Herniation of the Ovary into the Canal of Nuck in a 3 Month Old Female Infant: A Rare Entity Needing Urgent Ultrasonography Evaluationt

1. Abstract Indirectinguinalhernia of the canal of Nuckcontaining the pelvic organs such as ovary is a rare entity among females of pediatric age group which presentsass welling of labiamajora. It iscaused by congenitally failed closure of the processusvagin alisinfemale resulting in the formation of a potential space which is named as "canal of Nuck" through which pelvic organs herniate. Literature reviewshowedthatinfemaleinfantsaround15-20%ofthecases, thiscanalofNuckherniacontainsovarywithorwithoutherniation of fallopian tube. Early diagnosis is important as there is a high chance of ovarian torsion as well as incarceration in such cases. Therefore, we present ultrasonographic appearancees of indirect inguinal hernia of canal of Nuck containing ovary in 3-month old female infant who presented with complain of swelling of right labia majora since birth

Keywords: Inguinalhernias; Canalofnuck; Canalofnuckhernias; Processus vaginalis; Labia majora swelling

2. Introduction Hernia of inguinal canal in female of pediatric age group is an extremely rare condition [1, 2].It occurs 6 times less commonly in females than males. The cause of this is failure of closure oftheprocessusvaginalis,whichformsasmallprotrusionofparietal peritoneuminfemalesnamedas"canalofNuck"measuringabout 3 to 4 cms in isze.The term Canal of Nuck was first describedby Anton Nuck, a Dutch anatomist in 1691 [3,4,5]. It is a congenital entityinwhichtheprocessusvaginalisremainspatentinafemale. Thisresultsinformationofpotentialspacebetweentheperitoneal cavity, inguinal canal reaching upto the labia majora [4] in male childhisprocessusvaginalisaccompanieswithitthetestiswhile in female child it accompanies the round ligament which passes through the inguinal canal into the labia majora [2]. Usually the canal of Nuck obliterates almost at 8th month of gestation which starts from superior to inferior direction [3]. Failed obliterationof this canal results in herniation of abdomino-pelvic contents including abdominal fat, loops of bowel, abdominal fluid, part of urinary bladder and rarely ovary or uterus [3]. The patient may usually present with swelling of labia majora. Ultrasonography is noninvasive diagnostic investigation of choice for evaluation of thispathology[1,2].Herewepresentultrasonographicappearance of indirect inguinal hernia of canal of Nuck containing ovary in 3 montholdfemaleinfantwhopresentedwithcomplainofswelling of labia majora since birth.

3. Case Report A3 month old baby girl presented to pediatric surgery OPD with complainofrightlabialmajoraswellingsincebirthwhichincrease insizeduringcrying.Therewasnohistoryoffever.Thebabywas referred to Department of Radiology for ultrasonography of this swelling. Ultrasonography was performed by Linear High Frequencyprobewhichrevealedherniationofanovoidsolidstructure through abdominal cavity into the inguinal canal of Nuck. It contained few tiny cysts predominantly along its peripherally. There wasnoevidenceofperistalsiswithinit.Findingsweresuggestive ofherniationofrightovarythroughcanalofNuck.ColorDoppler Examination was also performed which showed preserved vascularitywithintheovaryexcludingthepossibilityofitstrangulation ortorsion.Astheherniawasirreduciblesothepatientunderwent surgicalexplorationrepairofrightinguinalhernia.Operativefindingsconfirmedthepresenceofviablerightovarywithintheherni- al sac (Figure 1 and 2).

4. Discussion The current reported incidence of inguinal hernia in pediatric age groupsalmostrangesfrom0.8%to4.4%[1].However,thishernia of the canal of Nuck is a rare entity in females of pediatric group [1,2,3].Itoccurswhenthereisfailureofobliterationofprocessus vaginalisinafemalewhichusuallyobliteratesat8monthofgestation.Ifitremainspatentthenthisresultinformationofapotential space (canal of Nuck) through which abdomino-pelvic contents herniate [1-7]. A well-known risk factor for this condition is prematurity which has a reported incidence of inguinal hernias from 7% to17% [3,7,8,9]. Risk of developing inguinal hernia persist until the age of 8 years in children who were born with very low birth weight [10]. Other risk factors include pulmonary disease, patients on mechanicalventilation,vigorouscryingandlongstandingconstipation where herniation is results from persistently increased intra-abdominal pressure [3,7]. Patient may usually present with the complaints of swelling of Labia Majora with or without pain. Different structures can be herniated through canal of Nuck i.e. abdominal fat, segments of bowelloops,abdominalfluid,urinarybladderandrarelyovaryor uterus.Around15%to20%ofthecases,thecanalofNuckhernia containsovarywithorwithoutthepresenceoffallopiantube[10]. One research showed that 10 out of 35 patients with surgically confirmed hernias of the canal of Nuck, hernia sac contained an ovoidsolidmasswithtinycystswhichwaslaterconfirmedbyoperative findings as an ovary. In 1 patient, the ovary was herniated togetherwithuterus[1,2].Herniationoftheovarythroughtheca- nal of Nuck should be diagnosed as ealy as possible as there is a high risk of ovarian torsion as well as incarceration in these cases and has been reported in up to 43% of patients [5,6,8].Therefore, prompt surgical intervention is necessary [3]. Ultrasound is the noninvasive diagnostic investigation of choice for evaluation of this pathology [8-11].The presence of follicles may be helpful in diagnosing ovary in the hernia sac which may appear as peripherally arranged tiny clear cysts measuring 1 to 7 mminsize.Theabsenceofperistalsisisanothersupportivefinding insuchcases[5].Incarcerationortorsionofovarycanbesuspect- ed when there is lack of blood flow on color Doppler ultrasound assessment [9]. Ultrasound examination should evaluate both inguinalregionsascontralateralherniacanbefoundin88%ofcases without any clinical sign of swelling [9]. CT scan and MRI are more commonly used in complicated cases and also for diagnosis in adult population [1,2]. Many other differentials are described for a labia majora swelling in a female child such as hydrocele, Lymphadenopathy, Abscess,endometriosisaswellasanybenignormalignantneoplasm [1,2,4,8]. Surgical correction is required in almost all inguinal hernias in pediatric females while in adult population, surgical correction is only used when the patient is being symptomatic while conservative approach is used in asymptomatic patients [1,4,12].

5. Conclusion Hernia of the canal of Nuck is a very rare entity in females of pediatric age group. It should be diagnosed as early as possible. Becausethereisahighriskofovariantorsionaswellasincarceration inthesecaseswhichneedimmediatemanagement.Itcanbediagnosed very easily by ultrasonography using linear high frequency probes. Therefore, very pediatric female patient presenting with labia majora swelling should be referred for sonologic evaluation to exclude the possibility of herniation of ovaries. Radiologists shouldalsobefamiliarwiththeanatomyofcanalofNuckaswell assonologicappearancesofcontentsofcanalofNuckhernia.The abovecaseofultrasonographicappearanceofindirectinguinal hernia of canal of Nuck containing ovary is a contribution in the literature for awareness of radiologists.

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Ashok Kumar. Herniation of the Ovary into the Canal of Nuck in a 3 Month Old Female Infant: A Rare Entity Needing Urgent Ultrasonography Evaluation. Annals of Clinical and Medical Case Reports 2022