Cervical ectopic pregnancy is implantation of the blastocyst in the endocervical canal below the internal os. It is a rare (<1% of all ectopics) but potentially life-threatening condition. IVF, prior curettage, cesarean section, and Asherman syndrome are risk factors. Implantation in the endocervical canal leads to inadequate decidual reaction due to the fibrous, muscle-deficient cervical stroma, predisposing to uncontrolled trophoblastic invasion. On US, the gestational sac is seen within the cervix below the internal os — the uterus may appear hourglass-shaped and the cervix may be barrel-shaped (expanded). Sliding sign is negative, which has critical diagnostic value in differentiating from miscarriage material in transit. Color Doppler shows peritrophoblastic vascularity confirming implantation.
Age Range
18-45
Peak Age
33
Gender
Female predominant
Prevalence
In cervical ectopic pregnancy, the blastocyst implants in the endocervical canal epithelium and trophoblastic villi invade the cervical stroma. Since cervical stroma lacks muscle tissue and consists predominantly of collagen fibril-rich fibrous tissue, it cannot form an adequate barrier as in myometrial decidual reaction — therefore trophoblastic invasion may progress uncontrolled and erode cervical vessels, potentially causing massive hemorrhage. However, cervical vascularity is more limited than uterine vascularity, so pregnancy growth is also limited and rarely reaches advanced gestational age. As the cervix expands, the lesion assumes a barrel shape with the internal os open — blood may drain externally through the cervix, causing early symptoms. The ultrasonographic combination of empty uterine fundus and expanded cervix creates the hourglass finding. The sliding sign test forms the basis of pathophysiological differentiation: an implanted ectopic sac adheres to cervical stroma via trophoblastic villi and does not displace with probe pressure; miscarriage material is free and slides within the canal. Peritrophoblastic vascularity results from trophoblastic invasion remodeling spiral arteries, manifesting as low-resistance arterial flow on Doppler — this finding is the second critical parameter for differentiating from miscarriage material (no vascularity).
Empty uterine fundus + implanted gestational sac in expanded cervix below internal os + sac not sliding with probe pressure — characteristic ultrasonographic combination for cervical ectopic pregnancy. Peritrophoblastic vascularity strengthens the diagnosis.
On TVUS, the gestational sac is seen in the endocervical canal below the internal os. The sac typically has regular contours and is surrounded by a decidual reaction ring. The uterine cavity is empty — fundal endometrium may be thickened from decidual reaction but contains no gestational sac. The cervix is expanded with cervical stroma forming a thin covering around the sac. Sac size is proportional to gestational age and may contain a yolk sac or fetal pole.
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A gestational sac measuring __ mm is seen within the cervix below the internal os on TVUS, consistent with cervical ectopic pregnancy; the uterine cavity is empty.
On sagittal US, the uterus appears hourglass-shaped: the fundal uterus is normal size (empty cavity) while the cervix is markedly expanded by the gestational sac. This contrast is characteristic of cervical ectopic pregnancy. Normal myometrial thickness is preserved at the fundus while the cervical region is stretched by the sac. The hourglass appearance is best evaluated on midline sagittal sections showing the entire uterine structure in a single image.
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The uterus shows hourglass appearance on sagittal US — empty fundus and cervix expanded by the gestational sac are noted.
Prominent peritrophoblastic vascularity is seen around the cervical sac on color Doppler — evidence of trophoblastic implantation. This vascularity shows low-resistance arterial flow pattern (RI typically <0.5). The trophoblastic vascular network may show 360-degree circular distribution around the sac. This finding is critical for differentiation from miscarriage material: miscarriage material is temporarily in the cervical canal without vascular connection, giving no Doppler signal; an implanted ectopic sac has remodeled spiral arteries and shows intense vascularity.
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Peritrophoblastic vascularity and low-resistance arterial flow around the cervical sac on color Doppler is consistent with cervical ectopic pregnancy.
On T2-weighted MRI, a high signal intensity gestational sac is seen within the cervix. Cervical stroma appears as low T2 signal fibrous tissue creating high contrast with the sac. Internal os level and sac position relative to the cavity are clearly evaluated on sagittal and coronal planes. The decidual reaction ring may show intermediate signal. Hemorrhagic areas may appear hyperintense on T1-weighted sequences — indicating active bleeding complication.
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A high signal intensity gestational sac within the cervix localized below the internal os is seen on T2-weighted MRI, consistent with cervical ectopic pregnancy.
When gentle pressure is applied to the cervix with the probe, the gestational sac maintains its position and does not slide (negative sliding sign). The sac is mechanically fixed as it adheres to cervical stroma via trophoblastic villi. Miscarriage material is free within the cervical canal and slides with pressure (positive sliding sign). This distinction differentiates cervical ectopic from miscarriage in transit and can be applied in seconds under real-time US. The test should be repeated multiple times for confirmation.
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The cervical sac does not slide with probe pressure (negative sliding sign) — finding favoring implanted cervical ectopic pregnancy.
CT is typically used for complication assessment — massive hemorrhage, hemoperitoneum, or interventional planning. Contrast CT evaluates hypervascular mass in the cervical region and pelvic free fluid. For uterine artery embolization planning, arterial phase demonstrates vascular anatomy — feeding vessels, course of bilateral uterine arteries, and cervical branching pattern are identified.
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A hypervascular mass in the cervical region is seen on contrast CT with accompanying pelvic free fluid — should be evaluated for hemorrhagic complication.
The internal os is closed without gestational sac transition — this finding helps differentiate cervical ectopic from lower uterine segment pregnancy descending to the cervix during miscarriage. Empty fundus confirms no intrauterine pregnancy in the uterine cavity. The endometrium may be thickened from decidual reaction but contains no sac or trophoblastic tissue.
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The internal os is closed and the uterine fundus is empty — cervical localization is confirmed.
Criteria
<8 weeks gestational age, small sac (<20 mm), minimally expanded cervix, β-hCG usually <10,000 mIU/mL
Distinct Features
Higher chance of medical treatment (MTX) — single or multi-dose MTX, local KCl injection options, conservative approach possible, highest fertility preservation probability
Criteria
>8 weeks gestational age, prominent barrel cervix, active bleeding may be present, β-hCG usually >10,000 mIU/mL, fetal cardiac activity may be present
Distinct Features
Surgical or interventional treatment required — uterine artery embolization + curettage (hemorrhage control), cervical balloon tamponade, rarely hysterectomy (last resort), low MTX success rate
Criteria
Fetal cardiac activity present, usually >6 weeks
Distinct Features
Urgent intervention prioritized — growth continues, rupture and massive hemorrhage risk progressively increases, MTX + local KCl or surgery
Distinguishing Feature
Tubal ectopic sac is in the adnexal region with normal cervix; cervical ectopic sac is within the cervix with normal adnexal region — localization difference clearly demonstrated on TVUS
Distinguishing Feature
Cesarean scar ectopic sac is at the anterior lower segment scar site related to myometrium; cervical ectopic sac is in the endocervical canal below the os — scar history and sac relationship to myometrium vs cervical stroma is distinguishing
Distinguishing Feature
Interstitial ectopic sac is within cornual myometrium showing eccentric localization (interstitial line sign positive); cervical ectopic sac is within cervix showing midline localization
Distinguishing Feature
Gestational trophoblastic disease shows 'snowstorm' pattern and very high β-hCG (>100,000); cervical ectopic has normal gestational sac structure and proportional β-hCG
Urgency
emergentManagement
interventionalBiopsy
Not NeededFollow-up
specialist-referralCervical ectopic pregnancy requires emergent management due to uncontrolled bleeding risk — the fibrous cervical stroma limits hemostatic capacity. Treatment options are determined by gestational age, β-hCG level, and presence of fetal cardiac activity. Early stage (<8 weeks, β-hCG <10,000, no FHR): MTX (single or multi-dose, systemic or local), US-guided local KCl injection. Advanced stage or failed medical treatment: uterine artery embolization + curettage (safe curettage with hemorrhage control), cervical balloon tamponade (Foley catheter cervical tamponade), hysteroscopic resection. Hysterectomy is applied as a last resort — fertility-sparing approach should always be prioritized. Post-treatment β-hCG monitoring is mandatory — weekly follow-up until negative. Persistent β-hCG elevation suggests residual trophoblastic tissue requiring additional treatment.
Cervical ectopic pregnancy is rare but dangerous — bleeding control is difficult because the cervix lacks contractile capacity. Treatment options include methotrexate (early, small, stable), uterine artery embolization + curettage, or hysterectomy (in case of massive hemorrhage). Cervix-preserving approaches are preferred for fertility preservation.