Obstetrics and Gynecology Clerkship Guide

Succeeding in your OB/GYN clerkship requires a unique blend of surgical assist skills, outpatient counseling acuity, and the ability to manage high-stakes emergencies for two patients simultaneously. This rotation immerses you in the full spectrum of reproductive health, from routine preventive care to the dynamic process of labor and delivery. Mastering the core clinical algorithms and communication skills here is not only essential for your shelf exam but foundational for virtually any field of medicine you choose to pursue.

Prenatal Care and Antepartum Management

Prenatal care is a structured process designed to optimize outcomes for the pregnant person and the fetus. The initial prenatal visit is comprehensive, involving a full history, physical exam, and a battery of tests. You must calculate the estimated date of delivery (EDD) using Naegele’s rule: take the first day of the last menstrual period (LMP), subtract 3 months, and add 7 days. For example, if the LMP was May 20, the EDD is February 27. This visit also establishes baseline labs, including blood type, antibody screen, complete blood count, and infectious disease testing.

Subsequent visits follow a standard schedule: every 4 weeks until 28 weeks, every 2 weeks until 36 weeks, and then weekly until delivery. At each visit, you will assess key parameters: maternal weight, blood pressure, fundal height (in centimeters, which should roughly equal the gestational age in weeks after 20 weeks), and fetal heart tones. A critical skill is fetal heart monitoring (FHR) interpretation, initially with a Doppler. You must identify the baseline FHR (110-160 bpm), note variability (moderate variability is reassuring), and recognize accelerations (indicative of fetal well-being). Understanding these fundamentals is crucial before advancing to electronic fetal monitoring in labor.

Labor, Delivery, and the Postpartum Period

Labor is divided into three distinct stages. The first stage begins with regular, painful contractions and cervical change and ends with full cervical dilation (10 cm). It has a latent phase (slow cervical dilation) and an active phase (more rapid dilation, typically ≥ 6 cm). The second stage is from complete dilation to delivery of the baby. Here, you will learn to assist with both spontaneous vaginal delivery and operative deliveries (vacuum, forceps). Key maneuvers include supporting the perineum, guiding the fetal head through restitution and external rotation, and clamping/cutting the umbilical cord.

The third stage involves delivery of the placenta, usually within 30 minutes. Active management with gentle traction on the cord and uterine fundal massage reduces the risk of postpartum hemorrhage. Immediately postpartum, you will participate in the “golden hour,” focusing on maternal-infant bonding and monitoring for immediate complications. Your role includes assessing uterine tone (a boggy uterus is a red flag), monitoring vital signs, and estimating blood loss—visual estimates are consistently low, so practice quantitative measurement.

Managing Common Pregnancy Complications

You will encounter several high-priority complications. Preeclampsia is new-onset hypertension ($\ge$140/90 mm Hg) after 20 weeks gestation with proteinuria or other end-organ dysfunction (e.g., thrombocytopenia, elevated liver enzymes, severe headache). It is a systemic disease of endothelial dysfunction. The definitive treatment is delivery, but before term, management focuses on controlling severe-range blood pressures (typically with labetalol or hydralazine) and preventing seizures with intravenous magnesium sulfate, which is both a potent anticonvulsant and a tocolytic.

Gestational diabetes mellitus (GDM) is carbohydrate intolerance first recognized in pregnancy. Screening is typically performed between 24-28 weeks with a 1-hour 50-g glucose challenge test, followed by a diagnostic 3-hour 100-g oral glucose tolerance test if positive. Management starts with medical nutrition therapy and glucose monitoring; insulin is the first-line pharmacologic agent if needed. Uncontrolled GDM carries risks of fetal macrosomia, shoulder dystocia, and neonatal hypoglycemia.

Core Gynecologic Health and Preventive Care

A major component of outpatient gynecology is preventive care and counseling. Cervical cancer screening follows specific guidelines: for average-risk patients aged 21-29, a Pap smear (cytology) alone every 3 years. For those 30-65, co-testing (Pap + HPV test) every 5 years is preferred. You must be able to counsel patients on abnormal results, such as ASC-US or LSIL, and understand the follow-up protocols, which may involve colposcopy and biopsy.

Contraception counseling requires a patient-centered approach. You should be familiar with the efficacy, mechanism, and non-contraceptive benefits of all major methods: long-acting reversible contraceptives (LARCs) like IUDs and implants (highest efficacy), hormonal methods (pills, patch, ring, injection), barrier methods, and fertility awareness-based methods. The key is to assess the patient’s goals (e.g., pregnancy timing, menstrual regulation) and contraindications (e.g., history of blood clots for estrogen-containing methods) to guide shared decision-making.

Recognizing and Responding to Gynecologic Emergencies

Speed and accuracy are critical in OB/GYN emergencies. A ectopic pregnancy is a pregnancy implanted outside the uterine cavity, most commonly in the fallopian tube. The classic triad is abdominal pain, vaginal bleeding, and an adnexal mass, but many presentations are subtle. It is a diagnosis you must actively rule out in any reproductive-age person with abdominal pain and a positive pregnancy test. Transvaginal ultrasound is diagnostic, showing an empty uterus with a beta-hCG level above the discriminatory zone (typically 1500-2000 mIU/mL). Management can be medical (with methotrexate) or surgical (salpingectomy), depending on stability and patient wishes.

Other critical emergencies include postpartum hemorrhage (remember the causes: Tone, Trauma, Tissue, Thrombin), shoulder dystocia (master the HELPERR mnemonic: Help, Episiotomy, Legs, Pressure, Enter, Remove, Roll), and ovarian torsion, which presents with severe, acute unilateral pelvic pain and requires urgent surgical intervention to salvage the ovary.

Common Pitfalls

• Misinterpreting Fetal Heart Tracings: The most common error is overreacting to benign variable decelerations or mislabeling early decelerations as concerning. Remember, late decelerations (which onset after the peak of a contraction and have a slow return to baseline) are the pattern most associated with uteroplacental insufficiency and require intervention.
• Failing to Quantify Blood Loss: Visually estimating 500 mL of blood on soaked laparotomy sponges and drapes is difficult. Consistently underestimating leads to delayed resuscitation. Make it a habit to verbally state, "Estimated blood loss is..." and use quantitative measures when possible (e.g., weighing sponges).
• Inadequate Counseling: Simply listing contraceptive options is not counseling. A pitfall is not exploring the patient’s lifestyle, preferences, and concerns. Effective counseling involves asking, "What is most important to you in a birth control method?" and tailoring the discussion from there.
• Delaying the Workup for Ectopic Pregnancy: In a stable patient with a pregnancy of unknown location (positive hCG, no intrauterine pregnancy on ultrasound), the pitfall is discharging without a clear plan. You must ensure close follow-up for repeat hCG levels in 48 hours. A rise that is suboptimal (<53%) or a plateau is highly suspicious for an ectopic pregnancy.

Summary

• Prenatal care is structured and revolves around serial assessment of maternal and fetal well-being, with accurate dating being foundational.
• Labor progresses through three stages; competence in interpreting fetal heart monitoring and assisting with delivery mechanics is a core clinical skill.
• Preeclampsia (managed with magnesium sulfate and delivery) and gestational diabetes are two major pregnancy complications requiring prompt recognition and protocol-driven management.
• Outpatient gynecology centers on preventive screening using current cervical cancer guidelines and providing patient-centered contraception counseling.
• Gynecologic emergencies like ectopic pregnancy and postpartum hemorrhage demand an immediate, systematic approach to diagnosis and treatment to prevent morbidity.