Reproductive Physiology, Pathology & Behavioral Science

Puberty Sequence

• Menarche typically follows thelarche by roughly 2 years; average onset 11–14 years.
• Male puberty runs later on average (~two years behind girls, often noted around age 15) and is driven by rising testosterone: testicular/genital growth, increased hair distribution, deepening of the voice, nocturnal emissions, and a lean-to-muscular growth spurt.
• Precocious puberty = secondary sexual characteristics before age 8 (girls) or 9 (boys).
  • Central (GnRH-dependent): premature activation of the hypothalamic pulse generator — FSH/LH rise appropriately and drive gonadal steroid production. Most central cases are idiopathic/familial early activation of an otherwise normal axis rather than a sign of underlying pathology, though it still warrants evaluation given the psychosocial impact of early development.
  • Peripheral (GnRH-independent): gonadotropin-independent excess sex steroid from a gonadal/adrenal tumor or exogenous source; FSH/LH are suppressed.
  • Incomplete/partial precocious puberty: an isolated pubertal feature appears early without the full cascade — premature thelarche (isolated early breast budding), premature adrenarche (isolated early axillary hair), premature pubarche (isolated early pubic hair). These are generally benign and self-limited, not a sign of a central or peripheral process, but should be distinguished from true precocious puberty on exam.
• Delayed puberty = no secondary sexual characteristics by age 13 (girls) or 14 (boys). Two broad buckets: hypergonadotropic (1°) causes where the gonad itself has failed (Turner syndrome, Klinefelter syndrome, chemotherapy/radiation injury) vs. hypogonadotropic (2°) causes where the central drive is missing (constitutional delay — the most common cause, essentially "late blooming" with a family history of the same; Kallmann syndrome; CNS lesions).

Genitalia, pubic hair, and breast development are each staged independently — a given patient can be at different Tanner stages for different features simultaneously.

The HPO Axis, Step by Step

Mittelschmerz ("middle pain") is unilateral, mid-cycle pelvic pain from the follicular rupture itself and the peritoneal irritation from the small amount of bleeding it causes — usually mild, but can mimic appendicitis closely enough to confuse the picture.

Follicular vs. Luteal Phase

Hormone Functions to Memorize Cold

The Follicle's Histologic Life Cycle

• Each cycle, a cohort of follicles is recruited but only one normally reaches dominance — the rest undergo atresia (programmed regression), which is the fate of the overwhelming majority of a woman's lifetime follicle pool.
• After ovulation, the ruptured follicle's remaining granulosa/theca cells luteinize to form the corpus luteum, which secretes progesterone.
• Without hCG rescue, the corpus luteum degenerates into the corpus albicans — an inactive, fibrotic scar — as progesterone withdraws and menses begins.

Hormonal Handoff Across Gestation

Pregnancy Terminology & a Second Placental Hormone

• Fertilization happens in the ampulla of the fallopian tube, typically within a day of ovulation; implantation follows about 6 days later.
• Embryonic (developmental) age is measured from fertilization and is the convention used in embryology. Gestational age — the one used clinically — is measured from the first day of the last menstrual period, roughly two weeks earlier, since it doesn't require knowing the exact fertilization date.
• Gravidity is the total number of pregnancies a person has had; parity is the number of those pregnancies that reached ≥20 weeks of gestation — a multiple gestation (e.g., twins) still only counts as one pregnancy toward both.
• Human placental lactogen (hPL), also called chorionic somatomammotropin, is a growth-hormone/prolactin-like hormone from the syncytiotrophoblast that rises steadily across gestation (tracking placental mass, so it's higher in multiple gestations). It increases maternal lipolysis and insulin resistance, which shifts more glucose and free fatty acids toward the fetus — helpful in a normal pregnancy, but the same mechanism is what tips a mother with limited pancreatic reserve into gestational diabetes. It also supports breast development alongside estrogen and progesterone.

Lactation — Why Milk Doesn't Come In Until After Delivery

• Prolactin rises progressively across gestation and is the hormone that actually drives milk production, but the high estrogen and progesterone of pregnancy directly block prolactin's action on breast tissue — this is what keeps lactation suppressed until delivery.
• Once the placenta is delivered, estrogen and progesterone fall sharply, unblocking prolactin's effect → milk production begins.
• Prolactin also suppresses GnRH pulsatility, which is why exclusive, frequent breastfeeding delays return of ovulation postpartum (though it is not a fully reliable contraceptive method on its own).

Abnormal Placentation

Memory anchor: previa = "in the way" (painless); abruption = "torn away" (painful).

Ectopic Pregnancy

• Implantation outside the uterine cavity, overwhelmingly in the fallopian tube.
• Risk factors share a common theme of prior tubal damage: pelvic inflammatory disease/salpingitis, prior tubal surgery, prior ectopic, endometriosis.
• Classic triad: amenorrhea, unilateral pelvic pain, vaginal bleeding — with β-hCG that rises more slowly than expected for gestational age and no intrauterine pregnancy on ultrasound once hCG crosses the discriminatory threshold.
• Tubal rupture is a surgical emergency (hemoperitoneum).

Hypertensive Disorders of Pregnancy

Gestational Trophoblastic Disease

Both mole types can produce hCG-driven downstream effects: hyperthyroidism (hCG weakly cross-stimulates the TSH receptor), theca lutein cysts, hyperemesis gravidarum, and preeclampsia unusually early (before 20 weeks) — an early-preeclampsia presentation should always prompt consideration of a molar pregnancy.

Choriocarcinoma

• A rare, aggressive malignancy of trophoblastic tissue (both cytotrophoblast and syncytiotrophoblast elements) that, unlike a mole, contains no chorionic villi.
• Most often follows an abnormal pregnancy — a molar pregnancy or a miscarriage — but can also arise nongestationally as a germ cell tumor in the ovary or testis (see the oncology sections below).
• Presents with abnormal uterine bleeding and the same hCG-driven effects as a mole, plus dyspnea/hemoptysis from early hematogenous spread to the lungs ("cannonball" metastases on chest imaging).
• Treated with methotrexate, to which it's highly sensitive.

Gestational Diabetes

• Placental hormones (human placental lactogen, cortisol, progesterone) are physiologically diabetogenic — they antagonize insulin to spare glucose for the fetus; gestational diabetes occurs when maternal insulin secretion cannot compensate.
• Screened via glucose challenge in the second trimester, confirmed with a formal oral glucose tolerance test.
• Fetal risk: hyperglycemia crosses the placenta → fetal hyperinsulinemia → macrosomia, birth trauma, and rebound neonatal hypoglycemia after cord clamping removes the maternal glucose supply.

Congenital (TORCH) Infections

• A shared group of organisms that cross the placenta (or infect intrapartum) and cause fetal anomalies, most severe with first-trimester exposure: Toxoplasma gondii, other agents (syphilis, varicella, parvovirus B19, HIV, hepatitis B), Rubella, Cytomegalovirus, Herpes simplex virus.
• Herpes simplex is the outlier — transmission is typically intrapartum (through an infected birth canal) rather than transplacental, which is why active genital lesions at term prompt cesarean delivery.

Prenatal Screening & Diagnostic Testing — Full Timeline

Worth separating two categories: screening tests estimate risk from maternal blood/imaging without fetal sampling (safe, non-diagnostic), while diagnostic tests sample fetal/placental tissue directly (small procedural risk, but definitive).

Apgar Score — Newborn Transition Assessment

• Scored at 1 and 5 minutes after birth (repeated later if persistently low); each of five categories is scored 0, 1, or 2, for a maximum of 10.
• Categories: skin color, heart rate, reflex irritability, muscle tone, and respiratory effort.
• Purpose is to flag a newborn needing resuscitation/closer monitoring, not to predict long-term neurologic outcome — a low 1-minute score that improves by 5 minutes is reassuring.

Peripartum Emergencies

Neonatal Birth Weight

Combined Hormonal Contraceptives

• Estrogen component: suppresses FSH → prevents dominant follicle selection.
• Progestin component: suppresses the LH surge (blocks ovulation), thickens cervical mucus, and thins the endometrium.
• Non-contraceptive benefits: lighter/more predictable menses, reduced risk of ovarian and endometrial cancer, improved acne/hirsutism (antiandrogenic progestins).
• Major risk: venous thromboembolism, amplified by smoking plus age >35 — this combination is an absolute contraindication.
• Also avoid in migraine with aura, uncontrolled hypertension, and known thrombophilia.
• Less commonly tested but real adverse effects: benign hepatic adenomas (rare but classically linked to long-term combined OCP use) and increased risk of cholesterol gallstone formation from estrogen's effect on bile cholesterol saturation.

Progestin-Only Methods

• Mechanism relies primarily on cervical mucus thickening and endometrial thinning rather than reliable ovulation suppression (with oral progestin-only pills).
• Preferred over estrogen-containing options in breastfeeding, smokers >35, or a history of thrombosis.
• Long-acting reversible options (implants, injections, hormonal IUD) have the lowest failure rates of any reversible method — failure rates are driven by consistency of use, and these remove the user-error variable.

Emergency & Termination Agents

• Levonorgestrel (emergency contraception): works primarily by delaying/blocking ovulation — ineffective once ovulation has already occurred.
• Mifepristone: competitive progesterone-receptor antagonist → withdraws progesterone support from the endometrium/decidua, used for medical termination, typically paired with a prostaglandin (misoprostol) to promote expulsion.

Ovarian Tumors — Organize by Cell of Origin

• Risk rises with the total number of lifetime ovulations — early menarche, late menopause, nulliparity all increase risk, since each ovulation cycle is a chance for DNA damage at the site of follicular rupture — and with BRCA1/BRCA2 mutations or Lynch syndrome. Risk falls with anything that suppresses ovulation: prior pregnancy, breastfeeding, and oral contraceptive use.
• Ovarian cancer is often called a "silent killer" because early-stage disease rarely causes symptoms — by the time it presents (bloating, early satiety, pelvic pressure), it has frequently already spread within the peritoneal cavity, which is part of why it carries the worst prognosis of the major gynecologic cancers.

Cervical Neoplasia — A Progression, Not a Single Event

• Risk factors converge on persistent high-risk HPV exposure: early coitarche, multiple partners, immunosuppression, smoking (a cervical-specific cofactor).
• Squamous cell carcinoma is the dominant histology; adenocarcinoma is less common but not HPV-independent.
• Invasive disease spreads laterally through the parametrium before it spreads far by blood — this pattern lets it compress the ureters as they run nearby, causing hydronephrosis and, eventually, renal failure if bilateral and untreated.

Non-neoplastic Uterine Conditions

Uterine Body Tumors

Vulvar & Vaginal Tumors

• Squamous cell carcinoma of the vulva: HPV-related pathway (younger patients) vs. chronic vulvar dermatosis pathway (older patients, HPV-independent).
• Extramammary Paget disease of the vulva: intraepithelial adenocarcinoma cells in the epidermis — unlike breast Paget disease, usually not associated with an underlying invasive carcinoma.
• Clear cell adenocarcinoma of the vagina: linked to in utero diethylstilbestrol (DES) exposure — a classic teratogen-cancer link.
• Sarcoma botryoides (embryonal rhabdomyosarcoma): grape-cluster mass protruding from the vagina in young girls (<5 years).

Non-neoplastic Vulvar & Vaginal Conditions

Extragonadal Germ Cell Tumors

• Germ cell tumors can occasionally arise outside the gonads, in the midline structures the primordial germ cells pass through during their migration to the genital ridge — most often the retroperitoneum, mediastinum, or pineal/suprasellar region in adults.
• In infants and young children, the most common of these is the sacrococcygeal teratoma.

Benign Breast Disease

Breast Carcinoma — In Situ vs. Invasive

• Distinction hinges on whether tumor cells have breached the basement membrane.
  • Ductal carcinoma in situ: confined within the duct; comedo subtype shows central caseous-type necrosis; can progress to invasive disease if untreated.
  • Lobular carcinoma in situ: often an incidental biopsy finding rather than a palpable mass; a strong marker of increased future breast cancer risk in either breast, more than a direct precursor lesion.
• Invasive ductal carcinoma is the most common breast malignancy overall.
• Invasive lobular carcinoma classically infiltrates in a single-file pattern due to loss of the E-cadherin adhesion protein; more often multicentric/bilateral.
• Paget disease of the nipple: eczematous nipple/areolar change from malignant cells tracking up the ductal system — essentially always signals an underlying ductal carcinoma (unlike the vulvar counterpart).
• Inflammatory breast cancer: dermal lymphatic invasion causes peau d'orange skin changes; an aggressive presentation that can mimic mastitis.

• Epidemiology worth having cold: breast cancer is the most common cancer diagnosed in women, but lung cancer remains the leading cause of cancer death in women — breast cancer is second. Most tumors arise in the upper outer quadrant, which contains the greatest volume of glandular tissue.
• Male breast cancer exists but is rare (roughly 1% of all breast cancer cases); it still carries meaningful BRCA2 association and should not be dismissed when a male patient presents with a breast mass.

Penile Pathology

Benign Prostatic Hyperplasia vs. Prostate Carcinoma

Prostatitis

• Presents with dysuria, urinary frequency/urgency, low back pain, and a warm, tender, boggy prostate on exam — distinct from the firm/nodular exam of carcinoma.
• Acute bacterial prostatitis: E. coli in older men; consider C. trachomatis/N. gonorrhoeae in younger, sexually active men.
• Chronic prostatitis: may be bacterial (recurrent/inadequately treated infection) or nonbacterial (nerve irritation, chemical/inflammatory causes without a clear organism).

Scrotal Masses — Distinguish by Palpation Findings

Testicular Germ Cell Tumors

• Unlike the ovary, the great majority of testicular tumors are malignant and of germ cell origin.
• Seminoma: most common type; radiosensitive; painless testicular enlargement, typically confined and curable.
• Non-seminomatous tumors (embryonal carcinoma, yolk sac tumor, choriocarcinoma, teratoma) tend to be more aggressive and often occur as mixed tumors; yolk sac tumor and choriocarcinoma are again marked by AFP and β-hCG respectively.
• Unlike the ovary, a testicular teratoma is treated as malignant regardless of how histologically mature/well-differentiated its tissue looks — the same tumor type behaves very differently depending on which gonad it arises in.
• Sex cord-stromal tumors (Leydig, Sertoli cell) are usually benign and, when functional, present with hormone-driven findings (gynecomastia, precocious puberty); Leydig cell tumors have a distinctive histologic clue — intracytoplasmic Reinke crystals.
• Cryptorchidism raises germ cell tumor risk even after surgical correction — correction reduces but does not eliminate the risk, and also protects the contralateral (normally descended) testis by allowing surveillance.
• Primary testicular lymphoma (usually diffuse large B-cell): not a germ cell tumor at all, but it's the most common testicular malignancy in men over 60 — worth keeping in the differential for a testicular mass in an older man. Often bilateral and aggressive.

Because hCG and TSH share a structurally identical α-subunit, a very high hCG (as in choriocarcinoma) can weakly stimulate the TSH receptor and produce symptoms of hyperthyroidism.

Abnormal Uterine Bleeding — Causes by Category

The formal classification system (PALM-COEIN) splits causes into structural (Polyp, Adenomyosis, Leiomyoma, Malignancy/hyperplasia) and nonstructural (Coagulopathy, Ovulatory dysfunction, Endometrial, Iatrogenic, Not-yet-classified) categories — grouped here by that same underlying logic.

• Structural: polyps, leiomyomas (fibroids), adenomyosis
• Ovulatory dysfunction: anovulatory cycles (extremes of reproductive age, PCOS)
• Coagulopathy: von Willebrand disease, especially in adolescents
• Neoplastic: endometrial hyperplasia/carcinoma — always must be excluded in a woman >45 or with risk factors
• Pregnancy-related: miscarriage, ectopic pregnancy
• Iatrogenic: anticoagulants, IUDs, hormonal therapy

Polycystic Ovary Syndrome (PCOS)

• Diagnosis (Rotterdam-style, 2 of 3): oligo/anovulation, clinical or biochemical hyperandrogenism, polycystic ovarian morphology on ultrasound.
• Core mechanism: insulin resistance → hyperinsulinemia → amplifies LH-driven theca androgen production and lowers hepatic SHBG (raises free androgen) → disrupted follicular maturation.
• Labs: LH/FSH ratio elevated, mildly elevated testosterone/DHEAS, chronic unopposed estrogen (from anovulation) predisposes to endometrial hyperplasia.
• Management principle: address the underlying insulin resistance (weight loss, metformin) and tailor hormonal therapy to whether the patient desires fertility (ovulation induction) or not (combined contraceptives/progestin, antiandrogens for hirsutism).

Endometriosis

• Ectopic endometrial glands/stroma outside the uterine cavity, most often on the ovaries, that respond to cyclic hormonal signals just like eutopic endometrium.
• Cyclic bleeding into a closed space → hemosiderin-laden "chocolate cyst" (endometrioma), fibrosis, adhesions.
• Classic presentation: cyclic pelvic pain worst just before/during menses, dyspareunia, infertility.
• Definitive diagnosis is surgical/laparoscopic visualization; medical management suppresses ovulation (hormonal contraceptives, GnRH agonists) to reduce cyclic stimulation.

Approach to Amenorrhea

Functional Ovarian Cysts

Usually asymptomatic incidental findings, but can rupture, bleed, or predispose to adnexal torsion.

Primary Dysmenorrhea

• Painful menses driven by prostaglandin-mediated uterine contractions that transiently reduce endometrial blood flow (ischemic pain) — a normal physiologic process taken to an uncomfortable extreme, not a sign of underlying pelvic pathology.
• First-line treatment is an NSAID (directly targets the prostaglandin synthesis driving the pain) or hormonal contraception (suppresses ovulation and thins the endometrium).
• Distinguish from secondary dysmenorrhea, where pain is caused by an identifiable lesion such as endometriosis, adenomyosis, or fibroids.

Primary Ovarian Insufficiency, Expanded

• Premature depletion/atresia of ovarian follicles causing a menopause-like state before age 40, in someone who has already gone through puberty.
• Most cases are idiopathic, but it's worth a karyotype and autoimmune workup — it's associated with chromosomal abnormalities (Turner syndrome, the fragile X premutation) and autoimmune oophoritis.
• Labs mirror menopause: low estrogen with compensatory high LH and (especially) high FSH.

• Defined retrospectively after 12 consecutive months of amenorrhea; average age ~51.
• Mechanism: depletion of the finite ovarian follicle pool → falling estrogen/inhibin → loss of negative feedback → FSH rises first and most (used as the lab marker).

Hormone Replacement Therapy — Balancing Benefit and Risk

• Effective for vasomotor symptoms and genitourinary atrophy; reduces fracture risk.
• Unopposed estrogen is contraindicated with an intact uterus — must add a progestin to prevent endometrial hyperplasia/carcinoma; estrogen alone is appropriate only post-hysterectomy.
• Increased risk with combined therapy: venous thromboembolism, stroke, and (with long-duration combined use) breast cancer.
• Contraindicated in a personal history of hormone-sensitive cancer, active liver disease, or unexplained vaginal bleeding.

Genital Ulcer Disease — Painful vs. Painless

Cervicitis / PID Organisms & Other Common STIs

Genitourinary Infections That Are Not Sexually Transmitted

• Candida albicans vulvovaginitis: thick, curd-like discharge, often precipitated by antibiotic use, diabetes, or pregnancy rather than by sexual contact.
• Escherichia coli and Staphylococcus saprophyticus: leading causes of community-acquired urinary tract infection, arising from periurethral/fecal flora rather than transmission.
• Toxic shock syndrome: caused by Staphylococcus aureus exotoxin acting as a superantigen — it cross-links MHC class II and the T-cell receptor outside the normal antigen-binding groove, causing massive nonspecific T-cell activation and a cytokine storm; classically associated with prolonged tampon use, but can also follow any focal staphylococcal colonization/infection (wounds, nasal packing).

Hormone Modulators

Anabolic-Androgenic Steroid Abuse

• Exogenous testosterone derivatives increase muscle mass, strength, and recovery, but chronic use suppresses the hypothalamic-pituitary-gonadal axis the same way any external androgen does — negative feedback drives GnRH, LH, and FSH down, which in turn shuts down endogenous testosterone production and spermatogenesis.
• Suspect it in a young man presenting with the combination of infertility, unusually high muscle mass, small/atrophic testes, and gynecomastia (from peripheral aromatization of the excess androgen to estrogen) — small testes plus high muscle bulk is the tell, since natural high testosterone wouldn't shrink the testes.
• Other effects: acne, aggression/mood swings ("roid rage"), polycythemia, an adverse LDL/HDL shift that raises cardiovascular risk, premature epiphyseal closure in adolescent users, and hepatotoxicity (including hepatic adenoma) — particularly with orally active agents.
• In females: virilization (hirsutism, voice changes, clitoromegaly), menstrual irregularity, and decreased breast size.
• Recovery of the axis after stopping is typically slow, since the pituitary and testes both need time to resensitize.

Uterotonics & Tocolytics

Erectile Dysfunction Agents

• PDE-5 inhibitors (sildenafil, vardenafil, tadalafil): prevent breakdown of cGMP → sustained smooth muscle relaxation and corporal blood flow.
• Absolute contraindication: concurrent nitrate use — combined nitric-oxide-pathway potentiation can cause severe, potentially fatal hypotension.
• Other adverse effects: headache, flushing, blue-tinged vision (transient PDE-6 cross-inhibition), priapism.

Penile/Urethral Anomalies

Quick anchor: "ventral-hypo, dorsal-epi" — ventral starts with a consonant like hypospadias' h, dorsal pairs with epispadias' higher position.

Disorders of Sex Development (Intersex Conditions)

Aromatase Deficiency — the Mirror Image of AIS

• An autosomal recessive inability to synthesize estrogen. Fetal adrenal androgens that would normally be aromatized to estrogen by the placenta instead spill over and get converted to testosterone peripherally.
• Because fetal androgens can cross the placenta, this virilizes both a 46,XX female fetus (atypical genitalia at birth) and the mother carrying it (acne, hirsutism during that pregnancy) — a useful two-patient clue that distinguishes it from a fetal-only process like CAH.

Working Out a DSD From Labs and Exam Findings

Naming Convention You'll See on Older Exam Material

• These older labels are organized by gonadal sex, not by the appearance of the external genitalia:
  • Female pseudohermaphroditism: ovaries are present (46,XX), but external genitalia are virilized by androgen excess — the CAH picture above is the classic example.
  • Male pseudohermaphroditism: testes are present (46,XY), but external genitalia are incompletely masculinized because of deficient testosterone/AMH action — AIS and 5α-reductase deficiency both fall under this umbrella.
  • True hermaphroditism (distinct from either "pseudo" category): both ovarian and testicular tissue coexist in the same individual, with genuinely ambiguous genitalia — rare, usually 46,XX.
• Memory hook: "pseudo" means the gonads are unambiguously one sex — only the external appearance is ambiguous; "true" hermaphroditism means the gonadal tissue itself is mixed.

Uterine Fusion Defects

• Caused by incomplete fusion of the paired paramesonephric ducts.
• Spectrum: septate uterus (persistent internal septum) → bicornuate uterus (only the upper/superior portion fails to fuse) → uterus didelphys (complete failure, duplicated uterus/cervix).
• Associated with recurrent pregnancy loss and malpresentation.

Hypogonadotropic Syndromes

• Kallmann syndrome: failure of GnRH-neuron migration from the olfactory placode → isolated GnRH deficiency → low FSH/LH → absent puberty.
• Classic pairing: anosmia (or hyposmia) + failure of pubertal development — the olfactory bulb defect is a developmental marker, not the cause of the endocrine problem.

Testicular/Inguinal Anomalies

• Cryptorchidism: failure of testicular descent; most resolve by 1 year; persistent cases carry increased risk of infertility and germ-cell malignancy (even after later orchiopexy).
• Congenital (indirect) inguinal hernia: patent processus vaginalis allows bowel to herniate alongside the spermatic cord; strongly linked to cryptorchidism.

Grouped here because advanced maternal age is a shared risk driver and these are reliably tested alongside reproductive/prenatal topics — not because they are reproductive-organ disease per se.

Autosomal Trisomies — Ranked by Frequency at Birth

Sex Chromosome Aneuploidies

Repeat-Expansion & Imprinting Disorders

• Fragile X syndrome: CGG trinucleotide repeat expansion, X-linked; large jaw/ears, long face, macroorchidism after puberty; second most common genetic cause of intellectual disability overall (most common inherited cause — trisomy 21 is more common overall but usually non-inherited).
• Prader-Willi syndrome: deletion of paternal 15q11–13 (only the paternal copy is normally expressed here) → hyperphagia/obesity, hypotonia, hypogonadism.
• Angelman syndrome: deletion of the same region but on the maternal allele → ataxic gait, seizures, inappropriate laughter.

Venous & Lymphatic Drainage

• The right ovarian/testicular vein drains directly into the IVC. The left ovarian/testicular vein takes a longer route, draining first into the left renal vein before reaching the IVC — this asymmetry, combined with the left vein entering the renal vein at a sharper angle, is why varicoceles are overwhelmingly left-sided (see the male pathology section).
• Lymphatic drainage follows embryologic origin rather than final adult position:
  • Ovaries, fallopian tubes, and the uterine fundus (structures that started high in the abdomen) → para-aortic nodes.
  • Body of the uterus and cervix → external iliac nodes.
  • Cervix and proximal vagina (and, in males, the prostate) → internal iliac nodes.
  • Distal vagina and vulva (and, in males, the scrotum) → superficial inguinal nodes, since these structures develop from external genital tissue.
  • Glans of the clitoris/penis → deep inguinal nodes.
  • Testes drain to the para-aortic nodes (not the inguinal nodes) because they, too, originate high in the abdomen before descending — an important exception when staging testicular cancer.

Ligaments Supporting the Uterus & Ovary

Adnexal Torsion & Pelvic Organ Prolapse

• Adnexal torsion: the ovary and tube twist around the infundibulopelvic and utero-ovarian ligaments, compressing the low-pressure venous/lymphatic outflow first while arterial inflow continues — this produces ovarian edema that eventually chokes off arterial supply too, leading to necrosis if not corrected. Usually occurs in an ovary enlarged by a cyst or mass; presents with acute pelvic pain, nausea/vomiting, and an adnexal mass, and is a surgical emergency.
• Pelvic organ prolapse: herniation of pelvic organs toward or through the vaginal walls, associated with multiparity, aging, and obesity (all of which weaken pelvic floor support). Classified by which compartment bulges: anterior (bladder — cystocele, the most common), posterior (rectum — rectocele, or small bowel — enterocele), or apical (uterus, cervix, or vaginal vault itself). Presents with pelvic pressure/bulging, urinary frequency, constipation, and sexual dysfunction; procidentia describes prolapse severe enough to involve all three compartments.

Epithelial Lining, Segment by Segment

Seminiferous Tubules — Who Does What

Where the Sex Steroids Actually Come From

• Estrogens: the ovary makes estradiol (the most potent form), the placenta makes estriol (the least potent, but a useful marker of fetal well-being since it rises roughly 1000-fold across pregnancy), and peripheral adipose tissue makes estrone via aromatization of androgens — this is the main source of estrogen after menopause and part of why postmenopausal obesity raises endometrial/breast cancer risk. Potency ranks estradiol > estrone > estriol.
• Androgens: the testis is the main source of testosterone and DHT; the adrenal cortex is the main source of DHEA and androstenedione. Potency ranks DHT > testosterone > androstenedione > DHEA. Testosterone itself drives growth of the penis/seminal vesicles, deepening of the voice, the male growth spurt, and libido, and (after peripheral aromatization to estrogen) closure of the epiphyseal plates; DHT specifically drives early differentiation of the penis/scrotum/prostate and, later in life, prostate growth and androgenic hair patterning/alopecia.

Autonomic Control of Male Sexual Response

• Erection is parasympathetic (pelvic splanchnic nerves, spinal levels S2–S4) — nitric oxide raises cGMP, relaxing smooth muscle and allowing arterial inflow; PDE-5 inhibitors work by preventing cGMP breakdown along this same pathway.
• Emission (movement of sperm/seminal fluid into the urethra) is sympathetic (hypogastric nerve, T11–L2).
• Expulsion (ejaculation itself) involves both visceral and somatic fibers via the pudendal nerve.
• A simple anchor: parasympathetic "points," sympathetic "squeezes" (emission), and the pudendal nerve "shoots" (expulsion) — the same S2–S4 roots that mediate erection also maintain the tone that keeps the penis from resting against the perineum.

Descent of the Gonads

• Both gonads originate high in the abdomen (near the future kidney level) and descend guided by the gubernaculum.
• Testis: descends fully through the inguinal canal into the scrotum — its accompanying peritoneal outpouching (processus vaginalis) normally obliterates, leaving the tunica vaginalis.
• Ovary: descends only into the pelvis; the gubernaculum remnant becomes the ovarian ligament (proximal) and round ligament of the uterus (distal, traverses the inguinal canal).

Perineal & Pelvic Floor Anatomy

• The perineum is conventionally split by an imaginary line between the two ischial tuberosities into two triangles: the urogenital triangle anteriorly (contains the external genitalia and urogenital diaphragm) and the anal triangle posteriorly (contains the anal canal and external anal sphincter).
• The perineal body is a fibromuscular node at the midpoint between the two triangles — several pelvic floor muscles converge here, which is why it is the structure deliberately incised (episiotomy) or torn during vaginal delivery.
• The urogenital diaphragm is the muscular sheet (bounded by superior and inferior fascial layers) that the urethra — and in females, the vagina — pierces on the way to the surface; it is the structural floor separating the deep and superficial perineal spaces.
• Superficial perineal fascia is continuous across regions under different names depending on location: Scarpa's fascia (anterior abdominal wall) continues as Colles' fascia (perineum) and, in the male, as Buck's/dartos-associated fascia of the penis — a single anatomic plane, three regional names.
• Erectile bodies: corpus cavernosum (paired, dorsal, primarily responsible for rigidity) and corpus spongiosum (single, ventral, surrounds the urethra and forms the glans — stays softer to keep the urethra patent during erection).
• Bulbospongiosus and ischiocavernosus muscles overlie the erectile bodies and assist erection/ejaculation and (in females) vaginal introitus constriction.

Genitourinary Trauma

• Most often blunt trauma (e.g., a motor vehicle collision).
• Renal injury: presents with flank bruising, flank pain, and hematuria, typically from a direct blow or a lower rib fracture.
• Bladder injury: a direct blow to a full bladder (classically a seatbelt) can rupture the dome — the weakest point — spilling urine into the peritoneal cavity, where it gets reabsorbed and raises BUN/creatinine. A pelvic fracture can instead perforate the anterior wall/neck of the bladder, leaking urine into the extraperitoneal (retropubic) space.
• Urethral injury occurs almost exclusively in males and presents with blood at the meatus, hematuria, and difficulty voiding — urethral catheterization should be avoided until the injury is characterized.
  • Anterior urethral injury: a straddle injury tears the spongy urethra, causing a scrotal hematoma.
  • Posterior urethral injury: a pelvic fracture disrupts the urethra at its weakest point (the bulbomembranous junction), leaking urine into the retropubic space and displacing the prostate upward ("high-riding" on exam).

Genetic vs. Gonadal vs. Phenotypic Sex

• Three separate layers of "sex" — genetic (karyotype), gonadal (histology of the gonad), and phenotypic (external appearance) — can be discordant in disease states.
• Gonads are bipotential through week 6; SRY protein (on the Y chromosome short arm) triggers testis-determining pathway starting week 7.
• No SRY → gonad defaults to ovary — female development is the constitutive/default pathway, not an actively induced one.

Gametogenesis Timing — a Frequently Tested Contrast

A distinction worth keeping straight: primary ciliary dyskinesia (Kartagener syndrome) impairs the sperm tail's own motility, causing infertility directly. Cystic fibrosis, by contrast, leaves sperm tail motility normal — infertility there comes from a structural problem (congenital bilateral absence of the vas deferens) rather than a motility defect.

Week-by-Week Milestones of Early Development

Twinning

• Dizygotic ("fraternal") twins come from two separately fertilized eggs — always two separate placentas and two separate amniotic sacs, regardless of timing.
• Monozygotic ("identical") twins come from a single fertilized egg that splits; how early the split happens determines how much the twins end up sharing:
  • Split at days 0–4: separate chorion and amnion (dichorionic/diamniotic) — same as fraternal twins on imaging.
  • Split at days 4–8 (most common timing): shared chorion, separate amnions (monochorionic/diamniotic).
  • Split at days 8–12: shared chorion and shared amnion (monochorionic/monoamniotic) — higher-risk pregnancy.
  • Split at day 13 or later: incomplete separation → conjoined twins.
• Twin-twin transfusion syndrome: occurs only in monochorionic pregnancies, where unbalanced vascular connections in the shared placenta shunt blood from one twin (donor — becomes volume-depleted, low amniotic fluid, "stuck" appearance) to the other (recipient — volume-overloaded, excess amniotic fluid).

Placenta & Amniotic Fluid

• The placenta has a fetal side and a maternal side. On the fetal side, the cytotrophoblast is the inner, cell-generating layer of the chorionic villi, while the syncytiotrophoblast is the outer, hormone-secreting layer (source of hCG) — it lacks class I MHC expression, which is thought to help it evade the maternal immune system. On the maternal side, the decidua basalis is endometrium-derived tissue containing the blood-filled lacunae where maternal and fetal circulations exchange gas and nutrients without directly mixing.
• Amniotic fluid is produced mainly by fetal urination (plus some fetal lung fluid) and cleared mainly by fetal swallowing.
  • Polyhydramnios (too much fluid): seen when the fetus can't swallow normally — esophageal or duodenal atresia, anencephaly — or with maternal diabetes, fetal anemia, or a multiple gestation.
  • Oligohydramnios (too little fluid): seen when the fetus can't produce/excrete urine normally — placental insufficiency, bilateral renal agenesis, posterior urethral valves. Severe, prolonged oligohydramnios can cause Potter sequence (limb and facial deformities, pulmonary hypoplasia, from physical compression without enough fluid cushioning).
• The umbilical cord normally contains two arteries (carry deoxygenated blood back to the placenta) and one vein (carries oxygenated blood to the fetus). A single umbilical artery ("two-vessel cord") is a soft marker for other congenital/chromosomal anomalies and warrants a closer anatomy survey.

Teratogen Exposures Worth Knowing Cold

Neonatal abstinence syndrome (most often from opioid exposure) is a distinct, non-teratogenic consequence of maternal substance use: the newborn experiences withdrawal after birth — poor feeding, irritability, high-pitched crying, tremors — rather than a structural birth defect; treatment is supportive, sometimes with a tapering opioid such as methadone or morphine.

Umbilical & Vitelline Remnant Anomalies

• The urachus is the fetal connection between the bladder and the umbilicus (via the allantois); it should obliterate before birth into the median umbilical ligament. Incomplete closure produces a spectrum: total failure → urine draining from the umbilicus (patent urachus); partial failure → a fluid-filled urachal cyst that can become infected; slight failure → a small outpouching of the bladder (vesicourachal diverticulum).
• The vitelline (omphalomesenteric) duct connects the midgut to the yolk sac and normally closes around week 7. Its failure spectrum mirrors the urachus: total failure → meconium draining from the umbilicus; partial failure → a vitelline duct cyst (raises volvulus risk); slight failure → a Meckel diverticulum, a true outpouching of the ileum that's usually silent but can contain ectopic gastric or pancreatic tissue and bleed.

Developmental Frameworks Across the Lifespan

Freud's framework proposes that psychic energy (libido) concentrates in a different bodily zone at each stage, and that unresolved conflict at any stage can leave a lasting personality imprint — a theoretical model rather than an empirically validated developmental sequence, unlike Piaget's stages.

Infant Reflexes & Gross Motor Milestones

Postpartum Mood Changes

• "Baby blues": mild, self-limited low mood/tearfulness affecting roughly half of new mothers in the first couple weeks postpartum, driven by the abrupt hormonal shift plus sleep loss and role adjustment — resolves without treatment.
• Postpartum major depression: a smaller but clinically significant fraction of women develop true major depression after delivery, persisting beyond the transient blues and warranting active treatment — screening at postpartum visits is standard practice.

Early Attachment — Classic Developmental Experiments

• Harlow (rhesus monkeys): infants preferred a soft cloth surrogate over a wire surrogate that provided food — contact comfort, not just nutrition, drives attachment; prolonged isolation produced lasting social/behavioral deficits.
• Bowlby: formalized attachment theory — consistent, responsive caregiving in infancy predicts secure attachment and later relational functioning.
• Spitz: documented that infants deprived of adequate mothering/stimulation (e.g., in institutional settings) show developmental delay and increased susceptibility to illness.
• Mahler: described the infant's psychological journey from fusion with the mother toward an independent sense of self, moving through phases of increasing separation and individuation over the first few years.
• Anaclitic depression: a withdrawn, unresponsive state in an infant following prolonged separation from an established maternal attachment figure, roughly in the latter half of the first year.

Child Abuse — Recognition

• Risk factors cluster around caregiver stress and isolation: parental substance use, poverty, domestic conflict, single-parent households, unrelated male partner in the home.
• Physical abuse red flags: injuries inconsistent with the stated mechanism or the child's developmental stage, fractures in varying stages of healing, patterned bruising, delayed presentation for care.
• Sexual abuse red flags: genital/anal trauma, recurrent STIs or UTIs in a child, sexualized behavior inconsistent with age.
• Long-term sequelae: PTSD, dissociative symptoms, depression, disordered eating, personality pathology.
• Physicians are legally mandated reporters — reporting is required, not discretionary, once abuse is reasonably suspected.

Gender & Sexual Orientation — Definitions

• Gender identity: an individual's internal sense of their own gender.
• Gender expression/role: outward presentation of gender through behavior, dress, etc.
• Sexual orientation: the direction of romantic/sexual attraction — independent of gender identity.
• These three constructs are conceptually distinct and can vary independently of one another.

Sexual Response & Dysfunction

• Physiologic sexual response proceeds through excitement → plateau → orgasm → resolution.
• Erection depends on parasympathetic-mediated arteriolar dilation (nitric oxide/cGMP pathway) plus compression of venous outflow; ejaculation is a sympathetically mediated event.
• Distinguishing organic from psychogenic erectile dysfunction: preserved erections during sleep (nocturnal tumescence, associated with REM) point to a psychogenic cause, since the physical machinery is clearly intact.
• Common dysfunctions: premature ejaculation (most common male complaint), and difficulty with arousal/lubrication (most common female complaint); vaginismus (involuntary spasm of the outer vaginal musculature) is frequently linked to a history of sexual trauma.

Family Therapy — Core Concept

• Treats the family as an interdependent system rather than treating the symptomatic member in isolation — even if only one person carries a diagnosis, all members participate in sessions.
• Goals: identify maladaptive communication/behavior patterns that sustain the problem, and improve boundaries and problem-solving across the family unit.

Paraphilic Disorders

Defined by recurrent, intense sexual interest in atypical objects, situations, or nonconsenting others, of a degree that causes distress or risk of harm. The standard clinical categories: