OB lecture

Uterus

Size: The uterus is typically the size of a fist, around 7.5 cm long and 5 cm wide, but it can expand significantly during pregnancy while accommodating a growing fetus.

Functions:

Houses the fetus, amniotic fluid, and placenta during pregnancy.
Undergoes extensive adaptations, including significant stretching to accommodate a growing fetus, which can weigh around 7 pounds at full term.
Provides a nurturing environment for the developing fetus and expels it during childbirth through strong muscular contractions.

Ovaries:
Location: The ovaries are a pair of small, almond-shaped organs located on either side of the uterus. They are responsible for producing eggs (ova) and hormones such as estrogen and progesterone.

Fallopian Tubes:
The fallopian tubes are not directly attached to the ovaries but are equipped with fimbriae, which are finger-like projections that help guide the egg from the ovary to the uterus.

The movement of fimbriae is crucial for capturing the egg, and any failure in their function may lead to ectopic pregnancy, where the embryo implants outside the uterus, usually in the fallopian tube.

Uterine Anatomy

Fundus:
The fundus is the uppermost part of the uterus and is a key indicator of fetal growth stage, where its size correlates with the gestational age.

Body:
The body of the uterus is a triangular-shaped chamber, the largest part, and is where the fertilized egg implants and develops into a fetus.

Cervix:
The cervix serves as the opening of the uterus. It needs to remain open during menstruation for the exit of menstrual blood but becomes sealed during pregnancy when a mucus plug forms, providing a barrier to protect the fetus.

Vagina:
The vagina is a muscular tube that serves as the birth canal through which the baby is delivered and provides a passage for menstrual fluids. It is an elastic structure that can stretch significantly during childbirth.

Perineum:
The perineum is the tissue located between the anus and vagina; it is critically important during delivery to prevent tearing.

Careful guidance during delivery can help avoid tearing of this tissue, and perineal massage may be recommended in some cases to help stretch the tissue.

Menstrual Cycle Overview

Average length: The average menstrual cycle is approximately 28 days, though it can vary from 21 to 35 days among individuals.

Women living together may synchronize their cycles due to pheromonal interactions, a phenomenon often referred to as the cohabitation effect.

Menstruation:
Menstruation begins with the shedding of the endometrial tissue, during which approximately 60-80 mL of blood is lost. Following this, estrogen levels rise, causing the rebuilding of the endometrial lining in preparation for a possible pregnancy.

Ovulation occurs around day 14, when a mature egg is expelled from the ovary; if not fertilized, the egg disintegrates within about 24 hours, and the cycle begins anew.

Gravida, Para, and Abortions (GPA)

Gravida (G):
Refers to the total number of pregnancies a woman has had, regardless of the outcome.

Para (P):
Indicates the total number of births a woman has had after 20 weeks of gestation, regardless of whether the infants were born alive or stillborn.

Abortions (A):
This term refers to miscarriages or elective terminations prior to 20 weeks.

Example: A woman with the designation G2P1A1 has had 2 pregnancies total, with 1 live birth and 1 miscarriage.

Fetal Development in the Mother’s Body

Amniotic Sac:
The amniotic sac contains between 0.5 to 1 liter of amniotic fluid, crucial for fetal movement, development, and protection against physical injury.

It allows for growth and development while acting as a buffer against external pressures.

Placenta:
The placenta is a unique organ that grows only during pregnancy and attaches securely to the uterine wall. It serves as the interface for nutrient and oxygen exchange between the mother and fetus, providing essential blood and nutrients while filtering waste.

After birth, it detaches from the uterus, potentially leaving scars that may affect future pregnancies.

Umbilical Cord:
The umbilical cord connects the placenta to the fetus and is generally about 22 inches long.

It contains one vein responsible for carrying oxygenated blood to the fetus and two arteries that remove deoxygenated blood.

Fetal Circulation:
Fetal circulation is designed to bypass the lungs, as they are non-functional until birth. Critical changes in this circulation system occur immediately after delivery to adapt to breathing air.

Fraction of Attention on Pregnancy

Trimester Division:

First Trimester (1-12 weeks): This is a critical phase for development; exposure to harmful substances like alcohol, tobacco, and drugs during this time can lead to congenital disabilities and other complications.
Second Trimester (13-26 weeks): Continues the phase of further development, with significant growth in fetal size and organs, where many women can begin to feel fetal movement.
Third Trimester (27-40 weeks): This is marked by significant weight gain, where the fetus typically triples in weight, and prepares for birth, with organ systems maturing further.

Pregnancy-Related Health Issues

Ectopic Pregnancy:
This condition occurs when a fertilized egg implants outside the uterus, typically in a fallopian tube. It can lead to serious complications like internal bleeding, requiring immediate medical intervention.

Placenta Previa:
A condition where the placenta covers the cervix, necessitating a cesarean section (C-section) to prevent severe bleeding during delivery, which can be life-threatening for both mother and baby.

Abruption Placenta:
This occurs when the placenta separates prematurely from the uterine wall, leading to significant bleeding and severe abdominal pain, posing risks to both maternal and fetal health.

Preeclampsia:
Characterized by elevated blood pressure and presence of protein in the urine, it can develop into a more severe condition (eclampsia), which may lead to seizures and has significant risks for both mother and baby if untreated.

Labor Stages

First Stage:
The labor process begins with the dilation and effacement of the cervix, allowing it to open to a maximum of 10 cm.

Contractions start slowly, intensifying in frequency and strength, requiring careful assessment throughout this stage.

Second Stage:
This stage involves the actual delivery of the baby after full dilation of the cervix is reached.

The mother may experience a strong urge to push, while the healthcare provider offers support and guidance to ensure a safe delivery.

Third Stage:
The final stage involves the expulsion of the placenta shortly after the baby is born, ensuring complete delivery and safeguarding maternal health.

Apgar Scoring

The Apgar score is a quick assessment performed on newborns at 1 and 5 minutes post-delivery, based on five criteria, each scoring from 0 to 2 points:

Appearance: Color of the baby
Pulse: Heart rate
Grimace: Response to stimuli
Activity: Muscle tone
Respiration: Breathing effort
Total scores range from 0 to 10, where:
Scores of 0-3 indicate critical care is needed.
Scores of 4-6 indicate monitoring and stimulation are essential.
Scores of 7 and above are generally healthy.

Newborn Resuscitation Protocol

Key points of management in newborn resuscitation include:

Keep the newborn warm to prevent hypothermia, a common issue that can arise shortly after birth.
Suctioning may be necessary if there is meconium present in the airways to clear them for effective breathing.
Providing stimulation by drying the baby off can significantly improve circulation and heart rate.
If the newborn's heart rate is below 60 beats per minute, immediate initiation of CPR is crucial.
If the Apgar score is low, implementing appropriate interventions as per medical guidelines is critical to ensuring the newborn’s health.

Conclusion

Awareness and understanding of the physiological, anatomical, and medical intricacies during pregnancy, labor, and postpartum care are essential for ensuring safety and effectiveness in obstetric care, ultimately promoting better health outcomes for both mothers and their newborns.