (coronary arteries), brain, and upper body with the most highly oxygenated blood.
5. Blood Flow from Right Atrium to Right Ventricle and Pulmonary Artery:A smaller amount of blood (mostly deoxygenated blood returning from the superior vena cava - SVC - draining the upper body) entering the right atrium passes into the right ventricle. This blood is then pumped into the pulmonary artery.
6. Bypass of Lungs (Ductus Arteriosus):Since the fetal lungs are non-functional and collapsed, pulmonary vascular resistance is very high. Only a small amount of blood from the pulmonary artery flows to the lungs (for nourishment). Most of the blood (about 90%) in the pulmonary artery is shunted through the ductus arteriosus directly into the descending aorta, bypassing the lungs. This blood mixes with the blood already in the aorta from the left ventricle.
7. Blood to Lower Body and Back to Placenta:The mixed blood in the descending aorta supplies the lower body of the fetus. Deoxygenated blood, along with fetal waste products, then returns to the placenta via the two umbilical arteries, which are branches of the fetal internal iliac arteries.
8. Exchange at the Placenta:In the placenta, carbon dioxide and waste products are transferred from fetal blood to maternal blood, and oxygen and nutrients are transferred from maternal blood to fetal blood, and the cycle repeats.

Changes at Birth: With the first breath, lung expansion decreases pulmonary vascular resistance, increasing blood flow to the lungs. Oxygen levels rise. This leads to functional closure of the foramen ovale (due to increased left atrial pressure) and ductus arteriosus (due to increased oxygen and decreased prostaglandins). Umbilical vessels constrict. The ductus venosus also constricts. These structures then gradually fibrose to become ligaments.

Answer: (Researched)

While this classification describes four main types, sometimes variations or mixed types are considered, hence "5 types" might refer to including a mixed category or a less common variant. The four classical types are based on the shape of the pelvic inlet:

• 1. Gynecoid Pelvis ("Female" Pelvis - approx. 50% of women): Inlet Shape: Rounded or slightly oval (transversely wide). Characteristics: Wide pubic arch (>90 degrees), adequate capacity in all planes, straight side walls, blunt ischial spines, shallow sacrum with good curve. Obstetric Significance: Most favorable type for vaginal delivery. Allows for easy engagement and passage of the fetal head.
• 2. Android Pelvis ("Male" Pelvis - approx. 20-30% of women): Inlet Shape: Heart-shaped or wedge-shaped (narrow anteriorly). Characteristics: Narrow pubic arch (<90 degrees), converging side walls, prominent ischial spines, straight and long sacrum, deep pelvic cavity. Obstetric Significance: Least favorable for vaginal delivery. Associated with difficult engagement, deep transverse arrest, increased likelihood of instrumental delivery or Cesarean section.
• 3. Anthropoid Pelvis (approx. 20-25% of women): Inlet Shape: Oval, with a long anteroposterior (AP) diameter and a shorter transverse diameter (like an ape's pelvis). Characteristics: Narrow pubic arch, adequate capacity in AP plane, straight or slightly diverging side walls, ischial spines may not be prominent, long and narrow sacrum. Obstetric Significance: Often leads to direct occipito-posterior (OP) or occipito-anterior (OA) engagement and delivery. Vaginal delivery is usually possible, but labor may be longer.
• 4. Platypelloid Pelvis ("Flat" Pelvis - rare, approx. 3-5% of women): Inlet Shape: Flattened oval, with a short anteroposterior diameter and a wide transverse diameter. Characteristics: Very wide pubic arch, divergent side walls, prominent ischial spines (can be), flat and short sacrum (often angulated sharply forward). Shallow pelvic cavity. Obstetric Significance: Fetal head may have difficulty engaging in the AP diameter. Transverse engagement often occurs. Associated with transverse arrest and increased need for Cesarean section.
• 5. Mixed Types:Most women do not have a "pure" pelvic type but rather a combination of features from different types (e.g., gynecoid-android, anthropoid-gynecoid). The obstetric outcome depends on which features predominate and the overall capacity of the pelvis relative to fetal size.

• 1. To Assess Pelvic Adequacy for Vaginal Delivery:Understanding pelvic anatomy, types, and key diameters helps the midwife clinically assess (pelvimetry) whether a woman's pelvis is likely to accommodate the passage of the fetal head during labor.
• 2. To Understand the Mechanism of Labour:Knowledge of pelvic planes and diameters is essential to understand how the fetal head navigates through the birth canal via cardinal movements (engagement, descent, flexion, internal rotation, extension, restitution, external rotation).
• 3. To Identify and Manage Cephalopelvic Disproportion (CPD):Allows the midwife to recognize signs suggesting a mismatch between fetal head size and pelvic capacity, which can lead to obstructed labor, and to make timely referrals.
• 4. To Interpret Findings from Vaginal Examinations During Labour:Understanding pelvic landmarks (e.g., ischial spines for station, sacrum, pubic arch) is crucial for accurately assessing labor progress (descent, position, rotation of fetal head).
• 5. To Anticipate and Manage Potential Labour Complications:Certain pelvic types (e.g., android, platypelloid) are associated with higher risks of malpositions, deep transverse arrest, or obstructed labor. Knowledge allows for increased vigilance.
• 6. To Advise on Maternal Positions During Labour and Delivery:Understanding how different maternal positions can alter pelvic diameters and facilitate fetal descent allows the midwife to guide the mother effectively (e.g., upright positions, squatting can increase pelvic outlet).
• 7. To Provide Appropriate Antenatal Counseling and Birth Planning:For women with borderline or abnormal pelves identified antenatally, the midwife can counsel them about potential labor challenges and help in planning the mode and place of delivery.
• 8. To Assist Safely with Instrumental Deliveries (if trained and authorized):Knowledge of pelvic anatomy is vital for the safe application of forceps or vacuum extractor.
• 9. To Understand Causes of Perineal Trauma:The relationship between the fetal head, pelvic outlet dimensions, and perineal stretching influences the risk of perineal tears.
• 10. To Educate Students and Colleagues:Midwives with good knowledge can teach and mentor others effectively.