Ileosigmoid knotting (ISK), the name of which was po
pularized by Shepherd in 1967
1, is the wrapping of
the ileum or sigmoid colon around the other one and
its mesentery, causing a double-loop obstruction (Figure
1). It remains
an unusual but severe form of intestinal obstruction
2-5.
Epidemiology:
The incidence of ISK is not well known, but it generally occurs
in areas with a high incidence of sigmoid volvulus (SV). ISK
is more common in African, Asian, Middle Eastern, Eastern and
Northern European, and South American countries, and also in
Turkey 2-6. The disease accounts for 18-50% of SV cases in
Eastern countries and 5-8% in Western countries 2.
ISK is common in adult males and the peak incidence is in
the 3rd-5th decades 2-7. ISK is also common in the late pregnancy
period in females 6.
Etiology:
The etiology of ISK is controversial 1-4,6,8. Certain anatomical
characteristics of the ileum and sigmoid colon, including
a hypermobile bowel with an elongated mesentery having a
narrow base (which may be acquired or rarely is congenital) are
a prerequisite for ISK 2,3,6. Another anatomical factor is the
presence of a relaxed anterior abdominal wall, which allows for
the bowel torsion 8,9.
The consumption of a high bulk diet in the presence of an
empty small bowel can predispose patients to ISK; therefore, the
incidence is high among Muslims who eat a single daily meal during
the Ramadan fast 10,11.
Some conditions including postoperative adhesions, internal
herniations, Meckel's diverticulum, and malrotations may be rare predisposing factors for ISK 2,3,6,12.
Pathophysiology:
When the mechanical double-loop obstruction occurs, both
the loops of ileum and the sigmoid colon become distended.
Both strangulation and thrombosis of the vessels contribute to
ischemia and gangrene in the ileum and sigmoid colon. The
gangrene may extend to the proximal part of the ileum, the cecum,
and rarely the distal part of the jejunum and ascending
colon 1-3,6. Shock, peritonitis, and endotoxemia occur because
of the volume loss into the bowel lumen, bacterial translocation
to the peritoneal cavity, and absorption of toxic products 2,3.
Classification:
ISK is classified into four types: Types I, II, III, and undetermined.
In Type I, the ileum revolves around the sigmoid colon;
in Type II, the sigmoid colon revolves around the ileum; in Type
III, the ileocecal segment revolves around the sigmoid colon; and
in the Undetermined Type, it is impossible to determine the revolved
segment 3. On the other hand, in 2009, using some
preoperative and operative criteria that are correlated with mortality,
a new classification was described for surgically treated ISK
13. In the new classification, the patients with ISK are classified
as follows: Class 1, patients with no risk factor (advanced age,
associated disease); Class 2, those with no shock or bowel gangrene but other risk factors mentioned above; Class 3, those with
shock; Class 4, those with ileum or sigmoid colon gangrene; Class
5, those with both shock and ileum or sigmoid colon gangrene;
Class 6, those with both ileum and sigmoid colon gangrene.
Clinical Presentation:
ISK generally shows a sudden onset, but the patients usually
present with a delay of a few days. The main symptoms are
abdominal pain, distention, obstipation, and vomiting. Other
complaints include nausea, diarrhea, anorexia, rectal bleeding,
and hematemesis 1-7.
The main signs are asymmetrical abdominal distention and
tenderness. Additional findings include hypokinetic-akinetic or
hyperkinetic bowel sounds, tympany, an empty rectum, visible
peristalsis, an abdominal mass, and a fecal odor of the breath.
In cases with gangrene or perforation and peritonitis, rectal mela
notic stool or rebound tenderness and muscular defense may be
seen 1-7.
Diagnosis:
There are no specific blood tests for diagnosing ISK 6. Plain
abdominal X-ray radiographs usually show a dilated sigmoid colon
in the right side of the abdomen and multiple small intestinal
air-fluid levels in the left side 2,3,6,14 (Figure 2). Barium or
water-soluble contrast enemas generally demonstrate the obs
tructive lumen, but the enemas are only used if the patients do
not have peritonitis, bowel gangrene, or perforation 2,14,15.
Abdominal computed tomography (CT) usually shows a twisted
and dilated sigmoid colon with whirled sigmoid mesentery, in
addition to twisted and dilated small intestinal segments 6,15-17. Although flexible endoscopy generally demonstrates a spiral
sphincter-like twist of the mucosa in the torsioned sigmoid colon,
it does not give any information about the small bowel 2,6.
Click Here to Zoom |
Fig 2: Plain erect abdominal x-ray film in ISK (a dilated sigmoid colon and
multiple small intestinal air-fluid levels). |
Click Here to Zoom |
Fig 3: Operative appearance of ISK (a twisted and dilated sigmoid colon
with twisted and dilated ileal segments). |
The accurate preoperative diagnosis of ISK is difficult, parti
cularly when CT is not used. The disease is generally misdiagnosed
as an obstructive (particularly SV) or nonobstructive emergency
in the preoperative period and the correct diagnosis is
made upon laparotomy or, in some cases, autopsy 2,6,18.
Treatment:
Initial management of patients with ISK consists of a rapid
and prompt resuscitation to correct fluid, electrolyte and acidbase
imbalances with central venous pressure (CVP) monitoring,
nasogastric decompression, parenteral feeding, and appropriate
use of antibiotics. After resuscitation, an emergency laparotomy
is necessary 2,3,6.
There is considerable controversy regarding the preferred
surgical procedure for ISK 2,3,6. Because untwisting the knot is
both difficult and risks toxin release and perforation, it has been
advised that the sigmoid colon be deflated by means of needle
deflation or colotomy, or en-bloc resection of the gangrenous
colon 2,6,19,20. In gangrenous cases, all gangrenous small
bowel segments are resected and bowel continuity is restored
by an enteroenterostomy, similarly, gangrenous sigmoid colon is
resected and a primary anastomosis is performed if the patient
is stable and a tension-free anastomosis is possible. Despite high
morbidity, an ileostomy or colostomy may be life-threatening particularly
in unstable cases or in cases with borderline ischemic
bowel 2,4,6,7. In nongangrenous cases, careful untying of the
knot may be performed as a sole surgical procedure in unstable
patients, or a volvulus-preventing procedure such as mesopexy,
mesoplasty or resection with primary anastomosis may be added
2,4,7.
Prognosis:
ISK has a grave prognosis. The mean mortality rate is 6.8-
8% in nongangrenous and 20-100% in gangrenous cases. The
morbidity rate is also high. The most common cause of death is
shock. The presence of advanced age, associated medical problems,
shock, bowel gangrene or perforation increases the mortality
rate 2-4,7,21.
Special Circumstances:
Ileosigmoid Knotting in Children
ISK is not common in children. The youngest case reported
in the literature is a two-week-old child. Vomiting and diarrhea
are more common in these cases, diagnosis is generally more dif-
ficult and mortality is higher 4,19,22,23.
Ileosigmoid Knotting in Elderly People
Like SV, ISK may be preceded by inactivity and pseudomegacolon,
and owing to psychiatric problems and chronic illnesses,
the diagnosis is often difficult. Advanced age and associated
comorbidities in elderly patients increase the mortality rate
2,3,7,8,13.
Ileosigmoid Knotting in Pregnancy
The obvious displacement of the bowel is a predisposing risk
factor for ISK. Normal pregnancy complaints may cloud the clinical
picture. Additionally, efforts to avoid the radiological evaluation
may contribute to a diagnostic delay. The mortality rate is
high according to the normal population 2,3,7.
Conflict interest statement The authors declare that they have
no conflict of interest to the publication of this article.
)
)
)