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The Cervix

The cervix is the inferior fibromuscular cylinder of the uterus that projects into the vaginal vault and contains the endocervical canal linking the uterine cavity to the vagina. For the reconstructive pelvic surgeon it matters in four ways: (1) it is the fulcrum of Level-I apical support through the cardinal and uterosacral ligaments; (2) it is the anatomic neighbor of the ureter — the classical "water under the bridge" at the uterine artery, the single most common site of iatrogenic ureteric injury; (3) it is the nerve-sparing problem of radical hysterectomy (the pelvic plexus runs in the cardinal and uterosacral ligaments); and (4) it is the site where HPV-driven cancer arises in the transformation zone and whose surgery and radiation directly generate the urogynecologic workload of later life — fistula, stenosis, neurogenic bladder. This article focuses on the surgical anatomy, the innervation relevant to nerve-sparing pelvic surgery, the structural support anatomy, and the reconstructive consequences of cervical disease and its treatment. Cervical cancer screening, obstetric cervical insufficiency, and molecular mucin biology are compressed to the depth a reconstructive urologist needs.

See also The Vagina for the surrounding fornices; The Ureters for the "water under the bridge" geometry; and Pelvic Neuroanatomy for the pelvic plexus.

Gross Anatomy​

The cervix is a ~3–4 cm cylinder that divides anatomically into two portions:[1][2]

  • Supravaginal portion — above the vaginal attachment, surrounded by the cardinal-ligament complex and paracervical tissues.
  • Vaginal portion (portio vaginalis) — protrudes into the vaginal vault, visible at speculum examination; demarcated from the vault by the anterior, posterior, and lateral fornices.

The canal extends from the internal os (communication with the uterine cavity) to the external os (communication with the vaginal vault). Normal external os is slit-like in parous women and round in nulliparas — a classically-examined morphology at pessary fitting and at colposcopy.

Three mucosal regions​

RegionEpitheliumSurface landmarks
Ectocervix (portio)Non-keratinized stratified squamous — continuous with vaginal epitheliumSmooth, pink at speculum
EndocervixSimple columnar mucus-secreting; surface thrown into plicae palmatae that increase surface areaRed, granular at speculum; lined by glands
Transformation zone (TZ)Zone of ongoing squamous metaplasia between the original and current squamocolumnar junctions (SCJ)The colposcopic/biopsy territory — >90% of cervical cancers arise here[3][4][5]

The TZ migrates outward onto the ectocervix at puberty under estrogen and returns into the endocervical canal at menopause, which is why postmenopausal cervical cancer screening requires endocervical sampling and why older women benefit less from visual colposcopic inspection alone.

Structural Supports — The Apex of Pelvic-Floor Reconstruction​

The cervix is the anchoring point of Level-I pelvic support in DeLancey's model. Two ligamentous / connective-tissue complexes suspend it:[11]

ComplexOriginInsertionContents
Cardinal ligament (Mackenrodt)Pelvic sidewall at the obturator internus fasciaLateral cervix and upper vaginaUterine artery and vein, ureter (at its midpoint), pelvic plexus autonomic fibers, lymphatics
Uterosacral ligament (USL)Presacral fascia at the level of S2–S4Posterior cervix and upper vaginaSympathetic fibers from the pelvic plexus; lymphatic channels

Both are more accurately described as condensations of endopelvic fascia and smooth muscle than as true ligaments. Clinically:

  • Apical prolapse (uterine / vault) represents failure of the cardinal-uterosacral (CUL) complex.
  • Sacrocolpopexy, USLS, Manchester (Fothergill), and vaginal hysterectomy with McCall culdoplasty all aim to re-establish or reinforce this complex.
  • Cervical elongation (disproportionate overgrowth of the cervix without true descent) is a masquerader of apical prolapse — recognition is important because treatment (cervical amputation ± reinforcement, or the Manchester procedure) differs from simple apical suspension.

Anatomical Relations — Why the Ureter Lives Under the Uterine Artery​

AspectRelationOperative note
AnteriorBladder base and trigone, separated by the vesicocervical/vesicouterine spaceThe plane of anterior dissection in hysterectomy, cervical cancer surgery, and vesicovaginal fistula repair
PosteriorRectum and the rectouterine pouch (Douglas')Approached via the posterior colpotomy; enterocele sits in this peritoneal pocket
LateralBroad ligament, cardinal ligament, uterine vessels, and ureter ~1.5–2 cm lateral to the cervix at the level of the isthmusSite of iatrogenic ureteric injury
Water under the bridge — the ureteric injury pattern

The uterine artery crosses anterior (over) the ureter within the cardinal ligament ~1.5–2 cm lateral to the cervix. This is the single most common site of iatrogenic ureteric injury in gynecologic surgery (hysterectomy, radical hysterectomy, USLS, deep paravaginal dissection). Stepwise identification — positive visualization of the ureter on the pelvic sidewall before clamping any lateral pedicle — is the definitive prevention.

Vascular Supply​

Arterial supply is overwhelmingly from the uterine artery (a branch of the internal iliac, anterior division), which gives off a cervicovaginal branch at the level of the isthmus.[7][8][9] Additional contributions come from the vaginal artery and, in limited fashion, the middle rectal artery.

The cervical stroma contains a distinctive high-density mucosal capillary plexus in the endocervical lamina propria, arranged in near-parallel bundles with few interconnections — an architecture suited to the dramatic vascular remodeling needed during pregnancy.[7] In the non-pregnant cervix this vascularity is the reason even superficial biopsies and LEEP excisions bleed.

Venous drainage parallels the arteries to the uterine and vaginal plexuses and thence the internal iliac vein.

Lymphatic drainage of the cervix runs to parametrial, obturator, internal iliac, external iliac, and common iliac nodes, with presacral drainage from the posterior lip — the anatomic basis of the parametrial and pelvic lymphadenectomy template in radical hysterectomy (Wertheim / Okabayashi / Querleu-Morrow classifications).

Innervation — Nerve-Sparing and Cervical Cancer Surgery​

The cervix is richly innervated — in fact more densely than the uterine corpus and fundus, with the highest neurotransmitter density in the reproductive tract.[10][11][12] This is the anatomic substrate of nerve-sparing radical hysterectomy.

SourcePathwayFunction
ParasympatheticS2–S4 pelvic nerve → inferior hypogastric plexus → cardinal ligament (lateral and inferior)Smooth muscle tone and vasodilation; afferent pain fibers
SympatheticT10–L2 hypogastric nerve → inferior hypogastric plexus → uterosacral ligament (posterior)Contraction, vasoconstriction; afferent pain fibers

The clinically decisive fact is that the pelvic plexus and its splanchnic branches to the bladder, rectum, and vagina run within the deep parts of the cardinal and uterosacral ligaments. Radical hysterectomy that divides these ligaments en bloc (classical Wertheim / Piver III) produces durable neurogenic bladder and sexual dysfunction; nerve-sparing radical hysterectomy (Querleu-Morrow type C2 with nerve preservation, or "Tokyo" type / Shingo Fujii) divides only the ventral sympathetic part of the ligaments and preserves the dorsolateral parasympathetic component — improving postoperative bladder emptying, rectal emptying, and sexual function without compromising oncologic outcome in appropriately selected patients.[10][11]

Cervical Mucus — Compressed to What's Clinically Useful​

Endocervical columnar cells produce a hydrated mucin gel that changes cyclically under estrogen and progesterone control:[13][14][15][16]

  • Periovulatory (estrogen-dominant) — thin, copious, low-viscosity, high-spinnbarkeit mucus with a "ferning" pattern when dried — permissive to sperm transit and partially protective to vaginal flora.
  • Luteal and pregnant (progesterone-dominant) — thick, scant, highly viscous, sperm-impermeable mucus that forms the cervical mucus plug of pregnancy — a mechanical and antimicrobial barrier to ascending infection.
  • Postmenopausal (hypoestrogenic) — atrophic, thin, reduced mucus, higher vaginal pH (as with vaginal atrophy; see The Vagina).

The clinical translations worth knowing at the reconstructive level are: topical vaginal estrogen reverses atrophic changes that compromise native-tissue prolapse repair and pessary fitting; cervical mucus penetrability testing (historical post-coital test) is of limited modern clinical utility; and cervical ectopy (visible columnar epithelium on the ectocervix) is a normal finding in younger women on OCPs or pregnant patients and rarely requires intervention.

Cervical Remodeling in Pregnancy (in broad strokes)​

The non-pregnant cervix is a stiff collagen-dominant organ; pregnancy transforms it into a compliant, extensible one through four sequential processes:[6][17][18][19][20]

  1. Softening — slow decrease in tensile strength from early pregnancy, with increasing tissue hydration and hydrophilic glycosaminoglycans.
  2. Ripening — rapid loss of compliance and tensile strength, increased water content, and collagen disaggregation.
  3. Dilation — active labor opens the cervix under uterine contraction.
  4. Postpartum repair — rapid return toward baseline structure.

Cervical insufficiency is premature entry into phases 1–2 at a gestation too early for viability — presenting as painless mid-trimester loss. Management is cerclage (McDonald, Shirodkar, or transabdominal) in appropriately selected patients — mostly outside the reconstructive urologist's remit, but relevant in the rare patient with prior cervical trauma, LEEP / cone excision, or trachelectomy presenting with a recurrent loss history.

Clinical Correlations for the Reconstructive Surgeon​

  • Hysterectomy and ureteric injury. The cervix is the single most common anatomic neighbor of an iatrogenically injured ureter. Know the uterine-artery–ureter geometry and positively identify the ureter before clamping any cardinal-ligament pedicle. Cystoscopic confirmation of ureteric patency at the end of complex gynecologic surgery is a reasonable safety step when suspicion is present.
  • Nerve-sparing radical hysterectomy. Division of only the ventral / sympathetic part of the cardinal and uterosacral ligaments preserves parasympathetic input to the bladder, rectum, and vagina, markedly reducing neurogenic-bladder and sexual-dysfunction rates. The anatomic distinction matters because a substantial fraction of the long-term urogynecologic workload after cervical-cancer treatment comes from non-nerve-sparing surgery combined with adjuvant radiation.
  • Apical prolapse and the cervix. Uterine prolapse is failure of the CUL complex. Options: vaginal hysterectomy with apical suspension (USL suspension or McCall culdoplasty), sacrospinous hysteropexy, sacrohysteropexy (mesh), and — when uterine preservation with cervical elongation is desired — the Manchester (Fothergill) procedure (cervical amputation + cardinal-ligament plication + anterior colporrhaphy).
  • Cervical elongation. Disproportionate cervical overgrowth mimics apical prolapse; at examination the uterine body may remain within the pelvis despite a cervix below the hymen. Treatment is trachelectomy or Manchester rather than apical suspension alone.
  • Conization and LEEP. Outpatient excisional procedures for CIN 2/3. Clinically relevant to obstetric outcomes (excision depth is associated with preterm delivery risk) and to the later reconstructive surgeon (cervical stenosis can cause hematometra or dysmenorrhea; cervical shortening affects fertility-preserving cerclage planning).[1]
  • Trachelectomy. Radical trachelectomy is a uterus-preserving operation for early-stage (≤ stage IB1 well-selected) cervical cancer; preserves fertility and entails cerclage. Bladder, ureter, and pelvic-plexus considerations mirror those of radical hysterectomy.
  • Supracervical (subtotal) hysterectomy and the retained cervix. Leaves the cervical stump in situ; the patient must continue cervical cancer screening. Complications include persistent cyclical bleeding, stump infection, and, rarely, stump carcinoma — each of which can present to a reconstructive surgeon years later.
  • Sequelae of pelvic radiation. Radiation for cervical cancer produces a characteristic urogynecologic pattern: vesicovaginal fistula, rectovaginal fistula, radiation cystitis, vaginal stenosis, ureteric stricture, and bladder atony — the reconstructive morbidity that follows successful oncologic therapy. Repair of radiation fistula mandates non-irradiated interposition flaps (Martius, gracilis, omental); simple local repair fails.
  • Vesicocervical space and vesicovaginal fistula. Most post-hysterectomy VVF sits at the vaginal cuff just above the trigone — an extension of the vesicocervical plane that was violated at hysterectomy. Repair requires wide mobilization into this plane and layered closure with Martius or peritoneal interposition. See The Vagina.
  • Cervical cancer and the reconstructive burden. Post-Wertheim and post-chemoradiation patients are high-volume referrals for fistula repair, continent/incontinent urinary diversion, neovaginal reconstruction, and neurogenic-bladder management. The preoperative workup should include examination under anesthesia, cystoscopy, and upper-tract imaging.
  • Cerclage. McDonald (transvaginal, easy), Shirodkar (transvaginal, subcutaneous submucosal), transabdominal (laparoscopic / open, for failed vaginal cerclage or after trachelectomy). Primarily the obstetrician's territory; relevant to the reconstructive surgeon when prior bladder / urethral surgery complicates access.
  • Cervical mucus plug and pessary fitting. Pessary success in postmenopausal women depends on a healthy epithelium and mucus layer; topical vaginal estrogen improves fit, comfort, and retention.

References​

1. Kyrgiou M, Athanasiou A, Arbyn M, et al. "Terminology for Cone Dimensions After Local Conservative Treatment for Cervical Intraepithelial Neoplasia and Early Invasive Cervical Cancer: 2022 Consensus Recommendations From ESGO, EFC, IFCPC, and ESP." Lancet Oncol. 2022;23(8):e385–e392. doi:10.1016/S1470-2045(22)00191-7

2. Barrios De Tomasi J, Opata MM, Mowa CN. "Immunity in the Cervix: Interphase Between Immune and Cervical Epithelial Cells." J Immunol Res. 2019;2019:7693183. doi:10.1155/2019/7693183

3. Aiyenuro A, Griffin H, Schichl K, et al. "Role of Reserve Cells in Metaplasia and the Development of Human Papillomavirus-Associated High-Grade Squamous Intraepithelial Lesions at the Cervical Transformation Zone." Lab Invest. 2025;105(7):104166. doi:10.1016/j.labinv.2025.104166

4. Regauer S, Reich O. "The Origin of Human Papillomavirus (HPV)-Induced Cervical Squamous Cancer." Curr Opin Virol. 2021;51:111–118. doi:10.1016/j.coviro.2021.09.012

5. Deng H, Hillpot E, Mondal S, Khurana KK, Woodworth CD. "HPV16-Immortalized Cells From Human Transformation Zone and Endocervix Are More Dysplastic Than Ectocervical Cells in Organotypic Culture." Sci Rep. 2018;8(1):15402. doi:10.1038/s41598-018-33865-2

6. Tantengco OAG, Menon R. "Contractile Function of the Cervix Plays a Role in Normal and Pathological Pregnancy and Parturition." Med Hypotheses. 2020;145:110336. doi:10.1016/j.mehy.2020.110336

7. Walocha JA, Litwin JA, Bereza T, Klimek-Piotrowska W, Miodoński AJ. "Vascular Architecture of Human Uterine Cervix Visualized by Corrosion Casting and Scanning Electron Microscopy." Hum Reprod. 2012;27(3):727–732. doi:10.1093/humrep/der458

8. Bereza T, Tomaszewski KA, Bałajewicz-Nowak M, et al. "The Vascular Architecture of the Supravaginal and Vaginal Parts of the Human Uterine Cervix: A Study Using Corrosion Casting and Scanning Electron Microscopy." J Anat. 2012;221(4):352–357. doi:10.1111/j.1469-7580.2012.01550.x

9. Höckel M, Horn LC, Fritsch H. "Association Between the Mesenchymal Compartment of Uterovaginal Organogenesis and Local Tumour Spread in Stage IB-IIB Cervical Carcinoma: A Prospective Study." Lancet Oncol. 2005;6(10):751–756. doi:10.1016/S1470-2045(05)70324-7

10. Giovannetti O, Tomalty D, Velikonja L, Jurkus C, Adams MA. "The Human Cervix: Comprehensive Review of Innervation and Clinical Significance." Clin Anat. 2023;36(1):118–127. doi:10.1002/ca.23960

11. Zhang J, Feng L, Lu Y, et al. "Distribution of Lymphatic Tissues and Autonomic Nerves in Supporting Ligaments Around the Cervix Uteri." Mol Med Rep. 2013;7(5):1458–1464. doi:10.3892/mmr.2013.1360

12. Di Tommaso S, Cavallotti C, Malvasi A, et al. "A Qualitative and Quantitative Study of the Innervation of the Human Non Pregnant Uterus." Curr Protein Pept Sci. 2017;18(2):140–148. doi:10.2174/1389203717666160330105341

13. Argüeso P, Spurr-Michaud S, Tisdale A, Gipson IK. "Variation in the Amount of T Antigen and N-Acetyllactosamine Oligosaccharides in Human Cervical Mucus Secretions With the Menstrual Cycle." J Clin Endocrinol Metab. 2002;87(12):5641–5648. doi:10.1210/jc.2002-020766

14. Gipson IK, Moccia R, Spurr-Michaud S, et al. "The Amount of MUC5B Mucin in Cervical Mucus Peaks at Midcycle." J Clin Endocrinol Metab. 2001;86(2):594–600. doi:10.1210/jcem.86.2.7174

15. Gipson IK. "Mucins of the Human Endocervix." Front Biosci. 2001;6:D1245–D1255. doi:10.2741/gipson

16. Brunelli R, Papi M, Arcovito G, et al. "Globular Structure of Human Ovulatory Cervical Mucus." FASEB J. 2007;21(14):3872–3876. doi:10.1096/fj.07-8189com

17. Ezebialu IU, Eke AC, Eleje GU, Nwachukwu CE. "Methods for Assessing Pre-Induction Cervical Ripening." Cochrane Database Syst Rev. 2015;(6):CD010762. doi:10.1002/14651858.CD010762.pub2

18. Iams JD. "Prevention of Preterm Parturition." N Engl J Med. 2014;370(3):254–261. doi:10.1056/NEJMcp1103640

19. Shi L, Hu L, Lee N, Fang S, Myers K. "Three-Dimensional Anisotropic Hyperelastic Constitutive Model Describing the Mechanical Response of Human and Mouse Cervix." Acta Biomater. 2022;150:277–294. doi:10.1016/j.actbio.2022.07.062

20. Nallasamy S, Palacios HH, Setlem R, et al. "Transcriptome and Proteome Dynamics of Cervical Remodeling in the Mouse During Pregnancy." Biol Reprod. 2021;105(5):1257–1271. doi:10.1093/biolre/ioab144