Canal of Nuck Hernia containing uterus in a pre-mature female infant: A rare type of hernia

Clinical History

A one-month-old premature female infant presented with an irreducible swelling in the left inguinal region. She had developed the swelling 4 weeks after birth. No inguinal swelling was noted at birth and the external genitalia appeared normal. On physical examination, a palpable swelling in the left inguinal region was seen.

Imaging Findings

Ultrasound examination was immediately performed, showing a cystic mass with central echogenic line suggesting the presence of the ovary and uterus within the hernia. We thought of a canal of Nuck hernia but to confirm the diagnosis, MRI was performed subsequently. The diagnosis of canal of Nuck hernia containing the uterus was confirmed by the MRI examination. Surgery confirmed the hernia sac containing the uterus, fallopian tube, and ovary. After freeing the attachment of the fallopian tube and uterus from the hernia sac and reducing all uterine adnexa back into the peritoneal cavity, high ligation of the hernia sac was performed. The post-operative course was uneventful.

Discussion

The canal of Nuck is similar to the patent process vaginalis in males. It is an abnormal patent pouch of peritoneum extending anterior to the round ligament of the uterus into the labia majora [1]. The processus vaginalis is usually obliterated by eight months of gestation. Inguinal hernia can develop in premature infants if this structure is often patent. The incidence of inguinal hernia containing the uterus is 5- 10 % [2, 3]. In the literature, only few case reports of canal of Nuck hernia containing the uterus have been reported.

Canal of Nuck results from incomplete obliteration of processus vaginalis which usually develops around the sixth month of fetal gestation. The female processus vaginalis is much smaller than its male counterpart and usually obliterates around the eight’ month of gestation. During this time the processus vaginalis is accompanied by the round ligament of the uterus and passes through the inguinal canal up to labium major. If the duct remains patent, it is termed canal of Nuck [3]. Incomplete obliteration of this canal can result in either an inguinal hernia or hydrocele.

Canal of Nuck hernia is extremely rare with lack of literature in surgical, paediatric and radiology books. It is seldom encountered in clinical practice. It is an important differential diagnosis for inguinal swelling in pre-mature infants. Other possible differentials include abscess, lymphadenopathy, lipoma or sarcoma. High-resolution ultrasound can show presence of ovaries and uterus within the hernia sac but only MRI can make a definitive diagnosis.

Irreducible inguinal hernias in premature infants may contain the uterus and adnexa. Prompt surgical intervention is mandatory to avoid irreversible injuries to the contained organs. As there is risk of damaging the herniated structures during the surgical procedure, a careful preoperative diagnosis is very important. Therefore, ultrasound and MRI should be routinely obtained in female infants with irreducible inguinal hernia.

Differential Diagnosis List

Final Diagnosis

Canal of Nuck hernia

URL:	https://eurorad.org/case/12968
DOI:	10.1594/EURORAD/CASE.12968
ISSN:	1563-4086