Blind loop syndrome after side-to-side ileocolonic anastomosis is a well-recognized entity even though its incidence and complication rates are not clearly defined. The inevitable dilation of the ileal cul-de-sac leads to stasis and bacterial overgrowth which eventually leads to mucosal ulceration and even full-thickness perforation. Blind loop syndrome may be an underestimated complication in the setting of digestive surgery. It should always be taken into account in cases of acute abdomen in patients who previously underwent right hemicolectomy. We herein report 3 patients who were diagnosed with perforative blind loop syndrome a few years after standard right hemicolectomy followed by a side-to-side ileocolonic anastomosis.

In the past, digestive continuity after right hemicolectomy was often restored through either end-to-end or end-to-side ileocolonic anastomosis. Due to the extensive implementation of laparoscopy in colonic surgery, side-to-side ileocolonic anastomosis has gained popularity because of the widespread use of linear staplers in this setting. Even in open surgery, mechanical side-to-side anastomoses are easy, quick and cost-effective because these can be performed using a single linear stapling device, while an end-to-side recontruction would require both linear and circular staplers to complete the anastomosis with additional costs.

Concurrently, intracorporeal anastomoses during laparoscopic right hemicolectomies can be exclusively carried out with linear staplers (endoGIA).

Yet, in 1906, Cannon and Murphy judged side-to-side anastomoses to be far from physiological, and advocated end-to-end reconstruction instead[1]. The same recommendation was reinforced by Pearse[2], Estes et al[3] and Holme[4] in further studies. A key reason why side-to-side anastomoses have been questioned lies in their substantial risk of progressive dilation at the level of the cul-de-sac, which might lead to enlarged pockets prone to stasis and bacterial overgrowth. Such alterations seem to predispose to the so-called “blind loop syndrome”[5,6]. The continuous enlargement of the blind loop may eventually cause mucosal ulcerations, intestinal bleeding and/or full-thickness viscus perforation.

There are limited data in the literature about the actual incidence of blind loop syndrome and its related morbidities because, generally, studies on intestinal anastomoses are exclusively focused on short-term postoperative complications (3 mo), whereas blind loop syndrome tends to develop years after surgery. We retrospectively reviewed 3 cases of blind loop perforation which occurred during long-term follow-up after standard right hemicolectomy followed by mechanical side-to-side ileocolonic anastomosis.

Nowadays, mechanical side-to-side anastomosis after right hemicolectomy is commonly performed either in open or laparoscopic surgery due to its simplicity and speed. In the short-term there is no clear advantage of a specific anastomotic configuration over others. On the other hand, side-to-side anastomoses have been criticized for being theoretically anti-physiologic and for the long-term risk of a blind loop[1].

Blind loops result in abnormal peristalsis causing filling rather than emptying of the pouch. Such dismotility-related stasis predisposes to bacterial overgrowth eventually followed by mucosal and/or transmural inflammatory changes of the intestinal wall. The consequent clinical scenario is referred as blind loop syndrome and may present with a wide spectrum of morbidities such as diarrhea, vitamin B12 deficiency, iron-deficiency anemia, ulcerations, bleeding and enteroliths[5]. At times, a pinpoint perforation of the blind loop may occur[5,7,8]. Partial disruption of the muscle layer in the side-to-side anastomosis causes dysmotility, diverting intestinal content more easily unto the blind loop. The cul-de-sac dilation may occur even after an end-to-side recontruction, though it appears more likely to happen after a side-to-side anastomosis[6]. Conversely, blind loops do not develop after end-to-end anastomoses. Stellamor et al[9] analyzed 66 ileocolonic resections, and identified 9 blind loops (average transverse diameter between 5 and 11 cm) out of 31 side-to-side anastomoses, whereas no blind loops were observed after 12 end-to-end anastomoses.

Only a few cases have been accurately described in literature. Estes et al[3] reported about a 10 cm blind loop which had increased to 46 cm after only a few months. Pollock described a blind loop which started as 2 cm in length and stretched to 15 cm after 1 year[10].

We believe this critical aspect of side-to-side anastomoses will be more intensively taken into consideration in light of their expanding use in the laparoscopic era. The likelihood of enlargement and tearing appear proportional to the span of the blind loop, the bigger the pouch the higher the risk of further lengthening and stretching. It is advisable to leave the bowel stump as short as possible, even if that does not necessarily prevent the loop from enlarging in the long-term. In addition, antiperistaltic anastomoses do not seem to abolish the risk of developing a cul-de-sac, as shown in one of our cases. Some authors reported incidental findings of long blind loops discovered during either autopsy studies or surgical interventions in asymptomatic individuals[6]. Thus, the sole development of a blind loop does not cause clinical manifestations per se.

We found in the literature only 11 cases of blind loop perforation, some presenting with acute, generalized peritonitis due to pinpoint perforation[5,6,8]. Lack of data precludes an accurate appraisal on those factors which might cause symptomatic complications in those with a blind loop.

Usually, blind loop syndrome occurs many years after bowel surgery. In a French review, 45 out of 69 patients with a blind loop developed abdominal symptoms more than 5 years after surgery[5]. In a retrospective study based on abdominal CT examinations of 30 patients with radiological features compatible with a blind loop (eventually resected in 4 cases), the mean and median time between surgery and imaging were 49.4 and 32.2 mo, respectively[11]. In our own series, all patients presented with perforation at least 2 years after a side-to-side ileocolonic anastomosis. A CT scan seems helpful and a focally dilated loop of the small bowel adjacent to surgical clips is a recurrent finding[11]. Even so, blind loops may be mistaken for diverticula, abscesses or obstructed bowel segments. Blind loop syndrome is primarily managed through a redo anastomosis in an end-to-end fashion. We chose to resect the perforated pouch sparing a new anastomosis, deeming this limited procedure safer in the emergency setting. Our patients are free of symptoms albeit after a short clinical follow-up (6-12 mo). Blind loop syndrome along with its complications is probably underestimated and further research is needed to define the real extent of the problem. In addition, a colorectal surgeon should be aware of this potential issue before choosing the ileocolonic anastomosis reconstructive technique.