Clinical overview
Sagittal pelvic relationships: uterus between bladder and rectum, with the posterior fornix below the pouch of Douglas.
Surgical anatomy is the substrate every gynaecological operation, ultrasound, and clinical decision sits on. A registrar who cannot name what lies one centimetre lateral to the ureter at the level of the uterine artery, or who confuses the rectovaginal septum with the pouch of Douglas, is one slip away from injury. This chapter contrasts the normal anatomy you must know cold with the common abnormal patterns (developmental, acquired, oncological) that change the operative field — because in real practice you almost never operate on textbook anatomy.
The female genital tract develops from the paramesonephric (Müllerian) ducts. Disorders along that developmental axis (agenesis, fusion, septation) account for most congenital abnormalities and frequently coexist with renal tract anomalies. Acquired distortion — fibroids, endometriosis, adhesions from previous surgery or pelvic infection, malignancy — is the more frequent operative reality.
Core knowledge
Uterine supports and the water-under-the-bridge relationship: the uterine artery crosses the ureter near the cervix.
External genitalia (vulva). Mons pubis, labia majora (homologous to scrotum), labia minora (which split anteriorly into the prepuce and frenulum of the clitoris), clitoris (glans, body, two crura), vestibule (containing the urethral and vaginal openings, paraurethral Skene's glands, and bilateral Bartholin's glands at 4 and 8 o'clock). Innervation is mostly pudendal (S2–S4); the anterior vulva receives ilioinguinal and genitofemoral branches.
Vagina. Fibromuscular tube ~7–9 cm posterior wall, ~6–8 cm anterior, with four fornices (anterior, posterior, two lateral). The posterior fornix lies directly below the pouch of Douglas — relevant for culdocentesis and for posterior colpotomy access. Lower third drains to inguinal nodes; upper two-thirds to internal/external iliac nodes (important for vulval-carcinoma and vaginal malignancy staging).
Uterus. Body, isthmus, cervix. Three layers: endometrium, myometrium, perimetrium (serosa). Anteverted-anteflexed in ~80%, retroverted in ~20%. Supported by:
- Cardinal (Mackenrodt's) ligaments — main lateral support, carry uterine vessels.
- Uterosacral ligaments — pass posterolaterally to S2–S4; carry sympathetic and parasympathetic supply.
- Round ligaments — through inguinal canals to labia majora; little support, useful surgical landmarks.
- Broad ligaments — peritoneal folds, not true ligaments.
Cervix. Portio vaginalis (visible at colposcopy), portio supravaginalis. Transformation zone is where columnar endocervical epithelium meets squamous ectocervical epithelium — the site of HPV-driven dysplasia. See hpv-pathology, cin-pathophysiology.
Fallopian tubes. Interstitial, isthmus, ampulla, infundibulum (with fimbriae). Fertilisation occurs in the ampulla. Tubal disease is implicated in ~50% of ectopic-pregnancy-management cases.
Ovaries. ~3 × 2 × 1 cm in reproductive age, smaller post-menopausally. Suspended by the suspensory (infundibulopelvic) ligament containing ovarian vessels — the key vascular pedicle to control in oophorectomy.
Vascular supply.
- Uterus: uterine artery (branch of anterior division of internal iliac).
- Ovary: ovarian artery (direct from aorta, just below renal arteries).
- The uterine artery crosses anterior to the ureter ~1.5–2 cm lateral to the cervical isthmus — the famous "water under the bridge." This is where ureteric injury most commonly occurs at hysterectomy.
Ureter course. Crosses the pelvic brim anterior to the bifurcation of the common iliac, runs along the medial leaf of the broad ligament, passes under the uterine artery, then anteromedially into the bladder. Three high-risk operative sites: pelvic brim (oophorectomy), under uterine artery (hysterectomy), at vaginal angle (colporrhaphy).
Lymphatic drainage.
- Vulva → superficial then deep inguinal nodes.
- Lower vagina → inguinal nodes; upper vagina/cervix/body of uterus → internal iliac, external iliac, obturator, then common iliac, para-aortic.
- Ovary → para-aortic (follows the ovarian vessels). This is why ovarian cancer skips pelvic nodes.
Pelvic floor. Levator ani (pubococcygeus, puborectalis, iliococcygeus) and the urogenital diaphragm. Damaged in obstetric trauma — see oasis, genital-prolapse.
Assessment
History. Cycle length, menarche/menopause, parity and deliveries, contraception, prior pelvic surgery (laparoscopy ports, midline scar, prior caesarean), prior pelvic infection or instrumentation, congenital anomalies known of self or first-degree relatives, urinary or bowel symptoms.
Examination.
- Inspection of vulva (asymmetry, scarring, dermatoses — lichen-sclerosus, pigmentation).
- Speculum: vaginal walls, cervix (parity, ectropion, polyps).
- Bimanual: uterine size, position, mobility; adnexa for masses or tenderness.
- Rectovaginal exam: posterior fornix, uterosacral nodularity (endometriosis), pouch of Douglas masses, septate hymen vs imperforate.
Imaging hierarchy.
- Transvaginal ultrasound (TVS) — first line for uterine and adnexal anatomy.
- 3D ultrasound or saline-infusion sonography — Müllerian anomalies, intracavitary lesions.
- MRI — gold standard for complex Müllerian anomalies, deep infiltrating endometriosis, and for surgical planning of fibroids or malignancy.
- IVU or CT urogram if renal tract anomaly suspected (and routinely with diagnosed Müllerian anomaly).
Management
Müllerian developmental patterns: distinguish septation, fusion defects, hemi-uterus and aplasia by cavity and fundal contour.
There is no "management of normal anatomy" — the management implication is operative planning. Abnormal anatomy changes consent, approach, and risk.
Müllerian anomalies (ESHRE/ESGE classification U0–U6).
- U1 dysmorphic uterus — usually no intervention.
- U2 septate uterus — hysteroscopic septum resection if recurrent miscarriage or infertility.
- U3 bicorporeal uterus (true didelphys/bicornuate) — usually managed expectantly; metroplasty rarely indicated.
- U4 hemi-uterus — counsel on obstetric risk (preterm, malpresentation, IUGR).
- U5 aplastic (MRKH) — psychosexual support, neovagina creation (Frank dilators first; surgical only if failed).
- Always screen for renal anomalies — unilateral renal agenesis in up to 30%.
Acquired distortion at operation.
- Fibroid uterus: identify pedicles, avoid blind clamping near the ureter — see fibroids.
- Frozen pelvis (endometriosis, prior PID): retrograde dissection from round ligament; consider intraoperative ureteric stents; multidisciplinary input.
- Adhesions from previous CS: open with extra care over the bladder reflection; risk of cystotomy.
Operative safety principles.
- Identify the ureter before dividing any pedicle near it.
- Develop the pararectal and paravesical spaces — they are the safe planes.
- "When in doubt, cystoscope" — fill bladder with methylene blue and check at the end of any difficult hysterectomy.
Red flags / pitfalls
- Assuming a "normal-feeling" uterus on bimanual is non-pregnant — always exclude pregnancy before any uterine procedure.
- Diagnosing a unicornuate uterus on 2D ultrasound alone — needs 3D or MRI.
- Missing a coexisting renal anomaly when a Müllerian anomaly is found.
- Confusing a bicornuate from a septate uterus on hysteroscopy — external fundal contour distinguishes them (laparoscopy or 3D US).
- Cutting the round ligament in a non-anatomic plane and entering the obliterated umbilical artery / bladder — a classic ureteric or bladder injury setup.
- Forgetting that the ovarian pedicle goes over the pelvic brim — clamps placed too low risk the ureter.
Evidence anchors
- ESHRE/ESGE Consensus on the classification of female genital tract congenital anomalies (Grimbizis et al., 2013, updated).
- BASHH UK National Guideline for the Management of Pelvic Inflammatory Disease (2018, 2019 update) (anatomical correlates; the current UK PID guideline — RCOG GTG 32 is archived and directs here).
- South African National Department of Health, Standard Treatment Guidelines (Hospital level, Adults, latest edition) — surgical principles in gynaecology.
- AAGL Practice Report on the diagnosis and management of submucosal leiomyomas (anatomy of intracavitary lesions).
- WHO classification of female genital tumours, 5th edition (anatomical bases of staging).