A nine-day-old male child born of full term normal
delivery was brought with complains of bilious vomiting and constipation since
day three of his life. Vomitings were projectile and followed feed about 5 to
10 minutes later. His birth weight was 2.2 kilograms and he had passed meconium
normally.
On examination, his general condition was fair with
a pulse rate of 84 beats per minute. Per abdominal examination revealed fullness
in the epigastrium. Per rectal tube was passed as far as possible for upto 20
cm but nothing came out. By the history of bilious vomiting and the child having
passed stools for the first three days, the possibilities of hypertrophic pyloric
stenosis and duodenal atresia were ruled out respectively. The clinical diagnosis
of duodenal or small bowel obstruction from other causes like Ladd’s band, volvulus
duodenal diaphragm was then made.
Radiological evaluation:
Plain abdominal film showed no abnormality.
Patient was then refered for Ultrasound examination of the abdomen.
Fig 1
It showed twisted mesenteric vessels which were swirling
in a clockwise direction. On putting colour flow seen in both vessels and classical
"Whirlpool sign" was seen suggestive of midgut volvulus.
This was followed by contrast studies with Barium.
It showed D-J flexure with jejunal to be on the right side of the midline
Fig 2
A diagnosis of malrotation with volvulus causing the
obstruction was made.
The child was operated. There was malrotation with
D-J flexure on the right side. There were few adhesions with volvulus. Malrotation
and volvulus were corrected with elective appendicectomy.
Discussion
Rotational abnormality of the gut can be entirely
asymptomatic but in other cases the sequelae are catastrophic when Ladd’s band
or volvulus leads to obstruction. Failure of normal embryological bowel rotation
leaves the superior mesenteric vein (SMV) anterior and to the left of the superior
mesenteric artery (SMA) as opposed to its normal position to the right of the
artery. When volvulus occurs the entire gut twists or corkscrews around the
SMA and leads to vascular compromise. This may be complicated with necrosis,
perforation and gangrene.
The findings are quite variable on a plain abdominal radiograph. They can range
from a normal appearing abdomen through one suggesting a gastric outlet to one
suggesting small bowel obstruction. The ultimate picture depends on the degree
of volvulus (i.e. number of twists of the bowel ), duration of volvulus and
the small bowel involved.
Contrast studies with Barium confirm the level of obstruction which is usually
towards the third and fourth parts of duodenum, and often demonstrates the compressing
band. The small bowel may show characteristic "corkscrew" or "spiral"
pattern.
Ultrasound examination plays an important role in determining the relation of
SMA and SMV. It also shows the obstructed duodenal C-loop with vigorous peristalsis.
When colour is used, the twisted mesenteric vessels are seen swirling in a clockwise
direction producing the "Whirlpool sign" as seen in this case. This
finding is highly specific for midgut volvulus.
CT or MR scanning are proposed as rapid non-invasive and specific alternatives.
The characteristic findings include the "whirl" sign of rotated mesentry
and "peacock tail" sign due to torsion of the bowel around the mesenteric
axis. CT also gives information about bowel ischaemia by the presence of bowel
wall thickening, intramural air and intraperitoneal fluid. On angiography, spiraling
of the branches of the twisted SMA produces a "barber pole" appearance
that suggests the diagnosis.
Although the Whirlpool sign on USG is highly specific for midgut volvulus, the
exact level of obstruction cannot be reliably determined on USG. Also, it is
sometimes difficult to assess the SMA and SMV on USG due to bowel gas. So USG
has not yet replaced Barium studies as far as malrotation with midgut volvulus
is concerned. However given the need for a rapid pre-operative diagnosis, CT
can be used along with USG as rapid non-invasive and specific alternative. CT
also gives idea about viability of the bowel loops.
In conclusion, in every child undergoing USG for the evaluation of vomiting,
SMA and SMV should carefully be assessed, preferably with colour. This will
hasten the process of the diagnosis and management, and prevent complications
like ischaemia, perforation or gangrene.
