Umbilicus

The belly button is one of the habitats closest to us, and yet it remains relatively unexplored. We analyzed bacteria and arachaea from the belly buttons of humans from two different populations sampled within a nation-wide citizen science project. We examined bacterial and archaeal phylotypes present and their diversity using multiplex pyrosequencing of 16S rDNA libraries. We then tested the oligarchy hypothesis borrowed from tropical macroecology, namely that the frequency of phylotypes in one sample of humans predicts its frequency in another independent sample. We also tested the predictions that frequent phylotypes (the oligarchs) tend to be common when present, and tend to be more phylogenetically clustered than rare phylotypes. Once rarefied to four hundred reads per sample, bacterial communities from belly buttons proved to be at least as diverse as communities known from other skin studies (on average 67 bacterial phylotypes per belly button). However, the belly button communities were strongly dominated by a few taxa: only 6 phylotypes occurred on >80% humans. While these frequent bacterial phylotypes (the archaea were all rare) are a tiny part of the total diversity of bacteria in human navels (<0.3% of phylotypes), they constitute a major portion of individual reads (~1/3), and are predictable among independent samples of humans, in terms of both the occurrence and evolutionary relatedness (more closely related than randomly drawn equal sets of phylotypes). Thus, the hypothesis that "oligarchs" dominate diverse assemblages appears to be supported by human-associated bacteria. Although it remains difficult to predict which species of bacteria might be found on a particular human, predicting which species are most frequent (or rare) seems more straightforward, at least for those species living in belly buttons.

ObjectiveThe aim of this prospective multicenter randomized controlled trial was to compare the efficacy of silver nitrate cauterization against that of topical steroid ointment in the treatment of neonatal umbilical granuloma.MethodsAn open-label, non-inferiority randomized controlled trial was conducted from January 2013 to January 2016. The primary endpoint for the silver nitrate cauterization and topical steroid ointment groups was the healing rate after 2 weeks of treatment, applying a non-inferiority margin of 10%. The healing rate was evaluated until completion of 3 weeks of treatment.ResultsParticipants comprised 207 neonates with newly diagnosed umbilical granuloma, randomized to receive silver nitrate cauterization (n = 104) or topical steroid ointment (n = 103). Healing rates after 2 weeks of treatment were 87.5% (91/104) in the silver nitrate cauterization and 82% (82/100) in the topical steroid ointment group group. The difference between groups was -5.5% (95% confidence interval, -19.1%, 8.4%), indicating that the non-inferiority criterion was not met. After 3 weeks of treatment, the healing rate with topical steroid ointment treatment was almost identical to that of silver nitrate cauterization (94/104 [90.4%] vs. 91/100 [91.0%]; 0.6% [-13.2 to 14.3]). No major complications occurred in either group.ConclusionsThis study did not establish non-inferiority of topical steroid ointment treatment relative to silver nitrate cauterization, presumably due to lower healing rates than expected leading to an underpowered trial. However, considering that silver nitrate cauterization carries a distinct risk of chemical burns and that the overall efficacy of topical steroid ointment treatment is similar to that of silver nitrate cauterization, topical steroid ointment might be considered as a good alternative in the treatment of neonatal umbilical granuloma due to its safety and simplicity. To clarify non-inferiority, a larger study is needed.

BackgroundThe umbilicus is crucial to the aesthetic appearance of the abdomen. With abdominoplasty and umbilicoplasty, placement of the umbilicus is essential and often left at the surgeon's discretion. This study aims to investigate the ideal male umbilical shape and location by examining photographs of top male models in 2019.MethodsIn this observational study, we examined 81 photographs of top male models to assess different ratios based on anatomical landmarks and umbilical appearance.ResultsThe ratio of the distance from the xiphoid to the center of umbilicus (XU) and corresponding distance from center of umbilicus to abdominal crease (UC) had the most reliability (ratio XU/UC, with average measurement: 1.68 ± 0.38), which placed the male navel at a similar position but marginally below the average female umbilicus. Our findings revealed that an oval horizontal is the ideal umbilical shape in males, which differs from what is most aesthetically pleasing in females (oval vertical). In addition, we introduced the SHAPE (Shape, Hood, Adiposity, Protrusion & Position, External piercing) classification for navel appearance to better define the umbilicus and its direct management.ConclusionsThis study establishes that the ideal male umbilicus differs from that of females; it should be placed at the XU/UC ratio of 1.68 ± 0.38 and aim for a horizontal shape with hooding (SHAPE: H II). The SHAPE classification facilitates a logical stepwise approach for the surgeon to refashion the umbilicus.Level of evidence ivThis journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

BackgroundThe increasing use of cross-sectional imaging-particularly abdominal computed tomography (CT)-together with the global rise in obesity has brought renewed attention to a fat-containing structure posterior to the umbilical scar that is frequently labeled as an "umbilical hernia" in radiology reports. Historical anatomical literature, however, describes this configuration as the umbilical canal, a variable, habitus-dependent space between the posterior surface of the linea alba and a reinforcing lamella of the transversalis fascia, often filled with preperitoneal fat and containing embryologic remnants of the umbilical vessels.PurposeTo revisit the anatomical foundations of the umbilical canal, correlate classical descriptions with modern CT appearances, and examine how contemporary surgical risk metrics may be inappropriately extrapolated to this structure.DiscussionClassical anatomical and surgical literature-from Scarpa, Richet, Gauderon, and Cullen to early twentieth-century surgical pathology-consistently distinguishes true umbilical hernia, defined by a peritoneal-lined sac, a fascial neck, and visceral content, from preperitoneal fat protrusions within the linea alba. Modern CT imaging frequently demonstrates a funnel-shaped, fat-filled tract posterior to the umbilical scar that corresponds to the historically described umbilical canal rather than a true hernia. Because this configuration lacks a peritoneal sac and a discrete fascial neck, applying hernia-based morphologic risk metrics may lead to diagnostic ambiguity.ConclusionRecognizing the umbilical canal as a distinct anatomical configuration rather than a true umbilical hernia may improve terminological precision in radiology reporting, enhance interdisciplinary communication, and help avoid potential overdiagnosis and unnecessary surgical referral.