Mucus plugging in the cervical canal (HSG)

Mucus Plugging in the Cervical Canal – Hysterosalpingography

Mucus plugging of the cervical canal refers to transient obstruction of the canal by thick cervical mucus. It is a benign and functional condition, commonly seen during certain phases of the menstrual cycle, in chronic cervicitis, or due to inadequate cervical preparation before hysterosalpingography (HSG). On HSG, mucus plugging is suggested by temporary filling defects or complete non-opacification of the uterine cavity that resolves after gentle flushing or repeat injection (Fig. 1).

Fig-1

Fig. 1—Hysterosalpingogram showing mucus plugging of the cervical canal. An amorphous, smooth filling defect is seen within the cervical canal with transient obstruction to contrast flow (arrow), which may clear on repeat injection.

Findings: The cervical canal shows partial or complete blockage by a smooth, non-fixed filling defect. The defect may change shape or disappear with gentle contrast injection. Subsequent opacification of the uterine cavity and fallopian tubes is usually normal.

Conclusion: Hysterosalpingographic appearance is consistent with mucus plugging of the cervical canal.

Patient Symptoms

Most patients are asymptomatic. Some may have a history of chronic vaginal discharge, cervicitis, or prior inconclusive HSG due to difficult contrast passage.

Procedure (Hysterosalpingography)

The examination is performed during the early proliferative phase of the menstrual cycle. If resistance is encountered, gentle flushing, slight repositioning of the cannula, or repeat injection may help clear the mucus plug and allow completion of the study.

Contrast Medium & Administration

A water-soluble iodinated contrast agent such as Iohexol or Iopamidol (300–350 mg iodine/mL) is used. The patient is positioned in the lithotomy position. Typically 5–8 mL of contrast is injected slowly under low pressure.

Instruments Used

• Sterile vaginal speculum (Cusco’s or Sims’)
• Leech–Wilkinson cannula
• Rubin cannula
• Balloon HSG catheter
• 10–20 mL sterile Luer-lock syringe
• Sterile connecting tubing
• Antiseptic solution
• Fluoroscopy unit

Safety Considerations

Excessive force should be avoided to prevent cervical trauma or false passage. Pregnancy and active pelvic infection must be excluded. Repeat imaging after clearing the mucus plug helps avoid false-positive diagnoses.

Related Conditions

Differential diagnoses include cervical stenosis, cervical synechiae, cervical polyp, and cervical malignancy. Resolution after repeat injection favors mucus plugging.

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Declaration

This case is presented for academic and educational purposes only. Patient confidentiality has been preserved and no identifiable information is disclosed.