Canal of Nuck Cyst

Pathophysiology of the Canal of Nuck

• Extension of the parietal peritoneum follows the round ligament as it passes to the inguinal canal.
• Usually gets obliterated.
• This evagination of the parietal peritoneum =  the canal of Nuck =  female counterpart of processus vaginalis in men.
• If it is:
  • Completely patent: Avenue for an indirect inguinal hernia and hydrocele (Canal of Nuck hernia).
  • Obliterated at the level of both the superficial and deep inguinal rings: Fluid may be trapped in between both ends of the canal, creating a Canal of Nuck cyst.
  • Obliterated at lower end – Infantile hydrocele / encysted hydrocele.
• Hydrocele vs cyst canal of Nuck : The terms hydrocele and cyst of Canal of Nuck are used interchangeably but these are separate pathologies.
• Symptoms: It usually presents as a painless swelling in the inguinal region. Infection can cause pain.

Imaging appearances:

• Canal of Nuck cyst is an inguinal cyst in females.
• US : Cystic lesion in the inguinal canal with posterior acoustic attenuation.
• CT : Hypodense lesion with our without internal septations.
• MRI: T1 isointense, T2 hyperintense, typical appearance of a cystic lesion.
• Can show peripheral enhancement.

Differentials for Canal of Nuck cyst

• Inguinal hernia containing fluid in patients with ascites.
• Soft tissue tumor.
• Endometriosis cyst
• Cyst
• Abscess
• Lymphadenopathy

Management:

Surgical excision or conservative management depending on patient presentation.

Detailed video with PACS based case images:

About the Author

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Dr. Amar Udare, MD, DNB

Dr. Amar Udare is a board-certified radiologist. He is currently working as a fellow radiologist at McMaster University, Canada. He has a passion for teaching (#FOAMrad and #FOAMed) and has been a semi-finalist for the 2018 and 2020 Aunt-Minnie Most effective Radiology Educator Awards. He has authored multiple peer-reviewed publications which can be accessed on PubMed and Google Scholar.