Introduction

Meckel’s diverticulum (MD) is a congenital true intestinal diverticulum, being the embryologic remnant of the omphalomesenteric-vitelline duct with average incidence of 0.3–3 % in the adult population [1–3]. Complications like bowel obstruction, haemorrhage, diverticulitis and hernia (Littre’s hernia) are rare and warrant surgical/medical attention. A preoperative imaging diagnosis of a perforated Littre’s inguinal hernia is not reported in the English literature to the best of the knowledge of the authors. We report a case of perforated Littre’s hernia presenting as lower abdominal wall cellulitis diagnosed on preoperative imaging.

Case report

A 50-year-old male was referred from the emergency department to us for computed tomography (CT) of abdomen and pelvis for evaluation of sudden worsening of pain in the right groin over a day. It was associated with fever, swelling and redness of the right lower abdomen, which had gradually increased over the previous 7 days. There was no history of nausea, vomiting or constipation. Clinical examination revealed tachycardia, 101 °F (38.33 °C) fever and normal blood pressure. Local examination revealed diffuse tenderness in the abdomen with induration and warmth of the right lower abdominal wall. It was associated with crepitus on palpation. There was a soft, tender, non-pulsatile, irreducible mass in the right groin.

Haematology showed leucocytosis with white blood count of 26,660/mm3. Blood culture revealed E. coli. In view of the clinical finding of crepitus in the right lower abdomen, the patient was referred for CT of the abdomen and pelvis.

CT of the abdomen and pelvis was performed on a 64 detector row CT machine (SOMATOM Definition, Siemens, Erlangen, Germany) which revealed an oral contrast opacified blind-ending pouch of bowel arising from the antimesenteric border of the distal ileal loop with herniation into the right inguinal canal (Fig. 1a). A full thickness breach (measuring approximately 1.2 cm) was noted along the lateral wall of the pouch, just proximal to its tip with extravasation of oral contrast into the inguinal region (Fig. 1b). Large ill-defined fluid density collection with air foci (giving mottled appearance) was noted in the anterior abdominal wall extending superiorly up to the right lower anterior chest wall (Fig. 1b). These findings suggested the diagnosis of Meckel’s diverticulum herniating into the inguinal canal (Littre’s hernia) with perforation of its wall leading to secondary subcutaneous emphysema. Also, a few small nodular hyperdensities were noted in the diverticulum proximal to the tip, likely to represent lithiasis (Fig. 2a). The appendix was of normal calibre and showed normal intraluminal air specks and oral contrast opacification (Fig. 2b). Proximal small-bowel loops were of normal calibre and there was normal distal passage of oral contrast material. The patient underwent emergency laparotomy with resection of a long Meckel’s diverticulum (Fig. 3), with small-bowel anastomosis and drainage of abdominal wall collection. The pus and collection was drained using a suction catheter and thus, unfortunately, a foreign body could not be isolated. Histopathology of the specimen confirmed Meckel’s diverticulum and showed no heterotopic tissue (Fig. 4).

Fig. 1
figure 1

Reformatted oblique sagittal curved planar images (CPR) of CT of abdomen and pelvis in venous (a) and oral contrast (b) phase showing long blind-ending pouch of bowel (thin arrows) arising from the antimesenteric border of the distal ileum (dashed arrow) suggesting Meckel’s diverticulum, and herniating into the right inguinal canal i.e. Littre’s hernia. Also noted is a breach in the lateral wall of the diverticulum (thick arrow) with extravasation of oral contrast in the inguinal region associated with adjacent inflammatory changes and subcutaneous emphysema (white asterisk)

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Fig. 2
figure 2

Reformatted oblique curved planar image of CT of abdomen and pelvis showing (a) a few nodular hyperdensities near the tip of Meckel’s diverticulum, suggestive of lithiasis (thin arrow). (b) Shows a normal calibre appendix (thick arrow), partially opacified with oral contrast with no adjacent inflammatory changes

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Fig. 3
figure 3

Intraoperative photograph (a) and surgical specimen (b) confirming radiological findings of blind-ending pouch (thin arrows) noted arising from the antimesenteric border of the distal ileum, suggestive of Meckel’s diverticulum, with a full thickness breach in its lateral wall (thick arrow) suggestive of perforation

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Fig. 4
figure 4

Histopathology slide of the specimen showing normal intestinal mucosa with no heterotopic tissue (thin arrow) with necrosed tissue at the site of perforation (thick arrow)

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Discussion

Meckel’s diverticulum is a congenital true intestinal diverticulum arising from the antimesenteric border of the small intestine, which contains all tissue layers of the bowel. It is a remnant of a proximal portion of embryologic omphalomesenteric-vitelline duct which connects the yolk sac to the mid gut through the umbilical cord. This duct usually obliterates by 5–8th gestation week; however, failure of closure may result in a diverticulum (most common), omphalomesenteric fistula or enterocyst. The incidence varies from 0.3 to 3 %, with equal distribution in both sexes; however, because of its asymptomatic nature, the actual incidence may be higher [1–3]. Males are slightly more predisposed to complications [3]. Most MDs measure 4–6 cm in length, 2 cm in diameter and are located proximal to the ileo-caecal junction at a distance of between 30–90 cm. On histology, it is normally lined by intestinal mucosa, though heterotopic mucosa may be frequently seen, with gastric mucosa being most common (52 %) followed by pancreatic mucosa (6 %) [4].

Usually patients are asymptomatic, though a few of them (4 %) may have complications and present with symptoms of pain due to diverticulitis, malaena/haematochezia, small-bowel obstruction, intussusception, perforation or Littre’s hernia (herniation into umbilical, femoral, lumbar, sciatic or inguinal canal; with the inguinal canal being the most common site for herniation) [1, 2]. Bleeding due to heterotopic mucosa is the most common complication in children (usually <2 years of age) while obstruction or diverticulitis are more common complications in adults. A true Littre’s hernia contains MD alone; however, cases of mixed Littre’s hernia containing small bowel or abdominal viscera in addition are also reported. Clinically, a distinction between herniation of the small-bowel loop versus MD is not apparent and thus diagnosis is usually perioperative. The progress of Littre’s hernia is more gradual than other hernias.

The clinical, pathological and radiological features of complicated MD are well known, however, it is difficult to establish a preoperative diagnosis [3, 5, 6]. Conventional barium studies reveal a saccular, blind-ending structure on the antimesenteric border of the ileum, with a characteristic triradiate fold mucosal pattern converging with the ileum [3]. Nuclear imaging using a pertechnetate scan can help in preoperative diagnosis in some cases having ectopic gastric mucosa. Its clinical importance is limited by the fact that it is an unsuitable investigation in unstable patients due to haemorrhage and lower prevalence of gastric mucosa in symptomatic adult patients [3]. Angiographic diagnosis of MD is based on identification of mucosal blush from a persistent vitelline artery which arises from distal ileal branches, though has less sensitivity [7]. CT remains the preoperative investigation of choice. On CT, MD is visualized as a rounded or tubular collection of air and fluid located in the abdomen and pelvis and communicating with the terminal small bowel with a varying sized neck. It originates from the antimesenteric border and may show opacification following oral contrast administration. MD is commonly visualized in the midline, with few cases reported on either side of the midline. In cases of complication, adjacent inflammatory changes, fluid collection, enteroliths and signs of perforation may be noted.

Uncomplicated MD needs to be differentiated from other blind-ending structures in relation to the small bowel, such as acquired solitary diverticula of the small intestine, communicating enteric duplication, pseudosacculations of motility disorders and Crohn’s disease [3]. Sometimes, a normal or acutely inflamed vermiform appendix may herniate into the inguinal canal. This is called ‘Amyand’s hernia’ and mimics a Littre’s hernia [8]. In Amyand’s hernia, the herniated blind-ending loop originates from the base of the caecum and may show associated appendicolith, inflammatory changes like wall thickening and enhancement, dilated lumen and adjacent fat stranding. The inflammation can be incidental or as a consequence of incarceration. However, in Littre’s hernia, the herniated blind-ending loop originates from the antimesenteric border of the distal ileum and enteroliths are rarely reported in Littre’s hernia. The size of the herniated loop is unreliable for identification purposes since collapsed small bowel, MD and appendix may all be the same calibre.

Lithiasis in cases of symptomatic MD is very rare, with unclear pathogenesis [6, 9]. The absence of heterotopic gastric mucosa leads to an alkaline environment facilitating precipitation of calcium, or abnormal peristalsis at the site of MD may result in stasis leading to lithiasis. The “stone” could be a fecolith, bezoar or gall stone [9].

Perforation in the case of Littre’s hernia may be due to either peptic ulceration from acid secretion related to gasric mucosa or compromised circulation and luminal patency at the narrow neck of the hernia [2, 10]. It presents with slowly progressive non-specific signs and symptoms, the most common being local inflammation, as in our case [2].

Complicated Meckel’s diverticulum is rare and is a diagnostic challenge both clinically as well as radiologically. CT is the imaging modality of choice which may show a blind-ending pouch arising from the antimesenteric border of the distal ileum with a varying sized neck showing opacification with oral contrast. While evaluating patients of acute abdomen and hernia, a high degree of suspicion of MD is to be kept in mind, especially when a blind-ending bowel pouch is encountered. Complications may have varying imaging features like surrounding inflammatory fat stranding, localized fluid or air fluid collection, lithiasis, intussusception and small-bowel obstruction. Confident diagnosis on imaging facilitates emergent laparotomy with resection of the MD and small-bowel anastomosis as a part of management.