THE UMBILICUSThe most common abnormality of the umbilicus is an umbilical hernia, described above.The important congenital abnormalities ofthe umbilicus are exomphalos and fitula, and thecommon acquired conditions (apart from hernias)are inflmmation and invasion by tumour.

Exomphalos (Fig. 14.19)This condition, present at birth, represents anintrauterine failure of the intestines to return to theabdomen, combined with a failure of the two sidesof the laterally developing abdominal wall to uniteto cover the embryonic defect.All layers of the abdominal wall are defiient overthe protruding intestines. Their only covering is a thin,transparent membrane formed from the remnant ofthe coverings of the yolk sac. Once this membraneis exposed to the air, it loses its thin, transparentappearance, becoming thicker and covered with anopaque, firinous exudate. Urgent surgery is required.

Umbilical fitulasFour structures pass through the umbilicus duringfetal development: the umbilical vein, the umbilicalarteries, the vitello-intestinal duct and the urachus.If either of the last two tubes fails to close properly,there will be an intestinal or a urinary fitula.A patent vitello-intestinal duct (Fig. 14.20) in theneonate produces an intermittent discharge ofmucus and sometimes faeces from the umbilicus. Itis a rare abnormality.

Sometimes there is visible smallintestinal mucosa lining an obvious fitula, but onother occasions there may only be a small flid leakand the condition mimics an umbilical granuloma.The duct connects to the ileum at the site of aMeckel’s diverticulum.A patent urachus can become a track throughwhich urine can leak onto the external surfaceof the abdomen through the umbilicus. This rarecondition occasionally presents in childhood, butmore commonly in adult life in association withchronic retention of urine caused by disease of theprostate.The patient complains of a watery discharge fromthe umbilicus.An umbilical discharge is nearly always caused byinfection in the umbilicus; nevertheless, rememberthe possibility of a urachal fitula, particularly if thereare symptoms of urinary obstruction or a palpablebladder.Both these embryonic tracts may partially close,leaving a patent segment that becomes a cyst(Fig. 14.21).A vitello-intestinal duct cyst is a small, spherical,mobile swelling deep to the umbilicus that istethered to the umbilicus and to the small bowel bya firous cord.A urachal cyst is an immobile swelling below theumbilicus deep to the abdominal muscles. It may

become large enough to flctuate and have a flidthrill. If it is still connected to the bladder, it mayvary in size and be diffiult to distinguish from achronically distended bladder.

Umbilical adenomaAn umbilical adenoma is a patch of intestinalepithelium left behind when the vitello-intestinalduct closes. It may produce a discharge from thedepths of the umbilicus, but more often protrudesfrom the umbilicus and looks like a raspberry.Although it resembles an umbilical granuloma,the cause is quite different. It will not resolvespontaneously.The mother complains that the baby has a lumpat the umbilicus and a mucous discharge.

OmphalitisInfection within the umbilicus is not uncommonin adults (Fig. 14.23). It is usually associated withinadequate hygiene and a sunken umbilicuscaused by obesity, made worse by any coexistingparaumbilical hernia. The condition is similar tothe intertrigo that occurs between folds of skinelsewhere associated with obesity and sweating,which become secondarily infected with skinorganisms that produce an unpleasant smell.The patient complains of umbilical discharge,pain and soreness.

On examination, the skin within and aroundthe umbilicus is red and tender, and exuding aseropurulent discharge with a characteristic foul smell.The whole umbilicus may feel indurated,especially if there is an ompholith or a tumour deposit.Although simple dermatitis or skin infection isby far the most common cause of a discharge fromthe umbilicus, it is essential to exclude the othercauses of an umbilical discharge, which are listed inRevision panel 14.7.True omphalitis is infection of the stump of theumbilical cord following inadequate postnatal careand cleanliness.

OmpholithWhen the sebaceous secretions that accumulatein the umbilicus are mixed with the broken hairsand flff from clothing that become sucked intothe umbilicus, the mixture can form a fim lump,

worthy of the name umbilical stone or ompholith.The outside tip of the concretions dries out and mayprotrude like a sebaceous horn. In certain parts ofthe UK, there is an old wives’ tale that if this stone isremoved, the sufferer will bleed to death!Routine personal hygiene will usually preventthe formation of an ompholith, but this is not alwaysas simple as it sounds, as the umbilicus can be deepand narrow, particularly in the obese.Small concretions are common and uncomplicated.An abscess will occasionally develop in a narrownecked umbilicus containing an ompholith. Thepatient feels unwell and has a very painful, throbbing,swollen umbilicus that may be diffiult to distinguishfrom a strangulated umbilical hernia.Pus tracking from an intra-abdominal abscessmay occasionally point at the umbilicus, the mostcommon cause being diverticular disease.

Secondary carcinoma(Sister Joseph’s nodule)A fim or hard nodule bulging into the umbilicus,underneath the skin or eroding through it, in a patientwho is losing weight and looks unwell is likely tobe a nodule of metastatic cancer (Fig. 14.24). Thispresentation always indicates advanced, widespreadintra-abdominal disease, and the primary tumour isusually in the abdomen.The tumour cells reach the umbilicus vialymphatics that run in the edge of the falciformligament alongside the obliterated umbilical vein, orby transperitoneal spread.

Nodules of secondary carcinoma may ulcerate,bleed and become infected. Rarely, the tumourdeposit is in continuity with bowel and there may bean acquired intestinal fistula.

EndometriomaIf, in a female patient, the umbilicus enlarges,becomes painful and discharges blood duringmenstruation, it may contain a patch of ectopicendometrial tissue.

Discolouration of the umbilicusThe following physical signs are rare, but the diseasesthat cause them are common and serious.A blue tinge around the umbilicus, caused bydilated, tortuous, sometimes visible, veins, is calleda caput medusae, after Medusa, the mythical Gorgonwho had small snakes on her scalp instead of hair.The dilated veins are collateral vessels that havedeveloped to circumvent portal vein obstruction.There will be other signs of portal hypertension andliver failure.Yellow-blue bruising around the umbilicus(Cullen’s sign) and in the flnk (Grey Turner’s sign; seeChapter 15) may be caused by pancreatic enzymesthat have tracked along the falciform ligament tothe umbilicus or across the retroperitoneal spaceto the loin and digested the subcutaneous tissuesfollowing an attack of severe acute pancreatitis. Bothappear a few days after the beginning of the acutesymptoms.

Bruising at the umbilicus can also be associatedwith intra-abdominal bleeding, particularly whenit is extraperitoneal. Causes include rupturedaortic aneurysms, ruptured ectopic pregnancy andaccidental periuterine bleeding in pregnancy