Discussion

Abdominal cocoon is an extremely rare cause of small bowel obstruction; it has been reported in previous literature to occur mainly in young adolescent women.1 However, a more recent study done in China showed that abdominal cocoon occurred mostly in Chinese men (87.7%), in the 65 patients who  were studied.2

The word cocoon came into English from French, which in turn borrowed it from an Occitan term for ‘eggshell’. The verb ‘cocoon’ has been with us since at least 1881. It is defined as ‘to wrap or envelop in or as if in a cocoon’.3

Abdominal cocoon on the other side was first described in 1978 by Foo et al.4 It refers to a rare condition where there is either total or partial encasement of the small bowel by a fibrocollagenous sac, which looks like a cocoon.1

It is also known to some authors as sclerosing peritonitis, sclerosing encapsulating peritonitis or peritonitis chronica fibrosa incapsulata.4

It has been reported as a disease of unknown pathogenesis that is unique in its feature by packing of the bowel within a dense fibrotic capsule leading to intestinal obstruction.5 It is quite important to differentiate this condition from a congenital peritoneal encapsulation of the small bowel with a thin transparent membrane, which is often found as an incidental finding at laparotomy and almost never causes intestinal obstruction.5

It can be classified as idiopathic or secondary.6 Regarding the causes of idiopathic cocooning, many theories have been postulated, but none have been proven so far.6 One of the commonly known theories that were found in earlier literature was that it was caused by retrograde menstruation with superimposed subclinical peritoneal infection, and that was formulated after noticing the majority of patients were adolescent girls in tropical countries,4 while in secondary abdominal cocoon multiple causes have been reported, including continuous ambulatory peritoneal dialysis, recurrent infective peritonitis, Ventriculoperitoneal shunts, treatment with beta blocker, Tuberculosis, sarcoidosis, familial Mediterranean fever, Systemic Lupus Erythematous, Gastrointestinal malignancies, protein S deficiency and fibrogenic foreign materials.6

In idiopathic abdominal cocoon, the intraoperative finding is that of a thin, easily separated capsule surrounding the small bowel, and as in the presented case can be separated through an avascular plane. In contrast in a secondary abdominal cocoon, it was reported that it was a rather dense fibrous capsule with interbowel adhesions, which are usually quite difficult to separate, as there is no avascular plane.7 This could be explained because of the chronic ongoing infection/inflammatory process, so the sac would be quite adherent.

The condition usually presents with clinical features of acute intestinal obstruction, and patients can give history of previous episodes that have been resolved. Some have been reported to present with a palpable abdominal mass with intestinal obstruction, as in one case reported by Basu et al in Surgery.7 In some studies it was found that the patients who present with idiopathic abdominal cocoon tend to be malnourished, and it was explained to be secondary to anorexia and abdominal pain secondary to recurrent attacks of intestinal obstruction.2

However despite preoperative imaging, diagnosis is done intraoperatively, since imaging can be non-specific. One reported sign on CT is the ‘cauliflower sign’, which is described as a serpentine configuration of dilated small bowel loops in a U-shaped cluster, and delayed transit in a small intestine contrast study is helpful.8 Useful CT and MRI findings are sacculated, dilated bowel loops and soft tissue capsule encircling the bowel loops, which are usually thick on imaging.2 9

One case report done by Ibrahim and Oludara,10 which was published in Tropical Doctor, discussed the management of this condition with surgical excision of the thick membrane, and freeing of the encased small intestine would lead to complete long-term recovery. Bowel is usually viable and resection is not required.

Another study showed that other organs can be encased by the sac (23% of the 65 studied patients); these organs included liver, stomach, appendix, right and left colon, and sigmoid colon.2 Management usually involves the same approach, which is stripping off the membrane.

Recurrence has not been reported, although some patients can present with adhesive intestinal obstruction, in view of all the dissection that has been done. But it usually resolves with the ‘drip and suck’ approach, and one study showed it to be only 6% of the patients.2

Ibrahim and Oludara10 recommend incident appendectomy because the appendix may be difficult to locate if the patient later develops acute appendicitis. But from my point of view now with the expertise in laparoscopic surgery, it is unlikely to be of an issue.