The development and closure of the processus vaginalis

Contemporary Review of Masses in the Canal of Nuck

Canal of Nuck masses is a rare occurrence that can cause swelling in the abdominal-inguinal region of females for various reasons. This condition arises due to an abnormal persistence of the processus vaginalis opening. Although Canal of Nuck pathology is not widely known among general surgeons or gynecologists due to its rarity, it has been associated with significant morbidity and requires further research. In this comprehensive review, we aim to summarize the embryology and anatomy of the Canal of Nuck, followed by a description of the various types of masses that can occur in this region. We discuss the clinical presentation and diagnostic workup of Canal of Nuck masses, including imaging modalities and differential diagnoses. Next, we review the surgical management of these masses, including open and laparoscopic approaches. Finally, we discuss the potential complications and long-term outcomes associated with Canal of Nuck pathology. This review aims to compile the presently accessible literature on anomalies occurring in the Canal of Nuck in females, with a particular focus on describing their pathological nature, diagnosis, and management. In summary, this review provides an up-to-date understanding of the pathology, diagnosis, and management of Canal of Nuck masses and aims to raise awareness of this under-recognized surgical challenge among healthcare providers.

Testicular descent: A review of a complex, multistaged process to identify potential hidden causes of UDT

BACKGROUND/PURPOSE

What causes normal descent of the testis in a fetus, and what goes wrong with this complex process to cause undescended testes (UDT), or cryptorchidism? Over the last 2 decades, most authors searching for the cause(s) of UDT have looked at the 2 main hormones involved, insulin-like hormone 3 (Insl3) and testosterone (T)/ dihydrotestosterone (DHT), and their known upstream (hypothalamic-pituitary axis) and intracellular 'downstream' pathways. Despite these detailed searches, the genetic causes of UDT remain elusive, which suggest the aetiology is multifactorial, and/or we are looking in the wrong place.

METHODS

In this review we highlight the intricate morphological steps involved in testicular descent, which we propose may contain the currently 'idiopathic' causes of UDT. By integrating decades of research, we have underlined many areas that have been overlooked in the search for causes of UDT.

RESULTS

It is quite likely that the common causes of UDT are still hidden in these areas, and we suggest examining these processes is worthwhile in the hope of finding the common genetic anomalies that lead to cryptorchidism. Given the fact that a fibrous barrier preventing descent is often described at orchidopexy, examination of the extracellular matrix enzymes needed to allow gubernacular migration may be a fruitful place to start.

CONCLUSION

This review of the complex anatomical steps and hormonal regulation of testicular descent highlights many areas of morphology and signalling pathways that have been overlooked in the search for causes of UDT.

Persistence of the processus vaginalis and its related disorders

The processus vaginalis is a blind-ended evagination of the abdominal wall that develops during fetal life and typically undergoes obliteration in early life. Persistence of the processus vaginalis is associated with a number of pathologies including congenital indirect inguinal hernias, communicating hydroceles, funicular and encysted hydroceles, canal of Nuck cysts, and acquired undescended testis. Whilst all are detectable sonographically, there is little educational material relevant to the field of ultrasound with much of the literature directed at surgical and primary care physicians. Furthermore, within the literature there is a lack of consensus on several areas including the anatomy and embryology of the processus vaginalis and the mechanisms behind its obliteration. As such the objective of this paper is to distil the information regarding the persistent processus vaginalis as it is relevant to ultrasound and in doing so address the literature gap for sonographers and sonologists. The anatomy and embryology of the persistent processus vaginalis will be discussed including causative mechanisms for anomalies with their sonographic appearance highlighted.

Frequency of inguinal herniotomy in Australia (1998-2017)

BACKGROUND/AIM

Closure of the processus vaginalis (PV) is considered as the last step of testicular descent. Therefore, patent processus vaginalis (PV), and inguinal hernias are linked to cryptorchidism. As the National Australian incidence of orchidopexy has decreased over the previous 20 years, we aimed to explore the incidence of inguinal herniotomy (including hydrocele) over time in Australia.

METHODS

The National Department of Human Services (DHS) database, and Bureau of Statistics database were obtained for the years 1998-2017. The numbers of inguinal herniotomies in patients aged 0-4, 5-14 and 15-24 yearswere examined with ethical approval.

RESULTS

Over the 20-year period, over 87,000 inguinal herniotomy procedures were performed in males. The incidence per year in males decreased across all ages over the 20-year period, but was most pronounced in infants and toddlers. Similar to males, the incidence in females decreased over time, with the ratio of procedures per head of population decreasing in children under 5 years of age. The ratio of male: females varied according to ages, and was between 2.8 and 6.2 males: 1 female.

CONCLUSION

This study suggests that fewer 0-4-year olds are undergoing inguinal herniotomy, compared with 20 years ago. This is likely due to a change in practice for the management of unilateral symptomatic hernias, from routine bilateral herniotomies, to unilateral surgery. As well as less aggressive surgical intervention for hydroceles in boys.

LEVEL OF EVIDENCE

III.

Suppurative appendicitis presenting as acute scrotum confounded by a testicular appendage

Patients presenting with testicular pain and swelling mandate an urgent urology review and scrotal exploration to prevent testicle loss due to torsion. Other pathology masquerading as torsion is extremely rare but can occur. We present one such case. A 14-year-old male presented with a 1-day history of right testicular swelling and tenderness. He was apyrexial and denied any other symptoms. Blood tests demonstrated raised inflammatory markers. He had lower left-sided abdominal tenderness with a swollen, erythematous right hemiscrotum. During an urgent scrotal exploration for testicular torsion, a purulent hydrocele with a patent process vaginalis was noted, but no torsion. Post-operative abdominal pain mandated a general surgical review and subsequent appendicectomy. The patient made a full recovery. Acute suppurative appendicitis presenting as a urological emergency is extremely rare. To make a correct diagnosis and prevent multiple surgeries, a joint urological and general surgical assessment with a high index of suspicion is required.

Migration of Ventriculoperitoneal Shunt into a Hernia Sac: An Unusual Complication of Ventriculoperitoneal Shunt Surgery in Children

We report 2 cases of ventriculoperitoneal (VP) shunt migration into an inguinal hernia sac. In both cases hernia manifested itself on the right side in late infancy. We attempted to analyse the anatomical and mechanical factors leading to shunt migration as seen in the X-rays of our cases.

The role of hepatocyte growth factor in the humoral regulation of inguinal hernia closure

BACKGROUND

Calcitonin gene-related peptide (CGRP) is proposed to indirectly cause inguinal hernia closure via hepatocyte growth factor (HGF). Studies have shown that CGRP and HGF cause processus vaginalis (PV) fusion in vitro. We localized the HGF receptor in the PV and tested whether CGRP was responsible for HGF release.

METHOD

Hernial sacs collected from 20 children (15 males, 4 females, 1 XY female) undergoing inguinal hernia repair were immunohistochemically stained for HGF receptor (c-met). Parietal peritoneum was stained for comparison. Hernial sacs from another 16 children (12 males, 4 females), with each sac divided into 4, were cultured, with and without CGRP, for 24 and 48 hours. Hepatocyte growth factor content was then assayed in the culture medium (4/16 children) and tissue extracts (12/16 children), using enzyme-linked immunosorbent assay. Children were aged 1 month to 10 years. Data were analyzed using paired Student t tests.

RESULTS

C-met localized to the PV epithelial surface in 17 of 20 hernial sacs and in the parietal peritoneum. Hepatocyte growth factor levels increased over time in 4 of 4 culture medium assays, with a significant difference in 1 of 4. Seven of 12 tissue extract assays had significant differences; however, 3 of 7 had decreased HGF levels.

CONCLUSION

The presence of HGF receptors in the PV is consistent with a role for HGF in triggering epithelial-mesenchymal transformation during inguinal hernia closure. The presence of HGF receptors in the parietal peritoneum suggests that regulation of this process is complex. Enzyme-linked immunosorbent assay results indicate that, in a subset of patients, exogenous CGRP may be responsible for HGF elevation and potentially implicates deficient endogenous CGRP as one cause for inguinal hernia patency.

Hernias and Ewing's sarcoma family of tumours: a pooled analysis and meta-analysis

BACKGROUND

Ewing's sarcoma family of tumours has been associated with a history of hernia and with a parental occupation of farming. However, the causes of these tumours remain unknown. We therefore aimed to investigate the association between hernia and Ewing's sarcoma family of tumours.

METHODS

We did a pooled analysis of two case-control studies and a meta-analysis of three case-control studies of Ewing's sarcoma family of tumours that had adequate information on history of hernia. The primary endpoint was development of a tumour from the Ewing's sarcoma family. 138 patients with such a tumour and 574 controls were included in the pooled analysis, and 357 patients with these tumours and 745 controls were included in the meta-analysis. Risk was assessed by an odds ratio (OR) and 95% CI by use of multivariate analysis with unconditional logistic regression for the pooled analysis and random effects model for the meta-analysis.

FINDINGS

Pooled analysis showed that children with Ewing's sarcoma family of tumours were more likely to have had an umbilical hernia than were controls (odds ratio [OR] 3.3 [95% CI 1.3-8.0]). Meta-analysis showed that children with Ewing's sarcoma family of tumours were more likely to have had a hernia (3.2 [1.9-5.7]).

INTERPRETATION

Ewing's sarcoma family of tumours and hernias (particularly inguinal hernias) have common embryological pathways of neuroectodermal origin, and environmental factors, such as farming, might link the two entities.

Could inguinal hernia be treated medically?

Inguinal hernia is the most common congenital anomaly requiring surgical correction. The cause of the hernia is, most commonly, persistence of the processus vaginalis. Study of testicular descent in rodents has revealed a role for the genitofemoral nerve and calcitonin gene-related peptide (CGRP). Since the testis cannot descend without the processus vaginalis, we wondered whether both descent and hernia closure might be regulated by the same mechanism. Therefore, we tested the idea that CGRP might be active in closure of the inguinal hernia. Using hernial sacs removed at herniotomy operation, fusion of the hernial surfaces was induced by CGRP, but not by CGRP 8-37, CGRP 27-37 or dihydrotestosterone. Hepatocyte growth factor also caused peritoneal obliteration in vitro. We propose that obliteration of the processus vaginalis is under the control of molecules released from the genitofemoral nerve, and that a chemical treatment of inguinal hernia is at least theoretically possible.

The etiology of indirect inguinal hernias: congenital and/or acquired?

The development of indirect inguinal hernias in infants is caused by a patent processus vaginalis (PPV). Consequently, this type of hernia is cured by simple herniotomy. In adults, however, herniotomy alone is accompanied by a high recurrence rate. This indicates that additional factors play a part in the development of indirect inguinal hernias in adults. The aim of this study was to determine the etiology of the development of an indirect hernia in adult life. Also, the prevalence of a PPV without clinical evidence of a hernia was determined and related to age. From November 1998 until February 2002, 599 patients from four different teaching hospitals, who underwent abdominal laparoscopy for various pathologies, were included. During laparoscopy, the deep inguinal ring was bilaterally inspected. Patients undergoing laparoscopy for inguinal hernia repair were excluded. Mean age was 45 years (range 8-89 years). Thirty-two percent (189/599) were male. Twelve percent (71/599) had PPV, all without clinical symptoms. Fifty-five percent (39/71) with PPV were male (P<0.0001). Fifty-nine percent (42/71) with PPV were right-sided, 29% (21/71) with PPV were left sided, and 12% (8/71) were bilateral (P=0.01). The prevalence of PPV in patients under 20 years was 22%. Of those between 20 and 30 years of age, 6% had PPV. Of those between 30 and 50 years, 24 patients (11%) had PPV. Of patients over 50 years, 33 (14%) had PPV. No significant differences between ages were observed. It is concluded that asymptomatic patent processus vaginalis frequently exists in adult life. The prevalence of PPV does not increase significantly with age. Assuming that indirect hernias start with asymptomatic peritoneal protrusion that can be observed laparoscopically, the incidence of PPV, like the incidence of adult indirect hernias, should increase in case of acquired etiology. Such an increase of incidence with age was not confirmed by our results. It is concluded that the etiology of indirect inguinal hernia in adults, as in infants, is congenital.

Fusion of childhood inguinal hernia induced by HGF and CGRP via an epithelial transition

BACKGROUND/PURPOSE

Recent evidence has suggested that calcitonin gene-related peptide (CGRP), which is released from the genitofemoral nerve, may trigger fusion of the patent processus vaginalis in children with inguinal hernia. The purpose of this study was to determine whether CGRP triggers the release of mesenchymal factors leading to subsequent fusion of the processus vaginalis.

METHODS

The response of cultured epithelial cells derived from the patent processus vaginalis was analysed by a novel in vitro culture system. Epithelial cells lining fresh hernial sacs (removed at inguinal herniotomy) were detached enzymatically and cultured for 72 hours on Micropore filters, in the presence of either 100 ng/mL hepatocyte growth factor (HGF), 7.4 x 10(-6) mol/L CGRP (amino acids 1 to 37), 7.4 x 10(-6) mol/L CGRP (8 to 37) antagonist, 10% fetal calf serum (FCS), or serum-free medium (SFM) alone. Transformation from an epithelial cell morphology to motile mesenchymal fibroblast-like cells was assessed by an average migration score (AMS), ranging from 0 with no sign of migration, to 3 with greater than 75% of cells migrating. Confocal microscopy was used to record changes in expression of epithelial (cytokeratin) and mesenchymal (vimentin) markers, as well as actin. Beta-catenin also was examined because it is part of the molecular complex that links cadherins to actin resulting in cell-cell adhesion.

RESULTS

Epithelial and mesenchymal markers underwent either down-regulation or up-regulation as epithelial cell sheets broke apart and individual cells commenced migration. The AMS after 72 hours of culture was 0.22 with SFM (control); with FCS the score was 1.4 (P < .01). The AMS score with CGRP (1 to 37) was 0.55 (P = .165) and with its analogue, CGRP (8 to 37), which is a competitive inhibitor, 0.67 (P = .309). Neither was significant. HGF caused a significant increase in the AMS to 1.56 (P = .01).

CONCLUSION

Both HGF and FCS (which contains various undefined peptides and growth factors) produced transformation of hernial sac epithelial cells, whereas CGRP and its inactive analogue did not. CGRP receptors are localised to mesenchymal fibroblasts within the processus vaginalis connective tissue, suggesting that CGRP could act indirectly via HGF, which, in turn, promotes fusion of the processus vaginalis. In the future, a nonsurgical treatment of inguinal herniae in children might be possible by the local administration of agents which promote fusion.