Second Trimester

Second Trimester Symptoms and Milestones

• Physical and Physiological Symptoms:

  • Appetite: Marked increase in appetite.

  • Abdomen: Abdominal expansion and expanding waistline.

  • Fetal Movement: Onset of perceptible fetal movements.

  • Skin Changes: Abdominal skin stretches, feeling tight and itchy; formation of stretch marks (striae gravidarum); brown patches on the face known as chloasma ("mask of pregnancy"); darkening of the areolas (darker skin around the nipples).

  • Ligament Aching: Aching pain on either side of the lower abdomen caused by the stretching of uterine support ligaments (round ligament pain).

  • Mucosal and Vascular Changes: Nasal congestion/problems, bleeding or swollen gums, dizziness, and leg cramps.

  • Breasts: Breast enlargement.

  • Respiratory System: Shortness of breath as the uterus grows.

  • Uterine Activity: Braxton Hicks contractions.

  • Infections and Discharge: Increased susceptibility to bladder and kidney infections; changes in vaginal discharge.

• Developmental and Clinical Milestones:

  • Quickening (First Fetal Movement Perception):

  • First pregnancy: Perceived at $20\text{--}22\,\text{weeks}$.

  • Subsequent pregnancies: Perceived at $16\text{--}20\,\text{weeks}$.

  • Rapid Fetal Growth: Period of rapid growth and organ maturity.

  • Gender Identification: Fetal sex becomes identifiable via ultrasound at $14\text{--}15\,\text{weeks}$.

  • Maternal Symptom Resolution: Significant improvement in nausea and vomiting (N&V) and noticeable surge in maternal energy.

Quad Screen Test

• Definition and Overview:

  • A prenatal maternal serum screening test that measures four specific substances in a pregnant woman's blood to evaluate the statistical risk of certain structural and chromosomal fetal birth defects.

  • Conditions Screened:

  • Down Syndrome (Trisomy 21)

  • Trisomy 13

  • Trisomy 18 (Edwards Syndrome)

  • Neural Tube Defects (NTD)

  • Screening Rate: Offered to all pregnant women, with an approximate $80\%$ uptake rate.

• High-Risk Indications:

  • Maternal age $> 35\,\text{years}$.

  • Prior history of giving birth to an infant with a chromosomal abnormality.

  • Family history of genetic abnormalities.

  • Pre-existing Type I diabetes.

• Timing:

  • Most accurate between $15\text{--}22\,\text{weeks}$ of gestation.

  • Optimal window for testing: $16\text{--}18\,\text{weeks}$.

• Biomarkers and Interpretation:

  • Alpha-Fetoprotein (AFP):

  • High AFP: Associated with neural tube defects (e.g., spina bifida, anencephaly), inaccurate gestational dating, or multiple gestations.

  • Low AFP: Associated with an increased risk of chromosomal abnormalities.

  • Human Chorionic Gonadotropin (hCG):

  • Combination of Low AFP, High hCG, and Low uE3 indicates an increased risk of Down syndrome.

  • Unconjugated Estriol (uE3):

  • Produced directly by the fetus.

  • Low levels indicate potential chromosomal defects (Down syndrome, Trisomy 13, Trisomy 18).

  • Inhibin-A:

  • Hormone produced by the placenta that serves as a functional marker of fetal health.

  • Elevated levels indicate an increased risk of Down syndrome.

  • Low Levels Across All Biomarkers: Suggests an elevated risk of Trisomy 18 (Edwards syndrome).

• Risk Thresholds and Follow-up:

  • The Quad screen is strictly a screening tool, not a definitive diagnostic test. Abnormal results require secondary diagnostic testing (such as amniocentesis or chorionic villus sampling [CVS]) to confirm a diagnosis.

  • Down Syndrome Risk Estimate Cutoff:

  • Screen Negative: Calculated risk $< 1/270$.

  • Screen Positive: Calculated risk $\ge 1/270$.

  • Trisomy 18 Risk Estimate Cutoff:

  • Screen Negative: Calculated risk $< 1/100$.

  • Screen Positive: Calculated risk $\ge 1/100$.

• Nursing Considerations:

  • Provide clear patient education on the distinction between screening and diagnostic tests.

  • Explain that results are adjusted for and influenced by maternal age, maternal weight, and accurate gestational age.

  • Facilitate referrals for genetic counseling and provide emotional support during risk evaluation.

Maternal Serum Alpha-Fetoprotein (AFP) Screening

• Mechanism and Physiology:

  • Alpha-fetoprotein is an oncofetal glycoprotein synthesized by the fetal liver.

  • Measured via maternal blood sampling between $15\text{--}20\,\text{weeks}$ of gestation ($16\text{--}18\,\text{weeks}$ optimal).

  • Neural tube defects cause exposed fetal tissue to leak increased amounts of AFP into amniotic fluid, which subsequently enters the maternal bloodstream via the placenta.

  • Placental dysfunction or physical damage allows elevated amounts of fetal AFP to cross into maternal blood circulation.

  • Offered to every pregnant patient; particularly useful when ultrasound visualization is sub-optimal or obstructed.

• Predictive Capabilities of Maternal Serum AFP:   

  

  • Obstetrical Problems and Pregnancy Complications:

  • Morbidly adherent placenta

  • Placenta accreta spectrum

  • Placental abruption

  • Placental necrosis

  • Placental insufficiency

  • Intrauterine growth restriction (IUGR)

  • Preterm birth

  • Preeclampsia

  • Fetal Anomalies Associated with Elevated (High) AFP:

  • Neural tube defects

  • Pulmonary dysplasia

  • Ventral abdominal wall defects

  • Fetal cancer

  • Fetal Anomalies Associated with Decreased (Low) AFP:

  • Aneuploidies (e.g., Down syndrome)

  • Congenital heart defects

  • Sudden infant death syndrome (SIDS)

Amniocentesis

• Procedure Overview:   

  

  • An invasive diagnostic procedure in which a hollow needle is inserted through the abdominal wall and uterus into the amniotic cavity under continuous ultrasound guidance to aspirate amniotic fluid.

  • Standard gestational timing: $15\text{--}20\,\text{weeks}$.

  • Performed in approximately $5\text{--}10\%$ of pregnant women.

• Standard Indications:

  • Advanced maternal age ($> 35\,\text{years}$), which carries a significantly increased risk for meiotic non-disjunction in maternal oocytes.

  • Family history of inherited genetic disorders.

  • Positive/abnormal serum screening results (e.g., Quad screen).

  • Structural fetal abnormalities identified on ultrasound.

  • Suspected intra-amniotic or fetal viral infection.

• Late Amniocentesis ($> 24\,\text{weeks}$):

  • Indications:

  • Polyhydramnios (therapeutic amnioreduction).

  • Fetal demise: Evaluates maceration of fetal tissue following death (enzymatic autolysis of cells and degeneration of connective tissue makes amniotic fluid easier to test).

  • Assessment of fetal lung maturity (e.g., in pregnancies complicated by maternal diabetes to determine delivery timing).

  • Procedural Modifications for Late Amniocentesis:

  • Patient is not placed in a completely flat supine position.

  • Patient must empty her bladder immediately prior to the procedure to minimize the risk of accidental bladder puncture.

• Procedure-Related Risks:

  • Miscarriage: Elevated risk if performed at $< 15\,\text{weeks}$; overall risk is $< 1\%$ when performed in the second trimester.

  • Infection: Pathogen transmission from mother to fetus or introduction of ambient/skin pathogens into the sterile amniotic cavity.

  • Bleeding: Maternal or fetal hemorrhage.

  • Preterm Labor: Induction of uterine contractions and labor.

  • Rh Isoimmunization: Feto-maternal hemorrhage causing blood mixing; requires post-procedure prophylaxis.

  • Direct Needle Injury: Mechanical trauma to the fetus or umbilical cord.

  • Placental Abruption: Disruption of the placental interface.

  • Amniotic Fluid Embolism (AFE): Extremely rare complication ($2$ documented cases in the past $55\,\text{years}$).

• Nursing Considerations:

  • Administer RhoGAM (Rho(D) immune globulin) to all Rh-negative, non-sensitized women.

  • Post-Procedure Monitoring: Monitor mother and fetus continuously for $1\,\text{hour}$ post-procedure for:

  • Heavy vaginal bleeding

  • Uterine cramping or abdominal pain

  • Maternal fever

  • Alterations in fetal heart rate (FHR)

  • Amniotic fluid leakage

  • Signs of infection at the needle insertion site

  • Discharge Instructions: Instruct patient to immediately report any clear vaginal fluid leakage, vaginal bleeding, severe abdominal pain, or systemic flu-like symptoms (fever, chills, muscle aches).

Ultrasound Testing

• Clinical Indications and Diagnostic Uses:

  • Gross Anatomy Survey: Comprehensive evaluation of major fetal organ systems to identify structural malformations.

  • EDC Confirmation: Confirmation of estimated date of confinement (most precise when performed in the first trimester).

  • Fetal Growth: Longitudinal biometry to track growth velocity.

  • Umbilical Cord Evaluation: Identification of insertion site and vessel count.

  • Placental Localization: Mapping of placental placement to rule out placenta previa (may require serial ultrasound scans).

  • Gender Identification: Anatomical identification of fetal sex.

  • Fetal Well-Being: Component of the Biophysical Profile (BPP) performed in the third trimester.

Cervical Incompetence and Cerclage Management

• Cervical Incompetence (Cervical Insufficiency):

  • Definition: Structural weakness resulting in premature, painless dilation and effacement of the cervix during the second trimester, leading to recurrent mid-trimester spontaneous abortion or preterm delivery.

  • Incidence: Occurs in $0.5\%$ of the general obstetric population and $8\%$ of women with a history of prior mid-trimester pregnancy loss.

  • Etiology and Risk Factors:

  • Cervical trauma (history of cervical lacerations during prior labor and delivery, mechanical cervical dilation during surgical procedures).

  • Multiple gestations (increased intrauterine pressure).

  • Genetic predisposition and connective tissue disorders.

  • Congenital uterine/cervical structural anomalies (e.g., irregularly shaped cervix or uterus).

  • Diagnostic Evaluation:

  • Clinical history of painless second-trimester cervical dilation.

  • Endovaginal Ultrasound Findings: Transvaginal cervical length measurement $< 25\,\text{mm}$ at or before $24\,\text{weeks}$ of gestation, cervical funneling (beaking of internal os), and progressive cervical effacement.     

    

  • Clinical Symptoms:

  • Pelvic/vaginal pressure

  • Light vaginal bleeding or spotting

  • Lower back ache

  • Mild uterine cramping or abdominal discomfort

  • Sudden change in the volume or character of vaginal discharge

• Cervical Cerclage Treatment:

  • Surgical placement of a purse-string suture or synthetic tape around the cervix to maintain structural integrity.

  • Performed in $< 1\%$ of pregnancies; successfully prevents preterm delivery in $50\text{--}70\%$ of selected high-risk cases.

  • Administered under local or regional anesthesia. A needle is passed through cervical tissue to reinforce the internal os.

  • Common surgical technique: McDonald (4-step) method.

  • Primary Goal: Maintain mechanical cervical closure until term ($37\,\text{weeks}$ ).

• Post-Cerclage Surgical Complications:

  • Vaginal bleeding

  • Intra-amniotic or cervical infection

  • Uterine contractions

  • Premature Rupture of Membranes (PROM), especially when membranes are exposed or bulging prior to placement

  • Cervical lacerations

  • Uterine trauma

  • Increased vaginal discharge and severe pelvic pain

• Nursing Considerations for Cerclage:

  • Continuous post-operative monitoring of uterine contraction activity and fetal heart rate (FHR).

  • Pharmacotherapy Administration:

  • Antibiotics: Not routinely indicated; administered if fetal membranes were exposed or visible prior to closure.

  • Tocolytics: Not routinely administered; utilized selectively if the patient exhibits symptoms of active preterm labor.

  • Analgesics: Acetaminophen (Tylenol) as needed for pain management.

  • Patient Post-Procedure Education: Instruct patient to immediately report signs of vaginal bleeding, regular uterine contractions, maternal fever, fluid leakage (ROM), or severe abdominal pain.

  • Cerclage Removal:

  • Elective removal performed at $36\text{--}37\,\text{weeks}$ of gestation, or emergently upon the onset of active labor or PROM.

  • Anesthesia is typically not required for suture removal.

  • Post-removal clinical monitoring is required to assess for contractions and evaluate FHR.